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/*!
 * chartjs-plugin-datalabels v2.0.0
 * https://chartjs-plugin-datalabels.netlify.app
 * (c) 2017-2021 chartjs-plugin-datalabels contributors
 * Released under the MIT license
 */
import { isNullOrUndef, merge, toFont, resolve, toPadding, valueOrDefault, callback, isObject, each } from 'chart.js/helpers';
import { defaults as defaults$1, ArcElement, PointElement, BarElement } from 'chart.js';

var devicePixelRatio = (function() {
  if (typeof window !== 'undefined') {
    if (window.devicePixelRatio) {
      return window.devicePixelRatio;
    }

    // devicePixelRatio is undefined on IE10
    // https://stackoverflow.com/a/20204180/8837887
    // https://github.com/chartjs/chartjs-plugin-datalabels/issues/85
    var screen = window.screen;
    if (screen) {
      return (screen.deviceXDPI || 1) / (screen.logicalXDPI || 1);
    }
  }

  return 1;
}());

var utils = {
  // @todo move this in Chart.helpers.toTextLines
  toTextLines: function(inputs) {
    var lines = [];
    var input;

    inputs = [].concat(inputs);
    while (inputs.length) {
      input = inputs.pop();
      if (typeof input === 'string') {
        lines.unshift.apply(lines, input.split('\n'));
      } else if (Array.isArray(input)) {
        inputs.push.apply(inputs, input);
      } else if (!isNullOrUndef(inputs)) {
        lines.unshift('' + input);
      }
    }

    return lines;
  },

  // @todo move this in Chart.helpers.canvas.textSize
  // @todo cache calls of measureText if font doesn't change?!
  textSize: function(ctx, lines, font) {
    var items = [].concat(lines);
    var ilen = items.length;
    var prev = ctx.font;
    var width = 0;
    var i;

    ctx.font = font.string;

    for (i = 0; i < ilen; ++i) {
      width = Math.max(ctx.measureText(items[i]).width, width);
    }

    ctx.font = prev;

    return {
      height: ilen * font.lineHeight,
      width: width
    };
  },

  /**
   * Returns value bounded by min and max. This is equivalent to max(min, min(value, max)).
   * @todo move this method in Chart.helpers.bound
   * https://doc.qt.io/qt-5/qtglobal.html#qBound
   */
  bound: function(min, value, max) {
    return Math.max(min, Math.min(value, max));
  },

  /**
   * Returns an array of pair [value, state] where state is:
   * * -1: value is only in a0 (removed)
   * *  1: value is only in a1 (added)
   */
  arrayDiff: function(a0, a1) {
    var prev = a0.slice();
    var updates = [];
    var i, j, ilen, v;

    for (i = 0, ilen = a1.length; i < ilen; ++i) {
      v = a1[i];
      j = prev.indexOf(v);

      if (j === -1) {
        updates.push([v, 1]);
      } else {
        prev.splice(j, 1);
      }
    }

    for (i = 0, ilen = prev.length; i < ilen; ++i) {
      updates.push([prev[i], -1]);
    }

    return updates;
  },

  /**
   * https://github.com/chartjs/chartjs-plugin-datalabels/issues/70
   */
  rasterize: function(v) {
    return Math.round(v * devicePixelRatio) / devicePixelRatio;
  }
};

function orient(point, origin) {
  var x0 = origin.x;
  var y0 = origin.y;

  if (x0 === null) {
    return {x: 0, y: -1};
  }
  if (y0 === null) {
    return {x: 1, y: 0};
  }

  var dx = point.x - x0;
  var dy = point.y - y0;
  var ln = Math.sqrt(dx * dx + dy * dy);

  return {
    x: ln ? dx / ln : 0,
    y: ln ? dy / ln : -1
  };
}

function aligned(x, y, vx, vy, align) {
  switch (align) {
  case 'center':
    vx = vy = 0;
    break;
  case 'bottom':
    vx = 0;
    vy = 1;
    break;
  case 'right':
    vx = 1;
    vy = 0;
    break;
  case 'left':
    vx = -1;
    vy = 0;
    break;
  case 'top':
    vx = 0;
    vy = -1;
    break;
  case 'start':
    vx = -vx;
    vy = -vy;
    break;
  case 'end':
    // keep natural orientation
    break;
  default:
    // clockwise rotation (in degree)
    align *= (Math.PI / 180);
    vx = Math.cos(align);
    vy = Math.sin(align);
    break;
  }

