--[[

  terminal - an interactive terminal

]]--

local context = {}

local function get_cmd_params(line)
	local cmd = ""
	local params = ""
	for w in line:gmatch("%w+") do
		if cmd == "" then
			cmd = w
		elseif params == "" then
			params = w
		else
			params = params .. " " .. w
		end
	end
	return cmd, params
end

local help = {
	append = "append text to a file",
	clear = "clear the output",
	echo = "echoes the input back to you",
	help = "display help information for commands",
	list = "list available files",
	lock = "lock the terminal",
	read = "read the content of a file",
	remove = "removes a file",
	unlock = "unlocks the terminal",
	write = "write text to a file",
}

local commands = {
	clear = function(output, params, c)
		return ""
	end,
	append = function(output, params, c)
		if not c.rw then
			return output .. "\nError: No write access"
		end
		local what, _ = get_cmd_params(params)
		if what == "" then
			return output .. "\nError: Missing file name"
		end
		c.writing = what
		return output .. "\nWriting \"" .. what .. "\". Enter STOP on a line by itself to finish"
	end,
	write = function(output, params, c)
		if not c.rw then
			return output .. "\nError: No write access"
		end
		local what, _ = get_cmd_params(params)
		if what == "" then
			return output .. "\nError: Missing file name"
		end
		c.writing = what
		local meta = minetest.get_meta(c.pos)
		local meta_files = meta:get_string("files")
		if meta_files and meta_files ~= "" then
			local files = minetest.parse_json(meta_files) or {}
			if files and files[what] then
				files[what] = ""
				meta:set_string("files", minetest.write_json(files))
			end
		end
		return output .. "\nWriting \"" .. what .. "\". Enter STOP on a line by itself to finish"
	end,
	remove = function(output, params, c)
		if not c.rw then
			return output .. "\nError: No write access"
		end
		local meta = minetest.get_meta(c.pos)
		local meta_files = meta:get_string("files")
		if not meta_files or meta_files == "" then
			return output .. "\nError: No such file"
		end
		local files = minetest.parse_json(meta_files) or {}
		local first, _ = get_cmd_params(params)
		if files[first] then
			files[first] = nil
		else
			return output .. "\nError: No such file"
		end
		meta:set_string("files", minetest.write_json(files))
		return output .. "\nRemoved \"" .. first .. "\""
	end,
	list = function(output, params, c)
		local meta = minetest.get_meta(c.pos)
		local meta_files = meta:get_string("files")
		local files
		if not meta_files or meta_files == "" then
			return output .. "\nError: No files found"
		end
		files = minetest.parse_json(meta_files) or {}
		if not files then
			return output .. "\nError: No files found"
		end
		for k, _ in pairs(files) do
			output = output .. "\n" .. k
		end
		return output
	end,
	echo = function(output, params, c)
		return output .. "\n" .. params
	end,
	read = function(output, params, c)
		local meta = minetest.get_meta(c.pos)
		local meta_files = meta:get_string("files")
		if not meta_files or meta_files == "" then
			return output .. "\nError: No such file"
		end
		local files = minetest.parse_json(meta_files) or {}
		local first, _ = get_cmd_params(params)
		if files[first] then
			return output .. "\n" .. files[first]
		else
			return output .. "\nError: No such file"
		end
	end,
	lock = function(output, params, c)
		if not c.rw then
			return output .. "\nError: no write access"
		end
		local meta = minetest.get_meta(c.pos)
		meta:set_int("locked", 1)
		return output .. "\n" .. "Terminal locked"
	end,
	unlock = function(output, params, c)
		return output .. "\n" .. "Error: unable to connect to authentication service"
	end,
	help = function(output, params, c)
		if params ~= "" then
			local h, _ = get_cmd_params(params)
			if help[h] then
				return output .. "\n" .. help[h]
			else
				return output .. "\nError: No help for \"" .. h .. "\""
			end
		end
		return output .. "\n" ..
			"Available commands:\n" ..
			"  append\n  clear\n  echo\n  help\n  list\n  lock\n" ..
			"  read\n  remove\n  unlock\n  write\n" ..
			"Type `help <command>` for more help about that command"
	end,
}

local function make_formspec(output, prompt)
	local f =
		"size[12,8]" ..
		"field_close_on_enter[input;false]" ..
		"textlist[0.4,0.5;11,6;output;"

	local c = 1
	for part in output:gmatch("[^\r\n]+") do
		f = f .. minetest.formspec_escape(part) .. ","
		c = c + 1
	end
	f = f .. minetest.formspec_escape(prompt) .. ";" .. c .. ";false]"

	f = f .. "field[0.7,7;11.2,1;input;;]"
	return f
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
	if formname ~= "terminal:" then
		return false
	end

