-- This order imposed here on the quest steps is the one in which the
-- quest steps have to be solved - as far as we can tell (the quest
-- may be in the process of beeing created and not logicly complete yet).
yl_speak_up.get_sorted_quest_step_list_by_prev_step = function(pname, q_id)
	if(not(q_id) or not(yl_speak_up.quests[q_id]) or not(yl_speak_up.quests[q_id].step_data)) then
		return {}
	end

	-- for now: sort alphabeticly
	local step_data = yl_speak_up.quests[q_id].step_data
	local liste = {}
	for k, v in pairs(step_data) do
		table.insert(liste, k)
	end
	table.sort(liste)
	return liste
end

--[[ still belongs to the above function
	-- add back links (or rather: forward links to quest steps that get enabled)
	local connected = table.copy(step_data)
	for k, v in pairs(connected) do
		-- will store the inverse data
		connected[k].inv_one_step_required = {}
		connected[k].inv_all_steps_require = {}
	end
	for k, v in pairs(connected) do
		if(k and v and v.one_step_required) then
			for i, s in ipairs(v.one_step_required) do
				table.insert(connected[s].inv_one_step_required, k)
			end
		end
		if(k and v and v.all_steps_required) then
			for i, s in ipairs(v.all_steps_required) do
				table.insert(connected[s].inv_all_steps_required, k)
			end
		end
	end
	-- get those quest steps that are not connected and not used yet
	local liste = {}
	for k, v in pairs(connected) do
		if(k and v
		  and #v.one_step_required == 0 and #v.all_steps_required == 0
		  and #v.inv_one_step_required == 0 and #v.inv_all_steps_required == 0) then
			table.insert(liste, k)
		end
	end
	-- sort alphabeticly
	table.sort(liste)
	-- remove those entries from our connection table (they're not connected anyway);
	-- we have already added them to the beginning of the list
	for i, v in ipairs(liste) do
		connected[v] = nil
	end


        return liste
end             
--]]


yl_speak_up.input_fs_add_quest_steps = function(player, formname, fields)
	local pname = player:get_player_name()

	if(fields and fields.back) then
		if(pname and yl_speak_up.speak_to[pname] and yl_speak_up.speak_to[pname].quest_step) then
			yl_speak_up.show_fs(player, "manage_quest_steps", yl_speak_up.speak_to[pname].quest_step)
			return
		end
	end
end


-- small helper function for yl_speak_up.get_fs_add_quest_steps;
-- lists all the quest steps found in liste in the order they occour there
yl_speak_up.quest_step_list_show_table = function(formspec, table_specs, liste, data, required_for_steps)
	local grey_if_zero = function(fs, n)
		if(n and n == 0) then
			table.insert(fs, "#444444")
		else
			table.insert(fs, "#FFFFFF")
		end
		table.insert(fs, minetest.formspec_escape(n))
	end

	table.insert(formspec, "tablecolumns["..
		"color;text,align=right;".. -- #d.one_step_required
		"color;text,align=right;".. -- #d.all_steps_required
		"color;text,align=right;".. -- #required_for_steps (quest steps that need this one)
		"color;text,align=left"..  -- name of quest step
		"]table[")
	table.insert(formspec, table_specs)
	local tmp = {}
	for i, s in ipairs(liste or {}) do
		local d = data[s]
		if(not(d.one_step_required) or type(d.one_step_required) ~= "table") then
			d.one_step_required = {}
		end
		grey_if_zero(tmp, #d.one_step_required)
		if(not(d.all_steps_required) or type(d.all_steps_required) ~= "table") then
			d.all_steps_required = {}
		end
		grey_if_zero(tmp, #d.all_steps_required)
		if(not(required_for_steps[s])) then
			required_for_steps[s] = {}
		end
		grey_if_zero(tmp, #required_for_steps[s])
		table.insert(tmp, "#AAFFAA")
		table.insert(tmp, minetest.formspec_escape(s))
	end
	table.insert(formspec, table.concat(tmp, ","))
	table.insert(formspec, ";]")
end


yl_speak_up.get_fs_add_quest_steps = function(player, param)
	local pname = player:get_player_name()
	if(not(pname) or not(yl_speak_up.speak_to[pname])) then
		return yl_speak_up.show_fs(player, "manage_quests")
	end
	local q_id = yl_speak_up.speak_to[pname].q_id
	-- TODO: check if the player can access that quest
	if(not(q_id)) then
		return yl_speak_up.show_fs(player, "manage_quests")
	end
	local quest = yl_speak_up.quests[q_id]
	if(not(quest)) then
		return yl_speak_up.show_fs(player, "manage_quests")
	end

	local step_data = quest.step_data
	-- find out if a quest step is required by other quest steps
	local required_for_steps = {}
	for s, d in pairs(step_data) do
		required_for_steps[s] = {}
	end
	for s, d in pairs(step_data) do
		if(s and d and d.one_step_required and type(d.one_step_required) == "table") then
			for i, s2 in ipairs(d.one_step_required) do
				table.insert(required_for_steps[s2], s) 
			end
		end
                if(s and d and d.all_steps_required and type(d.all_steps_required) == "table") then
			for i, s2 in ipairs(d.all_steps_required) do
				table.insert(required_for_steps[s2], s) 
			end
		end
	end


	local formspec = {}
	table.insert(formspec, "size[18,12]")
	-- add back button
	table.insert(formspec, "button[8,0;2,0.7;back;Back]")
	-- show which quest we're working at
	table.insert(formspec, "label[0.2,1.0;Quest ID:]")
	table.insert(formspec, "label[3.0,1.0;")
	table.insert(formspec, minetest.formspec_escape(q_id))
	table.insert(formspec, "]")
	table.insert(formspec, "label[0.2,1.5;Quest name:]")
	table.insert(formspec, "label[3.0,1.5;")
	table.insert(formspec, minetest.formspec_escape(quest.name or "- unknown -"))
	table.insert(formspec, "]")