  return {
    x: x,
    y: y,
    vx: vx,
    vy: vy
  };
}

// Line clipping (Cohen–Sutherland algorithm)
// https://en.wikipedia.org/wiki/Cohen–Sutherland_algorithm

var R_INSIDE = 0;
var R_LEFT = 1;
var R_RIGHT = 2;
var R_BOTTOM = 4;
var R_TOP = 8;

function region(x, y, rect) {
  var res = R_INSIDE;

  if (x < rect.left) {
    res |= R_LEFT;
  } else if (x > rect.right) {
    res |= R_RIGHT;
  }
  if (y < rect.top) {
    res |= R_TOP;
  } else if (y > rect.bottom) {
    res |= R_BOTTOM;
  }

  return res;
}

function clipped(segment, area) {
  var x0 = segment.x0;
  var y0 = segment.y0;
  var x1 = segment.x1;
  var y1 = segment.y1;
  var r0 = region(x0, y0, area);
  var r1 = region(x1, y1, area);
  var r, x, y;

  // eslint-disable-next-line no-constant-condition
  while (true) {
    if (!(r0 | r1) || (r0 & r1)) {
      // both points inside or on the same side: no clipping
      break;
    }

    // at least one point is outside
    r = r0 || r1;

    if (r & R_TOP) {
      x = x0 + (x1 - x0) * (area.top - y0) / (y1 - y0);
      y = area.top;
    } else if (r & R_BOTTOM) {
      x = x0 + (x1 - x0) * (area.bottom - y0) / (y1 - y0);
      y = area.bottom;
    } else if (r & R_RIGHT) {
      y = y0 + (y1 - y0) * (area.right - x0) / (x1 - x0);
      x = area.right;
    } else if (r & R_LEFT) {
      y = y0 + (y1 - y0) * (area.left - x0) / (x1 - x0);
      x = area.left;
    }

    if (r === r0) {
      x0 = x;
      y0 = y;
      r0 = region(x0, y0, area);
    } else {
      x1 = x;
      y1 = y;
      r1 = region(x1, y1, area);
    }
  }

  return {
    x0: x0,
    x1: x1,
    y0: y0,
    y1: y1
  };
}

function compute$1(range, config) {
  var anchor = config.anchor;
  var segment = range;
  var x, y;

  if (config.clamp) {
    segment = clipped(segment, config.area);
  }

  if (anchor === 'start') {
    x = segment.x0;
    y = segment.y0;
  } else if (anchor === 'end') {
    x = segment.x1;
    y = segment.y1;
  } else {
    x = (segment.x0 + segment.x1) / 2;
    y = (segment.y0 + segment.y1) / 2;
  }

  return aligned(x, y, range.vx, range.vy, config.align);
}

var positioners = {
  arc: function(el, config) {
    var angle = (el.startAngle + el.endAngle) / 2;
    var vx = Math.cos(angle);
    var vy = Math.sin(angle);
    var r0 = el.innerRadius;
    var r1 = el.outerRadius;

    return compute$1({
      x0: el.x + vx * r0,
      y0: el.y + vy * r0,
      x1: el.x + vx * r1,
      y1: el.y + vy * r1,
      vx: vx,
      vy: vy
    }, config);
  },

  point: function(el, config) {
    var v = orient(el, config.origin);
    var rx = v.x * el.options.radius;
    var ry = v.y * el.options.radius;

    return compute$1({
      x0: el.x - rx,
      y0: el.y - ry,
      x1: el.x + rx,
      y1: el.y + ry,
      vx: v.x,
      vy: v.y
    }, config);
  },

  bar: function(el, config) {
    var v = orient(el, config.origin);
    var x = el.x;
    var y = el.y;
    var sx = 0;
    var sy = 0;

    if (el.horizontal) {
      x = Math.min(el.x, el.base);
      sx = Math.abs(el.base - el.x);
    } else {
      y = Math.min(el.y, el.base);
      sy = Math.abs(el.base - el.y);
    }

    return compute$1({
      x0: x,
      y0: y + sy,
      x1: x + sx,
      y1: y,
      vx: v.x,
      vy: v.y
    }, config);
  },

  fallback: function(el, config) {
    var v = orient(el, config.origin);

    return compute$1({
      x0: el.x,
      y0: el.y,
      x1: el.x,
      y1: el.y,
      vx: v.x,
      vy: v.y
    }, config);
  }
};

var rasterize = utils.rasterize;

