// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * Formats string by replacing place holder with actual values.
 * @param {string} str String includes placeholder '$n'. n starts from 1.
 * @param {...*} var_args Values inserted into the place holders.
 * @return {string}
 */
function formatString(str, var_args) {
  var args = arguments;
  return str.replace(/\$[1-9]/g, function(placeHolder) {
    return args[placeHolder[1]];
  });
}

/**
 * Viewport class controls the way the image is displayed (scale, offset etc).
 * Screen size is same with window size by default. Change screen size and
 * position by changing screenTop and screenBottom.
 *
 * @param {!Window} targetWindow A window which this viewport is attached to.
 * @constructor
 * @extends {cr.EventTarget}
 * @struct
 */
function Viewport(targetWindow) {
  /**
   * Window
   * @private {!Window}
   */
  this.window_ = targetWindow;

  /**
   * Size of the full resolution image.
   * @type {!ImageRect}
   * @private
   */
  this.imageBounds_ = new ImageRect(0, 0, 0, 0);

  /**
   * Bounds of the image element on screen without zoom and offset.
   * @type {ImageRect}
   * @private
   */
  this.imageElementBoundsOnScreen_ = null;

  /**
   * Bounds of the image with zoom and offset.
   * @type {ImageRect}
   * @private
   */
  this.imageBoundsOnScreen_ = null;

  /**
   * Image bounds that is clipped with the screen bounds.
   * @type {ImageRect}
   * @private
   */
  this.imageBoundsOnScreenClipped_ = null;

  /**
   * Scale from the full resolution image to the screen displayed image. This is
   * not zoom operated by users.
   * @type {number}
   * @private
   */
  this.scale_ = 1;

  /**
   * Zoom ratio specified by user operations.
   * @type {number}
   * @private
   */
  this.zoom_ = 1;

  /**
   * Offset specified by user operations.
   * @type {number}
   * @private
   */
  this.offsetX_ = 0;

  /**
   * Offset specified by user operations.
   * @type {number}
   * @private
   */
  this.offsetY_ = 0;

  /**
   * Integer Rotation value.
   * The rotation angle is this.rotation_ * 90.
   * @type {number}
   * @private
   */
  this.rotation_ = 0;

  /**
   * Generation of the screen size image cache.
   * This is incremented every time when the size of image cache is changed.
   * @type {number}
   * @private
   */
  this.generation_ = 0;

  /**
   * Top margin of the screen.
   * @private {number}
   */
  this.screenTop_ = 0;

  /**
   * Bottom margin of the screen.
   * @private {number}
   */
  this.screenBottom_ = 0;

  /**
   * Window width.
   * @private {number}
   */
  this.windowWidth_ = this.window_.innerWidth;

  /**
   * Window height.
   * @private {number}
   */
  this.windowHeight_ = this.window_.innerHeight;

  this.window_.addEventListener('resize', this.onWindowResize_.bind(this));

  this.update_();
}

Viewport.prototype.__proto__ = cr.EventTarget.prototype;

/**
 * Zoom ratios.
 *
 * @type {Array<number>}
 * @const
 */
Viewport.ZOOM_RATIOS = [1, 1.5, 2, 3];

/**
 * Sets image size.
 * @param {number} width Image width.
 * @param {number} height Image height.
 */
Viewport.prototype.setImageSize = function(width, height) {
  this.imageBounds_ = ImageRect.createFromWidthAndHeight(width, height);
  this.update_();
};

/**
 * Handles window resize event.
 */
Viewport.prototype.onWindowResize_ = function(event) {
  this.windowWidth_ = event.target.innerWidth;
  this.windowHeight_ = event.target.innerHeight;
  this.update_();

  // Dispatches resize event of viewport.
  var resizeEvent = new Event('resize');
  this.dispatchEvent(resizeEvent);
};

/**
 * Sets screen top.
 * @param {number} top Top.
 */
Viewport.prototype.setScreenTop = function(top) {
  this.screenTop_ = top;
  this.update_();
};

/**
 * Sets screen bottom.
 * @param {number} bottom Bottom.
 */
Viewport.prototype.setScreenBottom = function(bottom) {
  this.screenBottom_ = bottom;
  this.update_();
};

