/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;

Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
Components.utils.import("resource://gre/modules/Services.jsm");
Components.utils.import("resource://gre/modules/PlacesUtils.jsm");

const TOPIC_SHUTDOWN = "places-shutdown";

/**
 * The Places Tagging Service
 */
function TaggingService() {
  // Observe bookmarks changes.
  PlacesUtils.bookmarks.addObserver(this, false);

  // Cleanup on shutdown.
  Services.obs.addObserver(this, TOPIC_SHUTDOWN, false);
}

TaggingService.prototype = {
  /**
   * Creates a tag container under the tags-root with the given name.
   *
   * @param aTagName
   *        the name for the new tag.
   * @returns the id of the new tag container.
   */
  _createTag: function TS__createTag(aTagName) {
    var newFolderId = PlacesUtils.bookmarks.createFolder(
      PlacesUtils.tagsFolderId, aTagName, PlacesUtils.bookmarks.DEFAULT_INDEX
    );
    // Add the folder to our local cache, so we can avoid doing this in the
    // observer that would have to check itemType.
    this._tagFolders[newFolderId] = aTagName;

    return newFolderId;
  },

  /**
   * Checks whether the given uri is tagged with the given tag.
   *
   * @param [in] aURI
   *        url to check for
   * @param [in] aTagName
   *        the tag to check for
   * @returns the item id if the URI is tagged with the given tag, -1
   *          otherwise.
   */
  _getItemIdForTaggedURI: function TS__getItemIdForTaggedURI(aURI, aTagName) {
    var tagId = this._getItemIdForTag(aTagName);
    if (tagId == -1)
      return -1;
    // Using bookmarks service API for this would be a pain.
    // Until tags implementation becomes sane, go the query way.
    let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase)
                                .DBConnection;
    let stmt = db.createStatement(
      "SELECT id FROM moz_bookmarks "
    + "WHERE parent = :tag_id "
    + "AND fk = (SELECT id FROM moz_places WHERE url = :page_url)"
    );
    stmt.params.tag_id = tagId;
    stmt.params.page_url = aURI.spec;
    try {
      if (stmt.executeStep()) {
        return stmt.row.id;
      }
    }
    finally {
      stmt.finalize();
    }
    return -1;
  },

  /**
   * Returns the folder id for a tag, or -1 if not found.
   * @param [in] aTag
   *        string tag to search for
   * @returns integer id for the bookmark folder for the tag
   */
  _getItemIdForTag: function TS_getItemIdForTag(aTagName) {
    for (var i in this._tagFolders) {
      if (aTagName.toLowerCase() == this._tagFolders[i].toLowerCase())
        return parseInt(i);
    }
    return -1;
  },

  /**
   * Makes a proper array of tag objects like  { id: number, name: string }.
   *
   * @param aTags
   *        Array of tags.  Entries can be tag names or concrete item id.
   * @return Array of tag objects like { id: number, name: string }.
   *
   * @throws Cr.NS_ERROR_INVALID_ARG if any element of the input array is not
   *         a valid tag.
   */
  _convertInputMixedTagsArray: function TS__convertInputMixedTagsArray(aTags)
  {
    return aTags.map(function (val)
    {
      let tag = { _self: this };
      if (typeof(val) == "number" && this._tagFolders[val]) {
        // This is a tag folder id.
        tag.id = val;
        // We can't know the name at this point, since a previous tag could
        // want to change it.
        tag.__defineGetter__("name", function () this._self._tagFolders[this.id]);
      }
      else if (typeof(val) == "string" && val.length > 0) {
        // This is a tag name.
        tag.name = val;
        // We can't know the id at this point, since a previous tag could
        // have created it.
        tag.__defineGetter__("id", function () this._self._getItemIdForTag(this.name));
      }
      else {
        throw Cr.NS_ERROR_INVALID_ARG;
      }
      return tag;
    }, this);
  },

  // nsITaggingService
  tagURI: function TS_tagURI(aURI, aTags)
  {
    if (!aURI || !aTags || !Array.isArray(aTags)) {
      throw Cr.NS_ERROR_INVALID_ARG;
    }

