/**
 * @license
 * Copyright (C) 2016 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.
 */
(function() {
  'use strict';

  const LookupQueryPatterns = {
    CHANGE_ID: /^\s*i?[0-9a-f]{8,40}\s*$/i,
    CHANGE_NUM: /^\s*[1-9][0-9]*\s*$/g,
  };

  const USER_QUERY_PATTERN = /^owner:\s?("[^"]+"|[^ ]+)$/;

  const LIMIT_OPERATOR_PATTERN = /\blimit:(\d+)/i;

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

    /**
     * Fired when the title of the page should change.
     *
     * @event title-change
     */

    behaviors: [
      Gerrit.BaseUrlBehavior,
      Gerrit.URLEncodingBehavior,
    ],

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

      /**
       * True when user is logged in.
       */
      _loggedIn: {
        type: Boolean,
        computed: '_computeLoggedIn(account)',
      },

      account: {
        type: Object,
        value: null,
      },

      /**
       * State persisted across restamps of the element.
       *
       * Need sub-property declaration since it is used in template before
       * assignment.
       * @type {{ selectedChangeIndex: (number|undefined) }}
       *
       */
      viewState: {
        type: Object,
        notify: true,
        value() { return {}; },
      },

      preferences: Object,

      _changesPerPage: Number,

      /**
       * Currently active query.
       */
      _query: {
        type: String,
        value: '',
      },

      /**
       * Offset of currently visible query results.
       */
      _offset: Number,

      /**
       * Change objects loaded from the server.
       */
      _changes: {
        type: Array,
        observer: '_changesChanged',
      },

      /**
       * For showing a "loading..." string during ajax requests.
       */
      _loading: {
        type: Boolean,
        value: true,
      },

      /** @type {?String} */
      _userId: {
        type: String,
        value: null,
      },
    },

    listeners: {
      'next-page': '_handleNextPage',
      'previous-page': '_handlePreviousPage',
    },

    attached() {
      this._loadPreferences();
    },

    _paramsChanged(value) {
      if (value.view !== Gerrit.Nav.View.SEARCH) { return; }

      this._loading = true;
      this._query = value.query;
      this._offset = value.offset || 0;
      if (this.viewState.query != this._query ||
          this.viewState.offset != this._offset) {
        this.set('viewState.selectedChangeIndex', 0);
        this.set('viewState.query', this._query);
        this.set('viewState.offset', this._offset);
      }

      this.fire('title-change', {title: this._query});

      this._getPreferences().then(prefs => {
        this._changesPerPage = prefs.changes_per_page;
        return this._getChanges();
      }).then(changes => {
        changes = changes || [];
        if (this._query && changes.length === 1) {
          for (const query in LookupQueryPatterns) {
            if (LookupQueryPatterns.hasOwnProperty(query) &&
                this._query.match(LookupQueryPatterns[query])) {
              this._replaceCurrentLocation(
                  Gerrit.Nav.getUrlForChange(changes[0]));
              return;
            }
          }
        }
        this._changes = changes;
        this._loading = false;
      });
    },

    _loadPreferences() {
      return this.$.restAPI.getLoggedIn().then(loggedIn => {
        if (loggedIn) {
          this._getPreferences().then(preferences => {
            this.preferences = preferences;
          });
        } else {
          this.preferences = {};
        }
      });
    },

    _replaceCurrentLocation(url) {
      window.location.replace(url);
    },

    _getChanges() {
      return this.$.restAPI.getChanges(this._changesPerPage, this._query,
          this._offset);
    },

    _getPreferences() {
      return this.$.restAPI.getPreferences();
    },

    _limitFor(query, defaultLimit) {
      const match = query.match(LIMIT_OPERATOR_PATTERN);
      if (!match) {
        return defaultLimit;
      }
      return parseInt(match[1], 10);
    },

    _computeNavLink(query, offset, direction, changesPerPage) {
      // Offset could be a string when passed from the router.
      offset = +(offset || 0);
      const limit = this._limitFor(query, changesPerPage);
      const newOffset = Math.max(0, offset + (limit * direction));
      return Gerrit.Nav.getUrlForSearchQuery(query, newOffset);
    },

    _computePrevArrowClass(offset) {
      return offset === 0 ? 'hide' : '';
    },

    _computeNextArrowClass(changes) {
      const more = changes.length && changes[changes.length - 1]._more_changes;
      return more ? '' : 'hide';
    },

    _computeNavClass(loading) {
      return loading || !this._changes || !this._changes.length ? 'hide' : '';
    },

    _handleNextPage() {
      if (this.$.nextArrow.hidden) { return; }
      page.show(this._computeNavLink(
          this._query, this._offset, 1, this._changesPerPage));
    },

    _handlePreviousPage() {
      if (this.$.prevArrow.hidden) { return; }
      page.show(this._computeNavLink(
          this._query, this._offset, -1, this._changesPerPage));
    },

    _changesChanged(changes) {
      if (!changes || !changes.length ||
          !USER_QUERY_PATTERN.test(this._query)) {
        this._userId = null;
        return;
      }
      this._userId = changes[0].owner.email;
    },

    _computeUserHeaderClass(userId) {
      return userId ? '' : 'hide';
    },

    _computePage(offset, changesPerPage) {
      return offset / changesPerPage + 1;
    },

    _computeLoggedIn(account) {
      return !!(account && Object.keys(account).length > 0);
    },
  });
})();