/**
 * Sets zoom value directly.
 * @param {number} zoom New zoom value.
 */
Viewport.prototype.setZoom = function(zoom) {
  var zoomMin = Viewport.ZOOM_RATIOS[0];
  var zoomMax = Viewport.ZOOM_RATIOS[Viewport.ZOOM_RATIOS.length - 1];
  var adjustedZoom = Math.max(zoomMin, Math.min(zoom, zoomMax));
  this.zoom_ = adjustedZoom;
  this.update_();
};

/**
 * Returns the value of zoom.
 * @return {number} Zoom value.
 */
Viewport.prototype.getZoom = function() {
  return this.zoom_;
};

/**
 * Sets the nearest larger value of ZOOM_RATIOS.
 */
Viewport.prototype.zoomIn = function() {
  var zoom = Viewport.ZOOM_RATIOS[0];
  for (var i = 0; i < Viewport.ZOOM_RATIOS.length; i++) {
    zoom = Viewport.ZOOM_RATIOS[i];
    if (zoom > this.zoom_)
      break;
  }
  this.setZoom(zoom);
};

/**
 * Sets the nearest smaller value of ZOOM_RATIOS.
 */
Viewport.prototype.zoomOut = function() {
  var zoom = Viewport.ZOOM_RATIOS[Viewport.ZOOM_RATIOS.length - 1];
  for (var i = Viewport.ZOOM_RATIOS.length - 1; i >= 0; i--) {
    zoom = Viewport.ZOOM_RATIOS[i];
    if (zoom < this.zoom_)
      break;
  }
  this.setZoom(zoom);
};

/**
 * Obtains whether the picture is zoomed or not.
 * @return {boolean}
 */
Viewport.prototype.isZoomed = function() {
  return this.zoom_ !== 1;
};

/**
 * Sets the rotation value.
 * @param {number} rotation New rotation value.
 */
Viewport.prototype.setRotation = function(rotation) {
  this.rotation_ = rotation;
  this.update_();
};


/**
 * Obtains the rotation value.
 * @return {number} Current rotation value.
 */
Viewport.prototype.getRotation = function() {
  return this.rotation_;
};

/**
 * Returns image scale so that it matches screen size as long as it does not
 * exceed maximum size.
 *
 * @param {number} width Width of image.
 * @param {number} height Height of image.
 * @param {number} maxWidth Max width of image.
 * @param {number} maxHeight Max height of image.
 * @return {number} The ratio of the full resotion image size and the calculated
 * displayed image size.
 * @private
 */
Viewport.prototype.getFittingScaleForImageSize_ = function(
    width, height, maxWidth, maxHeight) {
  return Math.min(
      maxWidth / width,
      maxHeight / height,
      this.getScreenBounds().width / width,
      this.getScreenBounds().height / height);
};

/**
 * Returns offset X.
 * @return {number} X-offset of the viewport.
 */
Viewport.prototype.getOffsetX = function() { return this.offsetX_; };

/**
 * Returns offset Y.
 * @return {number} Y-offset of the viewport.
 */
Viewport.prototype.getOffsetY = function() { return this.offsetY_; };

/**
 * Set the image offset in the viewport.
 * @param {number} x X-offset.
 * @param {number} y Y-offset.
 */
Viewport.prototype.setOffset = function(x, y) {
  if (this.offsetX_ == x && this.offsetY_ == y)
    return;
  this.offsetX_ = x;
  this.offsetY_ = y;
  this.update_();
};

/**
 * Returns image bounds.
 * @return {!ImageRect} The image bounds in image coordinates.
 */
Viewport.prototype.getImageBounds = function() { return this.imageBounds_; };

/**
 * Returns screen bounds.
 * @return {!ImageRect} The screen bounds in screen coordinates.
 */
Viewport.prototype.getScreenBounds = function() {
  return new ImageRect(
      0,
      this.screenTop_,
      this.windowWidth_,
      this.windowHeight_ - this.screenTop_ - this.screenBottom_);
};

