config = {
	c2 = {
		"app",
		"c2",
		"video",
		"pipeline",
		"asset",
		"ui",
		"maths",
		"model"
	},
	qstd = {
		"memory",
		"plat",
		"str",
		"pack"
	},
	cfg = {
		"cfgparse"
	},
	sc = {
		"sc",
		"includer"
	},
	packer = {
		"packer"
	},
	convtexture = {
		"convtexture"
	},
	convmodel = {
		"convmodel"
	},
	convmaterial = {
		"convmaterial"
	},
	shaders = {
		"triangle",
		"ui",
		"surface",
		"surface_depthonly",
		"sky",
		"mip_spec"
	},
	materials = {
		"bricks",
		"plastic",
	},
	models = {
		"monkey",
	},
	textures = {
		{ "22", "bmp", "bc1" },
		{ "kita", "bmp", "bc1" },
		{ "brick_albedo", "bmp", "bc1" },
		{ "brick_ao", "bmp", "bc4" },
		{ "brick_normal", "bmp", "bc5" },
		{ "sky", "hdr", "rgba16f" }
	}
}

local system = arg[1]
if system ~= "windows" and system ~= "unix" then
	print("Invalid system, needs to be 'windows' or 'unix'.")
	os.exit(1)
end

function build_unix()
	local compiler_c = nil
	local compiler_cpp = nil
	local ar = nil
	if os.execute("gcc --version") then
		compiler_c = "gcc"
		compiler_cpp = "g++"
	elseif os.execute("clang --version") then
		compiler_c = "clang"
		compiler_cpp = "clang++"
	end
	if os.execute("ar --version") then
		ar = "ar"
	end
	if not compiler_c or not compiler_cpp then
		print("didn't find a valid compiler :(")
		os.exit(2)
	end
	print("c   compiler: " .. compiler_c)
	print("c++ compiler: " .. compiler_cpp)
	print("ar:           " .. ar)

	local outfile = io.open("Makefile", "w")
	if not outfile then
		print("Failed to open Makefile.")
		exit(3)
	end
	local std_flag = {
		c   = "-std=gnu99",
		cpp = "-std=c++20"
	}
	outfile:write("# generated by configure.lua\n\n")
	outfile:write(
		"cflags = -pedantic -Wall -Wextra " ..
		"-Dplat_x11 -Dplat_x86 -Dplat_posix -Dallocation_default_alignment=8 " ..
		"-Icfg -Iqstd -Isc/glslang " ..
		"-MMD -MF $(basename $@).d " ..
		"\n\n"
	)

	outfile:write(".PHONY: all clean\n")
	outfile:write("all: c2\n\n")

	outfile:write("ifndef config\n")
	outfile:write("  config=debug\n")
	outfile:write("endif\n")
	outfile:write("ifeq ($(config),debug)\n")
	outfile:write("  opt_com = -DDEBUG -g -O0\n")
	outfile:write("  opt_lnk =\n")
	outfile:write("endif\n")
	outfile:write("ifeq ($(config),release)\n")
	outfile:write("  opt_com = -DNDEBUG -O3\n")
	outfile:write("  opt_lnk = -s\n")
	outfile:write("endif\n\n")

	local all_objs = {}
	local all_deps = {}
	local all_assets = {}
	local all_shaders = {}
	local function objs(com, ext, tab, dir)
		local std = std_flag[ext]
		for _, fname in ipairs(tab) do
			outfile:write(string.format(
				"%s%s.o: %s%s.%s\n\t%s %s $(opt_com) $(cflags) -c %s%s.%s -o %s%s.o\n",
				dir,
				fname,
				dir,
				fname,
				ext,
				com,
				std,
				dir,
				fname,
				ext,
				dir,
				fname
			))
			all_objs[#all_objs + 1] = dir .. fname .. '.o'
			all_deps[#all_deps + 1] = dir .. fname .. '.d'
		end
	end

	local function lib(com, tab, name, dir)
		objs(com, 'c', tab, dir)
		outfile:write(name .. ": ")
		for _, fname in ipairs(tab) do
			outfile:write(dir .. fname .. ".o ")
		end
		outfile:write("\n\t")
		outfile:write(ar .. " -rcs " .. name .. " ")
		for _, fname in ipairs(tab) do
			outfile:write(dir .. fname .. ".o ")
		end
		outfile:write("\n\n")
	end

	local function prog(type, com, tab, name, dir, dep, lib)
		objs(com, type, tab, dir)
		outfile:write(name .. ": ")
		for _, fname in ipairs(tab) do
			outfile:write(dir .. fname .. ".o ")
		end
		for _, fname in ipairs(dep) do
			outfile:write(fname .. " ")
		end
		outfile:write("\n\t")
		outfile:write(com .. " $(opt_lnk) $(lflags) -o " .. name .. " ")
		for _, fname in ipairs(tab) do
			outfile:write(dir .. fname .. ".o ")
		end
		for _, fname in ipairs(dep) do
			outfile:write(fname .. " ")
		end
		for _, fname in ipairs(lib) do
			outfile:write(fname .. " ")
		end
		outfile:write("\n\n")
	end

	local function shaders(stype, dtype, tool, tab)
		for _, fname in ipairs(tab) do
			outfile:write(string.format(
				"data/%s.%s: intermediate/%s.%s %s | data\n\t./%s intermediate/%s.%s data/%s.%s\n",
				fname,
				dtype,
				fname,
				stype,
				tool,
				tool,
				fname,
				stype,
				fname,
				dtype
			))
			all_shaders[#all_shaders + 1] = "data/" .. fname .. "." .. dtype
			all_assets[#all_assets + 1] = fname .. "." .. dtype
		end
		outfile:write("\n")
	end