    // This also does some input validation.
    let tags = this._convertInputMixedTagsArray(aTags);

    let taggingService = this;
    PlacesUtils.bookmarks.runInBatchMode({
      runBatched: function (aUserData)
      {
        tags.forEach(function (tag)
        {
          if (tag.id == -1) {
            // Tag does not exist yet, create it.
            this._createTag(tag.name);
          }

          if (this._getItemIdForTaggedURI(aURI, tag.name) == -1) {
            // The provided URI is not yet tagged, add a tag for it.
            // Note that bookmarks under tag containers must have null titles.
            PlacesUtils.bookmarks.insertBookmark(
              tag.id, aURI, PlacesUtils.bookmarks.DEFAULT_INDEX, null
            );
          }

          // Try to preserve user's tag name casing.
          // Rename the tag container so the Places view matches the most-recent
          // user-typed value.
          if (PlacesUtils.bookmarks.getItemTitle(tag.id) != tag.name) {
            // this._tagFolders is updated by the bookmarks observer.
            PlacesUtils.bookmarks.setItemTitle(tag.id, tag.name);
          }
        }, taggingService);
      }
    }, null);
  },

  /**
   * Removes the tag container from the tags root if the given tag is empty.
   *
   * @param aTagId
   *        the itemId of the tag element under the tags root
   */
  _removeTagIfEmpty: function TS__removeTagIfEmpty(aTagId) {
    let count = 0;
    let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase)
                                .DBConnection;
    let stmt = db.createStatement(
      "SELECT count(*) AS count FROM moz_bookmarks "
    + "WHERE parent = :tag_id"
    );
    stmt.params.tag_id = aTagId;
    try {
      if (stmt.executeStep()) {
        count = stmt.row.count;
      }
    }
    finally {
      stmt.finalize();
    }

    if (count == 0) {
      PlacesUtils.bookmarks.removeItem(aTagId);
    }
  },

  // nsITaggingService
  untagURI: function TS_untagURI(aURI, aTags)
  {
    if (!aURI || (aTags && !Array.isArray(aTags))) {
      throw Cr.NS_ERROR_INVALID_ARG;
    }

    if (!aTags) {
      // Passing null should clear all tags for aURI, see the IDL.
      // XXXmano: write a perf-sensitive version of this code path...
      aTags = this.getTagsForURI(aURI);
    }

    // This also does some input validation.
    let tags = this._convertInputMixedTagsArray(aTags);

    let taggingService = this;
    PlacesUtils.bookmarks.runInBatchMode({
      runBatched: function (aUserData)
      {
        tags.forEach(function (tag)
        {
          if (tag.id != -1) {
            // A tag could exist.
            let itemId = this._getItemIdForTaggedURI(aURI, tag.name);
            if (itemId != -1) {
              // There is a tagged item.
              PlacesUtils.bookmarks.removeItem(itemId);
            }
          }
        }, taggingService);
      }
    }, null);
  },

  // nsITaggingService
  getURIsForTag: function TS_getURIsForTag(aTagName) {
    if (!aTagName || aTagName.length == 0)
      throw Cr.NS_ERROR_INVALID_ARG;

    let uris = [];
    let tagId = this._getItemIdForTag(aTagName);
    if (tagId == -1)
      return uris;

    let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase)
                                .DBConnection;
    let stmt = db.createStatement(
      "SELECT h.url FROM moz_places h "
    + "JOIN moz_bookmarks b ON b.fk = h.id "
    + "WHERE b.parent = :tag_id "
    );
    stmt.params.tag_id = tagId;
    try {
      while (stmt.executeStep()) {
        try {
          uris.push(Services.io.newURI(stmt.row.url, null, null));
        } catch (ex) {}
      }
    }
    finally {
      stmt.finalize();
    }

    return uris;
  },

  // nsITaggingService
  getTagsForURI: function TS_getTagsForURI(aURI, aCount) {
    if (!aURI)
      throw Cr.NS_ERROR_INVALID_ARG;

    var tags = [];
    var bookmarkIds = PlacesUtils.bookmarks.getBookmarkIdsForURI(aURI);
    for (var i=0; i < bookmarkIds.length; i++) {
      var folderId = PlacesUtils.bookmarks.getFolderIdForItem(bookmarkIds[i]);
      if (this._tagFolders[folderId])
        tags.push(this._tagFolders[folderId]);
    }

