<!--
  The res/js/status.js file must be included before this file.

  This in an HTML Import-able file this contains the definition
  of the following elements:

    <commits-canvas-sk>

  To use this file import it:

    <link href="/res/imp/commits-canvas-sk.html" rel="import" />

  Usage:

    <commits-canvas-sk></commits-canvas-sk>

  Properties:
    //input
    branch_heads: Array<Object>, an array of Objects with the following attributes:
        head: String, the last commit revision in this branch.  If it is off the screen, it will
              not be drawn.
        name: String, the name of the branch.  Will be drawn next to the "head" commit.
    commits: Array<Object>, an array of commit objects, in chronological order with (at least), the
      following attributes:
        hash: String, the commit's revision
        parent: Array<String>, the hashes of any parents.
        timestamp: String, the commit's timestamp, formatted like: "2016-02-22T06:34:47-08:00"
    autoroll: Object, which is used to link to the recent autorolls. contains at least:
        currentRollRev: String, git hash of current roll
        lastRollRev: String, git hash of previous roll
        lastRollIssue: Number, issue number tied with previous roll

    //output
    commits_to_load: Number, the number of commits to load.
    reload: Number, the number of seconds that the status page should be reloaded.

  Methods:
    None.

  Events:
    None.
-->
<link rel="import" href="/res/imp/bower_components/paper-input/paper-input.html">

<dom-module id="commits-canvas-sk">
  <template>
    <style>
      #container {
        position: relative;
      }

      #reload {
        position: absolute;
        top: 0;
        left: 0;
      }

      .refresh {
        font-size: 12px;
        font-weight: normal;
        padding: 5px;
      }

      paper-input {
        display: inline-block;
      }
      :host{
        --paper-input-container-input: {
            font-size: 1.0em;
        };
      }
      div[prefix] {
        font-size: 1.0em;
      }

      #commitCanvas {
        position: absolute;
        top: 128px;
        left:0;
        width: 0;
        height: 0;
        z-index: -1;
      }

      #commitCanvas.pointer {
        cursor: pointer;
      }

    </style>

    <div id="container">

      <div id="reload" class="refresh">
        <paper-input type="number" value="{{reload}}" auto-validate no-label-float>
          <div prefix>Reload (s):&nbsp;</div>
        </paper-input>
        <paper-input type="number" value="{{commits_to_load}}" auto-validate no-label-float>
          <div prefix>Commits:&nbsp;</div>
        </paper-input>
        <div>Loaded {{_lastLoaded}}</div>
      </div>

      <!-- The tap event (which was originally used) does not always produce offsetY.
      on-click works for the Pixels (even when touching), so we use that.-->
      <canvas id="commitCanvas" on-click="handleclick" on-mousemove="handlemouseover"></canvas>

    </div>

  </template>
  <script>
  (function() {
    var MIN_CANVAS_WIDTH = 175;
    var commitY = 20;              // Vertical pixels used by each commit.
    var paddingX = 10;             // Left-side padding pixels.
    var paddingY = 20;             // Top padding pixels.
    var radius = 3;                // Radius of commit dots.
    var columnWidth = commitY;     // Pixel width of per-branch colums.
    // Colors used for the branches. Obtained from
    // http://blog.mollietaylor.com/2012/10/color-blindness-and-palette-choice.html
    var palette = [
      "#1B9E77", // Blue/green
      "#D95F02", // Red/orange
      "#7570B3", // Purple
      "#E7298A", // Pink
      "#66A61E", // Light green
      "#E6AB02", // Light orange
      "#A6761D", // Brown
      "#666666", // Gray
    ];
    var commitBg = "#FFFFFF";    // Background color of alternating commits.
    var commitBgAlt = "#EFEFEF"; // Background color of alternating commits.
    var font = "10px monospace"; // Font used for labels.

    var BRANCH_PREFIX = "origin/";

    // Draws a filled-in dot at the given center with the given radius and color.
    function drawDot(ctx, center, radius, color) {
      ctx.fillStyle = color;
      ctx.beginPath();
      ctx.arc(center.x, center.y, radius, 0, 2*Math.PI, false);
      ctx.fill();
      ctx.closePath();
    }

    // Object with an x and y-value.
    function Point(x, y) {
      this.x = x;
      this.y = y;
    }

    // Object representing a commit used for creating layout and drawing.
    function Commit(commitInfo, row) {
      this.hash = commitInfo.hash;
      this.timestamp = new Date(commitInfo.timestamp);
      this.row = row;
      this.column = -1;
      this.label = [];
      this.parents = commitInfo.parent || [];

      // The color for this commit.
      this.color = function() {
        return palette[this.column % palette.length];
      };