function boundingRects(model) {
  var borderWidth = model.borderWidth || 0;
  var padding = model.padding;
  var th = model.size.height;
  var tw = model.size.width;
  var tx = -tw / 2;
  var ty = -th / 2;

  return {
    frame: {
      x: tx - padding.left - borderWidth,
      y: ty - padding.top - borderWidth,
      w: tw + padding.width + borderWidth * 2,
      h: th + padding.height + borderWidth * 2
    },
    text: {
      x: tx,
      y: ty,
      w: tw,
      h: th
    }
  };
}

function getScaleOrigin(el, context) {
  var scale = context.chart.getDatasetMeta(context.datasetIndex).vScale;

  if (!scale) {
    return null;
  }

  if (scale.xCenter !== undefined && scale.yCenter !== undefined) {
    return {x: scale.xCenter, y: scale.yCenter};
  }

  var pixel = scale.getBasePixel();
  return el.horizontal ?
    {x: pixel, y: null} :
    {x: null, y: pixel};
}

function getPositioner(el) {
  if (el instanceof ArcElement) {
    return positioners.arc;
  }
  if (el instanceof PointElement) {
    return positioners.point;
  }
  if (el instanceof BarElement) {
    return positioners.bar;
  }
  return positioners.fallback;
}

function drawRoundedRect(ctx, x, y, w, h, radius) {
  var HALF_PI = Math.PI / 2;

  if (radius) {
    var r = Math.min(radius, h / 2, w / 2);
    var left = x + r;
    var top = y + r;
    var right = x + w - r;
    var bottom = y + h - r;

    ctx.moveTo(x, top);
    if (left < right && top < bottom) {
      ctx.arc(left, top, r, -Math.PI, -HALF_PI);
      ctx.arc(right, top, r, -HALF_PI, 0);
      ctx.arc(right, bottom, r, 0, HALF_PI);
      ctx.arc(left, bottom, r, HALF_PI, Math.PI);
    } else if (left < right) {
      ctx.moveTo(left, y);
      ctx.arc(right, top, r, -HALF_PI, HALF_PI);
      ctx.arc(left, top, r, HALF_PI, Math.PI + HALF_PI);
    } else if (top < bottom) {
      ctx.arc(left, top, r, -Math.PI, 0);
      ctx.arc(left, bottom, r, 0, Math.PI);
    } else {
      ctx.arc(left, top, r, -Math.PI, Math.PI);
    }
    ctx.closePath();
    ctx.moveTo(x, y);
  } else {
    ctx.rect(x, y, w, h);
  }
}

function drawFrame(ctx, rect, model) {
  var bgColor = model.backgroundColor;
  var borderColor = model.borderColor;
  var borderWidth = model.borderWidth;

  if (!bgColor && (!borderColor || !borderWidth)) {
    return;
  }

  ctx.beginPath();

  drawRoundedRect(
    ctx,
    rasterize(rect.x) + borderWidth / 2,
    rasterize(rect.y) + borderWidth / 2,
    rasterize(rect.w) - borderWidth,
    rasterize(rect.h) - borderWidth,
    model.borderRadius);

  ctx.closePath();

  if (bgColor) {
    ctx.fillStyle = bgColor;
    ctx.fill();
  }

  if (borderColor && borderWidth) {
    ctx.strokeStyle = borderColor;
    ctx.lineWidth = borderWidth;
    ctx.lineJoin = 'miter';
    ctx.stroke();
  }
}

function textGeometry(rect, align, font) {
  var h = font.lineHeight;
  var w = rect.w;
  var x = rect.x;
  var y = rect.y + h / 2;

  if (align === 'center') {
    x += w / 2;
  } else if (align === 'end' || align === 'right') {
    x += w;
  }

  return {
    h: h,
    w: w,
    x: x,
    y: y
  };
}

function drawTextLine(ctx, text, cfg) {
  var shadow = ctx.shadowBlur;
  var stroked = cfg.stroked;
  var x = rasterize(cfg.x);
  var y = rasterize(cfg.y);
  var w = rasterize(cfg.w);

  if (stroked) {
    ctx.strokeText(text, x, y, w);
  }

  if (cfg.filled) {
    if (shadow && stroked) {
      // Prevent drawing shadow on both the text stroke and fill, so
      // if the text is stroked, remove the shadow for the text fill.
      ctx.shadowBlur = 0;
    }

    ctx.fillText(text, x, y, w);

