// turn.js - 翻页库
(function ($) {
  'use strict';

  var has3d,

    vendor = '',

    PI = Math.PI,

    A90 = PI / 2,

    isTouch = 'ontouchstart' in window,

    events = (isTouch) ? { start: 'touchstart', move: 'touchmove', end: 'touchend' }
      : { start: 'mousedown', move: 'mousemove', end: 'mouseup' },

    // Contansts used for each corner
    // tl * tr
    // *     *
    // bl * br

    corners = {
      backward: ['bl', 'tl'],
      forward: ['br', 'tr'],
      all: ['tl', 'bl', 'tr', 'br']
    },

    displays = ['single', 'double'],

    // Default options

    turnOptions = {

      // First page

      page: 1,

      // Enables gradients

      gradients: true,

      // Duration of transition in milliseconds

      duration: 600,

      // Enables hardware acceleration

      acceleration: true,

      // Display

      display: 'double',

      // Events

      when: null
    },

    flipOptions = {

      // Back page

      folding: null,

      // Corners
      // backward: Activates both tl and bl corners
      // forward: Activates both tr and br corners
      // all: Activates all the corners

      corners: 'forward',

      // Size of the active zone of each corner

      cornerSize: 50,

      // Enables gradients

      gradients: true,

      // Duration of transition in milliseconds

      duration: 600,

      // Enables hardware acceleration

      acceleration: true,

      // Enables non-corner area flipping

      enableNonCorner: false,

      // Maximum folding distance ratio for non-corner flipping (0.1 - 1.0)

      maxFoldingDistance: 2,

      // Minimum drag distance to trigger non-corner flip

      minDragDistance: 30
    },

    // Number of pages in the DOM, minimum value: 6

    pagesInDOM = 6,

    pagePosition = {
      0: { top: 0, left: 0, right: 'auto', bottom: 'auto' },
      1: { top: 0, right: 0, left: 'auto', bottom: 'auto' }
    },

    // Gets basic attributes for a layer

    divAtt = function (top, left, zIndex, overf) {
      return {
        'css': {
          position: 'absolute',
          top: top,
          left: left,
          'overflow': overf || 'hidden',
          'z-index': zIndex || 'auto'
        }
      };
    },

    // Gets a 2D point from a bezier curve of four points

    bezier = function (p1, p2, p3, p4, t) {
      var mum1 = 1 - t,
        mum13 = mum1 * mum1 * mum1,
        mu3 = t * t * t;

      return point2D(Math.round(mum13 * p1.x + 3 * t * mum1 * mum1 * p2.x + 3 * t * t * mum1 * p3.x + mu3 * p4.x),
        Math.round(mum13 * p1.y + 3 * t * mum1 * mum1 * p2.y + 3 * t * t * mum1 * p3.y + mu3 * p4.y));
    },

    // Converts an angle from degrees to radians

    rad = function (degrees) {
      return degrees / 180 * PI;
    },

    // Converts an angle from radians to degrees

    deg = function (radians) {
      return radians / PI * 180;
    },

    // Gets a 2D point

    point2D = function (x, y) {
      return { x: x, y: y };
    },

    // Returns the traslate value

    translate = function (x, y, use3d) {
      return (has3d && use3d) ? ' translate3d(' + x + 'px,' + y + 'px, 0px) ' : ' translate(' + x + 'px, ' + y + 'px) ';
    },

    // Returns the rotation value

    rotate = function (degrees) {
      return ' rotate(' + degrees + 'deg) ';
    },

    // Checks if a property belongs to an object

    has = function (property, object) {
      return Object.prototype.hasOwnProperty.call(object, property);
    },

    // Gets the CSS3 vendor prefix

    getPrefix = function () {
      var vendorPrefixes = ['Moz', 'Webkit', 'Khtml', 'O', 'ms'],
        len = vendorPrefixes.length,
        vendor = '';

      while (len--)
        if ((vendorPrefixes[len] + 'Transform') in document.body.style)
          vendor = '-' + vendorPrefixes[len].toLowerCase() + '-';

      return vendor;
    },

    // Adds gradients

    gradient = function (obj, p0, p1, colors, numColors) {

      var j, cols = [];

      if (vendor == '-webkit-') {

        for (j = 0; j < numColors; j++)
          cols.push('color-stop(' + colors[j][0] + ', ' + colors[j][1] + ')');

        obj.css({ 'background-image': '-webkit-gradient(linear, ' + p0.x + '% ' + p0.y + '%,  ' + p1.x + '% ' + p1.y + '%, ' + cols.join(',') + ' )' });

      } else {

        // This procedure makes the gradients for non-webkit browsers
        // It will be reduced to one unique way for gradients in next versions

        p0 = { x: p0.x / 100 * obj.width(), y: p0.y / 100 * obj.height() };
        p1 = { x: p1.x / 100 * obj.width(), y: p1.y / 100 * obj.height() };

        var dx = p1.x - p0.x,
          dy = p1.y - p0.y,
          angle = Math.atan2(dy, dx),
          angle2 = angle - Math.PI / 2,
          diagonal = Math.abs(obj.width() * Math.sin(angle2)) + Math.abs(obj.height() * Math.cos(angle2)),
          gradientDiagonal = Math.sqrt(dy * dy + dx * dx),
          corner = point2D((p1.x < p0.x) ? obj.width() : 0, (p1.y < p0.y) ? obj.height() : 0),
          slope = Math.tan(angle),
          inverse = -1 / slope,
          x = (inverse * corner.x - corner.y - slope * p0.x + p0.y) / (inverse - slope),
          c = { x: x, y: inverse * x - inverse * corner.x + corner.y },
          segA = (Math.sqrt(Math.pow(c.x - p0.x, 2) + Math.pow(c.y - p0.y, 2)));

        for (j = 0; j < numColors; j++)
          cols.push(' ' + colors[j][1] + ' ' + ((segA + gradientDiagonal * colors[j][0]) * 100 / diagonal) + '%');

        obj.css({ 'background-image': vendor + 'linear-gradient(' + (-angle) + 'rad,' + cols.join(',') + ')' });
      }
    },

    turnMethods = {

      // Singleton constructor
      // $('#selector').turn([options]);

      init: function (opts) {

        // Define constants
        if (has3d === undefined) {
          has3d = 'WebKitCSSMatrix' in window || 'MozPerspective' in document.body.style;
          vendor = getPrefix();
        }

        var i, data = this.data(), ch = this.children();

        opts = $.extend({ width: this.width(), height: this.height() }, turnOptions, opts);
        data.opts = opts;
        data.pageObjs = {};
        data.pages = {};
        data.pageWrap = {};
        data.pagePlace = {};
        data.pageMv = [];
        data.totalPages = opts.pages || 0;

        if (opts.when)
          for (i in opts.when)
            if (has(i, opts.when))
              this.bind(i, opts.when[i]);


        this.css({ position: 'relative', width: opts.width, height: opts.height });

        this.turn('display', opts.display);

        if (has3d && !isTouch && opts.acceleration)
          this.transform(translate(0, 0, true));

        for (i = 0; i < ch.length; i++)
          this.turn('addPage', ch[i], i + 1);

        this.turn('page', opts.page);

        // allow setting active corners as an option
        corners = $.extend({}, corners, opts.corners);

        // Event listeners
        $(this).bind(events.start, function (e) {
          for (var page in data.pages) {
            if (has(page, data.pages) && flipMethods._eventStart.call(data.pages[page], e) === false) {
              if (isTouch)
                return true;
              return false;
            }
          }
        });

        $(document).bind(events.move, function (e) {
          for (var page in data.pages)
            if (has(page, data.pages))
              flipMethods._eventMove.call(data.pages[page], e);
        }).
          bind(events.end, function (e) {
            for (var page in data.pages)
              if (has(page, data.pages))
                flipMethods._eventEnd.call(data.pages[page], e);

