<!--
  -- Copyright 2013 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.
  -->

<polymer-element name="kb-modifier-key" class="unlocked dark" extends="kb-key"
    on-pointerout="{{out}}">
  <script>
    (function () {

      /**
       * The possible states of the key.
       * @const
       * @type {Enum}
       */
      var KEY_STATES = {
        PRESSED: "pressed", // Key-down.
        UNLOCKED: "unlocked", // Default state.
        TAPPED: "tapped", // Key-down followed by key-up.
        CHORDING: "chording", // Chording mode.
      };

      /**
       * A map of the state of all modifier keys.
       * @type {Object}
       */
      var states = {};

      Polymer('kb-modifier-key', {
        up: function(event) {
          if (this.state == KEY_STATES.PRESSED)
            this.state = KEY_STATES.TAPPED;
          else
            this.state = KEY_STATES.UNLOCKED;
          this.super([event]);
        },

        down: function(event) {
          // First transition state so that populateDetails generates
          // correct data.
          switch (this.state) {
            case KEY_STATES.UNLOCKED:
              this.state = KEY_STATES.PRESSED;
              break;
            case KEY_STATES.TAPPED:
              this.state = KEY_STATES.UNLOCKED;
              break;
            case KEY_STATES.PRESSED:
            case KEY_STATES.CHORDING:
              // We pressed another key at the same time,
              // so ignore second press.
              return;
            default:
              console.error("Undefined key state: " + state);
              break;
          }
          this.super([event]);
        },

        /**
         * Returns whether the modifier for this key is active.
         * @return {boolean}
         */
        isActive: function() {
          return this.state != KEY_STATES.UNLOCKED;
        },

        /**
         * Notifies key that a non-control keyed down.
         * A control key is defined as one of shift, control or alt.
         */
        onNonControlKeyDown: function() {
          switch(this.state) {
            case (KEY_STATES.PRESSED):
              this.state = KEY_STATES.CHORDING;
              break;
          }
        },

        /**
         * Notifies key that a non-control keyed was typed.
         * A control key is defined as one of shift, control or alt.
         */
        onNonControlKeyTyped: function() {
           switch(this.state) {
             case (KEY_STATES.TAPPED):
               this.state = KEY_STATES.UNLOCKED;
               break;
           }
        },

        /**
         * Called on a pointer-out event. Ends chording.
         * @param {event} event The pointer-out event.
         */
        out: function(event) {
          // TODO(rsadam): Add chording event so that we don't reset
          // when shift-chording.
          if (this.state == KEY_STATES.CHORDING) {
            this.state = KEY_STATES.UNLOCKED;
          }
        },

        /*
         * Overrides the autoRelease function to enable chording.
         */
        autoRelease: function() {
        },

        populateDetails: function(caller) {
          var detail = this.super([caller]);
          if (this.state != KEY_STATES.UNLOCKED)
            detail.activeModifier = this.charValue;
          return detail;
        },

        /**
         *  Resets the modifier key state.
         */
        reset: function() {
          this.state = KEY_STATES.UNLOCKED;
        },

        get state() {
          var key = this.charValue;
          if (!key)
            console.error("missing key for kb-modifier-key state: " + this);
          // All keys default to the unlock state.
          if (!(key in states))
            states[key] = KEY_STATES.UNLOCKED;
          return states[key];
        },

        set state(value) {
          var key = this.charValue;
          states[key] = value;
        }
      });
    })();
  </script>
</polymer-element>