    if (shadow && stroked) {
      ctx.shadowBlur = shadow;
    }
  }
}

function drawText(ctx, lines, rect, model) {
  var align = model.textAlign;
  var color = model.color;
  var filled = !!color;
  var font = model.font;
  var ilen = lines.length;
  var strokeColor = model.textStrokeColor;
  var strokeWidth = model.textStrokeWidth;
  var stroked = strokeColor && strokeWidth;
  var i;

  if (!ilen || (!filled && !stroked)) {
    return;
  }

  // Adjust coordinates based on text alignment and line height
  rect = textGeometry(rect, align, font);

  ctx.font = font.string;
  ctx.textAlign = align;
  ctx.textBaseline = 'middle';
  ctx.shadowBlur = model.textShadowBlur;
  ctx.shadowColor = model.textShadowColor;

  if (filled) {
    ctx.fillStyle = color;
  }
  if (stroked) {
    ctx.lineJoin = 'round';
    ctx.lineWidth = strokeWidth;
    ctx.strokeStyle = strokeColor;
  }

  for (i = 0, ilen = lines.length; i < ilen; ++i) {
    drawTextLine(ctx, lines[i], {
      stroked: stroked,
      filled: filled,
      w: rect.w,
      x: rect.x,
      y: rect.y + rect.h * i
    });
  }
}

var Label = function(config, ctx, el, index) {
  var me = this;

  me._config = config;
  me._index = index;
  me._model = null;
  me._rects = null;
  me._ctx = ctx;
  me._el = el;
};

merge(Label.prototype, {
  /**
   * @private
   */
  _modelize: function(display, lines, config, context) {
    var me = this;
    var index = me._index;
    var font = toFont(resolve([config.font, {}], context, index));
    var color = resolve([config.color, defaults$1.color], context, index);

    return {
      align: resolve([config.align, 'center'], context, index),
      anchor: resolve([config.anchor, 'center'], context, index),
      area: context.chart.chartArea,
      backgroundColor: resolve([config.backgroundColor, null], context, index),
      borderColor: resolve([config.borderColor, null], context, index),
      borderRadius: resolve([config.borderRadius, 0], context, index),
      borderWidth: resolve([config.borderWidth, 0], context, index),
      clamp: resolve([config.clamp, false], context, index),
      clip: resolve([config.clip, false], context, index),
      color: color,
      display: display,
      font: font,
      lines: lines,
      offset: resolve([config.offset, 0], context, index),
      opacity: resolve([config.opacity, 1], context, index),
      origin: getScaleOrigin(me._el, context),
      padding: toPadding(resolve([config.padding, 0], context, index)),
      positioner: getPositioner(me._el),
      rotation: resolve([config.rotation, 0], context, index) * (Math.PI / 180),
      size: utils.textSize(me._ctx, lines, font),
      textAlign: resolve([config.textAlign, 'start'], context, index),
      textShadowBlur: resolve([config.textShadowBlur, 0], context, index),
      textShadowColor: resolve([config.textShadowColor, color], context, index),
      textStrokeColor: resolve([config.textStrokeColor, color], context, index),
      textStrokeWidth: resolve([config.textStrokeWidth, 0], context, index)
    };
  },

  update: function(context) {
    var me = this;
    var model = null;
    var rects = null;
    var index = me._index;
    var config = me._config;
    var value, label, lines;

    // We first resolve the display option (separately) to avoid computing
    // other options in case the label is hidden (i.e. display: false).
    var display = resolve([config.display, true], context, index);

    if (display) {
      value = context.dataset.data[index];
      label = valueOrDefault(callback(config.formatter, [value, context]), value);
      lines = isNullOrUndef(label) ? [] : utils.toTextLines(label);

      if (lines.length) {
        model = me._modelize(display, lines, config, context);
        rects = boundingRects(model);
      }
    }

    me._model = model;
    me._rects = rects;
  },

  geometry: function() {
    return this._rects ? this._rects.frame : {};
  },

  rotation: function() {
    return this._model ? this._model.rotation : 0;
  },

  visible: function() {
    return this._model && this._model.opacity;
  },

  model: function() {
    return this._model;
  },

  draw: function(chart, center) {
    var me = this;
    var ctx = chart.ctx;
    var model = me._model;
    var rects = me._rects;
    var area;

    if (!this.visible()) {
      return;
    }

    ctx.save();

    if (model.clip) {
      area = model.area;
      ctx.beginPath();
      ctx.rect(
        area.left,
        area.top,
        area.right - area.left,
        area.bottom - area.top);
      ctx.clip();
    }

