package runner

import (
	"fmt"

	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
	"github.com/alexedwards/argon2id"
)

// RegisterPasswordFunctions registers password-related functions in the Lua state
func RegisterPasswordFunctions(state *luajit.State) error {
	if err := state.RegisterGoFunction("__password_hash", passwordHash); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__password_verify", passwordVerify); err != nil {
		return err
	}
	return nil
}

// passwordHash implements the Argon2id password hashing using alexedwards/argon2id
func passwordHash(state *luajit.State) int {
	if !state.IsString(1) {
		state.PushString("password_hash error: expected string password")
		return 1
	}

	password := state.ToString(1)

	params := &argon2id.Params{
		Memory:      64 * 1024,
		Iterations:  4,
		Parallelism: 4,
		SaltLength:  16,
		KeyLength:   32,
	}

	if state.IsTable(2) {
		state.GetField(2, "memory")
		if state.IsNumber(-1) {
			params.Memory = max(uint32(state.ToNumber(-1)), 8*1024)
		}
		state.Pop(1)

		state.GetField(2, "iterations")
		if state.IsNumber(-1) {
			params.Iterations = max(uint32(state.ToNumber(-1)), 1)
		}
		state.Pop(1)

		state.GetField(2, "parallelism")
		if state.IsNumber(-1) {
			params.Parallelism = max(uint8(state.ToNumber(-1)), 1)
		}
		state.Pop(1)

		state.GetField(2, "salt_length")
		if state.IsNumber(-1) {
			params.SaltLength = max(uint32(state.ToNumber(-1)), 8)
		}
		state.Pop(1)

		state.GetField(2, "key_length")
		if state.IsNumber(-1) {
			params.KeyLength = max(uint32(state.ToNumber(-1)), 16)
		}
		state.Pop(1)
	}

	hash, err := argon2id.CreateHash(password, params)
	if err != nil {
		state.PushString(fmt.Sprintf("password_hash error: %v", err))
		return 1
	}

	state.PushString(hash)
	return 1
}

// passwordVerify verifies a password against a hash
func passwordVerify(state *luajit.State) int {
	if !state.IsString(1) || !state.IsString(2) {
		state.PushBoolean(false)
		return 1
	}

	password := state.ToString(1)
	hash := state.ToString(2)

	match, err := argon2id.ComparePasswordAndHash(password, hash)
	if err != nil {
		state.PushBoolean(false)
		return 1
	}

	state.PushBoolean(match)
	return 1
}