          });

        data.done = true;
        return this;
      },

      // Adds a page from external data
      addPage: function (element, page) {

        var incPages = false,
          data = this.data(),
          lastPage = data.totalPages + 1;

        if (page) {
          if (page == lastPage) {
            page = lastPage;
            incPages = true;
          } else if (page > lastPage)
            throw new Error('It is impossible to add the page "' + page + '", the maximum value is: "' + lastPage + '"');

        } else {
          page = lastPage;
          incPages = true;
        }

        if (page >= 1 && page <= lastPage) {

          // Stop animations
          if (data.done) this.turn('stop');

          // Move pages if it's necessary
          if (page in data.pageObjs)
            turnMethods._movePages.call(this, page, 1);

          // Update number of pages
          if (incPages)
            data.totalPages = lastPage;

          // Add element
          data.pageObjs[page] = $(element).addClass('turn-page p' + page);

          // Add page
          turnMethods._addPage.call(this, page);

          // Update view
          if (data.done)
            this.turn('update');

          turnMethods._removeFromDOM.call(this);
        }

        return this;
      },

      // Adds a page from internal data

      _addPage: function (page) {

        var data = this.data(),
          element = data.pageObjs[page];

        if (element)
          if (turnMethods._necessPage.call(this, page)) {

            if (!data.pageWrap[page]) {

              var pageWidth = (data.display == 'double') ? this.width() / 2 : this.width(),
                pageHeight = this.height();

              element.css({ width: pageWidth, height: pageHeight });

              // Place
              data.pagePlace[page] = page;

              // Wrapper
              data.pageWrap[page] = $('<div/>', {
                'class': 'turn-page-wrapper',
                page: page,
                css: {
                  position: 'absolute',
                  overflow: 'hidden',
                  width: pageWidth,
                  height: pageHeight
                }
              }).
                css(pagePosition[(data.display == 'double') ? page % 2 : 0]);

              // Append to this
              this.append(data.pageWrap[page]);

              // Move data.pageObjs[page] (element) to wrapper
              data.pageWrap[page].prepend(data.pageObjs[page]);
            }

            // If the page is in the current view, create the flip effect
            if (!page || turnMethods._setPageLoc.call(this, page) == 1)
              turnMethods._makeFlip.call(this, page);

          } else {

            // Place
            data.pagePlace[page] = 0;

            // Remove element from the DOM
            if (data.pageObjs[page])
              data.pageObjs[page].remove();

          }

      },

      // Checks if a page is in memory

      hasPage: function (page) {

        return page in this.data().pageObjs;

      },

      // Prepares the flip effect for a page
      _makeFlip: function (page) {

        var data = this.data();

        if (!data.pages[page] && data.pagePlace[page] == page) {

          var single = data.display == 'single',
            even = page % 2;

          data.pages[page] = data.pageObjs[page].
            css({ width: (single) ? this.width() : this.width() / 2, height: this.height() }).
            flip({
              page: page,
              display: data.opts.display,
              next: (single && page === data.totalPages) ? page - 1 : ((even || single) ? page + 1 : page - 1),
              turn: this,
              duration: data.opts.duration,
              acceleration: data.opts.acceleration,
              corners: (single) ? 'all' : ((even) ? 'forward' : 'backward'),
              backGradient: data.opts.gradients,
              frontGradient: data.opts.gradients
            }).
            flip('disable', data.disabled).
            bind('pressed', turnMethods._pressed).
            bind('released', turnMethods._released).
            bind('start', turnMethods._start).
            bind('end', turnMethods._end).
            bind('flip', turnMethods._flip);
        }
        return data.pages[page];
      },

      // Makes pages within a range

      _makeRange: function () {

        var page,
          data = this.data(),
          range = this.turn('range');

        for (page = range[0]; page <= range[1]; page++)
          turnMethods._addPage.call(this, page);

      },

      // Returns a range of `pagesInDOM` pages that should be in the DOM
      // Example:
      // - page of the current view, return true
      // * page is in the range, return true
      // 0 page is not in the range, return false
      //
      // 1 2-3 4-5 6-7 8-9 10-11 12-13
      //    **  **  --   **  **

      range: function (page) {

        var remainingPages, left, right,
          data = this.data();
        page = page || data.tpage || data.page;
        var view = turnMethods._view.call(this, page);

        if (page < 1 || page > data.totalPages)
          throw new Error('"' + page + '" is not a page for range');

        view[1] = view[1] || view[0];

        if (view[0] >= 1 && view[1] <= data.totalPages) {

          remainingPages = Math.floor((pagesInDOM - 2) / 2);

          if (data.totalPages - view[1] > view[0]) {
            left = Math.min(view[0] - 1, remainingPages);
            right = 2 * remainingPages - left;
          } else {
            right = Math.min(data.totalPages - view[1], remainingPages);
            left = 2 * remainingPages - right;
          }

        } else {
          left = pagesInDOM - 1;
          right = pagesInDOM - 1;
        }

        return [Math.max(1, view[0] - left), Math.min(data.totalPages, view[1] + right)];

      },

      // Detects if a page is within the range of `pagesInDOM` from the current view

      _necessPage: function (page) {

        if (page === 0)
          return true;

        var range = this.turn('range');

        return page >= range[0] && page <= range[1];

      },

      // Releases memory by removing pages from the DOM

      _removeFromDOM: function () {

        var page, data = this.data();

        for (page in data.pageWrap)
          if (has(page, data.pageWrap) && !turnMethods._necessPage.call(this, page))
            turnMethods._removePageFromDOM.call(this, page);


      },

      // Removes a page from DOM and its internal references

      _removePageFromDOM: function (page) {

        var data = this.data();

        if (data.pages[page]) {
          var dd = data.pages[page].data();
          if (dd.f && dd.f.fwrapper)
            dd.f.fwrapper.remove();
          data.pages[page].remove();
          delete data.pages[page];
        }

        if (data.pageObjs[page])
          data.pageObjs[page].remove();

        if (data.pageWrap[page]) {
          data.pageWrap[page].remove();
          delete data.pageWrap[page];
        }

        delete data.pagePlace[page];

      },

      // Removes a page

      removePage: function (page) {

        var data = this.data();

        if (data.pageObjs[page]) {
          // Stop animations
          this.turn('stop');

          // Remove `page`
          turnMethods._removePageFromDOM.call(this, page);
          delete data.pageObjs[page];

          // Move the pages behind `page`
          turnMethods._movePages.call(this, page, -1);

          // Resize the size of this magazine
          data.totalPages = data.totalPages - 1;
          turnMethods._makeRange.call(this);

          // Check the current view
          if (data.page > data.totalPages)
            this.turn('page', data.totalPages);
        }

        return this;

      },

      // Moves pages

      _movePages: function (from, change) {

        var page,
          data = this.data(),
          single = data.display == 'single',
          move = function (page) {

            var next = page + change,
              odd = next % 2;

            if (data.pageObjs[page])
              data.pageObjs[next] = data.pageObjs[page].removeClass('page' + page).addClass('page' + next);

            if (data.pagePlace[page] && data.pageWrap[page]) {
              data.pagePlace[next] = next;
              data.pageWrap[next] = data.pageWrap[page].css(pagePosition[(single) ? 0 : odd]).attr('page', next);

              if (data.pages[page])
                data.pages[next] = data.pages[page].flip('options', {
                  page: next,
                  next: (single || odd) ? next + 1 : next - 1,
                  corners: (single) ? 'all' : ((odd) ? 'forward' : 'backward')
                });

              if (change) {
                delete data.pages[page];
                delete data.pagePlace[page];
                delete data.pageObjs[page];
                delete data.pageWrap[page];
                delete data.pageObjs[page];
              }
            }
          };

        if (change > 0)
          for (page = data.totalPages; page >= from; page--) move(page);
        else
          for (page = from; page <= data.totalPages; page++) move(page);

