/*

    Copyright (c) Manuel Stofer 2013 - rtp.ch - RTP.PinchZoom.js

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.

*/


/*global jQuery, console, define, setTimeout, window*/
(function () {
    'use strict';
    var definePinchZoom = function ($) {

        /**
         * Pinch zoom using jQuery
         * @version 0.0.2
         * @author Manuel Stofer <mst@rtp.ch>
         * @param el
         * @param options
         * @constructor
         */
        var PinchZoom = function (el, options) {
                this.el = $(el);
                this.zoomFactor = 1;
                this.lastScale = 1;
                this.offset = {
                    x: 0,
                    y: 0
                };
                this.options = $.extend({}, this.defaults, options);
                this.setupMarkup();
                this.bindEvents();
                this.update();
                // default enable.
                this.enable();

            },
            sum = function (a, b) {
                return a + b;
            },
            isCloseTo = function (value, expected) {
                return value > expected - 0.01 && value < expected + 0.01;
            };

        PinchZoom.prototype = {

            defaults: {
                tapZoomFactor: 2,
                zoomOutFactor: 1.3,
                animationDuration: 300,
                maxZoom: 4,
                minZoom: 0.5,
                lockDragAxis: false,
                use2d: true,
                zoomStartEventName: 'pz_zoomstart',
                zoomEndEventName: 'pz_zoomend',
                dragStartEventName: 'pz_dragstart',
                dragEndEventName: 'pz_dragend',
                doubleTapEventName: 'pz_doubletap'
            },

            /**
             * Event handler for 'dragstart'
             * @param event
             */
            handleDragStart: function (event) {
                this.el.trigger(this.options.dragStartEventName);
                this.stopAnimation();
                this.lastDragPosition = false;
                this.hasInteraction = true;
                this.handleDrag(event);
            },

            /**
             * Event handler for 'drag'
             * @param event
             */
            handleDrag: function (event) {

                if (this.zoomFactor > 1.0) {
                    var touch = this.getTouches(event)[0];
                    this.drag(touch, this.lastDragPosition);
                    this.offset = this.sanitizeOffset(this.offset);
                    this.lastDragPosition = touch;
                }
            },

            handleDragEnd: function () {
                this.el.trigger(this.options.dragEndEventName);
                this.end();
            },

            /**
             * Event handler for 'zoomstart'
             * @param event
             */
            handleZoomStart: function (event) {
                this.el.trigger(this.options.zoomStartEventName);
                this.stopAnimation();
                this.lastScale = 1;
                this.nthZoom = 0;
                this.lastZoomCenter = false;
                this.hasInteraction = true;
            },

            /**
             * Event handler for 'zoom'
             * @param event
             */
            handleZoom: function (event, newScale) {

                // a relative scale factor is used
                var touchCenter = this.getTouchCenter(this.getTouches(event)),
                    scale = newScale / this.lastScale;
                this.lastScale = newScale;

                // the first touch events are thrown away since they are not precise
                this.nthZoom += 1;
                if (this.nthZoom > 3) {

                    this.scale(scale, touchCenter);
                    this.drag(touchCenter, this.lastZoomCenter);
                }
                this.lastZoomCenter = touchCenter;
            },

            handleZoomEnd: function () {
                this.el.trigger(this.options.zoomEndEventName);
                this.end();
            },

            /**
             * Event handler for 'doubletap'
             * @param event
             */
            handleDoubleTap: function (event) {
                var center = this.getTouches(event)[0],
                    zoomFactor = this.zoomFactor > 1 ? 1 : this.options.tapZoomFactor,
                    startZoomFactor = this.zoomFactor,
                    updateProgress = (function (progress) {
                        this.scaleTo(startZoomFactor + progress * (zoomFactor - startZoomFactor), center);
                    }).bind(this);

                if (this.hasInteraction) {
                    return;
                }
                if (startZoomFactor > zoomFactor) {
                    center = this.getCurrentZoomCenter();
                }

                this.animate(this.options.animationDuration, updateProgress, this.swing);
                this.el.trigger(this.options.doubleTapEventName);
            },

