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 the ability to re-arrange the current grid to
michael@0:  * indicate the transformation that results from dropping a cell at a certain
michael@0:  * position.
michael@0:  */
michael@0: let gDropPreview = {
michael@0:   /**
michael@0:    * Rearranges the sites currently contained in the grid when a site would be
michael@0:    * dropped onto the given cell.
michael@0:    * @param aCell The drop target cell.
michael@0:    * @return The re-arranged array of sites.
michael@0:    */
michael@0:   rearrange: function DropPreview_rearrange(aCell) {
michael@0:     let sites = gGrid.sites;
michael@0: 
michael@0:     // Insert the dragged site into the current grid.
michael@0:     this._insertDraggedSite(sites, aCell);
michael@0: 
michael@0:     // After the new site has been inserted we need to correct the positions
michael@0:     // of all pinned tabs that have been moved around.
michael@0:     this._repositionPinnedSites(sites, aCell);
michael@0: 
michael@0:     return sites;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Inserts the currently dragged site into the given array of sites.
michael@0:    * @param aSites The array of sites to insert into.
michael@0:    * @param aCell The drop target cell.
michael@0:    */
michael@0:   _insertDraggedSite: function DropPreview_insertDraggedSite(aSites, aCell) {
michael@0:     let dropIndex = aCell.index;
michael@0:     let draggedSite = gDrag.draggedSite;
michael@0: 
michael@0:     // We're currently dragging a site.
michael@0:     if (draggedSite) {
michael@0:       let dragCell = draggedSite.cell;
michael@0:       let dragIndex = dragCell.index;
michael@0: 
michael@0:       // Move the dragged site into its new position.
michael@0:       if (dragIndex != dropIndex) {
michael@0:         aSites.splice(dragIndex, 1);
michael@0:         aSites.splice(dropIndex, 0, draggedSite);
michael@0:       }
michael@0:     // We're handling an external drag item.
michael@0:     } else {
michael@0:       aSites.splice(dropIndex, 0, null);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Correct the position of all pinned sites that might have been moved to
michael@0:    * different positions after the dragged site has been inserted.
michael@0:    * @param aSites The array of sites containing the dragged site.
michael@0:    * @param aCell The drop target cell.
michael@0:    */
michael@0:   _repositionPinnedSites:
michael@0:     function DropPreview_repositionPinnedSites(aSites, aCell) {
michael@0: 
michael@0:     // Collect all pinned sites.
michael@0:     let pinnedSites = this._filterPinnedSites(aSites, aCell);
michael@0: 
michael@0:     // Correct pinned site positions.
michael@0:     pinnedSites.forEach(function (aSite) {
michael@0:       aSites[aSites.indexOf(aSite)] = aSites[aSite.cell.index];
michael@0:       aSites[aSite.cell.index] = aSite;
michael@0:     }, this);
michael@0: 
michael@0:     // There might be a pinned cell that got pushed out of the grid, try to
michael@0:     // sneak it in by removing a lower-priority cell.
michael@0:     if (this._hasOverflowedPinnedSite(aSites, aCell))
michael@0:       this._repositionOverflowedPinnedSite(aSites, aCell);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Filter pinned sites out of the grid that are still on their old positions
michael@0:    * and have not moved.
michael@0:    * @param aSites The array of sites to filter.
michael@0:    * @param aCell The drop target cell.
michael@0:    * @return The filtered array of sites.
michael@0:    */
michael@0:   _filterPinnedSites: function DropPreview_filterPinnedSites(aSites, aCell) {
michael@0:     let draggedSite = gDrag.draggedSite;
michael@0: 
michael@0:     // When dropping on a cell that contains a pinned site make sure that all
michael@0:     // pinned cells surrounding the drop target are moved as well.
michael@0:     let range = this._getPinnedRange(aCell);
michael@0: 
michael@0:     return aSites.filter(function (aSite, aIndex) {
michael@0:       // The site must be valid, pinned and not the dragged site.
michael@0:       if (!aSite || aSite == draggedSite || !aSite.isPinned())
michael@0:         return false;
michael@0: 
michael@0:       let index = aSite.cell.index;
michael@0: 
michael@0:       // If it's not in the 'pinned range' it's a valid pinned site.
michael@0:       return (index > range.end || index < range.start);
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Determines the range of pinned sites surrounding the drop target cell.
michael@0:    * @param aCell The drop target cell.
michael@0:    * @return The range of pinned cells.