	local function models(tab)
		for _, fname in ipairs(tab) do
			outfile:write(string.format(
				"data/%s.mdl: convmodel intermediate/%s.glb ",
				fname, fname
			))
			for _, fname in ipairs(all_shaders) do
				outfile:write(fname .. " ")
			end
			outfile:write("| data\n\t")
			outfile:write(string.format(
				"./convmodel data intermediate/%s.glb data/%s.mdl\n",
				fname, fname
			))
			all_assets[#all_assets + 1] = fname .. ".mdl"
		end
		outfile:write("\n")
	end

	local function textures(tab)
		for _, c in ipairs(tab) do
			local fname = c[1]
			local ext = c[2]
			local fmt = c[3]
			outfile:write(string.format(
				"data/%s.tex: convtexture intermediate/%s.%s ",
				fname, fname, ext
			))
			outfile:write("| data\n\t")
			outfile:write(string.format(
				"./convtexture intermediate/%s.%s data/%s.tex %s\n",
				fname, ext, fname, fmt
			))
			all_assets[#all_assets + 1] = fname .. ".tex"
		end
		outfile:write("\n")
	end

	local function materials(tab)
		for _, fname in ipairs(tab) do
			outfile:write(string.format(
				"data/%s.mat: convmaterial intermediate/%s.mat ",
				fname, fname
			))
			outfile:write("| data\n\t")
			outfile:write(string.format(
				"./convmaterial intermediate/%s.mat data/%s.mat\n",
				fname, fname
			))
			all_assets[#all_assets + 1] = fname .. ".mat"
		end
		outfile:write("\n")
	end

	local function pack()
		outfile:write("pack: packer ")
		for _, fname in ipairs(all_assets) do
			outfile:write("data/" .. fname .. " ")
		end
		outfile:write("\n\t./packer pack data ")
		for _, fname in ipairs(all_assets) do
			outfile:write(fname .. " ")
		end
		outfile:write("\n\n")
	end

	lib(compiler_c, config.qstd, "libqstd.a", "qstd/")
	lib(compiler_c, config.cfg,  "libcfg.a",  "cfg/")
	prog(
		"cpp",
		compiler_cpp,
		config.sc,
		"shadercompiler",
		"sc/",
		{ "libqstd.a", "libcfg.a" },
		{
			"-Lsc/glslang/build/glslang",
			"-Lsc/glslang/build/SPIRV",
			"-Lsc/glslang/build/glslang/OSDependent/Unix",
			"-Lsc/glslang/build/External/spirv-tools/source",
			"-Lsc/glslang/build/External/spirv-tools/source/link",
			"-Lsc/glslang/build/External/spirv-tools/source/opt",
			"-lglslang",
			"-lglslang-default-resource-limits",
			"-lSPIRV",
			"-lMachineIndependent",
			"-lSPVRemapper",
			"-lOSDependent",
			"-lGenericCodeGen",
			"-lSPIRV-Tools-link",
			"-lSPIRV-Tools-opt",
			"-lSPIRV-Tools"
		}
	)
	prog(
		"cpp",
		compiler_cpp,
		config.c2,
		"c2",
		"",
		{ "libqstd.a" },
		{ "-lX11", "-lm" }
	)
	outfile:write("c2: pack\n\n")
	prog(
		"c",
		compiler_c,
		config.convtexture,
		"convtexture",
		"",
		{ "libqstd.a" },
		{}
	)
	prog(
		"c",
		compiler_c,
		config.convmodel,
		"convmodel",
		"",
		{ "libqstd.a" },
		{}
	)
	prog(
		"c",
		compiler_c,
		config.convmaterial,
		"convmaterial",
		"",
		{ "libqstd.a", "libcfg.a" },
		{}
	)
	prog(
		"c",
		compiler_c,
		config.packer,
		"packer",
		"",
		{ "libqstd.a" },
		{}
	)
	shaders("glsl", "csh", "shadercompiler", config.shaders)
	models(config.models)
	textures(config.textures)
	materials(config.materials)
	pack()
	outfile:write("data:\n\tmkdir -p data\n\n")
	outfile:write("-include ")
	for _, fname in ipairs(all_deps) do
		outfile:write(fname .. " ")
	end
	outfile:write("\n\n")
	outfile:write("clean:\n\trm -f ")
	for _, fname in ipairs(all_objs) do
		outfile:write(fname .. " ")
	end
	for _, fname in ipairs(all_deps) do
		outfile:write(fname .. " ")
	end
	for _, fname in ipairs(all_assets) do
		outfile:write("data/" .. fname .. " ")
	end
	outfile:write("\n\trm -f shadercompiler\n")
	outfile:write("\trmdir data\n")
	outfile:write("\trm -f c2\n")
	outfile:write("\trm -f convtexture\n")
	outfile:write("\trm -f convmodel\n")
	outfile:write("\trm -f convmaterial\n")
	outfile:write("\trm -f libqstd.a\n")
	outfile:write("\trm -f libcfg.a\n")
	outfile:write("\n")
	print("done.")
end

if system == "unix" then
	build_unix()
end

if system == "windows" then
	print("windows isn't done yet.")
end