            /**
             * Max / min values for the offset
             * @param offset
             * @return {Object} the sanitized offset
             */
            sanitizeOffset: function (offset) {
                var maxX = (this.zoomFactor - 1) * this.getContainerX(),
                    maxY = (this.zoomFactor - 1) * this.getContainerY(),
                    maxOffsetX = Math.max(maxX, 0),
                    maxOffsetY = Math.max(maxY, 0),
                    minOffsetX = Math.min(maxX, 0),
                    minOffsetY = Math.min(maxY, 0);

                return {
                    x: Math.min(Math.max(offset.x, minOffsetX), maxOffsetX),
                    y: Math.min(Math.max(offset.y, minOffsetY), maxOffsetY)
                };
            },

            /**
             * Scale to a specific zoom factor (not relative)
             * @param zoomFactor
             * @param center
             */
            scaleTo: function (zoomFactor, center) {
                this.scale(zoomFactor / this.zoomFactor, center);
            },

            /**
             * Scales the element from specified center
             * @param scale
             * @param center
             */
            scale: function (scale, center) {
                scale = this.scaleZoomFactor(scale);
                this.addOffset({
                    x: (scale - 1) * (center.x + this.offset.x),
                    y: (scale - 1) * (center.y + this.offset.y)
                });
            },

            /**
             * Scales the zoom factor relative to current state
             * @param scale
             * @return the actual scale (can differ because of max min zoom factor)
             */
            scaleZoomFactor: function (scale) {
                var originalZoomFactor = this.zoomFactor;
                this.zoomFactor *= scale;
                this.zoomFactor = Math.min(this.options.maxZoom, Math.max(this.zoomFactor, this.options.minZoom));
                return this.zoomFactor / originalZoomFactor;
            },

            /**
             * Drags the element
             * @param center
             * @param lastCenter
             */
            drag: function (center, lastCenter) {
                if (lastCenter) {
                  if(this.options.lockDragAxis) {
                    // lock scroll to position that was changed the most
                    if(Math.abs(center.x - lastCenter.x) > Math.abs(center.y - lastCenter.y)) {
                      this.addOffset({
                        x: -(center.x - lastCenter.x),
                        y: 0
                      });
                    }
                    else {
                      this.addOffset({
                        y: -(center.y - lastCenter.y),
                        x: 0
                      });
                    }
                  }
                  else {
                    this.addOffset({
                      y: -(center.y - lastCenter.y),
                      x: -(center.x - lastCenter.x)
                    });
                  }
                }
            },

            /**
             * Calculates the touch center of multiple touches
             * @param touches
             * @return {Object}
             */
            getTouchCenter: function (touches) {
                return this.getVectorAvg(touches);
            },

            /**
             * Calculates the average of multiple vectors (x, y values)
             */
            getVectorAvg: function (vectors) {
                return {
                    x: vectors.map(function (v) { return v.x; }).reduce(sum) / vectors.length,
                    y: vectors.map(function (v) { return v.y; }).reduce(sum) / vectors.length
                };
            },

            /**
             * Adds an offset
             * @param offset the offset to add
             * @return return true when the offset change was accepted
             */
            addOffset: function (offset) {
                this.offset = {
                    x: this.offset.x + offset.x,
                    y: this.offset.y + offset.y
                };
            },

            sanitize: function () {
                if (this.zoomFactor < this.options.zoomOutFactor) {
                    this.zoomOutAnimation();
                } else if (this.isInsaneOffset(this.offset)) {
                    this.sanitizeOffsetAnimation();
                }
            },

            /**
             * Checks if the offset is ok with the current zoom factor
             * @param offset
             * @return {Boolean}
             */
            isInsaneOffset: function (offset) {
                var sanitizedOffset = this.sanitizeOffset(offset);
                return sanitizedOffset.x !== offset.x ||
                    sanitizedOffset.y !== offset.y;
            },