      // Where to draw this commit.
      this.getBounds = function() {
        return new Point(paddingX, paddingY - commitY/4 + commitY * this.row);
      };

      // The center of this commit's dot.
      this.dotCenter = function() {
        var start = this.getBounds();
        var centerX = start.x + columnWidth * this.column + radius;
        var centerY = start.y - radius - 2;
        return new Point(centerX, centerY);
      };

      // Coordinates for drawing this commit's label.
      this.labelCoords = function() {
        var bounds = this.getBounds();
        var center = this.dotCenter();
        return new Point(center.x + 3 * radius, bounds.y - 1);
      };

      // Return the text for this commit's label, truncated to 24 characters.
      this.labelText = function() {
        return sk.truncate(this.label.join(","), 24);
      };

      // Return the estimated width of this commit's label text.
      this.labelWidth = function(ctx) {
        return ctx.measureText(this.labelText()).width;
      };

      // Draw an an alternating background color for this commit.
      this.drawBackground = function(ctx) {
        var startY = commitY * this.row;
        var bgColor = this.row % 2 ? commitBg : commitBgAlt;
        ctx.fillStyle = bgColor;
        ctx.fillRect(0, startY, ctx.canvas.clientWidth, startY + commitY);
      };

      // Draw a line connecting this commit to one of its parents.
      this.drawConnection = function(ctx, parent, allCommits) {
        var center = this.dotCenter();
        var to = parent.dotCenter();
        ctx.beginPath();
        ctx.moveTo(center.x, center.y);
        if (this.column == parent.column) {
          // Draw a straight line.
          ctx.lineTo(to.x, to.y);
        } else {
          // Draw a connector composed of five segments: a vertical line, an
          // arc, a horizontal line, another arc, and another vertical line.
          // One or more of the lines may have zero length.
          var arcRadius = commitY / 2;
          // The direction in which to draw the arc.
          var d = center.x > to.x ? 1 : -1;

          // We'll reuse these values, so pre-compute them.
          var halfPI = 0.5 * Math.PI;
          var oneAndHalfPI = 1.5 * Math.PI;

          // If there is at least one commit in the current commit's column
          // between the current commit and this parent, the first arc must
          // begin at the current commit: the first vertical line has zero
          // length. Otherwise, the length of the first vertical line is
          // flexible.
          var v1_flex = true;
          for (var i = 0; i < this.parents.length; i++) {
            var c = allCommits[this.parents[i]];
            if (!c) {
              console.warn("Cannot find " + this.parents[i]);
              continue;
            }
            if (this.timestamp > c.timestamp && c.timestamp > parent.timestamp) {
              if (this.column == c.column) {
                v1_flex = false;
                break;
              }
            }
          }

          // If there is at least one commit in the parent's column between the
          // current commit and this parent, the secon arc must end at the
          // parent commit: the second vertical line has zero length.
          // Otherwise, the length of the second vertical line is flexible.
          var v2_flex = true;
          for (var i = 0; i < parent.children.length; i++) {
            var c = allCommits[parent.children[i]];
            if (this.timestamp > c.timestamp && c.timestamp > parent.timestamp) {
              if (parent.column == c.column) {
                v2_flex = false;
                break;
              }
            }
          }

          // Arc information..
          var a1 = new Point(center.x - d * arcRadius, to.y - commitY);
          var a2 = new Point(to.x + d * arcRadius, to.y);

          // If both vertical lines are flexible, arbitrarily choose where to
          // put the arcs and horizontal line (eg. next to the parent).
          if (v1_flex && v2_flex) {
            a1.y = to.y - commitY;
            a2.y = to.y;
          }
          // If exactly one vertical line is flexible, put the arcs and
          // horizontal line where they must go.
          else if (v1_flex && !v2_flex) {
            a1.y = to.y - commitY;
            a2.y = to.y;
          } else if (!v1_flex && v2_flex) {
            a1.y = center.y;
            a2.y = center.y + commitY;
          }
          // If neither vertical line is flexible, then we have to place arcs
          // at both commits and the "horizontal" line becomes diagonal.
          else {
            a1.y = center.y;
            a2.y = to.y;
          }

          // Distance between the two arc centers.
          var dist = Math.sqrt(Math.pow(a2.x - a1.x, 2) + Math.pow(a2.y - a1.y, 2));
          // Length of the arc to draw.
          var arcLength = Math.PI - Math.acos(2*arcRadius / dist) - Math.acos((Math.abs(to.x - center.x) - 2*arcRadius) / dist);
          var a1_start = halfPI - d * halfPI;
          var a2_start = oneAndHalfPI - d * (halfPI - arcLength);

