#!/usr/bin/env lua
local function parse_pair(pair, value_first)
	if pair:sub(1, 1) == "#" then
		return
	end

	local idx = pair:find(" ")

	if idx then
		local first, second = pair:sub(1, idx - 1), pair:sub(idx + 1)

		if value_first and first:sub(1, 1) ~= "[" then
			return second, first
		else
			return first, second
		end
	else
		return pair
	end
end

local function parse_spec(name, value_first)
	local f = io.open("spec/" .. name, "r")
	local spec = {}
	local top

	for l in f:lines() do
		if l:sub(1, 1) == "\t" then
			local key, val = parse_pair(l:sub(2), value_first)

			if val then
				top[key] = val
			elseif key then
				table.insert(top, key)
			end
		else
			local key, val = parse_pair(l, value_first)

			if val then
				spec[key] = val
			elseif key then
				top = {}
				spec[key] = top
			end
		end
	end

	f:close()
	return spec
end

local casemap = parse_spec("casemap")

local function camel_case(snake)
	if casemap[snake] then
		return casemap[snake]
	end

	local camel = ""

	while #snake > 0 do
		local idx = snake:find("_") or #snake + 1

		camel = camel
			.. snake:sub(1, 1):upper()
			.. snake:sub(2, idx - 1)

		snake = snake:sub(idx + 1)
	end

	return camel
end

local funcs = ""

for name, fields in pairs(parse_spec("client/enum")) do
	local camel = camel_case(name)
	funcs = funcs .. "func luaPush" .. camel .. "(l *lua.State, val mt." .. camel .. ") {\n\tswitch val {\n"

	for _, var in ipairs(fields) do
		funcs = funcs .. "\tcase mt."
			.. (fields.prefix or "") .. camel_case(var) .. (fields.postfix or "")
			.. ":\n\t\t" .. (var == "no" and "l.PushNil()" or "l.PushString(\"" .. var .. "\")") .. "\n"
	end

	funcs = funcs .. "\t}\n}\n\n"
end

for name, fields in pairs(parse_spec("client/flag")) do
	local camel = camel_case(name)
	funcs = funcs .. "func luaPush" .. camel .. "(l *lua.State, val mt." .. camel .. ") {\n\tl.NewTable()\n"

	for _, var in ipairs(fields)	do
		funcs = funcs .. "\tif val&mt."
			.. (fields.prefix or "") .. camel_case(var) .. (fields.postfix or "")
			.. " != 0 {\n\t\tl.PushBoolean(true)\n\t\tl.SetField(-2, \"" .. var  .. "\")\n\t}\n"
	end

	funcs = funcs .. "}\n\n"
end

local push_type = {
	string = "l.PushString(string(VAL))",
	fixed_string = "l.PushString(string(VAL[:]))",
	boolean = "l.PushBoolean(bool(VAL))",
	integer = "l.PushInteger(int(VAL))",
	number = "l.PushNumber(float64(VAL))",
	vec2 = "luaPushVec2(l, [2]float64{float64(VAL[0]), float64(VAL[1])})",
	vec3 = "luaPushVec3(l, [3]float64{float64(VAL[0]), float64(VAL[1]), float64(VAL[2])})",
	box1 = "luaPushBox1(l, [2]float64{float64(VAL[0]), float64(VAL[1])})",
	box2 = "luaPushBox2(l, [2][2]float64{{float64(VAL[0][0]), float64(VAL[0][1])}, {float64(VAL[1][0]), float64(VAL[1][1])}})",
	box3 = "luaPushBox3(l, [2][3]float64{{float64(VAL[0][0]), float64(VAL[0][1]), float64(VAL[0][2])}, {float64(VAL[1][0]), float64(VAL[1][1]), float64(VAL[1][2])}})",
}

local function push_fields(fields, indent)
	local impl = ""
	
	for name, type in pairs(fields) do
		if name:sub(1, 1) ~= "[" then
			local camel = "val." .. camel_case(name)

			local idt = indent
			local condition = fields["[" .. name .. "]"]

			if condition then
				impl = impl .. indent .. "if " .. condition .. " {\n" 
				idt = idt .. "\t"
			end

			if push_type[type] then
				impl = impl .. idt .. push_type[type]:gsub("VAL", camel) .. "\n"
			else
				impl = impl .. idt .. "luaPush" .. camel_case(type) .. "(l, " .. camel .. ")\n"
			end

			impl = impl .. idt .. "l.SetField(-2, \"" .. name .. "\")\n"

			if condition then
				impl = impl .. indent .. "}\n"
			end
		end
	end

	return impl
end

for name, fields in pairs(parse_spec("client/struct", true)) do
	local camel = camel_case(name)
	funcs = funcs
		.. "func luaPush" .. camel .. "(l *lua.State, val mt." .. camel .. ") {\n\tl.NewTable()\n"
		.. push_fields(fields, "\t")
		.. "}\n\n"
end

local to_string_impl = ""
local to_lua_impl = ""

for name, fields in pairs(parse_spec("client/pkt", true)) do
	local case = "\tcase *mt.ToClt" .. camel_case(name) .. ":\n"

	to_string_impl = to_string_impl
		.. case .. "\t\treturn \"" .. name .. "\"\n"

	if next(fields) then
		to_lua_impl = to_lua_impl .. case .. push_fields(fields, "\t\t")
	end
end

local f = io.open("convert.go", "w")
f:write([[
// generated by mkconvert.lua, DO NOT EDIT
package main

import (
	"github.com/Shopify/go-lua"
	"github.com/anon55555/mt"
)

]] .. funcs .. [[
func pktToString(pkt *mt.Pkt) string {
	switch pkt.Cmd.(type) {
]] .. to_string_impl .. [[
	}
	panic("impossible")
	return ""
}

func pktToLua(l *lua.State, pkt *mt.Pkt) {
	if pkt == nil {
		l.PushNil()
		return
	}
	l.NewTable()
	l.PushString(pktToString(pkt))
	l.SetField(-2, "_type")
	switch val := pkt.Cmd.(type) {
]] .. to_lua_impl .. [[
	}
}
]])
f:close()