      },

      // Sets or Gets the display mode

      display: function (display) {

        var data = this.data(),
          currentDisplay = data.display;

        if (display) {

          if ($.inArray(display, displays) == -1)
            throw new Error('"' + display + '" is not a value for display');

          if (display == 'single') {
            if (!data.pageObjs[0]) {
              this.turn('stop').
                css({ 'overflow': 'hidden' });
              data.pageObjs[0] = $('<div />', { 'class': 'turn-page p-temporal' }).
                css({ width: this.width(), height: this.height() }).
                appendTo(this);
            }
          } else {
            if (data.pageObjs[0]) {
              this.turn('stop').
                css({ 'overflow': '' });
              data.pageObjs[0].remove();
              delete data.pageObjs[0];
            }
          }

          data.display = display;

          if (currentDisplay) {
            var size = this.turn('size');
            turnMethods._movePages.call(this, 1, 0);
            this.turn('size', size.width, size.height).
              turn('update');
          }

          return this;

        } else
          return currentDisplay;

      },

      // Detects if the pages are being animated

      animating: function () {

        return this.data().pageMv.length > 0;

      },

      // Disables and enables the effect

      disable: function (bool) {

        var page,
          data = this.data(),
          view = this.turn('view');

        data.disabled = bool === undefined || bool === true;

        for (page in data.pages)
          if (has(page, data.pages))
            data.pages[page].flip('disable', bool ? $.inArray(page, view) : false);

        return this;

      },

      // Gets and sets the size

      size: function (width, height) {

        if (width && height) {

          var data = this.data(), pageWidth = (data.display == 'double') ? width / 2 : width, page;

          this.css({ width: width, height: height });

          if (data.pageObjs[0])
            data.pageObjs[0].css({ width: pageWidth, height: height });

          for (page in data.pageWrap) {
            if (!has(page, data.pageWrap)) continue;
            data.pageObjs[page].css({ width: pageWidth, height: height });
            data.pageWrap[page].css({ width: pageWidth, height: height });
            if (data.pages[page])
              data.pages[page].css({ width: pageWidth, height: height });
          }

          this.turn('resize');

          return this;

        } else {

          return { width: this.width(), height: this.height() };

        }
      },

      // Resizes each page

      resize: function () {

        var page, data = this.data();

        if (data.pages[0]) {
          data.pageWrap[0].css({ left: -this.width() });
          data.pages[0].flip('resize', true);
        }

        for (page = 1; page <= data.totalPages; page++)
          if (data.pages[page])
            data.pages[page].flip('resize', true);


      },

      // Removes an animation from the cache

      _removeMv: function (page) {

        var i, data = this.data();

        for (i = 0; i < data.pageMv.length; i++)
          if (data.pageMv[i] == page) {
            data.pageMv.splice(i, 1);
            return true;
          }

        return false;

      },

      // Adds an animation to the cache

      _addMv: function (page) {

        var data = this.data();

        turnMethods._removeMv.call(this, page);
        data.pageMv.push(page);

      },

      // Gets indexes for a view

      _view: function (page) {

        var data = this.data();
        page = page || data.page;

        if (data.display == 'double')
          return (page % 2) ? [page - 1, page] : [page, page + 1];
        else
          return [page];

      },

      // Gets a view

      view: function (page) {

        var data = this.data(), view = turnMethods._view.call(this, page);

        return (data.display == 'double') ? [(view[0] > 0) ? view[0] : 0, (view[1] <= data.totalPages) ? view[1] : 0]
          : [(view[0] > 0 && view[0] <= data.totalPages) ? view[0] : 0];

      },

      // Stops animations

      stop: function (ok) {
        var i, opts, data = this.data(), pages = data.pageMv;

        data.pageMv = [];

        if (data.tpage) {
          data.page = data.tpage;
          delete data['tpage'];
        }

        for (i in pages) {
          if (!has(i, pages)) continue;
          opts = data.pages[pages[i]].data().f.opts;
          flipMethods._moveFoldingPage.call(data.pages[pages[i]], null);
          data.pages[pages[i]].flip('hideFoldedPage');
          data.pagePlace[opts.next] = opts.next;

          if (opts.force) {
            opts.next = (opts.page % 2 === 0) ? opts.page - 1 : opts.page + 1;
            delete opts['force'];
          }

        }

        this.turn('update');

        return this;
      },

      // Gets and sets the number of pages

      pages: function (pages) {

        var data = this.data();

        if (pages) {
          if (pages < data.totalPages) {

            for (var page = pages + 1; page <= data.totalPages; page++)
              this.turn('removePage', page);

            if (this.turn('page') > pages)
              this.turn('page', pages);
          }

          data.totalPages = pages;

          return this;
        } else
          return data.totalPages;

      },

      // Sets a page without effect

      _fitPage: function (page, ok) {

        var data = this.data(), newView = this.turn('view', page);

        if (data.page != page) {
          this.trigger('turning', [page, newView]);
          if ($.inArray(1, newView) != -1) this.trigger('first');
          if ($.inArray(data.totalPages, newView) != -1) this.trigger('last');
        }

        if (!data.pageObjs[page])
          return;

        data.tpage = page;

        this.turn('stop', ok);
        turnMethods._removeFromDOM.call(this);
        turnMethods._makeRange.call(this);
        this.trigger('turned', [page, newView]);

      },

      // Turns to a page

      _turnPage: function (page) {

        var current, next,
          data = this.data(),
          view = this.turn('view'),
          newView = this.turn('view', page);

        if (data.page != page) {
          this.trigger('turning', [page, newView]);
          if ($.inArray(1, newView) != -1) this.trigger('first');
          if ($.inArray(data.totalPages, newView) != -1) this.trigger('last');
        }

        if (!data.pageObjs[page])
          return;

        data.tpage = page;

        this.turn('stop');

        turnMethods._makeRange.call(this);

        if (data.display == 'single') {
          current = view[0];
          next = newView[0];
        } else if (view[1] && page > view[1]) {
          current = view[1];
          next = newView[0];
        } else if (view[0] && page < view[0]) {
          current = view[0];
          next = newView[1];
        }

        if (data.pages[current]) {

          var opts = data.pages[current].data().f.opts;
          data.tpage = next;

          if (opts.next != next) {
            opts.next = next;
            data.pagePlace[next] = opts.page;
            opts.force = true;
          }

          if (data.display == 'single')
            data.pages[current].flip('turnPage', (newView[0] > view[0]) ? 'br' : 'bl');
          else
            data.pages[current].flip('turnPage');
        }

      },

      // Gets and sets a page

      page: function (page) {

        page = parseInt(page, 10);
        var data = this.data();

        if (page > 0 && page <= data.totalPages) {
          if (!data.done || $.inArray(page, this.turn('view')) != -1)
            turnMethods._fitPage.call(this, page);
          else
            turnMethods._turnPage.call(this, page);

          return this;

        } else
          return data.page;

      },

      // Turns to the next view

      next: function () {

        var data = this.data();
        return this.turn('page', turnMethods._view.call(this, data.page).pop() + 1);

      },

      // Turns to the previous view

      previous: function () {

        var data = this.data();
        return this.turn('page', turnMethods._view.call(this, data.page).shift() - 1);

      },

      // Adds a motion to the internal list

      _addMotionPage: function () {

        var opts = $(this).data().f.opts,
          turn = opts.turn,
          dd = turn.data();

        opts.pageMv = opts.page;
        turnMethods._addMv.call(turn, opts.pageMv);
        dd.pagePlace[opts.next] = opts.page;
        turn.turn('update');

