(function () {
    'use strict';

    let timerDebounce = undefined;
    function debounce(duration, callback) {
      clearTimeout(timerDebounce);
      timerDebounce = setTimeout(function () {
        callback();
      }, duration);
      return timerDebounce;
    }
    function transitionAsPromise(triggeringFunc, el) {
      return new Promise(resolve => {
        const handleTransitionEnd = () => {
          el.removeEventListener('transitionend', handleTransitionEnd);
          resolve();
        };

        el.addEventListener('transitionend', handleTransitionEnd);
        const classesBefore = el.getAttribute('class');
        const stylesBefore = el.getAttribute('style');
        triggeringFunc();

        if (classesBefore === el.getAttribute('class') && stylesBefore === el.getAttribute('style')) {
          handleTransitionEnd();
        }

        if (parseFloat(getComputedStyle(el)['transitionDuration']) === 0) {
          handleTransitionEnd();
        }
      });
    }
    function loadImage({
      src,
      srcset,
      sizes
    }) {
      const image = new Image();
      image.src = src;

      if (srcset) {
        image.srcset = srcset;
      }

      if (sizes) {
        image.sizes = sizes;
      }

      if ('decode' in image) {
        return new Promise((resolve, reject) => {
          image.decode().then(() => {
            resolve(image);
          }).catch(() => {
            reject(image);
          });
        });
      } else {
        return new Promise((resolve, reject) => {
          image.onload = resolve(image);
          image.onerror = reject(image);
        });
      }
    }
    function fit(options) {
      let height;
      let width;
      const {
        imgHeight,
        imgWidth,
        containerHeight,
        containerWidth,
        canvasWidth,
        canvasHeight,
        imageSize
      } = options;
      const canvasRatio = canvasHeight / canvasWidth;
      const containerRatio = containerHeight / containerWidth;
      const imgRatio = imgHeight / imgWidth;

      if (imageSize == 'cover') {
        if (imgRatio < containerRatio) {
          height = containerHeight;
          width = height / imgRatio;
        } else {
          width = containerWidth;
          height = width * imgRatio;
        }
      } else if (imageSize == 'native') {
        height = imgHeight;
        width = imgWidth;
      } else {
        if (imgRatio > canvasRatio) {
          height = canvasHeight;
          width = height / imgRatio;
        } else {
          width = canvasWidth;
          height = width * imgRatio;
        }

        if (imageSize === 'scale-down' && (width >= imgWidth || height >= imgHeight)) {
          width = imgWidth;
          height = imgHeight;
        }
      }

      return {
        height: height,
        width: width
      };
    }
    function openFullScreen(wrapper) {
      if (wrapper.requestFullscreen) {
        wrapper.requestFullscreen();
        return true;
      } else if (wrapper.webkitRequestFullscreen) {
        wrapper.webkitRequestFullscreen();
        return true;
      } else if (wrapper.msRequestFullscreen) {
        wrapper.msRequestFullscreen();
        return true;
      } else {
        return false;
      }
    }
    function exitFullScreen() {
      if (document.exitFullscreen) {
        document.exitFullscreen();
        return false;
      } else if (document.webkitExitFullscreen) {
        document.webkitExitFullscreen();
        return false;
      } else if (document.msExitFullscreen) {
        document.msExitFullscreen();
        return false;
      } else {
        return true;
      }
    }

    const defaults = {
      container: document.body,
      // window or element
      className: undefined,
      imageSize: 'scale-down',
      // 'scale-down', 'contain', 'cover' or 'native'
      fullScreen: false,
      loop: false,
      linkImages: true,
      setIndex: 0,
      firstImageIndex: 0,
      lastImageIndex: false,
      currentImageIndex: undefined,
      allowZoom: true,
      closeOnBackgroundClick: true,
      setTitle: function () {
        return '';
      },
      description: function () {
        return this.images[this.settings.currentImageIndex].title;
      },
      pagination: function () {
        const last = this.settings.lastImageIndex + 1;
        const position = this.settings.currentImageIndex + 1;
        return position + '/' + last;
      },