/**
 * Returns device bounds.
 * @return {!ImageRect} The size of screen cache canvas.
 */
Viewport.prototype.getDeviceBounds = function() {
  return ImageRect.createFromWidthAndHeight(
      this.imageElementBoundsOnScreen_.width * window.devicePixelRatio,
      this.imageElementBoundsOnScreen_.height * window.devicePixelRatio);
};

/**
 * A counter that is incremented with each viewport state change.
 * Clients that cache anything that depends on the viewport state should keep
 * track of this counter.
 * @return {number} counter.
 */
Viewport.prototype.getCacheGeneration = function() { return this.generation_; };

/**
 * Returns image bounds in screen coordinates.
 * @return {!ImageRect} The image bounds in screen coordinates.
 */
Viewport.prototype.getImageBoundsOnScreen = function() {
  assert(this.imageBoundsOnScreen_);
  return this.imageBoundsOnScreen_;
};

/**
 * The image bounds on screen, which is clipped with the screen size.
 * @return {!ImageRect}
 */
Viewport.prototype.getImageBoundsOnScreenClipped = function() {
  assert(this.imageBoundsOnScreenClipped_);
  return this.imageBoundsOnScreenClipped_;
};

/**
 * Returns size in image coordinates.
 * @param {number} size Size in screen coordinates.
 * @return {number} Size in image coordinates.
 */
Viewport.prototype.screenToImageSize = function(size) {
  return size / this.scale_;
};

/**
 * Returns X in image coordinates.
 * @param {number} x X in screen coordinates.
 * @return {number} X in image coordinates.
 */
Viewport.prototype.screenToImageX = function(x) {
  return Math.round((x - this.imageBoundsOnScreen_.left) / this.scale_);
};

/**
 * Returns Y in image coordinates.
 * @param {number} y Y in screen coordinates.
 * @return {number} Y in image coordinates.
 */
Viewport.prototype.screenToImageY = function(y) {
  return Math.round((y - this.imageBoundsOnScreen_.top) / this.scale_);
};

/**
 * Returns a rectangle in image coordinates.
 * @param {!ImageRect} rect Rectangle in screen coordinates.
 * @return {!ImageRect} Rectangle in image coordinates.
 */
Viewport.prototype.screenToImageRect = function(rect) {
  return new ImageRect(
      this.screenToImageX(rect.left),
      this.screenToImageY(rect.top),
      this.screenToImageSize(rect.width),
      this.screenToImageSize(rect.height));
};

/**
 * Returns size in screen coordinates.
 * @param {number} size Size in image coordinates.
 * @return {number} Size in screen coordinates.
 */
Viewport.prototype.imageToScreenSize = function(size) {
  return size * this.scale_;
};

/**
 * Returns X in screen coordinates.
 * @param {number} x X in image coordinates.
 * @return {number} X in screen coordinates.
 */
Viewport.prototype.imageToScreenX = function(x) {
  return Math.round(this.imageBoundsOnScreen_.left + x * this.scale_);
};

/**
 * Returns Y in screen coordinates.
 * @param {number} y Y in image coordinates.
 * @return {number} Y in screen coordinates.
 */
Viewport.prototype.imageToScreenY = function(y) {
  return Math.round(this.imageBoundsOnScreen_.top + y * this.scale_);
};

/**
 * Returns a rectangle in screen coordinates.
 * @param {!ImageRect} rect Rectangle in image coordinates.
 * @return {!ImageRect} Rectangle in screen coordinates.
 */
Viewport.prototype.imageToScreenRect = function(rect) {
  return new ImageRect(
      this.imageToScreenX(rect.left),
      this.imageToScreenY(rect.top),
      Math.round(this.imageToScreenSize(rect.width)),
      Math.round(this.imageToScreenSize(rect.height)));
};

/**
 * Returns a rectangle with given geometry.
 * @param {number} width Width of the rectangle.
 * @param {number} height Height of the rectangle.
 * @param {number} offsetX X-offset of center position of the rectangle.
 * @param {number} offsetY Y-offset of center position of the rectangle.
 * @return {!ImageRect} Rectangle with given geometry.
 * @private
 */
Viewport.prototype.getCenteredRect_ = function(
    width, height, offsetX, offsetY) {
  var screenBounds = this.getScreenBounds();
  return new ImageRect(
      ~~((screenBounds.width - width) / 2) + offsetX,
      ~~((screenBounds.height - height) / 2) + screenBounds.top + offsetY,
      width,
      height);
};