      },

      // This event is called in context of flip

      _start: function (e, opts, corner) {

        var data = opts.turn.data(),
          event = $.Event('start');

        e.stopPropagation();

        opts.turn.trigger(event, [opts, corner]);

        if (event.isDefaultPrevented()) {
          e.preventDefault();
          return;
        }

        if (data.display == 'single') {

          var left = corner.charAt(1) == 'l';
          if ((opts.page == 1 && left) || (opts.page == data.totalPages && !left))
            e.preventDefault();
          else {
            if (left) {
              opts.next = (opts.next < opts.page) ? opts.next : opts.page - 1;
              opts.force = true;
            } else
              opts.next = (opts.next > opts.page) ? opts.next : opts.page + 1;
          }

        }

        turnMethods._addMotionPage.call(this);
      },

      // This event is called in context of flip

      _end: function (e, turned) {

        var that = $(this),
          data = that.data().f,
          opts = data.opts,
          turn = opts.turn,
          dd = turn.data();

        e.stopPropagation();

        if (turned || dd.tpage) {

          if (dd.tpage == opts.next || dd.tpage == opts.page) {
            delete dd['tpage'];
            turnMethods._fitPage.call(turn, dd.tpage || opts.next, true);
          }

        } else {
          turnMethods._removeMv.call(turn, opts.pageMv);
          turn.turn('update');
        }

      },

      // This event is called in context of flip

      _pressed: function () {

        var page,
          that = $(this),
          data = that.data().f,
          turn = data.opts.turn,
          pages = turn.data().pages;

        for (page in pages)
          if (page != data.opts.page)
            pages[page].flip('disable', true);

        return data.time = new Date().getTime();

      },

      // This event is called in context of flip

      _released: function (e, point) {

        var that = $(this),
          data = that.data().f;

        e.stopPropagation();

        if ((new Date().getTime()) - data.time < 400 || point.x < 0 || point.x > $(this).width()) {
          e.preventDefault();
          data.opts.turn.data().tpage = data.opts.next;
          data.opts.turn.turn('update');
          $(that).flip('turnPage');
        }

      },

      // This event is called in context of flip

      _flip: function () {

        var opts = $(this).data().f.opts;

        opts.turn.trigger('turn', [opts.next]);

      },

      // Calculate the z-index value for pages during the animation

      calculateZ: function (mv) {

        var i, page, nextPage, placePage, dpage,
          that = this,
          data = this.data(),
          view = this.turn('view'),
          currentPage = view[0] || view[1],
          r = { pageZ: {}, partZ: {}, pageV: {} },

          addView = function (page) {
            var view = that.turn('view', page);
            if (view[0]) r.pageV[view[0]] = true;
            if (view[1]) r.pageV[view[1]] = true;
          };

        for (i = 0; i < mv.length; i++) {
          page = mv[i];
          nextPage = data.pages[page].data().f.opts.next;
          placePage = data.pagePlace[page];
          addView(page);
          addView(nextPage);
          dpage = (data.pagePlace[nextPage] == nextPage) ? nextPage : page;
          r.pageZ[dpage] = data.totalPages - Math.abs(currentPage - dpage);
          r.partZ[placePage] = data.totalPages * 2 + Math.abs(currentPage - dpage);
        }

        return r;
      },

      // Updates the z-index and display property of every page

      update: function () {

        var page,
          data = this.data();

        if (data.pageMv.length && data.pageMv[0] !== 0) {

          // Update motion

          var apage,
            pos = this.turn('calculateZ', data.pageMv),
            view = this.turn('view', data.tpage);

          if (data.pagePlace[view[0]] == view[0]) apage = view[0];
          else if (data.pagePlace[view[1]] == view[1]) apage = view[1];

          for (page in data.pageWrap) {

            if (!has(page, data.pageWrap)) continue;

            data.pageWrap[page].css({ display: (pos.pageV[page]) ? '' : 'none', 'z-index': pos.pageZ[page] || 0 });

            if (data.pages[page]) {
              data.pages[page].flip('z', pos.partZ[page] || null);

              if (pos.pageV[page])
                data.pages[page].flip('resize');

              if (data.tpage)
                data.pages[page].flip('disable', true); // data.disabled || page!=apage
            }
          }

        } else {

          // Update static pages

          for (page in data.pageWrap) {
            if (!has(page, data.pageWrap)) continue;
            var pageLocation = turnMethods._setPageLoc.call(this, page);
            if (data.pages[page])
              data.pages[page].flip('disable', data.disabled || pageLocation != 1).flip('z', null);
          }
        }
      },

      // Sets the z-index and display property of a page
      // It depends on the current view

      _setPageLoc: function (page) {

        var data = this.data(),
          view = this.turn('view');

        if (page == view[0] || page == view[1]) {
          data.pageWrap[page].css({ 'z-index': data.totalPages, display: '' });
          return 1;
        } else if ((data.display == 'single' && page == view[0] + 1) || (data.display == 'double' && page == view[0] - 2 || page == view[1] + 2)) {
          data.pageWrap[page].css({ 'z-index': data.totalPages - 1, display: '' });
          return 2;
        } else {
          data.pageWrap[page].css({ 'z-index': 0, display: 'none' });
          return 0;
        }
      }
    },

    // Methods and properties for the flip page effect

    flipMethods = {

      // Constructor

      init: function (opts) {

        if (opts.gradients) {
          opts.frontGradient = true;
          opts.backGradient = true;
        }

        this.data({ f: {} });
        this.flip('options', opts);

        flipMethods._addPageWrapper.call(this);

        return this;
      },

      setData: function (d) {

        var data = this.data();

        data.f = $.extend(data.f, d);

        return this;
      },

      options: function (opts) {

        var data = this.data().f;

        if (opts) {
          flipMethods.setData.call(this, { opts: $.extend({}, data.opts || flipOptions, opts) });
          return this;
        } else
          return data.opts;

      },

      z: function (z) {

        var data = this.data().f;
        data.opts['z-index'] = z;
        data.fwrapper.css({ 'z-index': z || parseInt(data.parent.css('z-index'), 10) || 0 });

        return this;
      },

      _cAllowed: function () {

        return corners[this.data().f.opts.corners] || this.data().f.opts.corners;

      },

      // 检测非corner区域翻页
      _nonCornerActivated: function (e) {
        if (e.originalEvent === undefined) {
          return false;
        }

        var data = this.data().f;

        // 检查数据是否已初始化
        if (!data || !data.opts) {
          return false;
        }

        // 检查是否启用非corner翻页
        if (!data.opts.enableNonCorner) {
          return false;
        }

        e = (isTouch) ? e.originalEvent.touches : [e];

        var pos = data.parent.offset(),
          width = this.width(),
          height = this.height(),
          point = { x: Math.max(0, e[0].pageX - pos.left), y: Math.max(0, e[0].pageY - pos.top) },
          csz = data.opts.cornerSize || 50,
          allowedCorners = flipMethods._cAllowed.call(this),
          turnData = data.opts.turn ? data.opts.turn.data() : null;

        if (point.x <= 0 || point.y <= 0 || point.x >= width || point.y >= height) return false;

        // 检查是否在corner区域（如果在corner区域，则不处理）
        var inCorner = false;
        if (point.y < csz) inCorner = true;
        else if (point.y >= height - csz) inCorner = true;
        if (inCorner && (point.x <= csz || point.x >= width - csz)) return false;

        // 非corner区域翻页逻辑
        var virtualCorner = flipMethods._calculateVirtualCorner.call(this, point, allowedCorners, turnData);

        return virtualCorner;
      },

      // 改进的虚拟corner计算逻辑 - 实现新的翻页逻辑
      _calculateVirtualCorner: function (point, allowedCorners, turnData) {
        var width = this.width(),
          height = this.height(),
          data = this.data().f,
          virtualCorner = null;