          // Draw the connector: vertical line, arc, horizontal line, arc,
          // vertical line.
          ctx.lineTo(a1.x + d*arcRadius, a1.y);
          ctx.arc(a1.x, a1.y, arcRadius, a1_start, a1_start + d*arcLength, d < 0);
          // The middle line doesn't need to be explicitly drawn.
          ctx.arc(a2.x, a2.y, arcRadius, a2_start, a2_start - d*arcLength, d > 0);
          ctx.lineTo(to.x, to.y);
        }
        ctx.strokeStyle = this.color();
        ctx.stroke();
      };

      // Draw this commit's label.
      this.drawLabel = function(ctx) {
        if (this.label.length <= 0) {
          return;
        }
        labelCoords = this.labelCoords();
        var w = this.labelWidth(ctx);
        var h = parseInt(font);
        var paddingY = 3;
        var paddingX = 3;
        ctx.fillStyle = this.color();
        ctx.fillRect(labelCoords.x - paddingX, labelCoords.y - h, w + 2 * paddingX, h + paddingY);
        ctx.fillStyle = "#FFFFFF";
        ctx.fillText(this.labelText(), labelCoords.x, labelCoords.y);
      };

      this.draw = function(ctx, displayCommits) {
        var color = this.color();
        var center = this.dotCenter();

        // Connect the dots.
        for (var p = 0; p < this.parents.length; p++) {
          var parent = displayCommits[this.parents[p]];
          if (!displayCommits[this.parents[p]]) {
            console.warn("Cannot find " + this.parents[p]);
            continue;
          }
          this.drawConnection(ctx, parent, displayCommits);
        }

        // Draw a dot.
        drawDot(ctx, center, radius, color);

        // Draw a label, if applicable.
        this.drawLabel(ctx);
      };
    }

    // Follow commits by first parent, assigning the given column until we get
    // to a commit that we aren't going to draw.
    function traceCommits(displayCommits, commits, remaining, hash, column) {
      var usedColumn = false;
      while(remaining[hash]) {
        var c = displayCommits[hash];
        c.column = column;
        delete remaining[hash];
        hash = c.parents[0];
        usedColumn = true;
        // Special case for non-displayed parents.
        if (!displayCommits[hash]) {
          var parent = new Commit({
            hash: hash,
          }, commits.length);
          parent.column = c.column;
          displayCommits[hash] = parent;
        }
      }
      return usedColumn;
    }

    // Create Commit objects to be displayed. Assigns rows and columns for each
    // commit to assist in producing a nice layout.
    function prepareCommitsForDisplay(commits, branch_heads) {
      // Create a Commit object for each commit.
      var displayCommits = {}; // Commit objects by hash.
      var remaining = {};      // Not-yet-processed commits by hash.
      for (var i = 0; i < commits.length; i++) {
        var c = new Commit(commits[i], i)
        displayCommits[c.hash] = c;
        remaining[c.hash] = c;
      }

      // Pre-process the branches. We want master first, and no HEAD.
      var masterIdx = -1;
      var branches = [];
      for (var b = 0; b < branch_heads.length; b++) {
        if (branch_heads[b].name == "master") {
          masterIdx = b;
          branches.push(branch_heads[b]);
        }
      }
      for (var b = 0; b < branch_heads.length; b++) {
        var branch = branch_heads[b];
        if (b != masterIdx && branch.name != "HEAD") {
          branches.push(branch);
        }
      }

      // Trace each branch, placing commits on that branch in an associated column.
      var column = 0;
      for (var b = 0; b < branches.length; b++) {
        // Add a label to commits at branch heads.
        var hash = branches[b].head
        // The branch might have scrolled out of the time window. If so, just
        // skip it.
        if (!displayCommits[hash]) {
          continue
        }
        displayCommits[hash].label.push(branches[b].name);
        if (traceCommits(displayCommits, commits, remaining, hash, column)) {
          column++;
        }
      }

      // Add the remaining commits to their own columns.
      for (var hash in remaining) {
        if (traceCommits(displayCommits, commits, remaining, hash, column)) {
          column++;
        }
      }

      // Point all parents at their children, for convenience.
      for (var hash in displayCommits) {
        displayCommits[hash].children = [];
      }
      for (var hash in displayCommits) {
        var c = displayCommits[hash];
        if (c.parents) {
          for (var i = 0; i < c.parents.length; i++) {
            if (!displayCommits[c.parents[i]]) {
              console.warn("Cannot find " + c.parents[i]);
              continue;
            }
            displayCommits[c.parents[i]].children.push(c.hash);
          }
        }
      }

      return [displayCommits, column];
    }

    Polymer({
      is: "commits-canvas-sk",
      properties: {
        // input
        autoroll: {
          type: Object,
        },
        branch_heads: {
          type: Array,
        },
        commits: {
          type: Array,
        },
        repo_base: {
          type: String,
        },