      afterInitialize() {},

      afterMarkup() {},

      afterImageLoad() {},

      zoomedPaddingX: function (canvasWidth, imgWidth) {
        return 0;
      },
      zoomedPaddingY: function (canvasHeight, imgHeight) {
        return 0;
      }
    };
    class Chocolat {
      constructor(elements, settings) {
        this.settings = settings;
        this.elems = {};
        this.images = [];
        this.events = [];
        this.state = {
          fullScreenOpen: false,
          initialZoomState: null,
          initialized: false,
          timer: false,
          visible: false
        };
        this._cssClasses = ['chocolat-open', 'chocolat-in-container', 'chocolat-cover', 'chocolat-zoomable', 'chocolat-zoomed', 'chocolat-zooming-in', 'chocolat-zooming-out'];

        if (NodeList.prototype.isPrototypeOf(elements) || HTMLCollection.prototype.isPrototypeOf(elements)) {
          elements.forEach((el, i) => {
            this.images.push({
              title: el.getAttribute('title'),
              src: el.getAttribute('href'),
              srcset: el.getAttribute('data-srcset'),
              sizes: el.getAttribute('data-sizes')
            });
            this.off(el, 'click.chocolat');
            this.on(el, 'click.chocolat', e => {
              this.init(i);
              e.preventDefault();
            });
          });
        } else {
          this.images = elements;
        }

        if (this.settings.container instanceof Element || this.settings.container instanceof HTMLElement) {
          this.elems.container = this.settings.container;
        } else {
          this.elems.container = document.body;
        }

        this.api = {
          open: i => {
            i = parseInt(i) || 0;
            return this.init(i);
          },
          close: () => {
            return this.close();
          },
          next: () => {
            return this.change(1);
          },
          prev: () => {
            return this.change(-1);
          },
          goto: i => {
            return this.open(i);
          },
          current: () => {
            return this.settings.currentImageIndex;
          },
          position: () => {
            return this.position(this.elems.img);
          },
          destroy: () => {
            return this.destroy();
          },
          set: (property, value) => {
            this.settings[property] = value;
            return value;
          },
          get: property => {
            return this.settings[property];
          },
          getElem: name => {
            return this.elems[name];
          }
        };
      }

      init(i) {
        if (!this.state.initialized) {
          this.markup();
          this.attachListeners();
          this.settings.lastImageIndex = this.images.length - 1;
          this.state.initialized = true;
        }

        this.settings.afterInitialize.call(this);
        return this.load(i);
      }

      load(index) {
        if (!this.state.visible) {
          this.state.visible = true;
          setTimeout(() => {
            this.elems.overlay.classList.add('chocolat-visible');
            this.elems.wrapper.classList.add('chocolat-visible');
          }, 0);
          this.elems.container.classList.add('chocolat-open');
        }

        if (this.settings.fullScreen) {
          this.state.fullScreenOpen = openFullScreen(this.elems.wrapper);
        }

        if (this.settings.currentImageIndex === index) {
          return Promise.resolve();
        }

        let loaderTimer = setTimeout(() => {
          this.elems.loader.classList.add('chocolat-visible');
        }, 1000);
        let fadeOutPromise;
        let image;
        let fadeOutTimer = setTimeout(() => {
          fadeOutTimer = undefined;
          fadeOutPromise = transitionAsPromise(() => {
            this.elems.imageCanvas.classList.remove('chocolat-visible');
          }, this.elems.imageCanvas);
        }, 80);
        return loadImage(this.images[index]).then(loadedImage => {
          image = loadedImage;

          if (fadeOutTimer) {
            clearTimeout(fadeOutTimer);
            return Promise.resolve();
          } else {
            return fadeOutPromise;
          }
        }).then(() => {
          const nextIndex = index + 1;

          if (this.images[nextIndex] != undefined) {
            loadImage(this.images[nextIndex]);
          }

          this.settings.currentImageIndex = index;
          this.elems.description.textContent = this.settings.description.call(this);
          this.elems.pagination.textContent = this.settings.pagination.call(this);
          this.arrows();
          return this.position(image).then(() => {
            this.elems.loader.classList.remove('chocolat-visible');
            clearTimeout(loaderTimer);
            return this.appear(image);
          });
        }).then(() => {
          this.elems.container.classList.toggle('chocolat-zoomable', this.zoomable(image, this.elems.wrapper));
          this.settings.afterImageLoad.call(this);
        });
      }

