local NEWLINE = "\n"
local DESCRIPTION = "Command Tool"
local MAX_CMD_TOOLTIP_LEN = 48

local split_commands = function(commands_string)
	return string.split(commands_string, NEWLINE)
end

local set_commands = function(itemstack, commands_string)
	local meta = itemstack:get_meta()
	meta:set_string("cmd", commands_string)
	local cmds = split_commands(commands_string)
	local first_cmd
	if #cmds >= 1 then
		first_cmd = cmds[1]
		if string.len(first_cmd) > MAX_CMD_TOOLTIP_LEN then
			first_cmd = string.sub(first_cmd, 1, MAX_CMD_TOOLTIP_LEN) .. " (…)"
		end
		local tooltip = DESCRIPTION .. NEWLINE .. first_cmd
		if #cmds == 2 then
			tooltip = tooltip .. NEWLINE .. string.format("… and %d more command", #cmds - 1)
		elseif #cmds > 2 then
			tooltip = tooltip .. NEWLINE .. string.format("… and %d more commands", #cmds - 1)
		end
		meta:set_string("description", tooltip)
	else
		meta:set_string("description", "")
	end
	return itemstack
end

-- Returns a table of commands in a command tool itemstack
local get_commands = function(itemstack)
	local meta = itemstack:get_meta()
	local cmd_str = meta:get_string("cmd")
	local cmds = split_commands(cmd_str)
	return cmds
end

local execute_command = function(itemstack, player, pointed_thing)
	local player_name = player:get_player_name()
	local cmds = get_commands(itemstack)
	if not cmds then
		return
	end
	local player_privs = minetest.get_player_privs(player_name)
	for c=1, #cmds do
		local cmd = cmds[1]
		-- Split command string into command name and parameters
		local cmd_split = string.split(cmd, " ", false, 1)
		local cmd_name
		-- Perform some checks:
		-- 1. Command exists
		-- 2. Player has all required privileges
		if cmd_split then
			-- Get command name
			cmd_name = cmd_split[1]
			local cmd_params = ""
			if cmd_split[2] then
				cmd_params = cmd_split[2]
			end
			local def = minetest.registered_chatcommands[cmd_name]
			if def then
				local required_privs = def.privs
				for priv, _ in pairs(required_privs) do
					if player_privs[priv] ~= true then
						minetest.chat_send_player(player_name, "Insufficient privileges for using command “"..cmd_name.."”! You need the “"..priv.."” privilege.")
						return
					end
				end
				-- All tests survived!
				-- Call the command
				def.func(player_name, cmd_params)
			else
				minetest.chat_send_player(player_name, "The command “"..cmd_name.."” does not exist!")
				return
			end
		else
			minetest.chat_send_player(player_name, "Invalid command!")
			return
		end
		-- One iteration is done. We continue with the next command.
	end
end

local open_command_configuration = function(itemstack, player, pointed_thing)
	local player_name = player:get_player_name()
	local commands = get_commands(itemstack)
	local commands_str = ""
	if commands then
		for c=1, #commands do
			commands_str = commands_str .. commands[c]
			if c < #commands then
				commands_str = commands_str .. "\n"
			end
		end
	end
	local formspec =
			"size[6,6]"..
			"textarea[0.25,0;6,5;commands;Commands:;"..minetest.formspec_escape(commands_str).."]"..
			"button_exit[0.5,5;2,1;ok;OK]"..
			"button_exit[3.5,5;2,1;cancel;Cancel]"
	minetest.show_formspec(player_name, "cmdtool", formspec)
end

minetest.register_tool("cmdtool:cmdtool", {
	description = DESCRIPTION,
	inventory_image = "cmdtool_cmdtool.png",
	wield_imagee = "cmdtool_cmdtool.png",
	on_use = execute_command,
	on_place = open_command_configuration,
	on_secondary_use = open_command_configuration,
})

-- Set commands
minetest.register_on_player_receive_fields(function(player, formname, fields)
	if formname == "cmdtool" and fields.ok and fields.commands ~= nil then
		local wield_tool = player:get_wielded_item()
		if wield_tool:get_name() == "cmdtool:cmdtool" then
			local updated_tool = set_commands(wield_tool, fields.commands)
			player:set_wielded_item(updated_tool)
		end
	end
end)