        // output
        commits_to_load: {
          type: Number,
          value: 35,
          notify: true,
        },
        reload: {
          type: Number,
          value: 60,
          notify: true,
        },

        // private
        _linkMap: {
          // Number: String, number is index of commit in display, String is URL to link to.
          type: Object,
          computed: "_computeLinkMap(commits.*,autoroll.*, branch_heads.*)",
        },
        _lastLoaded: {
          type: String,
          value: "(not yet loaded)",
        },
      },

      observers: [
        "draw(commits.*, branch_heads.*)"
      ],

      draw: function() {
        var commits = this.commits;
        var branch_heads = this.branch_heads;
        this._lastLoaded = new Date().toLocaleTimeString();
        console.time("draw");
        // Initialize all commits.
        var prep = prepareCommitsForDisplay(commits, branch_heads);
        this.displayCommits = prep[0];
        var numColumns = prep[1];

        // Calculate the required canvas width based on the commit columns and
        // labels.
        // TODO(borenet): Further minimize this width by reordering the columns
        // based on which has the longest label.
        var dummyCtx = document.createElement("canvas").getContext("2d");
        dummyCtx.font = font;
        var longestWidth = 0;
        for (var i = 0; i < commits.length; i++) {
          var c = this.displayCommits[commits[i].hash];
          var w = c.labelWidth(dummyCtx);
          w += commitY * (c.column + 1);
          if (w > longestWidth) {
            longestWidth = w;
          }
        }

        // Redraw the canvas.
        var scale = window.devicePixelRatio || 1.0;
        var canvas = this.$.commitCanvas;
        this.canvasWidth = Math.max(longestWidth + paddingX, MIN_CANVAS_WIDTH);
        this.canvasHeight = commitY * commits.length;
        canvas.style.width = Math.floor(this.canvasWidth) + "px";
        canvas.style.height = Math.floor(this.canvasHeight) + "px";
        canvas.width = this.canvasWidth * scale;
        canvas.height = this.canvasHeight * scale;
        var ctx = canvas.getContext("2d");
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        ctx.setTransform(scale, 0, 0, scale, 0, 0);
        ctx.font = font;

        // Shade an alternating background.
        for (var i = 0; i < commits.length; i++) {
          this.displayCommits[commits[i].hash].drawBackground(ctx);
        }

        // Draw the commits.
        for (var i = 0; i < commits.length; i++) {
          this.displayCommits[commits[i].hash].draw(ctx, this.displayCommits);
        }

        console.timeEnd("draw");
      },

      // _computeLinkMap looks through all the branch_heads, finds the index of each
      // commit belonging to a branch and makes a map of index -> URL.  Then, it handles
      // the special case of current autoroll and previous autoroll.
      _computeLinkMap: function() {
        var linkMap = {};

        // Link to generic branch heads.
        this.branch_heads.forEach(function(branch) {
          var name = branch.name;
          if (branch.name.startsWith(BRANCH_PREFIX)) {
            var name = branch.name.slice(BRANCH_PREFIX.length);
          }
          // If the commit is not found in the range of commits, we will just be
          // overwriting the value at key "-1", which won't actually get used.
          var idx = this._indexOfRevision(branch.head);
          linkMap[idx] = this.repo_base + name;
        }.bind(this));

        // Link to the deps
        var idx = this._indexOfRevision(this.autoroll.currentRollRev);
        linkMap[idx] = "https://autoroll.skia.org",
        idx = this._indexOfRevision(this.autoroll.lastRollRev);
        linkMap[idx] = "https://crrev.com/" + this.autoroll.lastRollIssue

        return linkMap;
      },

      _indexOfRevision: function(revision) {
        var idx = -1;
        this.commits.forEach(function(c,i){
          if (c.hash === revision){
            idx = i;
          }
        });
        return idx;
      },

      // handleclick converts the click's offsetY (Y location relative to the tapped canvas) into index
      handleclick: function(e) {
        var y = (e && e.offsetY) || 1;
        var commitIdx = Math.floor(y / commitY);

        var link = this._linkMap[commitIdx];
        if (link){
          window.open(link);
        }
      },

      handlemouseover: function(e) {
        var commitIdx = Math.floor(e.offsetY / commitY);
        var link = this._linkMap[commitIdx];
        if (link){
          this.$.commitCanvas.classList.add("pointer");
        } else {
          this.$.commitCanvas.classList.remove("pointer");
        }
      },

    });
  })();
  </script>
</dom-module>