<!--
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->

<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../iron-range-behavior/iron-range-behavior.html">
<link rel="import" href="../paper-styles/color.html">
<link rel="import" href="../iron-flex-layout/iron-flex-layout.html">

<!--
The progress bars are for situations where the percentage completed can be
determined. They give users a quick sense of how much longer an operation
will take.

Example:

    <paper-progress value="10"></paper-progress>

There is also a secondary progress which is useful for displaying intermediate
progress, such as the buffer level during a streaming playback progress bar.

Example:

    <paper-progress value="10" secondary-progress="30"></paper-progress>

### Styling progress bar:

To change the active progress bar color:

    paper-progress {
       --paper-progress-active-color: #e91e63;
    }

To change the secondary progress bar color:

    paper-progress {
      --paper-progress-secondary-color: #f8bbd0;
    }

To change the progress bar background color:

    paper-progress {
      --paper-progress-container-color: #64ffda;
    }

Add the class `transiting` to a paper-progress to animate the progress bar when
the value changed. You can also customize the transition:

    paper-progress {
      --paper-progress-transition-duration: 0.08s;
      --paper-progress-transition-timing-function: ease;
      --paper-progress-transition-transition-delay: 0s;
    }

The following mixins are available for styling:

Custom property                             | Description                                 | Default
--------------------------------------------|---------------------------------------------|----------
--paper-progress-container-color            | Mixin applied to container                  | --google-grey-300
--paper-progress-transition-duration        | Duration of the transition                  | 0.008s
--paper-progress-transition-timing-function | The timing function for the transition      | ease
--paper-progress-transition-delay           | delay for the transition                    | 0s
--paper-progress-active-color               | The color of the active bar                 | --google-green-500
--paper-progress-secondary-color            | The color of the secondary bar              | --google-green-100
--paper-progress-disabled-active-color      | The color of the active bar if disabled     | --google-grey-500
--paper-progress-disabled-secondary-color   | The color of the secondary bar if disabled  | --google-grey-300
--paper-progress-height                     | The height of the progress bar              | 4px

@group Paper Elements
@element paper-progress
@hero hero.svg
@demo demo/index.html
-->

<dom-module id="paper-progress">
  <style>
    :host {
      display: block;
      width: 200px;
      position: relative;
      overflow: hidden;
    }

    #progressContainer {
      position: relative;
    }

    #progressContainer,
    /* the stripe for the indeterminate animation*/
    .indeterminate:after {
      height: var(--paper-progress-height, 4px);
    }

    #primaryProgress,
    #secondaryProgress,
    .indeterminate:after {
      @apply(--layout-fit);
    }

    #progressContainer,
    .indeterminate:after {
      background-color: var(--paper-progress-container-color, --google-grey-300);
    }

    :host(.transiting) #primaryProgress,
    :host(.transiting) #secondaryProgress {
      -webkit-transition-property: -webkit-transform;
      transition-property: transform;

      /* Duration */
      -webkit-transition-duration: var(--paper-progress-transition-duration, 0.08s);
      transition-duration: var(--paper-progress-transition-duration, 0.08s);

      /* Timing function */
      -webkit-transition-timing-function: var(--paper-progress-transition-timing-function, ease);
      transition-timing-function: var(--paper-progress-transition-timing-function, ease);

      /* Delay */
      -webkit-transition-delay: var(--paper-progress-transition-delay, 0s);
      transition-delay: var(--paper-progress-transition-delay, 0s);
    }

    #primaryProgress,
    #secondaryProgress {
      @apply(--layout-fit);
      -webkit-transform-origin: left center;
      transform-origin: left center;
      -webkit-transform: scaleX(0);
      transform: scaleX(0);
      will-change: transform;
    }

    #primaryProgress {
      background-color: var(--paper-progress-active-color, --google-green-500);
    }

    #secondaryProgress {
      position: relative;
      background-color: var(--paper-progress-secondary-color, --google-green-100);
    }

    :host([disabled]) #primaryProgress {
      background-color: var(--paper-progress-disabled-active-color, --google-grey-500);
    }

    :host([disabled]) #secondaryProgress {
      background-color: var(--paper-progress-disabled-active-color, --google-grey-300);
    }

    :host(:not([disabled])) #primaryProgress.indeterminate {
      -webkit-transform-origin: right center;
      transform-origin: right center;
      -webkit-animation: indeterminate-bar 2s linear infinite;
      animation: indeterminate-bar 2s linear infinite;
    }

    :host(:not([disabled])) #primaryProgress.indeterminate:after {
      content: "";
      -webkit-transform-origin: center center;
      transform-origin: center center;

