bl_info = {
    "name": "Toggle Ghost Frames Visibility",
    "description": "Re-assignable hotkey for toggling visibility of Ghost Frames for current Armature.",
    "author": "Ferdinand Joseph Fernandez",
    "version": (1, 0),
    "location": "Press F while in 3d View (whether in Pose Mode or in Object Mode), or while in Dopesheet",
    "support": "TESTING",
    "category": "Animation",
}

import bpy

def is_in_visible_layer(ob):
    ob_layers = ob.layers
    scene_layers = bpy.context.scene.layers

    for layer_index in range(len(ob_layers)):
        if ob_layers[layer_index] == True and scene_layers[layer_index] == True:
            return True

    return False

class ToggleGhostFrames(bpy.types.Operator):
    """Toggle Ghost Frames"""
    bl_idname = "animation.toggle_ghost_frames"
    bl_label = "Toggle Ghost Frames"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):
        ob = context.object

        if ob.type != 'ARMATURE':
            # Selected wasn't an armature.
            # Search whole scene for the first
            # armature that isn't hidden via the outliner,
            # and is in a layer that is currently visible.
            for scene_ob in bpy.context.scene.objects:
                if scene_ob.type != 'ARMATURE' or scene_ob.hide == True or is_in_visible_layer(scene_ob) == False:
                    continue

                ob = scene_ob
                break

        if ob.type == 'ARMATURE':
            armature = ob.data

            if armature.ghost_type == "CURRENT_FRAME":
                armature.ghost_type = "RANGE"
            elif armature.ghost_type == "RANGE":
                armature.ghost_type = "CURRENT_FRAME"

        return {'FINISHED'}

# keymaps are stored here so they can be accessed after registration
toggle_ghost_addon_keymaps = []

def register():
    bpy.utils.register_class(ToggleGhostFrames)

    # hotkey registration
    wm = bpy.context.window_manager
    kc = wm.keyconfigs.addon

    if kc:
        keymap_pose_toggle_ghost = kc.keymaps.new(name='Pose', space_type='EMPTY')
        keymap_item_pose_toggle_ghost = keymap_pose_toggle_ghost.keymap_items.new(ToggleGhostFrames.bl_idname, 'F', 'PRESS')

        keymap_object_toggle_ghost = kc.keymaps.new(name='Object Mode', space_type='EMPTY')
        keymap_item_object_toggle_ghost = keymap_object_toggle_ghost.keymap_items.new(ToggleGhostFrames.bl_idname, 'F', 'PRESS')

        keymap_dope_toggle_ghost = kc.keymaps.new(name='Dopesheet', space_type='DOPESHEET_EDITOR')
        keymap_item_dope_toggle_ghost = keymap_dope_toggle_ghost.keymap_items.new(ToggleGhostFrames.bl_idname, 'F', 'PRESS')

        # add to list so we can unregister afterwards
        toggle_ghost_addon_keymaps.append((keymap_pose_toggle_ghost, keymap_item_pose_toggle_ghost))
        toggle_ghost_addon_keymaps.append((keymap_object_toggle_ghost, keymap_item_object_toggle_ghost))
        toggle_ghost_addon_keymaps.append((keymap_dope_toggle_ghost, keymap_item_dope_toggle_ghost))

def unregister():

    # unregister hotkey
    wm = bpy.context.window_manager
    kc = wm.keyconfigs.addon
    if kc:
        for km, kmi in toggle_ghost_addon_keymaps:
            #print("Removing hotkey %s" % (kmi.idname))
            km.keymap_items.remove(kmi)
            # note: don't remove km, as it may contain hotkeys of other add-ons!
            #kc.keymaps.remove(km)

    # clear the list
    #addon_keymaps.clear()
    del toggle_ghost_addon_keymaps[:]

    bpy.utils.unregister_class(ToggleGhostFrames)

if __name__ == "__main__":
    register()