        // 双页模式逻辑
        if (turnData && turnData.display === 'double') {
          // 获取当前页面在双页视图中的位置
          var isLeftPage = data.opts.page % 2 === 0;

          if (isLeftPage) {
            // 左页
            virtualCorner = (point.y < height / 2) ? 'tl' : 'bl';
          } else {
            // 右页
            virtualCorner = (point.y < height / 2) ? 'tr' : 'br';
          }
        } else {
          // 单页模式
          var centerX = width / 2;
          var centerY = height / 2;

          if (point.x < centerX) {
            // 左半区
            virtualCorner = (point.y < centerY) ? 'tl' : 'bl';
          } else {
            // 右半区
            virtualCorner = (point.y < centerY) ? 'tr' : 'br';
          }
        }

        // 检查计算出的corner是否被允许
        if (virtualCorner && $.inArray(virtualCorner, allowedCorners) !== -1) {
          return {
            x: point.x,
            y: point.y,
            corner: virtualCorner,
            originalPoint: { x: point.x, y: point.y },
            isVirtual: true,
            // 添加拖动起始信息，用于改进拖动体验
            dragStartX: point.x,
            dragStartY: point.y,
            // 添加区域信息，用于判断是否应该显示折叠页动画
            dragArea: turnData && turnData.display === 'double' ?
              (data.opts.page % 2 === 0 ? 'leftPage' : 'rightPage') :
              (point.x < width / 2 ? 'left' : 'right')
          };
        }

        return false;
      },

      // 改进的虚拟corner映射
      _mapVirtualToRealCorner: function (virtualPoint) {
        if (!virtualPoint.isVirtual) return virtualPoint;

        // 获取真实corner的位置
        var realCorner = flipMethods._c.call(this, virtualPoint.corner);

        return {
          corner: virtualPoint.corner,
          x: virtualPoint.x,
          y: virtualPoint.y,
          isVirtual: true,
          dragArea: virtualPoint.dragArea,
          originalPoint: virtualPoint.originalPoint,
          realCorner: realCorner,
          dragStartX: virtualPoint.dragStartX,
          dragStartY: virtualPoint.dragStartY
        };
      },

      _cornerActivated: function (e) {
        if (e.originalEvent === undefined) {
          return false;
        }

        e = (isTouch) ? e.originalEvent.touches : [e];
        var data = this.data().f,
          pos = data.parent.offset(),
          width = this.width(),
          height = this.height(),
          c = { x: Math.max(0, e[0].pageX - pos.left), y: Math.max(0, e[0].pageY - pos.top) },
          csz = data.opts.cornerSize,
          allowedCorners = flipMethods._cAllowed.call(this);

        if (c.x <= 0 || c.y <= 0 || c.x >= width || c.y >= height) return false;

        if (c.y < csz) c.corner = 't';
        else if (c.y >= height - csz) c.corner = 'b';
        else return false;

        if (c.x <= csz) c.corner += 'l';
        else if (c.x >= width - csz) c.corner += 'r';
        else return false;

        return ($.inArray(c.corner, allowedCorners) == -1) ? false : c;

      },

      // 统一的区域激活检测函数
      _areaActivated: function (e) {
        // 首先检测corner区域
        var cornerResult = flipMethods._cornerActivated.call(this, e);
        if (cornerResult) {
          return cornerResult;
        }

        // 如果不在corner区域，检测非corner区域
        var nonCornerResult = flipMethods._nonCornerActivated.call(this, e);
        if (nonCornerResult) {
          return flipMethods._mapVirtualToRealCorner.call(this, nonCornerResult);
        }

        return false;
      },

      _foldingPage: function (corner) {

        var opts = this.data().f.opts;

        if (opts.folding) return opts.folding;
        else if (opts.turn) {
          var data = opts.turn.data();
          if (data.display == 'single') {
            var backPage = (data.pageObjs[opts.next]) ? data.pageObjs[0] : null;

            if (backPage && !backPage.hasClass('turn-page-back-fixed')) {
              backPage.addClass('turn-page-back-fixed').css({
                'background-color': '#ffffff',
                'background': '#ffffff'
              });
            }
            return backPage;
          } else {
            return data.pageObjs[opts.next];
          }
        }

      },

      _backGradient: function () {

        var data = this.data().f,
          turn = data.opts.turn,
          gradient = data.opts.backGradient &&
            (!turn || turn.data().display == 'single' || (data.opts.page != 2 && data.opts.page != turn.data().totalPages - 1));


        if (gradient && !data.bshadow)
          data.bshadow = $('<div/>', divAtt(0, 0, 1)).
            css({ 'position': '', width: this.width(), height: this.height() }).
            appendTo(data.parent);

        return gradient;

      },

      resize: function (full) {

        var data = this.data().f,
          width = this.width(),
          height = this.height(),
          size = Math.round(Math.sqrt(Math.pow(width, 2) + Math.pow(height, 2)));

        if (full) {
          data.wrapper.css({ width: size, height: size });
          data.fwrapper.css({ width: size, height: size }).
            children(':first-child').
            css({ width: width, height: height });

          data.fpage.css({ width: height, height: width });

          if (data.opts.frontGradient)
            data.ashadow.css({ width: height, height: width });

          if (flipMethods._backGradient.call(this))
            data.bshadow.css({ width: width, height: height });
        }

        if (data.parent.is(':visible')) {
          data.fwrapper.css({
            top: data.parent.offset().top,
            left: data.parent.offset().left
          });

          if (data.opts.turn)
            data.fparent.css({ top: -data.opts.turn.offset().top, left: -data.opts.turn.offset().left });
        }

        this.flip('z', data.opts['z-index']);

      },

      // Prepares the page by adding a general wrapper and another objects

      _addPageWrapper: function () {

        var att,
          data = this.data().f,
          parent = this.parent();

        if (!data.wrapper) {

          var left = this.css('left'),
            top = this.css('top'),
            width = this.width(),
            height = this.height(),
            size = Math.round(Math.sqrt(Math.pow(width, 2) + Math.pow(height, 2)));

          data.parent = parent;
          data.fparent = (data.opts.turn) ? data.opts.turn.data().fparent : $('#turn-fwrappers');

          if (!data.fparent) {
            var fparent = $('<div/>', { css: { 'pointer-events': 'none' } }).hide();
            fparent.data().flips = 0;

            if (data.opts.turn) {
              fparent.css(divAtt(-data.opts.turn.offset().top, -data.opts.turn.offset().left, 'auto', 'visible').css).
                appendTo(data.opts.turn);

              data.opts.turn.data().fparent = fparent;
            } else {
              fparent.css(divAtt(0, 0, 'auto', 'visible').css).
                attr('id', 'turn-fwrappers').
                appendTo($('body'));
            }

            data.fparent = fparent;
          }

          this.css({ position: 'absolute', top: 0, left: 0, bottom: 'auto', right: 'auto' });

          data.wrapper = $('<div/>', divAtt(0, 0, this.css('z-index'))).
            appendTo(parent).
            prepend(this);

          data.fwrapper = $('<div/>', divAtt(parent.offset().top, parent.offset().left)).
            hide().
            appendTo(data.fparent);

          data.fpage = $('<div/>', { css: { cursor: 'default' } }).
            appendTo($('<div/>', divAtt(0, 0, 0, 'visible')).
              appendTo(data.fwrapper));

          if (data.opts.frontGradient)
            data.ashadow = $('<div/>', divAtt(0, 0, 1)).
              appendTo(data.fpage);

          // Save data

          flipMethods.setData.call(this, data);

