-- Contains user interface elements
require("oct_utils")
require("termbox_defs")


-- visible_textboxes is a global list of all textboxes we can cycle through
-- it is, in principle, a circular list
-- the top of the list is the currently selected textbox
-- upon a switch (i.e. TAB key), the list is rotated
registered_textboxes = {}

function create_textbox(id, pos_x, pos_y, max_length, label)
   t = oct_tb_sprite_new()
   t["x"] = pos_x
   t["y"] = pos_y
   t["shape"] = label .. string.rep("_", max_length) -- what is displayed to user
   t["fg"] = TB_WHITE

   local textbox = {}
   textbox["sprite"] = t
   textbox["contents"] = "" -- what is returned when box is submitted
   textbox["max_length"] = max_length
   textbox["id"] = id
   textbox["label"] = label
   return textbox
end

function update_registered_textboxes_appearance()
   -- textbox at front is focused, set to green
   registered_textboxes[1]["sprite"]["fg"] = TB_GREEN
   -- set all other textboxes to unfocused (white colored)
   for i=2,#registered_textboxes
   do
	  registered_textboxes[i]["sprite"]["fg"] = TB_WHITE
   end   
end

function register_textbox(textbox)
   already_registered = false;
   for i=1,#registered_textboxes
   do
	  if (registered_textboxes[i] == textbox)
	  then
		 already_registered = true
	  end
   end

   if (already_registered)
   then
	  OCT_LOG_WARNING("Attempted to register an already-registered textbox")
   else
	  table.insert(registered_textboxes, 1, textbox)
   end
  
   update_registered_textboxes_appearance()
end

function unregister_textbox(textbox)
   removed = false
   for i=1,#registered_textboxes
   do
	  if (registered_textboxes[i] == textbox)
	  then
		 table.remove(registered_textboxes, i)
		 textbox["sprite"]["fg"] = TB_WHITE
		 removed = true
	  end
   end
   if not removed
   then
	  OCT_LOG_WARNING("Attempted to unregister an unregistered textbox")
   end
   update_registered_textboxes_appearance()
end

function textbox_contents_to_shape(contents, max_length)
   l = string.len(contents)
   ret_str = ""
   if (l < max_length+1)
   then
	  ret_str = contents
	  n_underscores = max_length - l
	  ret_str = ret_str .. string.rep("_", n_underscores)
   else -- show only the last max_length characters
	  ret_str = string.sub(contents, -max_length)
   end
   return ret_str
end


function handle_textbox(key, ch)
   local to_return = nil
   if (registered_textboxes[1] == nil)
   then
	  OCT_LOG_WARNING("Called handle_textbox when no textboxes are registered")
   else
	  -- Convert ch from a character code to a character
	  ch = string.char(ch)
	  
	  -- if nothing was pressed, ch is '\0' (null byte)
	  if (ch ~= '\0')
	  then
		 -- Update the contents of the textbox, this isn't displayed by default
		 registered_textboxes[1]["contents"] = registered_textboxes[1]["contents"] .. ch
	  end

	  if (key == TB_KEY_BACKSPACE2 or key == TB_KEY_BACKSPACE)
	  then
		 registered_textboxes[1]["contents"] = string.sub(registered_textboxes[1]["contents"], 1, string.len(registered_textboxes[1]["contents"])-1)
	  end

	  -- Update the user-visible sprite
	  if (registered_textboxes[1])
	  then
		 registered_textboxes[1]["sprite"]["shape"] = registered_textboxes[1]["label"] .. textbox_contents_to_shape(registered_textboxes[1]["contents"], registered_textboxes[1]["max_length"])
	  end	  

	  -- Submit our registered textboxes
	  if (key == TB_KEY_ENTER)
	  then
		 to_return = {}
		 for i=1,#registered_textboxes 
		 do
			curr = registered_textboxes[i]
			to_return[curr["id"]] = curr["contents"]
		 end
	  end

	  -- Rotate the registered textboxes
	  if (key == TB_KEY_TAB)
	  then
		 table.insert(registered_textboxes, 1, table.remove(registered_textboxes))
		 update_registered_textboxes_appearance()
	  end
   end
   
   return to_return
end