<?php

require_once "UserManagerDAO.php";

class DatabaseUserManager implements UserManagerDAO {

    private static $instance = null;
    public function __construct()
    {

        if (!file_exists(__DIR__ . '/../../db/users.db')) {
            try {
                $user = 'root';
                $pw = null;
                $dsn = 'sqlite:' . __DIR__ . '/../../db/users.db';

                $db = new PDO($dsn, $user, $pw);

                file_put_contents(
                    __DIR__ . '/../../db/test.txt',
                    'PDO funktioniert'
                );

                $db->exec("
                CREATE TABLE users (
                    email TEXT PRIMARY KEY,
                    vorname TEXT,
                    nachname TEXT,
                    password TEXT
                );
            ");

                unset($db);

            } catch (PDOException $e) {
                throw new RuntimeException($e->getMessage());
            }
        }
    }
    /**
     * Baut die Verbindung zur Datenbank auf.
     */
    private function getConnection()
    {
        try {
            $user = 'root';
            $pw = null;
            $dsn = 'sqlite:' . __DIR__ . '/../../db/users.db';

            return new PDO($dsn, $user, $pw);

        } catch (PDOException $e) {
            throw new RuntimeException($e->getMessage());
        }
    }

    /**
     * Singleton-Instanz zurückgeben.
     */
    public static function getInstance()
    {
        if (self::$instance == null) {
            self::$instance = new DatabaseUserManager();
        }

        return self::$instance;
    }


    public function findUser($email)
    {
        try {
            $db = $this->getConnection();

            $sql = "SELECT * FROM users WHERE email = :email";

            $command = $db->prepare($sql);

            if (!$command) {
                throw new RuntimeException("Benutzer konnte nicht geladen werden.");
            }

            $command->execute([
                ":email" => $email
            ]);

            $user = $command->fetch(PDO::FETCH_ASSOC);

            return $user ?: null;

        } catch (PDOException $e) {
            throw new RuntimeException($e->getMessage());
        }
    }

    public function addUser($email, $vorname, $nachname, $password)
    {
        try {
            $db = $this->getConnection();

            $db->beginTransaction();

            $existingUser = $this->findUser($email);

            if ($existingUser !== null) {
                $db->rollBack();
                throw new InvalidArgumentException(
                    "Diese E-Mail-Adresse wird bereits verwendet."
                );
            }

            $sql = "
                INSERT INTO users (
                    email,
                    vorname,
                    nachname,
                    password
                )
                VALUES (
                    :email,
                    :vorname,
                    :nachname,
                    :password
                )
            ";

            $command = $db->prepare($sql);

            if (!$command) {
                $db->rollBack();
                throw new RuntimeException(
                    "Benutzer konnte nicht gespeichert werden."
                );
            }

            $success = $command->execute([
                ":email" => $email,
                ":vorname" => $vorname,
                ":nachname" => $nachname,
                ":password" => $password
            ]);

            if (!$success) {
                $db->rollBack();
                throw new RuntimeException(
                    "Benutzer konnte nicht gespeichert werden."
                );
            }

            $db->commit();

        } catch (PDOException $e) {
            throw new RuntimeException($e->getMessage());
        }
    }

    public function updateUser(
        $oldEmail,
        $newEmail,
        $vorname,
        $nachname,
        $password = null
    ) {
        try {
            $db = $this->getConnection();

            if ($oldEmail !== $newEmail) {

                $existingUser = $this->findUser($newEmail);

                if ($existingUser !== null) {
                    throw new InvalidArgumentException(
                        "Diese E-Mail-Adresse wird bereits verwendet."
                    );
                }
            }

            if (!empty($password)) {

                $sql = "
                    UPDATE users
                    SET
                        email = :newEmail,
                        vorname = :vorname,
                        nachname = :nachname,
                        password = :password
                    WHERE email = :oldEmail
                ";

                $params = [
                    ":newEmail" => $newEmail,
                    ":vorname" => $vorname,
                    ":nachname" => $nachname,
                    ":password" => password_hash(
                        $password,
                        PASSWORD_DEFAULT
                    ),
                    ":oldEmail" => $oldEmail
                ];

            } else {

                $sql = "
                    UPDATE users
                    SET
                        email = :newEmail,
                        vorname = :vorname,
                        nachname = :nachname
                    WHERE email = :oldEmail
                ";

                $params = [
                    ":newEmail" => $newEmail,
                    ":vorname" => $vorname,
                    ":nachname" => $nachname,
                    ":oldEmail" => $oldEmail
                ];
            }

            $command = $db->prepare($sql);

            if (!$command) {
                throw new RuntimeException(
                    "Benutzer konnte nicht aktualisiert werden."
                );
            }

            $command->execute($params);

            return $command->rowCount() > 0;

        } catch (PDOException $e) {
            throw new RuntimeException($e->getMessage());
        }
    }

    public function deleteUser($email)
    {
        try {
            $db = $this->getConnection();

            $sql = "DELETE FROM users WHERE email = :email";

            $command = $db->prepare($sql);

            if (!$command) {
                throw new RuntimeException(
                    "Benutzer konnte nicht gelöscht werden."
                );
            }

            $command->execute([
                ":email" => $email
            ]);

            return $command->rowCount() > 0;

        } catch (PDOException $e) {
            throw new RuntimeException($e->getMessage());
        }
    }

}