          // Set size
          flipMethods.resize.call(this, true);
        }

      },

      // Takes a 2P point from the screen and applies the transformation

      _fold: function (point) {

        var that = this,
          a = 0,
          alpha = 0,
          beta,
          px,
          gradientEndPointA,
          gradientEndPointB,
          gradientStartV,
          gradientSize,
          gradientOpacity,
          mv = point2D(0, 0),
          df = point2D(0, 0),
          tr = point2D(0, 0),
          width = this.width(),
          height = this.height(),
          folding = flipMethods._foldingPage.call(this),
          tan = Math.tan(alpha),
          data = this.data().f,
          ac = data.opts.acceleration,
          h = data.wrapper.height(),
          o = flipMethods._c.call(this, point.corner),
          top = point.corner.substr(0, 1) == 't',
          left = point.corner.substr(1, 1) == 'l',

          compute = function () {
            var rel = point2D((o.x) ? o.x - point.x : point.x, (o.y) ? o.y - point.y : point.y),
              tan = (Math.atan2(rel.y, rel.x)),
              middle;

            alpha = A90 - tan;
            a = deg(alpha);
            middle = point2D((left) ? width - rel.x / 2 : point.x + rel.x / 2, rel.y / 2);

            var gamma = alpha - Math.atan2(middle.y, middle.x),
              distance = Math.max(0, Math.sin(gamma) * Math.sqrt(Math.pow(middle.x, 2) + Math.pow(middle.y, 2)));

            tr = point2D(distance * Math.sin(alpha), distance * Math.cos(alpha));

            if (alpha > A90) {

              tr.x = tr.x + Math.abs(tr.y * Math.tan(tan));
              tr.y = 0;

              if (Math.round(tr.x * Math.tan(PI - alpha)) < height) {

                point.y = Math.sqrt(Math.pow(height, 2) + 2 * middle.x * rel.x);
                if (top) point.y = height - point.y;
                return compute();

              }
            }

            if (alpha > A90) {
              var beta = PI - alpha, dd = h - height / Math.sin(beta);
              mv = point2D(Math.round(dd * Math.cos(beta)), Math.round(dd * Math.sin(beta)));
              if (left) mv.x = - mv.x;
              if (top) mv.y = - mv.y;
            }

            px = Math.round(tr.y / Math.tan(alpha) + tr.x);

            var side = width - px,
              sideX = side * Math.cos(alpha * 2),
              sideY = side * Math.sin(alpha * 2);
            df = point2D(Math.round((left ? side - sideX : px + sideX)), Math.round((top) ? sideY : height - sideY));


            // GRADIENTS

            gradientSize = side * Math.sin(alpha);
            var endingPoint = flipMethods._c2.call(that, point.corner),
              far = Math.sqrt(Math.pow(endingPoint.x - point.x, 2) + Math.pow(endingPoint.y - point.y, 2));

            gradientOpacity = (far < width) ? far / width : 1;

            if (data.opts.frontGradient) {

              gradientStartV = gradientSize > 100 ? (gradientSize - 100) / gradientSize : 0;
              gradientEndPointA = point2D(gradientSize * Math.sin(A90 - alpha) / height * 100, gradientSize * Math.cos(A90 - alpha) / width * 100);

              if (top) gradientEndPointA.y = 100 - gradientEndPointA.y;
              if (left) gradientEndPointA.x = 100 - gradientEndPointA.x;
            }

            if (flipMethods._backGradient.call(that)) {

              gradientEndPointB = point2D(gradientSize * Math.sin(alpha) / width * 100, gradientSize * Math.cos(alpha) / height * 100);
              if (!left) gradientEndPointB.x = 100 - gradientEndPointB.x;
              if (!top) gradientEndPointB.y = 100 - gradientEndPointB.y;
            }
            //

            tr.x = Math.round(tr.x);
            tr.y = Math.round(tr.y);

            return true;
          },

          transform = function (tr, c, x, a) {

            var f = ['0', 'auto'], mvW = (width - h) * x[0] / 100, mvH = (height - h) * x[1] / 100,
              v = { left: f[c[0]], top: f[c[1]], right: f[c[2]], bottom: f[c[3]] },
              aliasingFk = (a != 90 && a != -90) ? (left ? -1 : 1) : 0;

            x = x[0] + '% ' + x[1] + '%';

            that.css(v).transform(rotate(a) + translate(tr.x + aliasingFk, tr.y, ac), x);

            data.fpage.parent().css(v);
            data.wrapper.transform(translate(-tr.x + mvW - aliasingFk, -tr.y + mvH, ac) + rotate(-a), x);

            data.fwrapper.transform(translate(-tr.x + mv.x + mvW, -tr.y + mv.y + mvH, ac) + rotate(-a), x);
            data.fpage.parent().transform(rotate(a) + translate(tr.x + df.x - mv.x, tr.y + df.y - mv.y, ac), x);

            if (data.opts.frontGradient)
              gradient(data.ashadow,
                point2D(left ? 100 : 0, top ? 100 : 0),
                point2D(gradientEndPointA.x, gradientEndPointA.y),
                [[gradientStartV, 'rgba(0,0,0,0)'],
                [((1 - gradientStartV) * 0.8) + gradientStartV, 'rgba(0,0,0,' + (0.2 * gradientOpacity) + ')'],
                [1, 'rgba(255,255,255,' + (0.2 * gradientOpacity) + ')']],
                3,
                alpha);

            if (flipMethods._backGradient.call(that))
              gradient(data.bshadow,
                point2D(left ? 0 : 100, top ? 0 : 100),
                point2D(gradientEndPointB.x, gradientEndPointB.y),
                [[0.8, 'rgba(0,0,0,0)'],
                [1, 'rgba(0,0,0,' + (0.3 * gradientOpacity) + ')'],
                [1, 'rgba(0,0,0,0)']],
                3);

          };

        switch (point.corner) {
          case 'tl':
            // 放宽边界限制，允许向左上方超出
            point.x = Math.max(point.x, -width * 0.2);
            point.y = Math.max(point.y, -height * 0.2);
            compute();
            transform(tr, [1, 0, 0, 1], [100, 0], a);
            data.fpage.transform(translate(-height, -width, ac) + rotate(90 - a * 2), '100% 100%');
            folding.transform(rotate(90) + translate(0, -height, ac), '0% 0%');
            break;
          case 'tr':
            // 放宽边界限制，允许向右上方超出
            point.x = Math.min(point.x, width + width * 0.2);
            point.y = Math.max(point.y, -height * 0.2);
            compute();
            transform(point2D(-tr.x, tr.y), [0, 0, 0, 1], [0, 0], -a);
            data.fpage.transform(translate(0, -width, ac) + rotate(-90 + a * 2), '0% 100%');
            folding.transform(rotate(270) + translate(-width, 0, ac), '0% 0%');
            break;
          case 'bl':
            // 放宽边界限制，允许向左下方超出
            point.x = Math.max(point.x, -width * 0.2);
            point.y = Math.min(point.y, height + height * 0.2);
            compute();
            transform(point2D(tr.x, -tr.y), [1, 1, 0, 0], [100, 100], -a);
            data.fpage.transform(translate(-height, 0, ac) + rotate(-90 + a * 2), '100% 0%');
            folding.transform(rotate(270) + translate(-width, 0, ac), '0% 0%');
            break;
          case 'br':
            // 放宽边界限制，允许向右下方超出
            point.x = Math.min(point.x, width + width * 0.2);
            point.y = Math.min(point.y, height + height * 0.2);
            compute();
            transform(point2D(-tr.x, -tr.y), [0, 1, 1, 0], [0, 100], a);
            data.fpage.transform(rotate(90 - a * 2), '0% 0%');
            folding.transform(rotate(90) + translate(0, -height, ac), '0% 0%');

            break;
        }

        data.point = point;

      },

      _moveFoldingPage: function (bool) {

        var data = this.data().f,
          folding = flipMethods._foldingPage.call(this);

        if (folding) {
          if (bool) {
            if (!data.fpage.children()[data.ashadow ? '1' : '0']) {
              flipMethods.setData.call(this, { backParent: folding.parent() });
              data.fpage.prepend(folding);
            }
          } else {
            if (data.backParent)
              data.backParent.prepend(folding);