	-- input validation
	local name = player:get_player_name()
	local c = context[name]
	if not c then
		minetest.log("error", name .. " sends invalid formspec data")
		return true
	end

	local line = fields.input
	if line and line ~= "" then
		local output = c.output or ""
		minetest.sound_play("terminal_keyboard_clicks", {pos = c.pos})

		if c.writing then
			-- this shouldn't get reached, but just to be safe, check ro
			if not c.rw then
				c.writing = nil
				output = output .. "\n" .. line
				output = output .. "\nError: no write access"
				c.output = output
				minetest.show_formspec(name, "terminal:", make_formspec(output, "> "))
				return true
			end
			-- are we writing a file?
			if line == "STOP" then
				-- done writing a file
				c.writing = nil
				output = output .. "\n" .. line
				c.output = output
				minetest.show_formspec(name, "terminal:", make_formspec(output, "> "))
				return true
			end
			local meta = minetest.get_meta(c.pos)
			local meta_files = meta:get_string("files")
			local files = {}
			if not meta_files or meta_files == "" then
				files[c.writing] = line
			else
				files = minetest.parse_json(meta_files) or {}
				if not files[c.writing] then
					files[c.writing] = line
				else
					files[c.writing] = files[c.writing] .. "\n" .. line
				end
			end
			if string.len(files[c.writing]) < 16384 then
				local json = minetest.write_json(files)
				if string.len(json) < 49152 then
					meta:set_string("files", json)
					output = output .. "\n" .. line
				else
					output = output .. "\n" .. "Error: no space left on device"
				end
			else
				output = output .. "\n" .. "Error: maximum file length exceeded"
			end
			c.output = output
			minetest.show_formspec(name, "terminal:", make_formspec(output, ""))
		else
			-- else parse cmd
			output = output .. "\n> " .. line

			local meta = minetest.get_meta(c.pos)
			local cmd, params = get_cmd_params(line)
			if meta:get_int("locked") == 1 and cmd ~= "unlock" then
				output = output .. "\nError: Terminal locked, type \"unlock\" to unlock it"
				c.output = output
				minetest.show_formspec(name, "terminal:", make_formspec(output, "> "))
				return true
			end

			local fn = commands[cmd]
			if fn then
				output = fn(output, params, c)
			else
				output = output .. "\n" .. "Error: Syntax Error. Try \"help\""
			end
			c.output = output
			minetest.show_formspec(name, "terminal:", make_formspec(output, "> "))
		end
	elseif fields.quit then
		context[name] = nil
		minetest.sound_play("terminal_power_off", {pos = c.pos})
	else
		minetest.log("error", name .. " sends invalid formspec data")
		return true
	end
	return true
end)

local terminal_use = function(pos, node, clicker, itemstack, pointed_thing)
	if not clicker then
		return
	end
	local name = clicker:get_player_name()
	context[name] = {
		pos = pos,
		rw = false,
		output = "",
	}
	if boxes.players_editing_boxes[name] or
			(not boxes.players_in_boxes[name] and minetest.check_player_privs(clicker, "server")) then
		-- allow rw access
		context[name].rw = true
	end
	-- send formspec to player
	minetest.show_formspec(name, "terminal:", make_formspec("", "> "))
	minetest.sound_play("terminal_power_on", {pos = pos})
	-- trigger on first use
	local meta = minetest.get_meta(pos)
	if meta:get_int("locked") ~= 1 then
		mech.trigger(pos)
		minetest.after(1.0, mech.untrigger, pos)
	end
end


minetest.register_node("terminal:terminal", {
	description = "An interactive terminal console emulator access interface unit controller",
	drawtype = "mesh",
	mesh = "terminal.obj",
	groups = {mech = 1, trigger = 1},
	tiles = {
		{name = "terminal_base.png"},
		{name = "terminal_idle.png", animation = {type = "vertical_frames", aspect_w = 14, aspect_h = 13, length = 4.0}},
	},
	paramtype = "light",
	paramtype2 = "facedir",
	on_trigger = function(pos)
		local meta = minetest.get_meta(pos)
		minetest.sound_play("terminal_power_on", {pos = pos})
		meta:set_int("locked", 0)
	end,
	on_untrigger = function(pos)
		local meta = minetest.get_meta(pos)
		minetest.sound_play("terminal_power_off", {pos = pos})
		meta:set_int("locked", 1)
	end,
	on_rightclick = terminal_use,
})