            /**
             * Creates an animation moving to a sane offset
             */
            sanitizeOffsetAnimation: function () {
                var targetOffset = this.sanitizeOffset(this.offset),
                    startOffset = {
                        x: this.offset.x,
                        y: this.offset.y
                    },
                    updateProgress = (function (progress) {
                        this.offset.x = startOffset.x + progress * (targetOffset.x - startOffset.x);
                        this.offset.y = startOffset.y + progress * (targetOffset.y - startOffset.y);
                        this.update();
                    }).bind(this);

                this.animate(
                    this.options.animationDuration,
                    updateProgress,
                    this.swing
                );
            },

            /**
             * Zooms back to the original position,
             * (no offset and zoom factor 1)
             */
            zoomOutAnimation: function () {
                var startZoomFactor = this.zoomFactor,
                    zoomFactor = 1,
                    center = this.getCurrentZoomCenter(),
                    updateProgress = (function (progress) {
                        this.scaleTo(startZoomFactor + progress * (zoomFactor - startZoomFactor), center);
                    }).bind(this);

                this.animate(
                    this.options.animationDuration,
                    updateProgress,
                    this.swing
                );
            },

            /**
             * Updates the aspect ratio
             */
            updateAspectRatio: function () {
                this.setContainerY(this.getContainerX() / this.getAspectRatio());
            },

            /**
             * Calculates the initial zoom factor (for the element to fit into the container)
             * @return the initial zoom factor
             */
            getInitialZoomFactor: function () {
                // use .offsetWidth instead of width()
                // because jQuery-width() return the original width but Zepto-width() will calculate width with transform.
                // the same as .height()
                return this.container[0].offsetWidth / this.el[0].offsetWidth;
            },

            /**
             * Calculates the aspect ratio of the element
             * @return the aspect ratio
             */
            getAspectRatio: function () {
                return this.el[0].offsetWidth / this.el[0].offsetHeight;
            },

            /**
             * Calculates the virtual zoom center for the current offset and zoom factor
             * (used for reverse zoom)
             * @return {Object} the current zoom center
             */
            getCurrentZoomCenter: function () {

                // uses following formula to calculate the zoom center x value
                // offset_left / offset_right = zoomcenter_x / (container_x - zoomcenter_x)
                var length = this.container[0].offsetWidth * this.zoomFactor,
                    offsetLeft  = this.offset.x,
                    offsetRight = length - offsetLeft -this.container[0].offsetWidth,
                    widthOffsetRatio = offsetLeft / offsetRight,
                    centerX = widthOffsetRatio * this.container[0].offsetWidth / (widthOffsetRatio + 1),

                // the same for the zoomcenter y
                    height = this.container[0].offsetHeight * this.zoomFactor,
                    offsetTop  = this.offset.y,
                    offsetBottom = height - offsetTop - this.container[0].offsetHeight,
                    heightOffsetRatio = offsetTop / offsetBottom,
                    centerY = heightOffsetRatio * this.container[0].offsetHeight / (heightOffsetRatio + 1);

                // prevents division by zero
                if (offsetRight === 0) { centerX = this.container[0].offsetWidth; }
                if (offsetBottom === 0) { centerY = this.container[0].offsetHeight; }

                return {
                    x: centerX,
                    y: centerY
                };
            },

            canDrag: function () {
                return !isCloseTo(this.zoomFactor, 1);
            },

            /**
             * Returns the touches of an event relative to the container offset
             * @param event
             * @return array touches
             */
            getTouches: function (event) {
                var position = this.container.offset();
                return Array.prototype.slice.call(event.touches).map(function (touch) {
                    return {
                        x: touch.pageX - position.left,
                        y: touch.pageY - position.top
                    };
                });
            },

            /**
             * Animation loop
             * does not support simultaneous animations
             * @param duration
             * @param framefn
             * @param timefn
             * @param callback
             */
            animate: function (duration, framefn, timefn, callback) {
                var startTime = new Date().getTime(),
                    renderFrame = (function () {
                        if (!this.inAnimation) { return; }
                        var frameTime = new Date().getTime() - startTime,
                            progress = frameTime / duration;
                        if (frameTime >= duration) {
                            framefn(1);
                            if (callback) {
                                callback();
                            }
                            this.update();
                            this.stopAnimation();
                            this.update();
                        } else {
                            if (timefn) {
                                progress = timefn(progress);
                            }
                            framefn(progress);
                            this.update();
                            requestAnimationFrame(renderFrame);
                        }
                    }).bind(this);
                this.inAnimation = true;
                requestAnimationFrame(renderFrame);
            },

