Add box to reverse index, appends -rev if checked

When box element is toggled, invoke a revised
sort option that appends "-rev" to the sort
dropdown value when box is checked. If this value
changes while box is checked, the new sort is
still reversed.

If "-rev" is already given by previously saved
sort or custom board navigation option, pick the
correct dropdown value and check box
automatically.

Wrap previous sorting implementation, determining
if "-rev" is tacked on and doing the reverse work
at the end.

src/General/Index.coffee

@@ -95,17 +95,24 @@ Index =
     @hideLabel = $ '#hidden-label', @navLinks
     $.on $('#hidden-toggle a', @navLinks), 'click', @cb.toggleHiddenThreads
 
-    # Drop-down menus
+    # Drop-down menus and reverse sort toggle
+    @selectRev   = $ '#index-rev',  @navLinks
     @selectMode  = $ '#index-mode', @navLinks
     @selectSort  = $ '#index-sort', @navLinks
     @selectSize  = $ '#index-size', @navLinks
+    $.on @selectRev,  'change', @cb.sort
     $.on @selectMode, 'change', @cb.mode
     $.on @selectSort, 'change', @cb.sort
     $.on @selectSize, 'change', $.cb.value
     $.on @selectSize, 'change', @cb.size
     for select in [@selectMode, @selectSize]
       select.value = Conf[select.name]
-    @selectSort.value = Index.currentSort
+    @selectSort.value = do ->
+      if Index.currentSort.slice(-4) is '-rev'
+        Index.selectRev.checked = true
+        return Index.currentSort.slice(0,-4)
+      else
+        return Index.currentSort
 
     # Thread container
     @root = $.el 'div', className: 'board json-index'
@@ -252,7 +259,8 @@ Index =
       Index.pageLoad false
 
     sort: ->
-      Index.pushState {sort: @value}
+      value = if Index.selectRev.checked then Index.selectSort.value + "-rev" else Index.selectSort.value
+      Index.pushState {sort: value}
       Index.pageLoad false
 
     resort: (e) ->
@@ -452,7 +460,13 @@ Index =
     $('#hidden-toggle a', Index.navLinks).textContent = 'Show'
 
   setupSort: ->
-    Index.selectSort.value = Index.currentSort
+    Index.selectRev.checked = false
+    Index.selectSort.value  = do ->
+      if Index.currentSort.slice(-4) is '-rev'
+        Index.selectRev.checked = true
+        return Index.currentSort.slice(0,-4)
+      else
+        return Index.currentSort
 
   getPagesNum: ->
     if Index.search
@@ -750,7 +764,13 @@ Index =
   sort: ->
     {liveThreadIDs, liveThreadData} = Index
     return unless liveThreadData
-    Index.sortedThreadIDs = switch Index.currentSort
+    Index.sortedThreadIDs = do ->
+      if Index.currentSort.slice(-4) == "-rev"
+        currentSort = Index.currentSort.slice(0,-4)
+        reverse = true
+      else
+        currentSort = Index.currentSort
+      sorted = switch currentSort
         when 'lastreply'
           [liveThreadData...].sort((a, b) ->
             a = num[num.length - 1] if (num = a.last_replies)
@@ -769,6 +789,7 @@ Index =
         when 'birth'      then [liveThreadIDs... ].sort (a, b) -> b - a
         when 'replycount' then [liveThreadData...].sort((a, b) -> b.replies - a.replies).map (post) -> post.no
         when 'filecount'  then [liveThreadData...].sort((a, b) -> b.images  - a.images ).map (post) -> post.no
+      return if reverse then [sorted...].reverse() else sorted
     if Index.search and (threadIDs = Index.querySearch Index.search)
       Index.sortedThreadIDs = threadIDs
     # Sticky threads