/**
 * Resets zoom and offset.
 */
Viewport.prototype.resetView = function() {
  this.zoom_ = 1;
  this.offsetX_ = 0;
  this.offsetY_ = 0;
  this.rotation_ = 0;
  this.update_();
};

/**
 * Recalculate the viewport parameters.
 * @private
 */
Viewport.prototype.update_ = function() {
  // Update scale.
  this.scale_ = this.getFittingScaleForImageSize_(
      this.imageBounds_.width, this.imageBounds_.height,
      this.imageBounds_.width, this.imageBounds_.height);

  // Limit offset values.
  var zoomedWidht;
  var zoomedHeight;
  if (this.rotation_ % 2 == 0) {
    zoomedWidht = ~~(this.imageBounds_.width * this.scale_ * this.zoom_);
    zoomedHeight = ~~(this.imageBounds_.height * this.scale_ * this.zoom_);
  } else {
    var scale = this.getFittingScaleForImageSize_(
        this.imageBounds_.height, this.imageBounds_.width,
        this.imageBounds_.height, this.imageBounds_.width);
    zoomedWidht = ~~(this.imageBounds_.height * scale * this.zoom_);
    zoomedHeight = ~~(this.imageBounds_.width * scale * this.zoom_);
  }
  var dx = Math.max(zoomedWidht - this.getScreenBounds().width, 0) / 2;
  var dy = Math.max(zoomedHeight - this.getScreenBounds().height, 0) / 2;
  this.offsetX_ = ImageUtil.clamp(-dx, this.offsetX_, dx);
  this.offsetY_ = ImageUtil.clamp(-dy, this.offsetY_, dy);

  // Image bounds on screen.
  this.imageBoundsOnScreen_ = this.getCenteredRect_(
      zoomedWidht, zoomedHeight, this.offsetX_, this.offsetY_);

  // Image bounds of element (that is not applied zoom and offset) on screen.
  var oldBounds = this.imageElementBoundsOnScreen_;
  this.imageElementBoundsOnScreen_ = this.getCenteredRect_(
      ~~(this.imageBounds_.width * this.scale_),
      ~~(this.imageBounds_.height * this.scale_),
      0,
      0);
  if (!oldBounds ||
      this.imageElementBoundsOnScreen_.width != oldBounds.width ||
      this.imageElementBoundsOnScreen_.height != oldBounds.height) {
    this.generation_++;
  }

  // Image bounds on screen clipped with the screen bounds.
  var left = Math.max(this.imageBoundsOnScreen_.left, 0);
  var top = Math.max(this.imageBoundsOnScreen_.top, this.screenTop_);
  var right = Math.min(
      this.imageBoundsOnScreen_.right, this.getScreenBounds().width);
  var bottom = Math.min(this.imageBoundsOnScreen_.bottom,
      this.getScreenBounds().height + this.screenTop_);
  this.imageBoundsOnScreenClipped_ = new ImageRect(
      left, top, right - left, bottom - top);
};

/**
 * Clones the viewport.
 * @return {!Viewport} New instance.
 */
Viewport.prototype.clone = function() {
  var viewport = new Viewport(this.window_);
  viewport.imageBounds_ = ImageRect.createFromBounds(this.imageBounds_);
  viewport.scale_ = this.scale_;
  viewport.zoom_ = this.zoom_;
  viewport.offsetX_ = this.offsetX_;
  viewport.offsetY_ = this.offsetY_;
  viewport.screenTop_ = this.screenTop_;
  viewport.screenBottom_ = this.screenBottom_;
  viewport.windowWidth_ = this.windowWidth_;
  viewport.windowHeight_ = this.windowHeight_;
  viewport.rotation_ = this.rotation_;
  viewport.generation_ = this.generation_;
  viewport.update_();
  return viewport;
};

