// Copyright (c) 2012 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.

'use strict';

/**
 * @fileoverview Code for the viewport.
 */
base.require('base.events');

base.exportTo('tracing', function() {

  /**
   * The TimelineViewport manages the transform used for navigating
   * within the timeline. It is a simple transform:
   *   x' = (x+pan) * scale
   *
   * The timeline code tries to avoid directly accessing this transform,
   * instead using this class to do conversion between world and viewspace,
   * as well as the math for centering the viewport in various interesting
   * ways.
   *
   * @constructor
   * @extends {base.EventTarget}
   */
  function TimelineViewport(parentEl) {
    this.parentEl_ = parentEl;
    this.modelTrackContainer_ = null;
    this.scaleX_ = 1;
    this.panX_ = 0;
    this.panY_ = 0;
    this.gridTimebase_ = 0;
    this.gridStep_ = 1000 / 60;
    this.gridEnabled_ = false;
    this.hasCalledSetupFunction_ = false;

    this.onResize_ = this.onResize_.bind(this);
    this.onModelTrackControllerScroll_ =
        this.onModelTrackControllerScroll_.bind(this);

    // The following code uses an interval to detect when the parent element
    // is attached to the document. That is a trigger to run the setup function
    // and install a resize listener.
    this.checkForAttachInterval_ = setInterval(
        this.checkForAttach_.bind(this), 250);

    this.markers = [];
  }

  TimelineViewport.prototype = {
    __proto__: base.EventTarget.prototype,

    /**
     * Allows initialization of the viewport when the viewport's parent element
     * has been attached to the document and given a size.
     * @param {Function} fn Function to call when the viewport can be safely
     * initialized.
     */
    setWhenPossible: function(fn) {
      this.pendingSetFunction_ = fn;
    },

    /**
     * @return {boolean} Whether the current timeline is attached to the
     * document.
     */
    get isAttachedToDocument_() {
      var cur = this.parentEl_;
      // Allow not providing a parent element, used by tests.
      if (cur === undefined)
        return;
      while (cur.parentNode)
        cur = cur.parentNode;
      return cur == this.parentEl_.ownerDocument;
    },

    onResize_: function() {
      this.dispatchChangeEvent();
    },

    /**
     * Checks whether the parentNode is attached to the document.
     * When it is, it installs the iframe-based resize detection hook
     * and then runs the pendingSetFunction_, if present.
     */
    checkForAttach_: function() {
      if (!this.isAttachedToDocument_ || this.clientWidth == 0)
        return;

      if (!this.iframe_) {
        this.iframe_ = document.createElement('iframe');
        this.iframe_.style.cssText =
            'position:absolute;width:100%;height:0;border:0;visibility:hidden;';
        this.parentEl_.appendChild(this.iframe_);

        this.iframe_.contentWindow.addEventListener('resize', this.onResize_);
      }

      var curSize = this.parentEl_.clientWidth + 'x' +
          this.parentEl_.clientHeight;
      if (this.pendingSetFunction_) {
        this.lastSize_ = curSize;
        try {
          this.pendingSetFunction_();
        } catch (ex) {
          console.log('While running setWhenPossible:',
              ex.message ? ex.message + '\n' + ex.stack : ex.stack);
        }
        this.pendingSetFunction_ = undefined;
      }

      window.clearInterval(this.checkForAttachInterval_);
      this.checkForAttachInterval_ = undefined;
    },

    /**
     * Fires the change event on this viewport. Used to notify listeners
     * to redraw when the underlying model has been mutated.
     */
    dispatchChangeEvent: function() {
      base.dispatchSimpleEvent(this, 'change');
    },

    dispatchMarkersChangeEvent_: function() {
      base.dispatchSimpleEvent(this, 'markersChange');
    },

    detach: function() {
      if (this.checkForAttachInterval_) {
        window.clearInterval(this.checkForAttachInterval_);
        this.checkForAttachInterval_ = undefined;
      }
      if (this.iframe_) {
        this.iframe_.removeEventListener('resize', this.onResize_);
        this.parentEl_.removeChild(this.iframe_);
      }
    },

    getStateInViewCoordinates: function() {
      return {
        panX: this.xWorldVectorToView(this.panX),
        panY: this.panY,
        scaleX: this.scaleX
      };
    },