            /**
             * Stops the animation
             */
            stopAnimation: function () {
                this.inAnimation = false;
            },

            /**
             * Swing timing function for animations
             * @param p
             * @return {Number}
             */
            swing: function (p) {
                return -Math.cos(p * Math.PI) / 2  + 0.5;
            },

            getContainerX: function () {
                return this.container[0].offsetWidth;
            },

            getContainerY: function () {
                return this.container[0].offsetHeight;
            },

            setContainerY: function (y) {
                return this.container.height(y);
            },

            /**
             * Creates the expected html structure
             */
            setupMarkup: function () {
                this.container = $('<div class="pinch-zoom-container"></div>');
                this.el.before(this.container);
                this.container.append(this.el);

                this.container.css({
                    'overflow': 'hidden',
                    'position': 'relative'
                });

                // Zepto doesn't recognize `webkitTransform..` style
                this.el.css({
                    '-webkit-transform-origin': '0% 0%',
                    '-moz-transform-origin': '0% 0%',
                    '-ms-transform-origin': '0% 0%',
                    '-o-transform-origin': '0% 0%',
                    'transform-origin': '0% 0%',
                    'position': 'absolute'
                });
            },

            end: function () {
                this.hasInteraction = false;
                this.sanitize();
                this.update();
            },

            /**
             * Binds all required event listeners
             */
            bindEvents: function () {
                detectGestures(this.container.get(0), this);
                // Zepto and jQuery both know about `on`
                $(window).on('resize', this.update.bind(this));
                $(this.el).find('img').on('load', this.update.bind(this));
            },

            /**
             * Updates the css values according to the current zoom factor and offset
             */
            update: function () {

                if (this.updatePlaned) {
                    return;
                }
                this.updatePlaned = true;

                setTimeout((function () {
                    this.updatePlaned = false;
                    this.updateAspectRatio();

                    var zoomFactor = this.getInitialZoomFactor() * this.zoomFactor,
                        offsetX = -this.offset.x / zoomFactor,
                        offsetY = -this.offset.y / zoomFactor,
                        transform3d =   'scale3d('     + zoomFactor + ', '  + zoomFactor + ',1) ' +
                            'translate3d(' + offsetX    + 'px,' + offsetY    + 'px,0px)',
                        transform2d =   'scale('       + zoomFactor + ', '  + zoomFactor + ') ' +
                            'translate('   + offsetX    + 'px,' + offsetY    + 'px)',
                        removeClone = (function () {
                            if (this.clone) {
                                this.clone.remove();
                                delete this.clone;
                            }
                        }).bind(this);

                    // Scale 3d and translate3d are faster (at least on ios)
                    // but they also reduce the quality.
                    // PinchZoom uses the 3d transformations during interactions
                    // after interactions it falls back to 2d transformations
                    if (!this.options.use2d || this.hasInteraction || this.inAnimation) {
                        this.is3d = true;
                        removeClone();
                        this.el.css({
                            '-webkit-transform':  transform3d,
                            '-o-transform':       transform2d,
                            '-ms-transform':      transform2d,
                            '-moz-transform':     transform2d,
                            'transform':        transform3d
                        });
                    } else {

                        // When changing from 3d to 2d transform webkit has some glitches.
                        // To avoid this, a copy of the 3d transformed element is displayed in the
                        // foreground while the element is converted from 3d to 2d transform
                        if (this.is3d) {
                            this.clone = this.el.clone();
                            this.clone.css('pointer-events', 'none');
                            this.clone.appendTo(this.container);
                            setTimeout(removeClone, 200);
                        }
                        this.el.css({
                            '-webkit-transform':  transform2d,
                            '-o-transform':       transform2d,
                            '-ms-transform':      transform2d,
                            '-moz-transform':     transform2d,
                            'transform':        transform2d
                        });
                        this.is3d = false;
                    }
                }).bind(this), 0);
            },