    // sort the tag list
    tags.sort(function(a, b) {
        return a.toLowerCase().localeCompare(b.toLowerCase());
      });
    if (aCount)
      aCount.value = tags.length;
    return tags;
  },

  __tagFolders: null, 
  get _tagFolders() {
    if (!this.__tagFolders) {
      this.__tagFolders = [];

      let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase)
                                  .DBConnection;
      let stmt = db.createStatement(
        "SELECT id, title FROM moz_bookmarks WHERE parent = :tags_root "
      );
      stmt.params.tags_root = PlacesUtils.tagsFolderId;
      try {
        while (stmt.executeStep()) {
          this.__tagFolders[stmt.row.id] = stmt.row.title;
        }
      }
      finally {
        stmt.finalize();
      }
    }

    return this.__tagFolders;
  },

  // nsITaggingService
  get allTags() {
    var allTags = [];
    for (var i in this._tagFolders)
      allTags.push(this._tagFolders[i]);
    // sort the tag list
    allTags.sort(function(a, b) {
        return a.toLowerCase().localeCompare(b.toLowerCase());
      });
    return allTags;
  },

  // nsITaggingService
  get hasTags() {
    return this._tagFolders.length > 0;
  },

  // nsIObserver
  observe: function TS_observe(aSubject, aTopic, aData) {
    if (aTopic == TOPIC_SHUTDOWN) {
      PlacesUtils.bookmarks.removeObserver(this);
      Services.obs.removeObserver(this, TOPIC_SHUTDOWN);
    }
  },

  /**
   * If the only bookmark items associated with aURI are contained in tag
   * folders, returns the IDs of those items.  This can be the case if
   * the URI was bookmarked and tagged at some point, but the bookmark was
   * removed, leaving only the bookmark items in tag folders.  If the URI is
   * either properly bookmarked or not tagged just returns and empty array.
   *
   * @param   aURI
   *          A URI (string) that may or may not be bookmarked
   * @returns an array of item ids
   */
  _getTaggedItemIdsIfUnbookmarkedURI:
  function TS__getTaggedItemIdsIfUnbookmarkedURI(aURI) {
    var itemIds = [];
    var isBookmarked = false;

    // Using bookmarks service API for this would be a pain.
    // Until tags implementation becomes sane, go the query way.
    let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase)
                                .DBConnection;
    let stmt = db.createStatement(
      "SELECT id, parent "
    + "FROM moz_bookmarks "
    + "WHERE fk = (SELECT id FROM moz_places WHERE url = :page_url)"
    );
    stmt.params.page_url = aURI.spec;
    try {
      while (stmt.executeStep() && !isBookmarked) {
        if (this._tagFolders[stmt.row.parent]) {
          // This is a tag entry.
          itemIds.push(stmt.row.id);
        }
        else {
          // This is a real bookmark, so the bookmarked URI is not an orphan.
          isBookmarked = true;
        }
      }
    }
    finally {
      stmt.finalize();
    }

    return isBookmarked ? [] : itemIds;
  },

  // nsINavBookmarkObserver
  onItemAdded: function TS_onItemAdded(aItemId, aFolderId, aIndex, aItemType,
                                       aURI, aTitle) {
    // Nothing to do if this is not a tag.
    if (aFolderId != PlacesUtils.tagsFolderId ||
        aItemType != PlacesUtils.bookmarks.TYPE_FOLDER)
      return;