    setStateInViewCoordinates: function(state) {
      this.panX = this.xViewVectorToWorld(state.panX);
      this.panY = state.panY;
    },

    onModelTrackControllerScroll_: function(e) {
      this.panY_ = this.modelTrackContainer_.scrollTop;
    },

    set modelTrackContainer(m) {

      if (this.modelTrackContainer_)
        this.modelTrackContainer_.removeEventListener('scroll',
            this.onModelTrackControllerScroll_);

      this.modelTrackContainer_ = m;
      this.modelTrackContainer_.addEventListener('scroll',
          this.onModelTrackControllerScroll_);
    },

    get scaleX() {
      return this.scaleX_;
    },
    set scaleX(s) {
      var changed = this.scaleX_ != s;
      if (changed) {
        this.scaleX_ = s;
        this.dispatchChangeEvent();
      }
    },

    get panX() {
      return this.panX_;
    },
    set panX(p) {
      var changed = this.panX_ != p;
      if (changed) {
        this.panX_ = p;
        this.dispatchChangeEvent();
      }
    },

    get panY() {
      return this.panY_;
    },
    set panY(p) {
      this.panY_ = p;
      this.modelTrackContainer_.scrollTop = p;
    },

    setPanAndScale: function(p, s) {
      var changed = this.scaleX_ != s || this.panX_ != p;
      if (changed) {
        this.scaleX_ = s;
        this.panX_ = p;
        this.dispatchChangeEvent();
      }
    },

    xWorldToView: function(x) {
      return (x + this.panX_) * this.scaleX_;
    },

    xWorldVectorToView: function(x) {
      return x * this.scaleX_;
    },

    xViewToWorld: function(x) {
      return (x / this.scaleX_) - this.panX_;
    },

    xViewVectorToWorld: function(x) {
      return x / this.scaleX_;
    },

    xPanWorldPosToViewPos: function(worldX, viewX, viewWidth) {
      if (typeof viewX == 'string') {
        if (viewX == 'left') {
          viewX = 0;
        } else if (viewX == 'center') {
          viewX = viewWidth / 2;
        } else if (viewX == 'right') {
          viewX = viewWidth - 1;
        } else {
          throw new Error('unrecognized string for viewPos. left|center|right');
        }
      }
      this.panX = (viewX / this.scaleX_) - worldX;
    },

    xPanWorldBoundsIntoView: function(worldMin, worldMax, viewWidth) {
      if (this.xWorldToView(worldMin) < 0)
        this.xPanWorldPosToViewPos(worldMin, 'left', viewWidth);
      else if (this.xWorldToView(worldMax) > viewWidth)
        this.xPanWorldPosToViewPos(worldMax, 'right', viewWidth);
    },

    xSetWorldBounds: function(worldMin, worldMax, viewWidth) {
      var worldWidth = worldMax - worldMin;
      var scaleX = viewWidth / worldWidth;
      var panX = -worldMin;
      this.setPanAndScale(panX, scaleX);
    },

    get gridEnabled() {
      return this.gridEnabled_;
    },

    set gridEnabled(enabled) {
      if (this.gridEnabled_ == enabled)
        return;

      this.gridEnabled_ = enabled && true;
      this.dispatchChangeEvent();
    },

    get gridTimebase() {
      return this.gridTimebase_;
    },

    set gridTimebase(timebase) {
      if (this.gridTimebase_ == timebase)
        return;
      this.gridTimebase_ = timebase;
      this.dispatchChangeEvent();
    },

    get gridStep() {
      return this.gridStep_;
    },

    applyTransformToCanvas: function(ctx) {
      ctx.transform(this.scaleX_, 0, 0, 1, this.panX_ * this.scaleX_, 0);
    },

    addMarker: function(positionWorld) {
      var marker = new ViewportMarker(this, positionWorld);
      this.markers.push(marker);
      this.dispatchChangeEvent();
      this.dispatchMarkersChangeEvent_();
      return marker;
    },

    removeMarker: function(marker) {
      for (var i = 0; i < this.markers.length; ++i) {
        if (this.markers[i] === marker) {
          this.markers.splice(i, 1);
          this.dispatchChangeEvent();
          this.dispatchMarkersChangeEvent_();
          return true;
        }
      }
    },