    ctx.globalAlpha = utils.bound(0, model.opacity, 1);
    ctx.translate(rasterize(center.x), rasterize(center.y));
    ctx.rotate(model.rotation);

    drawFrame(ctx, rects.frame, model);
    drawText(ctx, model.lines, rects.text, model);

    ctx.restore();
  }
});

var MIN_INTEGER = Number.MIN_SAFE_INTEGER || -9007199254740991; // eslint-disable-line es/no-number-minsafeinteger
var MAX_INTEGER = Number.MAX_SAFE_INTEGER || 9007199254740991;  // eslint-disable-line es/no-number-maxsafeinteger

function rotated(point, center, angle) {
  var cos = Math.cos(angle);
  var sin = Math.sin(angle);
  var cx = center.x;
  var cy = center.y;

  return {
    x: cx + cos * (point.x - cx) - sin * (point.y - cy),
    y: cy + sin * (point.x - cx) + cos * (point.y - cy)
  };
}

function projected(points, axis) {
  var min = MAX_INTEGER;
  var max = MIN_INTEGER;
  var origin = axis.origin;
  var i, pt, vx, vy, dp;

  for (i = 0; i < points.length; ++i) {
    pt = points[i];
    vx = pt.x - origin.x;
    vy = pt.y - origin.y;
    dp = axis.vx * vx + axis.vy * vy;
    min = Math.min(min, dp);
    max = Math.max(max, dp);
  }

  return {
    min: min,
    max: max
  };
}

function toAxis(p0, p1) {
  var vx = p1.x - p0.x;
  var vy = p1.y - p0.y;
  var ln = Math.sqrt(vx * vx + vy * vy);

  return {
    vx: (p1.x - p0.x) / ln,
    vy: (p1.y - p0.y) / ln,
    origin: p0,
    ln: ln
  };
}

var HitBox = function() {
  this._rotation = 0;
  this._rect = {
    x: 0,
    y: 0,
    w: 0,
    h: 0
  };
};

merge(HitBox.prototype, {
  center: function() {
    var r = this._rect;
    return {
      x: r.x + r.w / 2,
      y: r.y + r.h / 2
    };
  },

  update: function(center, rect, rotation) {
    this._rotation = rotation;
    this._rect = {
      x: rect.x + center.x,
      y: rect.y + center.y,
      w: rect.w,
      h: rect.h
    };
  },

  contains: function(point) {
    var me = this;
    var margin = 1;
    var rect = me._rect;

    point = rotated(point, me.center(), -me._rotation);

    return !(point.x < rect.x - margin
      || point.y < rect.y - margin
      || point.x > rect.x + rect.w + margin * 2
      || point.y > rect.y + rect.h + margin * 2);
  },

  // Separating Axis Theorem
  // https://gamedevelopment.tutsplus.com/tutorials/collision-detection-using-the-separating-axis-theorem--gamedev-169
  intersects: function(other) {
    var r0 = this._points();
    var r1 = other._points();
    var axes = [
      toAxis(r0[0], r0[1]),
      toAxis(r0[0], r0[3])
    ];
    var i, pr0, pr1;

    if (this._rotation !== other._rotation) {
      // Only separate with r1 axis if the rotation is different,
      // else it's enough to separate r0 and r1 with r0 axis only!
      axes.push(
        toAxis(r1[0], r1[1]),
        toAxis(r1[0], r1[3])
      );
    }

    for (i = 0; i < axes.length; ++i) {
      pr0 = projected(r0, axes[i]);
      pr1 = projected(r1, axes[i]);

      if (pr0.max < pr1.min || pr1.max < pr0.min) {
        return false;
      }
    }

    return true;
  },

  /**
   * @private
   */
  _points: function() {
    var me = this;
    var rect = me._rect;
    var angle = me._rotation;
    var center = me.center();

    return [
      rotated({x: rect.x, y: rect.y}, center, angle),
      rotated({x: rect.x + rect.w, y: rect.y}, center, angle),
      rotated({x: rect.x + rect.w, y: rect.y + rect.h}, center, angle),
      rotated({x: rect.x, y: rect.y + rect.h}, center, angle)
    ];
  }
});

function coordinates(el, model, geometry) {
  var point = model.positioner(el, model);
  var vx = point.vx;
  var vy = point.vy;

  if (!vx && !vy) {
    // if aligned center, we don't want to offset the center point
    return {x: point.x, y: point.y};
  }

  var w = geometry.w;
  var h = geometry.h;