      position({
        naturalHeight,
        naturalWidth
      }) {
        const fitOptions = {
          imgHeight: naturalHeight,
          imgWidth: naturalWidth,
          containerHeight: this.elems.container.clientHeight,
          containerWidth: this.elems.container.clientWidth,
          canvasWidth: this.elems.imageCanvas.clientWidth,
          canvasHeight: this.elems.imageCanvas.clientHeight,
          imageSize: this.settings.imageSize
        };
        const {
          width,
          height
        } = fit(fitOptions);
        return transitionAsPromise(() => {
          Object.assign(this.elems.imageWrapper.style, {
            width: width + 'px',
            height: height + 'px'
          });
        }, this.elems.imageWrapper);
      }

      appear(image) {
        this.elems.imageWrapper.removeChild(this.elems.img);
        this.elems.img = image;
        this.elems.img.setAttribute('class', 'chocolat-img');
        this.elems.imageWrapper.appendChild(this.elems.img);
        const fadeInPromise = transitionAsPromise(() => {
          this.elems.imageCanvas.classList.add('chocolat-visible');
        }, this.elems.imageCanvas);
        return fadeInPromise;
      }

      change(step) {
        if (!this.state.visible) {
          return;
        }

        if (!this.settings.linkImages) {
          return;
        }

        this.zoomOut();
        const requestedImage = this.settings.currentImageIndex + parseInt(step);

        if (requestedImage > this.settings.lastImageIndex) {
          if (this.settings.loop) {
            return this.load(this.settings.firstImageIndex);
          }
        } else if (requestedImage < this.settings.firstImageIndex) {
          if (this.settings.loop) {
            return this.load(this.settings.lastImageIndex);
          }
        } else {
          return this.load(requestedImage);
        }
      }

      arrows() {
        if (this.settings.loop) {
          this.elems.left.classList.add('active');
          this.elems.right.classList.add('active');
        } else if (this.settings.linkImages) {
          this.elems.right.classList.toggle('active', this.settings.currentImageIndex !== this.settings.lastImageIndex);
          this.elems.left.classList.toggle('active', this.settings.currentImageIndex !== this.settings.firstImageIndex);
        } else {
          this.elems.left.classList.remove('active');
          this.elems.right.classList.remove('active');
        }
      }

      close() {
        if (this.state.fullScreenOpen) {
          this.state.fullScreenOpen = exitFullScreen();
          return;
        }

        this.state.visible = false;
        const promiseOverlay = transitionAsPromise(() => {
          this.elems.overlay.classList.remove('chocolat-visible');
        }, this.elems.overlay);
        const promiseWrapper = transitionAsPromise(() => {
          this.elems.wrapper.classList.remove('chocolat-visible');
        }, this.elems.wrapper);
        return Promise.all([promiseOverlay, promiseWrapper]).then(() => {
          this.elems.container.classList.remove('chocolat-open');
        });
      }

      destroy() {
        for (let i = this.events.length - 1; i >= 0; i--) {
          const {
            element,
            eventName
          } = this.events[i];
          this.off(element, eventName);
        }

        if (!this.state.initialized) {
          return;
        }

        if (this.state.fullScreenOpen) {
          this.state.fullScreenOpen = exitFullScreen();
        }

        this.settings.currentImageIndex = undefined;
        this.state.visible = false;
        this.state.initialized = false;
        this.elems.container.classList.remove(...this._cssClasses);
        this.elems.wrapper.parentNode.removeChild(this.elems.wrapper);
      }

      markup() {
        this.elems.container.classList.add('chocolat-open', this.settings.className);

        if (this.settings.imageSize == 'cover') {
          this.elems.container.classList.add('chocolat-cover');
        }

        if (this.elems.container !== document.body) {
          this.elems.container.classList.add('chocolat-in-container');
        }