      -webkit-animation: indeterminate-splitter 2s linear infinite;
      animation: indeterminate-splitter 2s linear infinite;
    }

    @-webkit-keyframes indeterminate-bar {
      0% {
        -webkit-transform: scaleX(1) translateX(-100%);
      }
      50% {
        -webkit-transform: scaleX(1) translateX(0%);
      }
      75% {
        -webkit-transform: scaleX(1) translateX(0%);
        -webkit-animation-timing-function: cubic-bezier(.28,.62,.37,.91);
      }
      100% {
        -webkit-transform: scaleX(0) translateX(0%);
      }
    }

    @-webkit-keyframes indeterminate-splitter {
      0% {
        -webkit-transform: scaleX(.75) translateX(-125%);
      }
      30% {
        -webkit-transform: scaleX(.75) translateX(-125%);
        -webkit-animation-timing-function: cubic-bezier(.42,0,.6,.8);
      }
      90% {
        -webkit-transform: scaleX(.75) translateX(125%);
      }
      100% {
        -webkit-transform: scaleX(.75) translateX(125%);
      }
    }

    @keyframes indeterminate-bar {
      0% {
        transform: scaleX(1) translateX(-100%);
      }
      50% {
        transform: scaleX(1) translateX(0%);
      }
      75% {
        transform: scaleX(1) translateX(0%);
        animation-timing-function: cubic-bezier(.28,.62,.37,.91);
      }
      100% {
        transform: scaleX(0) translateX(0%);
      }
    }

    @keyframes indeterminate-splitter {
      0% {
        transform: scaleX(.75) translateX(-125%);
      }
      30% {
        transform: scaleX(.75) translateX(-125%);
        animation-timing-function: cubic-bezier(.42,0,.6,.8);
      }
      90% {
        transform: scaleX(.75) translateX(125%);
      }
      100% {
        transform: scaleX(.75) translateX(125%);
      }
    }
  </style>
  <template>
    <div id="progressContainer">
      <div id="secondaryProgress" hidden$="[[_hideSecondaryProgress(secondaryRatio)]]"></div>
      <div id="primaryProgress"></div>
    </div>
  </template>
</dom-module>

<script>
  Polymer({

    is: 'paper-progress',

    behaviors: [
      Polymer.IronRangeBehavior
    ],

    properties: {

      /**
       * The number that represents the current secondary progress.
       */
      secondaryProgress: {
        type: Number,
        value: 0
      },

      /**
       * The secondary ratio
       */
      secondaryRatio: {
        type: Number,
        value: 0,
        readOnly: true
      },

      /**
       * Use an indeterminate progress indicator.
       */
      indeterminate: {
        type: Boolean,
        value: false,
        observer: '_toggleIndeterminate'
      },

      /**
       * True if the progress is disabled.
       */
      disabled: {
        type: Boolean,
        value: false,
        reflectToAttribute: true,
        observer: '_disabledChanged'
      }
    },

    observers: [
      '_progressChanged(secondaryProgress, value, min, max)'
    ],

    hostAttributes: {
      role: 'progressbar'
    },

    _toggleIndeterminate: function(indeterminate) {
      // If we use attribute/class binding, the animation sometimes doesn't translate properly
      // on Safari 7.1. So instead, we toggle the class here in the update method.
      this.toggleClass('indeterminate', indeterminate, this.$.primaryProgress);
    },

    _transformProgress: function(progress, ratio) {
      var transform = 'scaleX(' + (ratio / 100) + ')';
      progress.style.transform = progress.style.webkitTransform = transform;
    },

    _mainRatioChanged: function(ratio) {
      this._transformProgress(this.$.primaryProgress, ratio);
    },

    _progressChanged: function(secondaryProgress, value, min, max) {
      secondaryProgress = this._clampValue(secondaryProgress);
      value = this._clampValue(value);

      var secondaryRatio = this._calcRatio(secondaryProgress) * 100;
      var mainRatio = this._calcRatio(value) * 100;

      this._setSecondaryRatio(secondaryRatio);
      this._transformProgress(this.$.secondaryProgress, secondaryRatio);
      this._transformProgress(this.$.primaryProgress, mainRatio);

      this.secondaryProgress = secondaryProgress;

      this.setAttribute('aria-valuenow', value);
      this.setAttribute('aria-valuemin', min);
      this.setAttribute('aria-valuemax', max);
    },

    _disabledChanged: function(disabled) {
      this.setAttribute('aria-disabled', disabled ? 'true' : 'false');
    },

    _hideSecondaryProgress: function(secondaryRatio) {
      return secondaryRatio === 0;
    }

  });

</script>