  // take in account the label rotation
  var rotation = model.rotation;
  var dx = Math.abs(w / 2 * Math.cos(rotation)) + Math.abs(h / 2 * Math.sin(rotation));
  var dy = Math.abs(w / 2 * Math.sin(rotation)) + Math.abs(h / 2 * Math.cos(rotation));

  // scale the unit vector (vx, vy) to get at least dx or dy equal to
  // w or h respectively (else we would calculate the distance to the
  // ellipse inscribed in the bounding rect)
  var vs = 1 / Math.max(Math.abs(vx), Math.abs(vy));
  dx *= vx * vs;
  dy *= vy * vs;

  // finally, include the explicit offset
  dx += model.offset * vx;
  dy += model.offset * vy;

  return {
    x: point.x + dx,
    y: point.y + dy
  };
}

function collide(labels, collider) {
  var i, j, s0, s1;

  // IMPORTANT Iterate in the reverse order since items at the end of the
  // list have an higher weight/priority and thus should be less impacted
  // by the overlapping strategy.

  for (i = labels.length - 1; i >= 0; --i) {
    s0 = labels[i].$layout;

    for (j = i - 1; j >= 0 && s0._visible; --j) {
      s1 = labels[j].$layout;

      if (s1._visible && s0._box.intersects(s1._box)) {
        collider(s0, s1);
      }
    }
  }

  return labels;
}

function compute(labels) {
  var i, ilen, label, state, geometry, center, proxy;

  // Initialize labels for overlap detection
  for (i = 0, ilen = labels.length; i < ilen; ++i) {
    label = labels[i];
    state = label.$layout;

    if (state._visible) {
      // Chart.js 3 removed el._model in favor of getProps(), making harder to
      // abstract reading values in positioners. Also, using string arrays to
      // read values (i.e. var {a,b,c} = el.getProps(["a","b","c"])) would make
      // positioners inefficient in the normal case (i.e. not the final values)
      // and the code a bit ugly, so let's use a Proxy instead.
      proxy = new Proxy(label._el, {get: (el, p) => el.getProps([p], true)[p]});

      geometry = label.geometry();
      center = coordinates(proxy, label.model(), geometry);
      state._box.update(center, geometry, label.rotation());
    }
  }

  // Auto hide overlapping labels
  return collide(labels, function(s0, s1) {
    var h0 = s0._hidable;
    var h1 = s1._hidable;

    if ((h0 && h1) || h1) {
      s1._visible = false;
    } else if (h0) {
      s0._visible = false;
    }
  });
}

var layout = {
  prepare: function(datasets) {
    var labels = [];
    var i, j, ilen, jlen, label;

    for (i = 0, ilen = datasets.length; i < ilen; ++i) {
      for (j = 0, jlen = datasets[i].length; j < jlen; ++j) {
        label = datasets[i][j];
        labels.push(label);
        label.$layout = {
          _box: new HitBox(),
          _hidable: false,
          _visible: true,
          _set: i,
          _idx: j
        };
      }
    }

    // TODO New `z` option: labels with a higher z-index are drawn
    // of top of the ones with a lower index. Lowest z-index labels
    // are also discarded first when hiding overlapping labels.
    labels.sort(function(a, b) {
      var sa = a.$layout;
      var sb = b.$layout;

      return sa._idx === sb._idx
        ? sb._set - sa._set
        : sb._idx - sa._idx;
    });

    this.update(labels);

    return labels;
  },

  update: function(labels) {
    var dirty = false;
    var i, ilen, label, model, state;

    for (i = 0, ilen = labels.length; i < ilen; ++i) {
      label = labels[i];
      model = label.model();
      state = label.$layout;
      state._hidable = model && model.display === 'auto';
      state._visible = label.visible();
      dirty |= state._hidable;
    }

    if (dirty) {
      compute(labels);
    }
  },

  lookup: function(labels, point) {
    var i, state;

    // IMPORTANT Iterate in the reverse order since items at the end of
    // the list have an higher z-index, thus should be picked first.

