// package main is the main package for the LapisDeploy program
package main

import (
	"errors"

	lua "github.com/yuin/gopher-lua"
)

// Configuration stores information retrieved from a configuration file
type Configuration struct {
	port      int64
	sites_dir string
	matrix    struct {
		homeserver string
		username   string
		password   string
		room_id    string
	}
}

// getStringFromTable retrieves a string from a table on the lua stack using the key passed in.
func getStringFromTable(L *lua.LState, lobj lua.LValue, key string, out *string) (bool, error) {
	lv := L.GetTable(lobj, lua.LString(key))
	if text, ok := lv.(lua.LString); ok { // Value is string
		*out = string(text)
	} else if _, ok := lv.(*lua.LNilType); !ok { // Value is not a string, and is not nil
		return true, errors.New("'" + key + "' is not a string")
	} else { // Value is nil
		return false, errors.New("'" + key + "' is nil")
	}
	return true, nil
}

// getIntFromTable retrieves an integer from a table on the Lua stack using the key passed in.
func getIntFromTable(L *lua.LState, lobj lua.LValue, key string, out *int64) (bool, error) {
	lv := L.GetTable(lobj, lua.LString(key))
	if int, ok := lv.(lua.LNumber); ok { // Value is number
		*out = int64(int)
	} else if _, ok := lv.(*lua.LNilType); !ok { // Value is not a number, and is not nil
		return true, errors.New("'" + key + "' is not a number")
	} else { // Value is nil
		return false, errors.New("'" + key + "' is nil")
	}
	return true, nil
}

// getTableFromTable retrieves a nested table from the Lua stack using the key passed in.
func getTableFromTable(L *lua.LState, lobj lua.LValue, key string, out *lua.LValue) bool {
	lv := L.GetTable(lobj, lua.LString(key))
	*out = lv
	if _, ok := lv.(*lua.LNilType); ok {
		return false
	}
	return true
}

// parseConfig parses the JSON configuration file at 'path' and stores the contents in 'config'
func parseConfig(path string, config *Configuration) {
	// Lua state setup
	L := lua.NewState()
	defer L.Close()

	L.DoFile(path)
	table := L.Get(-1) // Get the table returned by the config file

	// Main config
	if _, err := getStringFromTable(L, table, "sites_dir", &config.sites_dir); err != nil {
		panic(err)
	}
	if _, err := getIntFromTable(L, table, "port", &config.port); err != nil {
		panic(err)
	}

	// Matrix config
	var matrix lua.LValue
	getTableFromTable(L, table, "matrix", &matrix)
	if _, err := getStringFromTable(L, matrix, "homeserver", &config.matrix.homeserver); err != nil {
		panic(err)
	}
	if _, err := getStringFromTable(L, matrix, "username", &config.matrix.username); err != nil {
		panic(err)
	}
	if _, err := getStringFromTable(L, matrix, "password", &config.matrix.password); err != nil {
		panic(err)
	}
	if _, err := getStringFromTable(L, matrix, "room_id", &config.matrix.room_id); err != nil {
		panic(err)
	}
}