local CXX = "clang++"

local config = {
	["buildmode"]="debug",
	["target"]="x86_64-windows",
	["max_parallel"]=1
}

local program_output = "build/lbs"
local source_dirs = {"src"}
local include_dirs = {"include", "src", "thirdparty/luajit/src"}
local library_dirs = {"thirdparty/luajit/src"}
local linker_inputs = {"lua51", "luajit"}
local defines = {}
local additional_arguments = {"-std=c++20"}

function load_config(cfg_table, args)
	for i=1,#args,1 do
		k = args[i]	
		if (k:sub(1,2) == "-j") then
			if (tonumber(k:sub(3,-1),10) > 0) then
				cfg_table.max_parallel = tonumber(k:sub(3,-1),10)
			elseif (tonumber(args[i+1],10) > 0) then
				cfg_table.max_parallel = tonumber(args[i+1],10)
				i = i + 1
			else
				print("ERROR: -j option must be formatted as -j<num> or -j <num>. Numbers must be positive integers greater than 0")
				return -1
			end
		else
			cfg_table.buildmode = k
		end
	end
	return cfg_table
end

local function compile()

	local base_cmd = CXX .. " -c "
	
	for _,v in pairs(include_dirs) do base_cmd = base_cmd .. "-I\"" .. v .. "\" " end
	for k,v in pairs(defines) do base_cmd = base_cmd .. "-D" .. k .. "=" .. v .. " " end
	for _,v in pairs(additional_arguments) do base_cmd = base_cmd .. v .. " " end

	local src_args = {}
	for _,src_dir in pairs(source_dirs) do
		if (fs.is_dir(src_dir)) then
			for fsobj in fs.forall(src_dir) do
				if (fs.is_file(fsobj) and fs.extension(fsobj) == ".cpp") then
					src_args[#src_args+1] = fsobj .. " -o obj/" .. fsobj .. ".o"
				end
			end
		else
			print("[WARN ] Source directory " .. src_dir .. " does not exist!")
		end
	end

	ec, stdout = platform.exec_parallel(base_cmd, config.max_parallel, src_args)
	for i,ec in pairs(ec) do
		if (ec ~= 0) then
			print("Command \"" .. base_cmd .. src_args[i] .. "\" failed with exit code " .. tostring(ec) .. "and output;")
			print(stdout[i])
			print()
		end
	end
end

local function link()
	local cmd = CXX .. " "
	for _,lib_dir in pairs(library_dirs) do cmd = cmd .. "-L\"" .. lib_dir .. "\" " end
	for _,lnk in pairs(linker_inputs) do cmd = cmd .. "-l\"" .. lnk .. "\" " end

	for _,src_dir in pairs(source_dirs) do
		if (fs.is_dir(src_dir)) then
			for fsobj in fs.forall(src_dir) do
				if (fs.is_file(fsobj) and fs.extension(fsobj) == ".cpp") then
					cmd = cmd .. "obj/" .. fsobj .. ".o "
				end
			end
		else
			print("[WARN ] Source directory " .. src_dir .. " does not exist!")
		end
	end
	cmd = cmd .. "-o " .. program_output
	local platform_seps = {}
	for match in config.target:gmatch("[^-]+") do platform_seps[#platform_seps+1] = match end
	if (platform_seps[2] == "windows") then cmd = cmd .. ".exe " else cmd = cmd .. " " end

	ec, stdout = platform.exec(cmd, {})
	if (ec ~= 0) then
		print("Command \"" .. cmd .. "\" failed with exit code " .. tostring(ec) .. " and output;")
		print(stdout)
		print()
	end
end

function build(...)
	local args = {...}
	config = load_config(config, args)
	print("Building " .. config.buildmode .. " with up to " .. tostring(config.max_parallel) .. " concurrent jobs")
	compile()
	link()
end

return 0