    this._tagFolders[aItemId] = aTitle;
  },

  onItemRemoved: function TS_onItemRemoved(aItemId, aFolderId, aIndex,
                                           aItemType, aURI) {
    // Item is a tag folder.
    if (aFolderId == PlacesUtils.tagsFolderId && this._tagFolders[aItemId]) {
      delete this._tagFolders[aItemId];
    }
    // Item is a bookmark that was removed from a non-tag folder.
    else if (aURI && !this._tagFolders[aFolderId]) {
      // If the only bookmark items now associated with the bookmark's URI are
      // contained in tag folders, the URI is no longer properly bookmarked, so
      // untag it.
      let itemIds = this._getTaggedItemIdsIfUnbookmarkedURI(aURI);
      for (let i = 0; i < itemIds.length; i++) {
        try {
          PlacesUtils.bookmarks.removeItem(itemIds[i]);
        } catch (ex) {}
      }
    }
    // Item is a tag entry.  If this was the last entry for this tag, remove it.
    else if (aURI && this._tagFolders[aFolderId]) {
      this._removeTagIfEmpty(aFolderId);
    }
  },

  onItemChanged: function TS_onItemChanged(aItemId, aProperty,
                                           aIsAnnotationProperty, aNewValue,
                                           aLastModified, aItemType) {
    if (aProperty == "title" && this._tagFolders[aItemId])
      this._tagFolders[aItemId] = aNewValue;
  },

  onItemMoved: function TS_onItemMoved(aItemId, aOldParent, aOldIndex,
                                      aNewParent, aNewIndex, aItemType) {
    if (this._tagFolders[aItemId] && PlacesUtils.tagsFolderId == aOldParent &&
        PlacesUtils.tagsFolderId != aNewParent)
      delete this._tagFolders[aItemId];
  },

  onItemVisited: function () {},
  onBeforeItemRemoved: function () {},
  onBeginUpdateBatch: function () {},
  onEndUpdateBatch: function () {},

  //////////////////////////////////////////////////////////////////////////////
  //// nsISupports

  classID: Components.ID("{bbc23860-2553-479d-8b78-94d9038334f7}"),

  _xpcom_factory: XPCOMUtils.generateSingletonFactory(TaggingService),

  QueryInterface: XPCOMUtils.generateQI([
    Ci.nsITaggingService
  , Ci.nsINavBookmarkObserver
  , Ci.nsIObserver
  ])
};


function TagAutoCompleteResult(searchString, searchResult,
                               defaultIndex, errorDescription,
                               results, comments) {
  this._searchString = searchString;
  this._searchResult = searchResult;
  this._defaultIndex = defaultIndex;
  this._errorDescription = errorDescription;
  this._results = results;
  this._comments = comments;
}

TagAutoCompleteResult.prototype = {
  
  /**
   * The original search string
   */
  get searchString() {
    return this._searchString;
  },

  /**
   * The result code of this result object, either:
   *         RESULT_IGNORED   (invalid searchString)
   *         RESULT_FAILURE   (failure)
   *         RESULT_NOMATCH   (no matches found)
   *         RESULT_SUCCESS   (matches found)
   */
  get searchResult() {
    return this._searchResult;
  },

  /**
   * Index of the default item that should be entered if none is selected
   */
  get defaultIndex() {
    return this._defaultIndex;
  },

  /**
   * A string describing the cause of a search failure
   */
  get errorDescription() {
    return this._errorDescription;
  },

  /**
   * The number of matches
   */
  get matchCount() {
    return this._results.length;
  },

  get typeAheadResult() false,

  /**
   * Get the value of the result at the given index
   */
  getValueAt: function PTACR_getValueAt(index) {
    return this._results[index];
  },

  getLabelAt: function PTACR_getLabelAt(index) {
    return this.getValueAt(index);
  },

  /**
   * Get the comment of the result at the given index
   */
  getCommentAt: function PTACR_getCommentAt(index) {
    return this._comments[index];
  },

  /**
   * Get the style hint for the result at the given index
   */
  getStyleAt: function PTACR_getStyleAt(index) {
    if (!this._comments[index])
      return null;  // not a category label, so no special styling

    if (index == 0)
      return "suggestfirst";  // category label on first line of results

    return "suggesthint";   // category label on any other line of results
  },

  /**
   * Get the image for the result at the given index
   */
  getImageAt: function PTACR_getImageAt(index) {
    return null;
  },

  /**
   * Remove the value at the given index from the autocomplete results.
   * If removeFromDb is set to true, the value should be removed from
   * persistent storage as well.
   */
  removeValueAt: function PTACR_removeValueAt(index, removeFromDb) {
    this._results.splice(index, 1);
    this._comments.splice(index, 1);
  },

