<!--
Copyright (C) 2015 The Android Open Source Project

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

<link rel="import" href="../bower_components/polymer/polymer.html">
<link rel="import" href="../bower_components/iron-ajax/iron-ajax.html">
<link rel="import" href="gr-change-list.html">

<dom-module id="gr-change-list-view">
  <template>
    <style>
      :host {
        background-color: var(--view-background-color);
        display: block;
        margin: 0 1.25rem;
      }
      gr-change-list {
        margin-top: 1em;
        width: 100%;
      }
      nav {
        margin-bottom: 1em;
        padding: .5em 0;
        text-align: center;
      }
      nav a {
        display: inline-block;
      }
      nav a:first-of-type {
        margin-right: .5em;
      }
      [hidden] {
        display: none !important;
      }
    </style>
    <iron-ajax
        auto
        url="/changes/"
        params="[[_computeQueryParams(query, offset)]]"
        json-prefix=")]}'"
        last-response="{{_changes}}"
        debounce-duration="300"></iron-ajax>
    <gr-change-list changes="{{_changes}}"></gr-change-list>
    <nav>
      <a href$="[[_computeNavLink(query, offset, -1)]]"
         hidden$="[[_hidePrevArrow(offset)]]">&larr; Prev</a>
      <a href$="[[_computeNavLink(query, offset, 1)]]"
         hidden$="[[_hideNextArrow(_changes.length)]]">Next &rarr;</a>
    </nav>
  </template>
  <script>
  (function() {
    'use strict';

    var DEFAULT_NUM_CHANGES = 25;

    Polymer({
      is: 'gr-change-list-view',

      properties: {
        /**
         * URL params passed from the router.
         */
        params: {
          type: Object,
          observer: '_paramsChanged',
        },

        /**
         * Change objects loaded from the server.
         */
        _changes: Array,
      },

      _paramsChanged: function(value) {
        this.query = value.query;
        this.offset = value.offset || 0;
      },

      _computeQueryParams: function(query, offset) {
        var options = Changes.listChangesOptionsToHex(
            Changes.ListChangesOption.LABELS,
            Changes.ListChangesOption.DETAILED_ACCOUNTS
        );
        var obj = {
          n: DEFAULT_NUM_CHANGES,  // Number of results to return.
          O: options,
          S: offset || 0,
        };
        if (query && query.length > 0) {
          obj.q = query;
        }
        return obj;
      },

      _computeNavLink: function(query, offset, direction) {
        // Offset could be a string when passed from the router.
        offset = +(offset || 0);
        var newOffset = Math.max(0, offset + (25 * direction));
        var href = '/q/' + query;
        if (newOffset > 0) {
          href += ',' + newOffset;
        }
        return href;
      },

      _hidePrevArrow: function(offset) {
        return offset == 0;
      },

      _hideNextArrow: function(changesLen) {
        return changesLen < DEFAULT_NUM_CHANGES;
      },

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