michael@0: #ifdef 0
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: #endif
michael@0: 
michael@0: /**
michael@0:  * This singleton provides functionality to update the current grid to a new
michael@0:  * set of pinned and blocked sites. It adds, moves and removes sites.
michael@0:  */
michael@0: let gUpdater = {
michael@0:   /**
michael@0:    * Updates the current grid according to its pinned and blocked sites.
michael@0:    * This removes old, moves existing and creates new sites to fill gaps.
michael@0:    * @param aCallback The callback to call when finished.
michael@0:    */
michael@0:   updateGrid: function Updater_updateGrid(aCallback) {
michael@0:     let links = gLinks.getLinks().slice(0, gGrid.cells.length);
michael@0: 
michael@0:     // Find all sites that remain in the grid.
michael@0:     let sites = this._findRemainingSites(links);
michael@0: 
michael@0:     let self = this;
michael@0: 
michael@0:     // Remove sites that are no longer in the grid.
michael@0:     this._removeLegacySites(sites, function () {
michael@0:       // Freeze all site positions so that we can move their DOM nodes around
michael@0:       // without any visual impact.
michael@0:       self._freezeSitePositions(sites);
michael@0: 
michael@0:       // Move the sites' DOM nodes to their new position in the DOM. This will
michael@0:       // have no visual effect as all the sites have been frozen and will
michael@0:       // remain in their current position.
michael@0:       self._moveSiteNodes(sites);
michael@0: 
michael@0:       // Now it's time to animate the sites actually moving to their new
michael@0:       // positions.
michael@0:       self._rearrangeSites(sites, function () {
michael@0:         // Try to fill empty cells and finish.
michael@0:         self._fillEmptyCells(links, aCallback);
michael@0: 
michael@0:         // Update other pages that might be open to keep them synced.
michael@0:         gAllPages.update(gPage);
michael@0:       });
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Takes an array of links and tries to correlate them to sites contained in
michael@0:    * the current grid. If no corresponding site can be found (i.e. the link is
michael@0:    * new and a site will be created) then just set it to null.
michael@0:    * @param aLinks The array of links to find sites for.
michael@0:    * @return Array of sites mapped to the given links (can contain null values).
michael@0:    */
michael@0:   _findRemainingSites: function Updater_findRemainingSites(aLinks) {
michael@0:     let map = {};
michael@0: 
michael@0:     // Create a map to easily retrieve the site for a given URL.
michael@0:     gGrid.sites.forEach(function (aSite) {
michael@0:       if (aSite)
michael@0:         map[aSite.url] = aSite;
michael@0:     });
michael@0: 
michael@0:     // Map each link to its corresponding site, if any.
michael@0:     return aLinks.map(function (aLink) {
michael@0:       return aLink && (aLink.url in map) && map[aLink.url];
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Freezes the given sites' positions.
michael@0:    * @param aSites The array of sites to freeze.
michael@0:    */
michael@0:   _freezeSitePositions: function Updater_freezeSitePositions(aSites) {
michael@0:     aSites.forEach(function (aSite) {
michael@0:       if (aSite)
michael@0:         gTransformation.freezeSitePosition(aSite);
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Moves the given sites' DOM nodes to their new positions.
michael@0:    * @param aSites The array of sites to move.
michael@0:    */
michael@0:   _moveSiteNodes: function Updater_moveSiteNodes(aSites) {
michael@0:     let cells = gGrid.cells;
michael@0: 
michael@0:     // Truncate the given array of sites to not have more sites than cells.
michael@0:     // This can happen when the user drags a bookmark (or any other new kind
michael@0:     // of link) onto the grid.
michael@0:     let sites = aSites.slice(0, cells.length);
michael@0: 
michael@0:     sites.forEach(function (aSite, aIndex) {
michael@0:       let cell = cells[aIndex];
michael@0:       let cellSite = cell.site;
michael@0: 
michael@0:       // The site's position didn't change.
michael@0:       if (!aSite || cellSite != aSite) {
michael@0:         let cellNode = cell.node;
michael@0: 
michael@0:         // Empty the cell if necessary.
michael@0:         if (cellSite)
michael@0:           cellNode.removeChild(cellSite.node);
michael@0: 
michael@0:         // Put the new site in place, if any.
michael@0:         if (aSite)
michael@0:           cellNode.appendChild(aSite.node);
michael@0:       }
michael@0:     }, this);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Rearranges the given sites and slides them to their new positions.
michael@0:    * @param aSites The array of sites to re-arrange.
michael@0:    * @param aCallback The callback to call when finished.
michael@0:    */
michael@0:   _rearrangeSites: function Updater_rearrangeSites(aSites, aCallback) {
michael@0:     let options = {callback: aCallback, unfreeze: true};
michael@0:     gTransformation.rearrangeSites(aSites, options);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Removes all sites from the grid that are not in the given links array or
michael@0:    * exceed the grid.
michael@0:    * @param aSites The array of sites remaining in the grid.
michael@0:    * @param aCallback The callback to call when finished.
michael@0:    */
michael@0:   _removeLegacySites: function Updater_removeLegacySites(aSites, aCallback) {
michael@0:     let batch = [];
michael@0: 
michael@0:     // Delete sites that were removed from the grid.
michael@0:     gGrid.sites.forEach(function (aSite) {
michael@0:       // The site must be valid and not in the current grid.
michael@0:       if (!aSite || aSites.indexOf(aSite) != -1)
michael@0:         return;
michael@0: 
michael@0:       let deferred = Promise.defer();
michael@0:       batch.push(deferred.promise);
michael@0: 
michael@0:       // Fade out the to-be-removed site.
michael@0:       gTransformation.hideSite(aSite, function () {
michael@0:         let node = aSite.node;
michael@0: 
michael@0:         // Remove the site from the DOM.
michael@0:         node.parentNode.removeChild(node);
michael@0:         deferred.resolve();
michael@0:       });
michael@0:     });
michael@0: 
michael@0:     Promise.all(batch).then(aCallback);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Tries to fill empty cells with new links if available.
michael@0:    * @param aLinks The array of links.
michael@0:    * @param aCallback The callback to call when finished.
michael@0:    */
michael@0:   _fillEmptyCells: function Updater_fillEmptyCells(aLinks, aCallback) {
michael@0:     let {cells, sites} = gGrid;
michael@0:     let batch = [];
michael@0: 
michael@0:     // Find empty cells and fill them.
michael@0:     sites.forEach(function (aSite, aIndex) {
michael@0:       if (aSite || !aLinks[aIndex])
michael@0:         return;
michael@0: 
michael@0:       let deferred = Promise.defer();
michael@0:       batch.push(deferred.promise);
michael@0: 
michael@0:       // Create the new site and fade it in.
michael@0:       let site = gGrid.createSite(aLinks[aIndex], cells[aIndex]);
michael@0: 
michael@0:       // Set the site's initial opacity to zero.
michael@0:       site.node.style.opacity = 0;
michael@0: 
michael@0:       // Flush all style changes for the dynamically inserted site to make
michael@0:       // the fade-in transition work.
michael@0:       window.getComputedStyle(site.node).opacity;
michael@0:       gTransformation.showSite(site, function () deferred.resolve());
michael@0:     });
michael@0: 
michael@0:     Promise.all(batch).then(aCallback);
michael@0:   }
michael@0: };