  // nsISupports
  QueryInterface: XPCOMUtils.generateQI([
    Ci.nsIAutoCompleteResult
  ])
};

// Implements nsIAutoCompleteSearch
function TagAutoCompleteSearch() {
  XPCOMUtils.defineLazyServiceGetter(this, "tagging",
                                     "@mozilla.org/browser/tagging-service;1",
                                     "nsITaggingService");
}

TagAutoCompleteSearch.prototype = {
  _stopped : false, 

  /*
   * Search for a given string and notify a listener (either synchronously
   * or asynchronously) of the result
   *
   * @param searchString - The string to search for
   * @param searchParam - An extra parameter
   * @param previousResult - A previous result to use for faster searching
   * @param listener - A listener to notify when the search is complete
   */
  startSearch: function PTACS_startSearch(searchString, searchParam, result, listener) {
    var searchResults = this.tagging.allTags;
    var results = [];
    var comments = [];
    this._stopped = false;

    // only search on characters for the last tag
    var index = Math.max(searchString.lastIndexOf(","), 
      searchString.lastIndexOf(";"));
    var before = ''; 
    if (index != -1) {  
      before = searchString.slice(0, index+1);
      searchString = searchString.slice(index+1);
      // skip past whitespace
      var m = searchString.match(/\s+/);
      if (m) {
         before += m[0];
         searchString = searchString.slice(m[0].length);
      }
    }

    if (!searchString.length) {
      var newResult = new TagAutoCompleteResult(searchString,
        Ci.nsIAutoCompleteResult.RESULT_NOMATCH, 0, "", results, comments);
      listener.onSearchResult(self, newResult);
      return;
    }
    
    var self = this;
    // generator: if yields true, not done
    function doSearch() {
      var i = 0;
      while (i < searchResults.length) {
        if (self._stopped)
          yield false;
        // for each match, prepend what the user has typed so far
        if (searchResults[i].toLowerCase()
                            .indexOf(searchString.toLowerCase()) == 0 &&
            comments.indexOf(searchResults[i]) == -1) {
          results.push(before + searchResults[i]);
          comments.push(searchResults[i]);
        }
    
        ++i;

        /* TODO: bug 481451
         * For each yield we pass a new result to the autocomplete
         * listener. The listener appends instead of replacing previous results,
         * causing invalid matchCount values.
         *
         * As a workaround, all tags are searched through in a single batch,
         * making this synchronous until the above issue is fixed.
         */

        /*
        // 100 loops per yield
        if ((i % 100) == 0) {
          var newResult = new TagAutoCompleteResult(searchString,
            Ci.nsIAutoCompleteResult.RESULT_SUCCESS_ONGOING, 0, "", results, comments);
          listener.onSearchResult(self, newResult);
          yield true;
        }
        */
      }

      let searchResult = results.length > 0 ?
                           Ci.nsIAutoCompleteResult.RESULT_SUCCESS :
                           Ci.nsIAutoCompleteResult.RESULT_NOMATCH;
      var newResult = new TagAutoCompleteResult(searchString, searchResult, 0,
                                                "", results, comments);
      listener.onSearchResult(self, newResult);
      yield false;
    }
    
    // chunk the search results via the generator
    var gen = doSearch();
    while (gen.next());
    gen.close();
  },

  /**
   * Stop an asynchronous search that is in progress
   */
  stopSearch: function PTACS_stopSearch() {
    this._stopped = true;
  },

  //////////////////////////////////////////////////////////////////////////////
  //// nsISupports

  classID: Components.ID("{1dcc23b0-d4cb-11dc-9ad6-479d56d89593}"),

  _xpcom_factory: XPCOMUtils.generateSingletonFactory(TagAutoCompleteSearch),

  QueryInterface: XPCOMUtils.generateQI([
    Ci.nsIAutoCompleteSearch
  ])
};

let component = [TaggingService, TagAutoCompleteSearch];
var NSGetFactory = XPCOMUtils.generateNSGetFactory(component);