michael@0:    */
michael@0:   _getPinnedRange: function DropPreview_getPinnedRange(aCell) {
michael@0:     let dropIndex = aCell.index;
michael@0:     let range = {start: dropIndex, end: dropIndex};
michael@0: 
michael@0:     // We need a pinned range only when dropping on a pinned site.
michael@0:     if (aCell.containsPinnedSite()) {
michael@0:       let links = gPinnedLinks.links;
michael@0: 
michael@0:       // Find all previous siblings of the drop target that are pinned as well.
michael@0:       while (range.start && links[range.start - 1])
michael@0:         range.start--;
michael@0: 
michael@0:       let maxEnd = links.length - 1;
michael@0: 
michael@0:       // Find all next siblings of the drop target that are pinned as well.
michael@0:       while (range.end < maxEnd && links[range.end + 1])
michael@0:         range.end++;
michael@0:     }
michael@0: 
michael@0:     return range;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Checks if the given array of sites contains a pinned site that has
michael@0:    * been pushed out of the grid.
michael@0:    * @param aSites The array of sites to check.
michael@0:    * @param aCell The drop target cell.
michael@0:    * @return Whether there is an overflowed pinned cell.
michael@0:    */
michael@0:   _hasOverflowedPinnedSite:
michael@0:     function DropPreview_hasOverflowedPinnedSite(aSites, aCell) {
michael@0: 
michael@0:     // If the drop target isn't pinned there's no way a pinned site has been
michael@0:     // pushed out of the grid so we can just exit here.
michael@0:     if (!aCell.containsPinnedSite())
michael@0:       return false;
michael@0: 
michael@0:     let cells = gGrid.cells;
michael@0: 
michael@0:     // No cells have been pushed out of the grid, nothing to do here.
michael@0:     if (aSites.length <= cells.length)
michael@0:       return false;
michael@0: 
michael@0:     let overflowedSite = aSites[cells.length];
michael@0: 
michael@0:     // Nothing to do if the site that got pushed out of the grid is not pinned.
michael@0:     return (overflowedSite && overflowedSite.isPinned());
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * We have a overflowed pinned site that we need to re-position so that it's
michael@0:    * visible again. We try to find a lower-priority cell (empty or containing
michael@0:    * an unpinned site) that we can move it to.
michael@0:    * @param aSites The array of sites.
michael@0:    * @param aCell The drop target cell.
michael@0:    */
michael@0:   _repositionOverflowedPinnedSite:
michael@0:     function DropPreview_repositionOverflowedPinnedSite(aSites, aCell) {
michael@0: 
michael@0:     // Try to find a lower-priority cell (empty or containing an unpinned site).
michael@0:     let index = this._indexOfLowerPrioritySite(aSites, aCell);
michael@0: 
michael@0:     if (index > -1) {
michael@0:       let cells = gGrid.cells;
michael@0:       let dropIndex = aCell.index;
michael@0: 
michael@0:       // Move all pinned cells to their new positions to let the overflowed
michael@0:       // site fit into the grid.
michael@0:       for (let i = index + 1, lastPosition = index; i < aSites.length; i++) {
michael@0:         if (i != dropIndex) {
michael@0:           aSites[lastPosition] = aSites[i];
michael@0:           lastPosition = i;
michael@0:         }
michael@0:       }
michael@0: 
michael@0:       // Finally, remove the overflowed site from its previous position.
michael@0:       aSites.splice(cells.length, 1);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Finds the index of the last cell that is empty or contains an unpinned
michael@0:    * site. These are considered to be of a lower priority.
michael@0:    * @param aSites The array of sites.
michael@0:    * @param aCell The drop target cell.
michael@0:    * @return The cell's index.
michael@0:    */
michael@0:   _indexOfLowerPrioritySite:
michael@0:     function DropPreview_indexOfLowerPrioritySite(aSites, aCell) {
michael@0: 
michael@0:     let cells = gGrid.cells;
michael@0:     let dropIndex = aCell.index;
michael@0: 
michael@0:     // Search (beginning with the last site in the grid) for a site that is
michael@0:     // empty or unpinned (an thus lower-priority) and can be pushed out of the
michael@0:     // grid instead of the pinned site.
michael@0:     for (let i = cells.length - 1; i >= 0; i--) {
michael@0:       // The cell that is our drop target is not a good choice.
michael@0:       if (i == dropIndex)
michael@0:         continue;
michael@0: 
michael@0:       let site = aSites[i];
michael@0: 
michael@0:       // We can use the cell only if it's empty or the site is un-pinned.
michael@0:       if (!site || !site.isPinned())
michael@0:         return i;
michael@0:     }
michael@0: 
michael@0:     return -1;
michael@0:   }
michael@0: };