    findMarkerNear: function(positionWorld, nearnessInViewPixels) {
      // Converts pixels into distance in world.
      var nearnessThresholdWorld = this.xViewVectorToWorld(
          nearnessInViewPixels);
      for (var i = 0; i < this.markers.length; ++i) {
        if (Math.abs(this.markers[i].positionWorld - positionWorld) <=
            nearnessThresholdWorld) {
          var marker = this.markers[i];
          return marker;
        }
      }
      return undefined;
    },

    drawGridLines: function(ctx, viewLWorld, viewRWorld) {
      if (!this.gridEnabled)
        return;

      var x = this.gridTimebase;

      ctx.beginPath();
      while (x < viewRWorld) {
        if (x >= viewLWorld) {
          // Do conversion to viewspace here rather than on
          // x to avoid precision issues.
          var vx = this.xWorldToView(x);
          ctx.moveTo(vx, 0);
          ctx.lineTo(vx, ctx.canvas.height);
        }
        x += this.gridStep;
      }
      ctx.strokeStyle = 'rgba(255,0,0,0.25)';
      ctx.stroke();
    },

    drawMarkerArrows: function(ctx, viewLWorld, viewRWorld, drawHeight) {
      for (var i = 0; i < this.markers.length; ++i) {
        this.markers[i].drawTriangle_(ctx, viewLWorld, viewRWorld,
                                      ctx.canvas.height, drawHeight, this);
      }
    },

    drawMarkerLines: function(ctx, viewLWorld, viewRWorld) {
      for (var i = 0; i < this.markers.length; ++i) {
        this.markers[i].drawLine(ctx, viewLWorld, viewRWorld,
            ctx.canvas.height, this);
      }
    }
  };

  /**
   * Represents a marked position in the world, at a viewport level.
   * @constructor
   */
  function ViewportMarker(vp, positionWorld) {
    this.viewport_ = vp;
    this.positionWorld_ = positionWorld;
    this.selected_ = false;
  }

  ViewportMarker.prototype = {
    get positionWorld() {
      return this.positionWorld_;
    },

    set positionWorld(positionWorld) {
      this.positionWorld_ = positionWorld;
      this.viewport_.dispatchChangeEvent();
    },

    set selected(selected) {
      this.selected_ = selected;
      this.viewport_.dispatchChangeEvent();
    },

    get selected() {
      return this.selected_;
    },

    get color() {
      if (this.selected)
        return 'rgb(255,0,0)';
      return 'rgb(0,0,0)';
    },

    drawTriangle_: function(ctx, viewLWorld, viewRWorld,
                            canvasH, rulerHeight, vp) {
      ctx.beginPath();

      var ts = this.positionWorld_;
      if (ts < viewLWorld || ts > viewRWorld)
        return;

      var viewX = vp.xWorldToView(ts);
      ctx.moveTo(viewX, rulerHeight);
      ctx.lineTo(viewX - 3, rulerHeight / 2);
      ctx.lineTo(viewX + 3, rulerHeight / 2);
      ctx.lineTo(viewX, rulerHeight);
      ctx.closePath();
      ctx.fillStyle = this.color;
      ctx.fill();

      if (rulerHeight === canvasH)
        return;

      // Draw line from bottom of triangle to the bottom of our canvas.
      ctx.beginPath();
      ctx.moveTo(viewX, rulerHeight);
      ctx.lineTo(viewX, canvasH);
      ctx.closePath();
      ctx.strokeStyle = this.color;
      ctx.stroke();
    },

    drawLine: function(ctx, viewLWorld, viewRWorld, canvasH, vp) {
      ctx.beginPath();
      var ts = this.positionWorld_;
      if (ts >= viewLWorld && ts < viewRWorld) {
        var viewX = vp.xWorldToView(ts);
        ctx.moveTo(viewX, 0);
        ctx.lineTo(viewX, canvasH);
      }
      ctx.strokeStyle = this.color;
      ctx.stroke();
    }
  };

  return {
    TimelineViewport: TimelineViewport,
    ViewportMarker: ViewportMarker
  };
});