        this.elems.wrapper = document.createElement('div');
        this.elems.wrapper.setAttribute('id', 'chocolat-content-' + this.settings.setIndex);
        this.elems.wrapper.setAttribute('class', 'chocolat-wrapper');
        this.elems.container.appendChild(this.elems.wrapper);
        this.elems.overlay = document.createElement('div');
        this.elems.overlay.setAttribute('class', 'chocolat-overlay');
        this.elems.wrapper.appendChild(this.elems.overlay);
        this.elems.loader = document.createElement('div');
        this.elems.loader.setAttribute('class', 'chocolat-loader');
        this.elems.wrapper.appendChild(this.elems.loader);
        this.elems.layout = document.createElement('div');
        this.elems.layout.setAttribute('class', 'chocolat-layout');
        this.elems.wrapper.appendChild(this.elems.layout);
        this.elems.top = document.createElement('div');
        this.elems.top.setAttribute('class', 'chocolat-top');
        this.elems.layout.appendChild(this.elems.top);
        this.elems.center = document.createElement('div');
        this.elems.center.setAttribute('class', 'chocolat-center');
        this.elems.layout.appendChild(this.elems.center);
        this.elems.left = document.createElement('div');
        this.elems.left.setAttribute('class', 'chocolat-left');
        this.elems.center.appendChild(this.elems.left);
        this.elems.imageCanvas = document.createElement('div');
        this.elems.imageCanvas.setAttribute('class', 'chocolat-image-canvas');
        this.elems.center.appendChild(this.elems.imageCanvas);
        this.elems.imageWrapper = document.createElement('div');
        this.elems.imageWrapper.setAttribute('class', 'chocolat-image-wrapper');
        this.elems.imageCanvas.appendChild(this.elems.imageWrapper);
        this.elems.img = document.createElement('img');
        this.elems.img.setAttribute('class', 'chocolat-img');
        this.elems.imageWrapper.appendChild(this.elems.img);
        this.elems.right = document.createElement('div');
        this.elems.right.setAttribute('class', 'chocolat-right');
        this.elems.center.appendChild(this.elems.right);
        this.elems.bottom = document.createElement('div');
        this.elems.bottom.setAttribute('class', 'chocolat-bottom');
        this.elems.layout.appendChild(this.elems.bottom);
        this.elems.close = document.createElement('span');
        this.elems.close.setAttribute('class', 'chocolat-close');
        this.elems.top.appendChild(this.elems.close);
        this.elems.description = document.createElement('span');
        this.elems.description.setAttribute('class', 'chocolat-description');
        this.elems.bottom.appendChild(this.elems.description);
        this.elems.pagination = document.createElement('span');
        this.elems.pagination.setAttribute('class', 'chocolat-pagination');
        this.elems.bottom.appendChild(this.elems.pagination);
        this.elems.setTitle = document.createElement('span');
        this.elems.setTitle.setAttribute('class', 'chocolat-set-title');
        this.elems.setTitle.textContent = this.settings.setTitle();
        this.elems.bottom.appendChild(this.elems.setTitle);
        this.elems.fullscreen = document.createElement('span');
        this.elems.fullscreen.setAttribute('class', 'chocolat-fullscreen');
        this.elems.bottom.appendChild(this.elems.fullscreen);
        this.settings.afterMarkup.call(this);
      }

      attachListeners() {
        this.off(document, 'keydown.chocolat');
        this.on(document, 'keydown.chocolat', e => {
          if (this.state.initialized) {
            if (e.keyCode == 37) {
              this.change(-1);
            } else if (e.keyCode == 39) {
              this.change(1);
            } else if (e.keyCode == 27) {
              this.close();
            }
          }
        });
        const right = this.elems.wrapper.querySelector('.chocolat-right');
        this.off(right, 'click.chocolat');
        this.on(right, 'click.chocolat', () => {
          this.change(+1);
        });
        const left = this.elems.wrapper.querySelector('.chocolat-left');
        this.off(left, 'click.chocolat');
        this.on(left, 'click.chocolat', () => {
          this.change(-1);
        });
        this.off(this.elems.close, 'click.chocolat');
        this.on(this.elems.close, 'click.chocolat', this.close.bind(this));
        this.off(this.elems.fullscreen, 'click.chocolat');
        this.on(this.elems.fullscreen, 'click.chocolat', () => {
          if (this.state.fullScreenOpen) {
            this.state.fullScreenOpen = exitFullScreen();
            return;
          }

          this.state.fullScreenOpen = openFullScreen(this.elems.wrapper);
        });

        if (this.settings.closeOnBackgroundClick) {
          this.off(this.elems.overlay, 'click.chocolat');
          this.on(this.elems.overlay, 'click.chocolat', this.close.bind(this));
        }

        this.off(this.elems.wrapper, 'click.chocolat');
        this.on(this.elems.wrapper, 'click.chocolat', () => {
          if (this.state.initialZoomState === null || !this.state.visible) {
            return;
          }

