#!/usr/bin/env lua

local candran = require("candran").setup()
local util = require("candran.util")
local argparse = require("argparse")
local unpack = unpack or table.unpack

-- Parse args --

local parser = argparse()
	:name "can"
	:description("Candran "..candran.VERSION.." interpreter by Reuh.")
	:epilog "For more info, see https://github.com/Reuh/candran"

parser:argument("filename", "Candran file to run. Use - to read from standard input. Start the REPL if no filename given.")
	:args "?"

util.cli.addCandranOptions(parser)

local args = parser:parse()

local options = util.cli.makeCandranOptions(args)

-- Run --

-- stdin
if args.filename == "-" then
	local f, err = candran.load(io.read("*a"), "stdin", nil, options)
	if not f then
		io.stderr:write("can: "..err.."\n")
		os.exit(1)
	end
	local r, e = xpcall(f, candran.messageHandler)
	if not r then
		io.stderr:write(e.."\n")
		os.exit(1)
	end
-- file
elseif args.filename then
	local f, err = candran.loadfile(args.filename, nil, options)
	if not f then
		io.stderr:write("can: "..err.."\n")
		os.exit(1)
	else
		local r, e = xpcall(f, candran.messageHandler)
		if not r then
			io.stderr:write(e.."\n")
			os.exit(1)
		end
	end
-- REPL
else
	candran.default = util.merge(candran.default, options)

	-- Setup linenoise
	local s, l = pcall(require, "linenoise")
	if not s then -- pure Lua compatibility thingy
		l = {
			linenoise = function(prompt)
				io.write(prompt)
				local s, line = pcall(io.read)
				if not s then
					if line == "interrupted!" then
						return nil
					else
						return nil, err
					end
				end
				return line
			end,
			historyadd = function() end,
			setcompletion = function() end,
			sethints = function() end,
			enableutf8 = function() end
		}
	end
	local keywords = {
		-- Lua
		"and", "break", "do", "else", "elseif", "end", "false", "for", "function", "goto",
		"if", "in", "local", "nil", "not", "or", "repeat", "return", "then", "true",
		"until", "while",
		-- Candran
		"continue", "let", "push"
	}
	l.enableutf8()
	l.setcompletion(function(comp, line)
		local var = line:match("[a-zA-Z_][a-zA-Z_0-9]*$")
		if var then
			for _, k in ipairs(keywords) do
				if k:match("^"..var) then
					comp:add(line .. k:sub(#var+1))
				end
			end
			for k in pairs(_ENV) do
				if k:match("^"..var) then
					comp:add(line .. k:sub(#var+1))
				end
			end
		end
	end)
	l.sethints(function(line)
		local var = line:match("[a-zA-Z_][a-zA-Z_0-9]*$")
		if var then
			for _, k in ipairs(keywords) do
				if k:match("^"..var) then
					return k:sub(#var+1), { color = 2, bold = true }
				end
			end
			for k in pairs(_ENV) do
				if k:match("^"..var) then
					return k:sub(#var+1), { color = 2 }
				end
			end
		end
	end)

	-- Introduction
	print("Candran " .. candran.VERSION .. ", targeting " .. candran.default.target)
	candran.setup()

	-- only perform static imports once, on startup
	do
		local r, e = candran.load("local _", "stdin")
		if not r then
			print("In static import: "..e)
		else
			r, e = pcall(r)
			if not r then
				print("In static import: "..e)
			end
		end
		candran.default.import = {}
	end

	-- REPL loop
	local multiline = false -- true if wait for another line
	local buffer
	while true do
		local line, err = l.linenoise(multiline and ">> " or "> ")

		-- exit
		if not line then
			if not err then
				if multiline then
					multiline = false
					line = ""
				else
					return
				end
			else
				error(err)
			end
		end

		-- history
		if line:match("[^%s]") then
			l.historyadd(line)
		end

		-- multiline
		if multiline then
			buffer = buffer .. "\n" .. line
			multiline = false
		else
			buffer = line
		end

		-- print shortcut 
		if buffer:match("^=") then
			buffer = buffer:gsub("^=", "return tostring(") .. ")"
		end

		-- exec
		local r, e = candran.load(buffer, "stdin")
		if not r then
			if e:match("expected '[end})]+' to close") then
				multiline = true
			else
				print(e)
			end
		else
			local t = { pcall(r) }
			if t[1] == false then
				print(t[2])
			elseif #t > 1 then
				print(unpack(t, 2))
			end
		end
	end
end