package main

import (
	"database/sql"
	"fmt"

	_ "github.com/mattn/go-sqlite3"
	"golang.org/x/crypto/bcrypt"
)

const (
	bcryptCost = 12
)

func Register(db *sql.DB, username, password string) error {
	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
	if err != nil {
		return err
	}

	err = Transaction(db, func(tx *sql.Tx) error {
		_, err := tx.Exec(
			`INSERT INTO users (username, password_bcrypt) VALUES(?, ?);`,
			username,
			hash,
		)
		return err
	})

	return err
}

func Authenticate(db *sql.DB, username, password string) error {
	var hash []byte
	err := Transaction(db, func(tx *sql.Tx) error {
		row := tx.QueryRow(
			`SELECT password_bcrypt from users WHERE username=?;`,
			username,
		)

		return row.Scan(&hash)
	})
	if err != nil {
		return fmt.Errorf("Failed to get password hash from database: %w", err)
	}

	return bcrypt.CompareHashAndPassword(hash, []byte(password))
}