    for (i = labels.length - 1; i >= 0; --i) {
      state = labels[i].$layout;

      if (state && state._visible && state._box.contains(point)) {
        return labels[i];
      }
    }

    return null;
  },

  draw: function(chart, labels) {
    var i, ilen, label, state, geometry, center;

    for (i = 0, ilen = labels.length; i < ilen; ++i) {
      label = labels[i];
      state = label.$layout;

      if (state._visible) {
        geometry = label.geometry();
        center = coordinates(label._el, label.model(), geometry);
        state._box.update(center, geometry, label.rotation());
        label.draw(chart, center);
      }
    }
  }
};

var formatter = function(value) {
  if (isNullOrUndef(value)) {
    return null;
  }

  var label = value;
  var keys, klen, k;
  if (isObject(value)) {
    if (!isNullOrUndef(value.label)) {
      label = value.label;
    } else if (!isNullOrUndef(value.r)) {
      label = value.r;
    } else {
      label = '';
      keys = Object.keys(value);
      for (k = 0, klen = keys.length; k < klen; ++k) {
        label += (k !== 0 ? ', ' : '') + keys[k] + ': ' + value[keys[k]];
      }
    }
  }

  return '' + label;
};

/**
 * IMPORTANT: make sure to also update tests and TypeScript definition
 * files (`/test/specs/defaults.spec.js` and `/types/options.d.ts`)
 */

var defaults = {
  align: 'center',
  anchor: 'center',
  backgroundColor: null,
  borderColor: null,
  borderRadius: 0,
  borderWidth: 0,
  clamp: false,
  clip: false,
  color: undefined,
  display: true,
  font: {
    family: undefined,
    lineHeight: 1.2,
    size: undefined,
    style: undefined,
    weight: null
  },
  formatter: formatter,
  labels: undefined,
  listeners: {},
  offset: 4,
  opacity: 1,
  padding: {
    top: 4,
    right: 4,
    bottom: 4,
    left: 4
  },
  rotation: 0,
  textAlign: 'start',
  textStrokeColor: undefined,
  textStrokeWidth: 0,
  textShadowBlur: 0,
  textShadowColor: undefined
};

/**
 * @see https://github.com/chartjs/Chart.js/issues/4176
 */

var EXPANDO_KEY = '$datalabels';
var DEFAULT_KEY = '$default';

function configure(dataset, options) {
  var override = dataset.datalabels;
  var listeners = {};
  var configs = [];
  var labels, keys;

  if (override === false) {
    return null;
  }
  if (override === true) {
    override = {};
  }

  options = merge({}, [options, override]);
  labels = options.labels || {};
  keys = Object.keys(labels);
  delete options.labels;

  if (keys.length) {
    keys.forEach(function(key) {
      if (labels[key]) {
        configs.push(merge({}, [
          options,
          labels[key],
          {_key: key}
        ]));
      }
    });
  } else {
    // Default label if no "named" label defined.
    configs.push(options);
  }

  // listeners: {<event-type>: {<label-key>: <fn>}}
  listeners = configs.reduce(function(target, config) {
    each(config.listeners || {}, function(fn, event) {
      target[event] = target[event] || {};
      target[event][config._key || DEFAULT_KEY] = fn;
    });

    delete config.listeners;
    return target;
  }, {});

  return {
    labels: configs,
    listeners: listeners
  };
}

function dispatchEvent(chart, listeners, label) {
  if (!listeners) {
    return;
  }

  var context = label.$context;
  var groups = label.$groups;
  var callback$1;

  if (!listeners[groups._set]) {
    return;
  }

  callback$1 = listeners[groups._set][groups._key];
  if (!callback$1) {
    return;
  }

  if (callback(callback$1, [context]) === true) {
    // Users are allowed to tweak the given context by injecting values that can be
    // used in scriptable options to display labels differently based on the current
    // event (e.g. highlight an hovered label). That's why we update the label with
    // the output context and schedule a new chart render by setting it dirty.
    chart[EXPANDO_KEY]._dirty = true;
    label.update(context);
  }
}

function dispatchMoveEvents(chart, listeners, previous, label) {
  var enter, leave;

  if (!previous && !label) {
    return;
  }

  if (!previous) {
    enter = true;
  } else if (!label) {
    leave = true;
  } else if (previous !== label) {
    leave = enter = true;
  }

  if (leave) {
    dispatchEvent(chart, listeners.leave, previous);
  }
  if (enter) {
    dispatchEvent(chart, listeners.enter, label);
  }
}

function handleMoveEvents(chart, event) {
  var expando = chart[EXPANDO_KEY];
  var listeners = expando._listeners;
  var previous, label;

  if (!listeners.enter && !listeners.leave) {
    return;
  }

  if (event.type === 'mousemove') {
    label = layout.lookup(expando._labels, event);
  } else if (event.type !== 'mouseout') {
    return;
  }