	-- add new quest step
	table.insert(formspec, "label[0.2,2.2;Add a new quest step named:]")
	table.insert(formspec, "field[1.0,2.4;10,0.7;add_quest_step;;]")

	local current_step = nil
	local this_step_data = nil
	if(pname and yl_speak_up.speak_to[pname] and yl_speak_up.speak_to[pname].quest_step) then
		current_step = yl_speak_up.speak_to[pname].quest_step
		this_step_data = step_data[current_step]
	end
	local mode = ""
	if(pname and yl_speak_up.speak_to[pname] and yl_speak_up.speak_to[pname].quest_step_mode) then
		mode = yl_speak_up.speak_to[pname].quest_step_mode
	end
	local y_pos = 3.3
	if(current_step and mode == "insert_after_prev_step") then
		local prev_step = "-"
		if(this_step_data and this_step_data.one_step_required and #this_step_data.one_step_required > 0) then
			prev_step = #this_step_data.one_step_required[1]
		end
		table.insert(formspec, "label[0.2,3.3;between the previous step:]")
		table.insert(formspec, "label[1.0,3.7;")
		table.insert(formspec, minetest.colorize("#AAFFAA", minetest.formspec_escape(prev_step)))
		table.insert(formspec, "]")
		table.insert(formspec, "label[0.2,4.1;and the currently selected step:]")
		table.insert(formspec, "label[1.0,4.5;")
		table.insert(formspec, minetest.colorize("#FFFF00", minetest.formspec_escape(current_step)))
		table.insert(formspec, "]")
		y_pos = 5.3
	elseif(current_step and mode == "insert_before_next_step") then
		local next_step = "-"
		if(current_step and required_for_steps[current_step] and #required_for_steps[current_step] > 0) then
			next_step = #required_for_steps[current_step][1]
		end
		table.insert(formspec, "label[0.2,3.3;between the currently selected step:]")
		table.insert(formspec, "label[1.0,3.7;")
		table.insert(formspec, minetest.colorize("#FFFF00", minetest.formspec_escape(current_step)))
		table.insert(formspec, "]")
		table.insert(formspec, "label[0.2,4.1;and the next step:]")
		table.insert(formspec, "label[1.0,4.5;")
		table.insert(formspec, minetest.colorize("#AAFFAA", minetest.formspec_escape(next_step)))
		table.insert(formspec, "]")
		y_pos = 5.3
	elseif(current_step and mode == "add_to_one_needed") then
		table.insert(formspec, "label[0.2,3.3;as a requirement to the currently selected step:]")
		table.insert(formspec, "label[1.0,3.7;")
		table.insert(formspec, minetest.colorize("#FFFF00", minetest.formspec_escape(current_step)))
		table.insert(formspec, "]")
		table.insert(formspec, "label[0.2,4.1;so that "..
					minetest.colorize("#9999FF", "at least one")..
					" of these requirements is fulfilled:]")
		yl_speak_up.quest_step_list_show_table(formspec,
					"0.2,4.3;11.0,3.0;delete_from_one_step_required;",
					step_data[current_step].one_step_required,
					step_data, required_for_steps)
		table.insert(formspec, "label[0.2,7.5;(Click on an entry to delete it from the list above.)]")
		y_pos = 8.3
	elseif(current_step and mode == "add_to_all_needed") then
		table.insert(formspec, "label[0.2,3.3;as a requirement to the currently selected step:]")
		table.insert(formspec, "label[1.0,3.7;")
		table.insert(formspec, minetest.colorize("#FFFF00", minetest.formspec_escape(current_step)))
		table.insert(formspec, "]")
		table.insert(formspec, "label[0.2,4.1;so that "..
					minetest.colorize("#9999FF", "all")..
					" of these requirements are fulfilled:]")
		yl_speak_up.quest_step_list_show_table(formspec,
					"0.2,4.3;11.0,3.0;delete_from_all_steps_required;",
					step_data[current_step].all_steps_required,
					step_data, required_for_steps)
		table.insert(formspec, "label[0.2,7.5;(Click on an entry to delete it from the list above.)]")
		y_pos = 8.3
	end

	-- TODO: temporary!
	local available_steps = {}
	for k, v in pairs(step_data) do
		table.insert(available_steps, k)
	end
	table.sort(available_steps)
	table.insert(formspec, "label[0.2,")
	table.insert(formspec, tostring(y_pos))
	table.insert(formspec, ";or select an existing quest step from the list below:]")
	yl_speak_up.quest_step_list_show_table(formspec,
		"0.2,"..tostring(y_pos + 0.2)..";11.0,3.0;add_from_available;",
		available_steps,
		step_data, required_for_steps)

	-- TODO: write before which quest step we want to insert (if that is what is selected)
	return table.concat(formspec, "")
end