          this.elems.container.classList.add('chocolat-zooming-out');
          this.zoomOut().then(() => {
            this.elems.container.classList.remove('chocolat-zoomed');
            this.elems.container.classList.remove('chocolat-zooming-out');
          });
        });
        this.off(this.elems.imageWrapper, 'click.chocolat');
        this.on(this.elems.imageWrapper, 'click.chocolat', e => {
          if (this.state.initialZoomState === null && this.elems.container.classList.contains('chocolat-zoomable')) {
            e.stopPropagation();
            this.elems.container.classList.add('chocolat-zooming-in');
            this.zoomIn(e).then(() => {
              this.elems.container.classList.add('chocolat-zoomed');
              this.elems.container.classList.remove('chocolat-zooming-in');
            });
          }
        });
        this.on(this.elems.wrapper, 'mousemove.chocolat', e => {
          if (this.state.initialZoomState === null || !this.state.visible) {
            return;
          }

          const rect = this.elems.wrapper.getBoundingClientRect();
          const pos = {
            top: rect.top + window.scrollY,
            left: rect.left + window.scrollX
          };
          const height = this.elems.wrapper.clientHeight;
          const width = this.elems.wrapper.clientWidth;
          const imgWidth = this.elems.img.width;
          const imgHeight = this.elems.img.height;
          const coord = [e.pageX - width / 2 - pos.left, e.pageY - height / 2 - pos.top];
          let mvtX = 0;

          if (imgWidth > width) {
            const paddingX = this.settings.zoomedPaddingX(imgWidth, width);
            mvtX = coord[0] / (width / 2);
            mvtX = ((imgWidth - width) / 2 + paddingX) * mvtX;
          }

          let mvtY = 0;

          if (imgHeight > height) {
            const paddingY = this.settings.zoomedPaddingY(imgHeight, height);
            mvtY = coord[1] / (height / 2);
            mvtY = ((imgHeight - height) / 2 + paddingY) * mvtY;
          }

          this.elems.img.style.marginLeft = -mvtX + 'px';
          this.elems.img.style.marginTop = -mvtY + 'px';
        });
        this.on(window, 'resize.chocolat', e => {
          if (!this.state.initialized || !this.state.visible) {
            return;
          }

          debounce(50, () => {
            const fitOptions = {
              imgHeight: this.elems.img.naturalHeight,
              imgWidth: this.elems.img.naturalWidth,
              containerHeight: this.elems.wrapper.clientHeight,
              containerWidth: this.elems.wrapper.clientWidth,
              canvasWidth: this.elems.imageCanvas.clientWidth,
              canvasHeight: this.elems.imageCanvas.clientHeight,
              imageSize: this.settings.imageSize
            };
            const {
              width,
              height
            } = fit(fitOptions);
            this.position(this.elems.img).then(() => {
              this.elems.container.classList.toggle('chocolat-zoomable', this.zoomable(this.elems.img, this.elems.wrapper));
            });
          });
        });
      }

      zoomable(image, wrapper) {
        const wrapperWidth = wrapper.clientWidth;
        const wrapperHeight = wrapper.clientHeight;
        const isImageZoomable = this.settings.allowZoom && (image.naturalWidth > wrapperWidth || image.naturalHeight > wrapperHeight) ? true : false;
        const isImageStretched = image.clientWidth > image.naturalWidth || image.clientHeight > image.naturalHeight;
        return isImageZoomable && !isImageStretched;
      }

      zoomIn(e) {
        this.state.initialZoomState = this.settings.imageSize;
        this.settings.imageSize = 'native';
        return this.position(this.elems.img);
      }

      zoomOut(e) {
        this.settings.imageSize = this.state.initialZoomState || this.settings.imageSize;
        this.state.initialZoomState = null;
        this.elems.img.style.margin = 0;
        return this.position(this.elems.img);
      }

      on(element, eventName, cb) {
        // const eventName = this.settings.setIndex + '-' + eventName
        const length = this.events.push({
          element,
          eventName,
          cb
        });
        element.addEventListener(eventName.split('.')[0], this.events[length - 1].cb);
      }

      off(element, eventName) {
        // const eventName = this.settings.setIndex + '-' + eventName
        const index = this.events.findIndex(event => {
          return event.element === element && event.eventName === eventName;
        });

        if (this.events[index]) {
          element.removeEventListener(eventName.split('.')[0], this.events[index].cb);
          this.events.splice(index, 1);
        }
      }

    }

    const instances = [];

    window.Chocolat = function (elements, options) {
      const settings = Object.assign({}, defaults, {
        images: []
      }, options, {
        setIndex: instances.length
      });
      const instance = new Chocolat(elements, settings);
      instances.push(instance);
      return instance;
    };

}());