          }
        }

      },

      _showFoldedPage: function (c, animate) {

        var folding = flipMethods._foldingPage.call(this),
          dd = this.data(),
          data = dd.f;

        if (!data.point || data.point.corner != c.corner) {
          var event = $.Event('start');
          this.trigger(event, [data.opts, c.corner]);

          if (event.isDefaultPrevented())
            return false;
        }


        if (folding) {

          if (animate) {

            var that = this, point = (data.point && data.point.corner == c.corner) ? data.point : flipMethods._c.call(this, c.corner, 1);

            this.animatef({
              from: [point.x, point.y], to: [c.x, c.y], duration: 500, frame: function (v) {
                c.x = Math.round(v[0]);
                c.y = Math.round(v[1]);
                flipMethods._fold.call(that, c);
              }
            });

          } else {

            flipMethods._fold.call(this, c);
            if (dd.effect && !dd.effect.turning)
              this.animatef(false);

          }

          if (!data.fwrapper.is(':visible')) {
            data.fparent.show().data().flips++;
            flipMethods._moveFoldingPage.call(this, true);
            data.fwrapper.show();

            if (data.bshadow)
              data.bshadow.show();
          }

          return true;
        }

        return false;
      },

      hide: function () {

        var data = this.data().f,
          folding = flipMethods._foldingPage.call(this);

        if ((--data.fparent.data().flips) === 0)
          data.fparent.hide();

        this.css({ left: 0, top: 0, right: 'auto', bottom: 'auto' }).transform('', '0% 100%');

        data.wrapper.transform('', '0% 100%');

        data.fwrapper.hide();

        if (data.bshadow)
          data.bshadow.hide();

        folding.transform('', '0% 0%');

        return this;
      },

      hideFoldedPage: function (animate) {

        var data = this.data().f;
        var data = this.data().f;

        if (!data.point) return;

        var that = this,
          p1 = data.point,
          hide = function () {
            data.point = null;
            that.flip('hide');
            that.trigger('end', [false]);
          };

        if (animate) {
          var p4 = flipMethods._c.call(this, p1.corner),
            top = (p1.corner.substr(0, 1) == 't'),
            delta = (top) ? Math.min(0, p1.y - p4.y) / 2 : Math.max(0, p1.y - p4.y) / 2,
            p2 = point2D(p1.x, p1.y + delta),
            p3 = point2D(p4.x, p4.y - delta);

          this.animatef({
            from: 0,
            to: 1,
            frame: function (v) {
              var np = bezier(p1, p2, p3, p4, v);
              p1.x = np.x;
              p1.y = np.y;
              flipMethods._fold.call(that, p1);
            },
            complete: hide,
            duration: 800,
            hiding: true
          });

        } else {
          this.animatef(false);
          hide();
        }
      },

      turnPage: function (corner) {

        var that = this,
          data = this.data().f;

        corner = { corner: (data.corner) ? data.corner.corner : corner || flipMethods._cAllowed.call(this)[0] };

        var p1 = data.point || flipMethods._c.call(this, corner.corner, (data.opts.turn) ? data.opts.turn.data().opts.elevation : 0),
          p4 = flipMethods._c2.call(this, corner.corner);

        this.trigger('flip').
          animatef({
            from: 0,
            to: 1,
            frame: function (v) {
              var np = bezier(p1, p1, p4, p4, v);
              corner.x = np.x;
              corner.y = np.y;
              flipMethods._showFoldedPage.call(that, corner);
            },

            complete: function () {
              that.trigger('end', [true]);
            },
            duration: data.opts.duration,
            turning: true
          });

        data.corner = null;
      },

      moving: function () {

        return 'effect' in this.data();

      },

      isTurning: function () {

        return this.flip('moving') && this.data().effect.turning;

      },

      _eventStart: function (e) {
        var data = this.data().f;

        if (!data.disabled && !this.flip('isTurning')) {
          data.corner = flipMethods._areaActivated.call(this, e);
          if (data.corner && flipMethods._foldingPage.call(this, data.corner)) {
            // 设置预备状态，但不立即触发 pressed 事件
            data.prepareState = {
              corner: data.corner,
              startTime: new Date().getTime(),
              pressed: false
            };

            flipMethods._moveFoldingPage.call(this, true);

            // 只有在传统corner区域才立即触发 pressed 事件
            // 对于虚拟corner（非corner区域），等待拖动确认
            if (!data.corner.isVirtual) {
              this.trigger('pressed', [data.point]);
              data.prepareState.pressed = true;
            }

            return false;
          } else
            data.corner = null;
        }
      },

      _eventMove: function (e) {

        var data = this.data().f;
        if (!data.disabled) {
          e = (isTouch) ? e.originalEvent.touches : [e];

          if (data.corner) {
            let pos = data.parent.offset();
            let currentMouseX = e[0].pageX - pos.left;
            let currentMouseY = e[0].pageY - pos.top;

            // 检查是否是虚拟corner（非corner区域拖拽）
            if (data.corner.isVirtual) {
              // 计算拖动距离，提高效率，只使用
              let dragDistance = Math.abs(currentMouseX - data.corner.dragStartX);

              // 最小拖动距离阈值
              let minDragDistance = data.opts.minDragDistance || 30;
              if (dragDistance < minDragDistance) {
                // 拖动距离太小，不执行翻页效果
                return;
              }
              else {
                // 如果还没有触发 pressed 事件，现在触发
                if (data.prepareState && !data.prepareState.pressed) {
                  this.trigger('pressed', [data.point]);
                  data.prepareState.pressed = true;
                }

                // 单页特殊处理
                if (data.opts.display === 'single') {
                  // 判断滑动方向，判断在左右半区，同向滑动直接翻页不播放翻页特效。
                  let direction = currentMouseX - data.corner.dragStartX > 0 ? 'right' : 'left';

                  // 方向
                  if (direction === data.corner.dragArea) {
                    if (direction === 'right') {
                      // 向右翻页
                      // 设置翻页从左下角开始
                      data.corner.corner = 'bl';
                      this.turn('next');
                    } else {
                      // 向左翻页
                      // 设置翻页从右下角开始
                      data.corner.corner = 'br';
                      this.turn('previous');
                    }

                    // 清理操作
                    data.corner.isVirtual = false;
                    data.corner.dragStartX = 0;
                    data.corner.dragStartY = 0;
                    return;
                  }
                }
              }

              // 根据拖动轨迹计算真实的折叠点
              var foldPoint = flipMethods._calculateNonCornerFoldPoint.call(this,
                data.corner.corner, currentMouseX - data.corner.dragStartX, currentMouseY - data.corner.dragStartY,
                dragDistance, data.corner.realCorner);

              data.corner.x = foldPoint.x;
              data.corner.y = foldPoint.y;
            } else {
              // 传统corner拖拽，直接使用鼠标位置
              data.corner.x = currentMouseX;
              data.corner.y = currentMouseY;
            }

            flipMethods._showFoldedPage.call(this, data.corner);

          } else if (!this.data().effect && this.is(':visible')) { // roll over
            // 注释掉悬停效果，避免模糊，代价是鼠标悬停没有卷边效果，代价值得。
            /*
            var corner = flipMethods._areaActivated.call(this, e[0]);
            if (corner) {
              var origin = flipMethods._c.call(this, corner.corner, data.opts.cornerSize / 2);
              corner.x = origin.x;
              corner.y = origin.y;
              flipMethods._showFoldedPage.call(this, corner, true);
            }
            else
              flipMethods.hideFoldedPage.call(this, true);
            */
          }
        }
      },

      // 新增：根据拖动轨迹计算真实的折叠点
      _calculateNonCornerFoldPoint: function (corner, dragDeltaX, dragDeltaY, dragDistance, realCorner) {
        var data = this.data().f;
        var width = this.width();
        var height = this.height();
        var maxFoldingDistance = data.opts.maxFoldingDistance || 0.6;