            /**
             * Enables event handling for gestures
             */
            enable: function() {
              this.enabled = true;
            },

            /**
             * Disables event handling for gestures
             */
            disable: function() {
              this.enabled = false;
            }
        };

        var detectGestures = function (el, target) {
            var interaction = null,
                fingers = 0,
                lastTouchStart = null,
                startTouches = null,

                setInteraction = function (newInteraction, event) {
                    if (interaction !== newInteraction) {

                        if (interaction && !newInteraction) {
                            switch (interaction) {
                                case "zoom":
                                    target.handleZoomEnd(event);
                                    break;
                                case 'drag':
                                    target.handleDragEnd(event);
                                    break;
                            }
                        }

                        switch (newInteraction) {
                            case 'zoom':
                                target.handleZoomStart(event);
                                break;
                            case 'drag':
                                target.handleDragStart(event);
                                break;
                        }
                    }
                    interaction = newInteraction;
                },

                updateInteraction = function (event) {
                    if (fingers === 2) {
                        setInteraction('zoom');
                    } else if (fingers === 1 && target.canDrag()) {
                        setInteraction('drag', event);
                    } else {
                        setInteraction(null, event);
                    }
                },

                targetTouches = function (touches) {
                    return Array.prototype.slice.call(touches).map(function (touch) {
                        return {
                            x: touch.pageX,
                            y: touch.pageY
                        };
                    });
                },

                getDistance = function (a, b) {
                    var x, y;
                    x = a.x - b.x;
                    y = a.y - b.y;
                    return Math.sqrt(x * x + y * y);
                },

                calculateScale = function (startTouches, endTouches) {
                    var startDistance = getDistance(startTouches[0], startTouches[1]),
                        endDistance = getDistance(endTouches[0], endTouches[1]);
                    return endDistance / startDistance;
                },

                cancelEvent = function (event) {
                    event.stopPropagation();
                    event.preventDefault();
                },

                detectDoubleTap = function (event) {
                    var time = (new Date()).getTime();

                    if (fingers > 1) {
                        lastTouchStart = null;
                    }

                    if (time - lastTouchStart < 300) {
                        cancelEvent(event);

                        target.handleDoubleTap(event);
                        switch (interaction) {
                            case "zoom":
                                target.handleZoomEnd(event);
                                break;
                            case 'drag':
                                target.handleDragEnd(event);
                                break;
                        }
                    }

                    if (fingers === 1) {
                        lastTouchStart = time;
                    }
                },
                firstMove = true;

            el.addEventListener('touchstart', function (event) {
                if(target.enabled) {
                    firstMove = true;
                    fingers = event.touches.length;
                    detectDoubleTap(event);
                }
            });

            el.addEventListener('touchmove', function (event) {
                if(target.enabled) {
                    if (firstMove) {
                        updateInteraction(event);
                        if (interaction) {
                            cancelEvent(event);
                        }
                        startTouches = targetTouches(event.touches);
                    } else {
                        switch (interaction) {
                            case 'zoom':
                                target.handleZoom(event, calculateScale(startTouches, targetTouches(event.touches)));
                                break;
                            case 'drag':
                                target.handleDrag(event);
                                break;
                        }
                        if (interaction) {
                            cancelEvent(event);
                            target.update();
                        }
                    }

                    firstMove = false;
                }
            });

            el.addEventListener('touchend', function (event) {
                if(target.enabled) {
                    fingers = event.touches.length;
                    updateInteraction(event);
                }
            });
        };

        return PinchZoom;
    };

    if (typeof define !== 'undefined' && define.amd) {
        define(['jquery'], function ($) {
            return definePinchZoom($);
        });
    } else {
        window.RTP = window.RTP || {};
        window.RTP.PinchZoom = definePinchZoom(window.$);
    }
}).call(this);