/**
 * Obtains CSS transformation string that matches the image dimension with
 * |screenRect|.
 * @param {number} width Width of image.
 * @param {number} height Height of image.
 * @param {!ImageRect} screenRect Rectangle in window coordinate system. The
 *     origin of the coordinate system is located at the left upper of the
 *     window.
 */
Viewport.prototype.getScreenRectTransformation = function(
    width, height, screenRect) {
  var dx = screenRect.left + (screenRect.width - width) / 2;
  var dy = screenRect.top + (screenRect.height - height) / 2;

  return formatString(
      'translate($1px,$2px) scale($3,$4)',
      dx, dy, screenRect.width / width, screenRect.height / height);
};

/**
 * Obtains CSS transformation string that places the cropped image at the
 * original position in the whole image.
 * @param {number} width Width of cropped image.
 * @param {number} height Width of cropped image.
 * @param {number} wholeWidthMax Max width value that is used for layouting
 *     whole image.
 * @param {number} wholeHeightMax Max height value that is used for layouting
 *     whole image.
 * @param {!ImageRect} cropRect Crop rectangle in the whole image. The origin is
 *     left upper of the whole image.
 */
Viewport.prototype.getCroppingTransformation = function(
    width,
    height,
    wholeWidthMax,
    wholeHeightMax,
    cropRect) {
  var fittingScale = this.getFittingScaleForImageSize_(
      wholeWidthMax, wholeHeightMax, wholeWidthMax, wholeHeightMax);
  var wholeWidth = wholeWidthMax * fittingScale;
  var wholeHeight = wholeHeightMax * fittingScale;
  var wholeRect = this.getCenteredRect_(wholeWidth, wholeHeight, 0, 0);
  return this.getScreenRectTransformation(
      width,
      height,
      new ImageRect(
          wholeRect.left + cropRect.left * fittingScale,
          wholeRect.top + cropRect.top * fittingScale,
          cropRect.width * fittingScale,
          cropRect.height * fittingScale));
};

/**
 * Obtains CSS transformation for the screen image.
 * @param {number} width Width of image.
 * @param {number} height Height of image.
 * @param {number=} opt_dx Amount of horizontal shift.
 * @return {string} Transformation description.
 */
Viewport.prototype.getTransformation = function(width, height, opt_dx) {
  return this.getTransformationInternal_(
      width,
      height,
      this.rotation_,
      this.zoom_,
      this.offsetX_ + (opt_dx || 0),
      this.offsetY_);
};

/**
 * Obtains CSS transformation that makes the rotated image fit the original
 * image. The new rotated image that the transformation is applied to looks the
 * same with original image.
 *
 * @param {number} width Width of image.
 * @param {number} height Height of image.
 * @param {number} rotation Number of clockwise 90 degree rotation. The rotation
 *     angle of the image is rotation * 90.
 * @return {string} Transformation description.
 */
Viewport.prototype.getRotatingTransformation = function(
    width, height, rotation) {
  return this.getTransformationInternal_(
      width, height, rotation, 1, 0, 0);
};

/**
 * Obtains CSS transformation that placed the image in the application window.
 * @param {number} width Width of image.
 * @param {number} height Height of image.
 * @param {number} rotation Number of clockwise 90 degree rotation. The rotation
 *     angle of the image is rotation * 90.
 * @param {number} zoom Zoom rate.
 * @param {number} offsetX Horizontal offset.
 * @param {number} offsetY Vertical offset.
 * @private
 */
Viewport.prototype.getTransformationInternal_ = function(
    width,
    height,
    rotation,
    zoom,
    offsetX,
    offsetY) {
  var rotatedWidth = rotation % 2 ? height : width;
  var rotatedHeight = rotation % 2 ? width : height;
  var rotatedMaxWidth = rotation % 2 ?
      this.imageBounds_.height : this.imageBounds_.width;
  var rotatedMaxHeight = rotation % 2 ?
      this.imageBounds_.width : this.imageBounds_.height;

  // Scale.
  var fittingScale = this.getFittingScaleForImageSize_(
      rotatedWidth, rotatedHeight, rotatedMaxWidth, rotatedMaxHeight);

  // Offset for centering.
  var rect = this.getCenteredRect_(width, height, offsetX, offsetY);
  return formatString(
      'translate($1px,$2px) scale($3) rotate($4deg)',
      rect.left,
      rect.top,
      fittingScale * zoom,
      rotation * 90);
};