  previous = expando._hovered;
  expando._hovered = label;
  dispatchMoveEvents(chart, listeners, previous, label);
}

function handleClickEvents(chart, event) {
  var expando = chart[EXPANDO_KEY];
  var handlers = expando._listeners.click;
  var label = handlers && layout.lookup(expando._labels, event);
  if (label) {
    dispatchEvent(chart, handlers, label);
  }
}

var plugin = {
  id: 'datalabels',

  defaults: defaults,

  beforeInit: function(chart) {
    chart[EXPANDO_KEY] = {
      _actives: []
    };
  },

  beforeUpdate: function(chart) {
    var expando = chart[EXPANDO_KEY];
    expando._listened = false;
    expando._listeners = {};     // {<event-type>: {<dataset-index>: {<label-key>: <fn>}}}
    expando._datasets = [];      // per dataset labels: [Label[]]
    expando._labels = [];        // layouted labels: Label[]
  },

  afterDatasetUpdate: function(chart, args, options) {
    var datasetIndex = args.index;
    var expando = chart[EXPANDO_KEY];
    var labels = expando._datasets[datasetIndex] = [];
    var visible = chart.isDatasetVisible(datasetIndex);
    var dataset = chart.data.datasets[datasetIndex];
    var config = configure(dataset, options);
    var elements = args.meta.data || [];
    var ctx = chart.ctx;
    var i, j, ilen, jlen, cfg, key, el, label;

    ctx.save();

    for (i = 0, ilen = elements.length; i < ilen; ++i) {
      el = elements[i];
      el[EXPANDO_KEY] = [];

      if (visible && el && chart.getDataVisibility(i) && !el.skip) {
        for (j = 0, jlen = config.labels.length; j < jlen; ++j) {
          cfg = config.labels[j];
          key = cfg._key;

          label = new Label(cfg, ctx, el, i);
          label.$groups = {
            _set: datasetIndex,
            _key: key || DEFAULT_KEY
          };
          label.$context = {
            active: false,
            chart: chart,
            dataIndex: i,
            dataset: dataset,
            datasetIndex: datasetIndex
          };

          label.update(label.$context);
          el[EXPANDO_KEY].push(label);
          labels.push(label);
        }
      }
    }

    ctx.restore();

    // Store listeners at the chart level and per event type to optimize
    // cases where no listeners are registered for a specific event.
    merge(expando._listeners, config.listeners, {
      merger: function(event, target, source) {
        target[event] = target[event] || {};
        target[event][args.index] = source[event];
        expando._listened = true;
      }
    });
  },

  afterUpdate: function(chart, options) {
    chart[EXPANDO_KEY]._labels = layout.prepare(
      chart[EXPANDO_KEY]._datasets,
      options);
  },

  // Draw labels on top of all dataset elements
  // https://github.com/chartjs/chartjs-plugin-datalabels/issues/29
  // https://github.com/chartjs/chartjs-plugin-datalabels/issues/32
  afterDatasetsDraw: function(chart) {
    layout.draw(chart, chart[EXPANDO_KEY]._labels);
  },

  beforeEvent: function(chart, args) {
    // If there is no listener registered for this chart, `listened` will be false,
    // meaning we can immediately ignore the incoming event and avoid useless extra
    // computation for users who don't implement label interactions.
    if (chart[EXPANDO_KEY]._listened) {
      var event = args.event;
      switch (event.type) {
      case 'mousemove':
      case 'mouseout':
        handleMoveEvents(chart, event);
        break;
      case 'click':
        handleClickEvents(chart, event);
        break;
      }
    }
  },

  afterEvent: function(chart) {
    var expando = chart[EXPANDO_KEY];
    var previous = expando._actives;
    var actives = expando._actives = chart.getActiveElements();
    var updates = utils.arrayDiff(previous, actives);
    var i, ilen, j, jlen, update, label, labels;

    for (i = 0, ilen = updates.length; i < ilen; ++i) {
      update = updates[i];
      if (update[1]) {
        labels = update[0].element[EXPANDO_KEY] || [];
        for (j = 0, jlen = labels.length; j < jlen; ++j) {
          label = labels[j];
          label.$context.active = (update[1] === 1);
          label.update(label.$context);
        }
      }
    }

    if (expando._dirty || updates.length) {
      layout.update(expando._labels);
      chart.render();
    }

    delete expando._dirty;
  }
};

export default plugin;