        // 获取起点（拖动开始点）和终点（当前鼠标位置）
        var startX = data.corner.dragStartX;
        var startY = data.corner.dragStartY;
        var endX = startX + dragDeltaX;
        var endY = startY + dragDeltaY;

        // 获取参考corner的位置
        var referenceCorner = flipMethods._c.call(this, corner);

        // 计算拖动向量
        var dragVectorX = endX - startX;
        var dragVectorY = endY - startY;

        // 如果拖动距离太小，返回参考corner
        if (Math.abs(dragVectorX) < 5 && Math.abs(dragVectorY) < 5) {
          return {
            x: referenceCorner.x,
            y: referenceCorner.y
          };
        }

        // 计算拖动线段的中点
        var midX = (startX + endX) / 2;
        var midY = (startY + endY) / 2;

        // 计算从中点到参考corner的垂直向量
        // 如果拖动向量是(dx, dy)，那么垂直向量是(-dy, dx)或(dy, -dx)
        var perpX = -dragVectorY;
        var perpY = dragVectorX;

        // 归一化垂直向量
        var perpLength = Math.sqrt(perpX * perpX + perpY * perpY);
        if (perpLength > 0) {
          perpX = perpX / perpLength;
          perpY = perpY / perpLength;
        }

        // 计算从中点到参考corner的向量
        var toCornerX = referenceCorner.x - midX;
        var toCornerY = referenceCorner.y - midY;

        // 计算参考corner在垂直线上的投影点（折叠轴上的点）
        var projectionOnPerp = toCornerX * perpX + toCornerY * perpY;
        var axisPointX = midX + projectionOnPerp * perpX;
        var axisPointY = midY + projectionOnPerp * perpY;

        // 计算参考corner关于折叠轴的对称点
        var symmetricX = 2 * axisPointX - referenceCorner.x;
        var symmetricY = 2 * axisPointY - referenceCorner.y;

        // 计算折叠强度（基于拖动距离）
        var foldIntensity = Math.min(dragDistance / (Math.min(width, height) * 0.4), 1);

        // 应用最大折叠距离限制
        var maxDistance = Math.min(width, height) * maxFoldingDistance;
        var symmetricDistance = Math.sqrt(
          Math.pow(symmetricX - referenceCorner.x, 2) +
          Math.pow(symmetricY - referenceCorner.y, 2)
        );

        var foldX, foldY;
        if (symmetricDistance > maxDistance && symmetricDistance > 0) {
          // 限制折叠距离
          var scale = maxDistance / symmetricDistance;
          foldX = referenceCorner.x + (symmetricX - referenceCorner.x) * scale * foldIntensity;
          foldY = referenceCorner.y + (symmetricY - referenceCorner.y) * scale * foldIntensity;
        } else {
          // 应用折叠强度
          foldX = referenceCorner.x + (symmetricX - referenceCorner.x) * foldIntensity;
          foldY = referenceCorner.y + (symmetricY - referenceCorner.y) * foldIntensity;
        }

        // 放宽边界限制，允许超出边界以获得更自然的翻页效果
        // 根据corner类型应用宽松的边界限制
        switch (corner) {
          case 'tl':
            // 允许向左上方超出边界
            foldX = Math.max(foldX, -width * 0.3);
            foldY = Math.max(foldY, -height * 0.3);
            break;
          case 'tr':
            // 允许向右上方超出边界
            foldX = Math.min(foldX, width * 1.3);
            foldY = Math.max(foldY, -height * 0.3);
            break;
          case 'bl':
            // 允许向左下方超出边界
            foldX = Math.max(foldX, -width * 0.3);
            foldY = Math.min(foldY, height * 1.3);
            break;
          case 'br':
            // 允许向右下方超出边界
            foldX = Math.min(foldX, width * 1.3);
            foldY = Math.min(foldY, height * 1.3);
            break;
        }

        return {
          x: foldX,
          y: foldY
        };
      },

      disable: function (disable) {

        flipMethods.setData.call(this, { 'disabled': disable });
        return this;

      },

      _c: function (corner, opts) {

        opts = opts || 0;
        return ({
          tl: point2D(opts, opts),
          tr: point2D(this.width() - opts, opts),
          bl: point2D(opts, this.height() - opts),
          br: point2D(this.width() - opts, this.height() - opts)
        })[corner];

      },

      _c2: function (corner) {

        return {
          tl: point2D(this.width() * 2, 0),
          tr: point2D(-this.width(), 0),
          bl: point2D(this.width() * 2, this.height()),
          br: point2D(-this.width(), this.height())
        }[corner];
      },

      _eventEnd: function () {

        var data = this.data().f;

        if (!data.disabled) {
          // 如果存在 data.point，执行原有的清理逻辑
          if (data.point) {
            var event = $.Event('released');
            this.trigger(event, [data.point]);
            if (!event.isDefaultPrevented())
              flipMethods.hideFoldedPage.call(this, true);
          }

          // 无论是否存在 data.point，都要清理 corner 状态
          if (data.corner) {
            // 重新启用其他页面（撤销 _pressed 中的禁用操作）
            flipMethods._reEnableOtherPages.call(this);
          }
        }

        // 清理状态
        data.corner = null;
        if (data.prepareState) {
          delete data.prepareState;
        }

      },

      // 重新启用其他页面（撤销 _pressed 中的禁用操作）
      _reEnableOtherPages: function () {
        var data = this.data().f;

        if (data.opts.turn) {
          var turn = data.opts.turn,
            turnData = turn.data(),
            pages = turnData.pages;

          for (var page in pages) {
            if (page != data.opts.page && pages[page]) {
              pages[page].flip('disable', turnData.disabled || false);
            }
          }
        }
      }
    },

    cla = function (that, methods, args) {

      if (!args[0] || typeof (args[0]) == 'object')
        return methods.init.apply(that, args);
      else if (methods[args[0]] && args[0].toString().substr(0, 1) != '_')
        return methods[args[0]].apply(that, Array.prototype.slice.call(args, 1));
      else
        throw args[0] + ' is an invalid value';
    };

  $.extend($.fn, {

    flip: function (req, opts) {
      return cla(this, flipMethods, arguments);
    },

    turn: function (req) {
      return cla(this, turnMethods, arguments);
    },

    transform: function (transform, origin) {

      var properties = {};

      if (origin)
        properties[vendor + 'transform-origin'] = origin;

      properties[vendor + 'transform'] = transform;

      return this.css(properties);

    },

    animatef: function (point) {

      var data = this.data();

      if (data.effect)
        clearInterval(data.effect.handle);

      if (point) {

        if (!point.to.length) point.to = [point.to];
        if (!point.from.length) point.from = [point.from];
        if (!point.easing) point.easing = function (x, t, b, c, data) { return c * Math.sqrt(1 - (t = t / data - 1) * t) + b; };

        var j, diff = [],
          len = point.to.length,
          that = this,
          fps = point.fps || 30,
          time = - fps,
          f = function () {
            var j, v = [];
            time = Math.min(point.duration, time + fps);

            for (j = 0; j < len; j++)
              v.push(point.easing(1, time, point.from[j], diff[j], point.duration));

            point.frame((len == 1) ? v[0] : v);

            if (time == point.duration) {
              clearInterval(data.effect.handle);
              delete data['effect'];
              that.data(data);
              if (point.complete)
                point.complete();
            }
          };

        for (j = 0; j < len; j++)
          diff.push(point.to[j] - point.from[j]);

        data.effect = point;
        data.effect.handle = setInterval(f, fps);
        this.data(data);
        f();
      } else {
        delete data['effect'];
      }
    }
  });


  $.isTouch = isTouch;

})(jQuery);
