<?php

require_once "UserManagerDAO.php";

class DatabaseUserManager implements UserManagerDAO {

    private static $instance = null;

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

            $db->exec("
                CREATE TABLE IF NOT EXISTS users (
                    email TEXT PRIMARY KEY,
                    vorname TEXT NOT NULL,
                    nachname TEXT NOT NULL,
                    password TEXT NOT NULL
                );
            ");

            unset($db);

        } catch (PDOException $e) {
            throw new RuntimeException("Benutzerdatenbank konnte nicht erstellt werden.");
        }
    }

    private function getConnection()
    {
        try {
            $dsn = 'sqlite:' . __DIR__ . '/../../db/users.db';

            $db = new PDO($dsn, null, null);
            $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            return $db;

        } catch (PDOException $e) {
            throw new RuntimeException("Verbindung zur Benutzerdatenbank fehlgeschlagen.");
        }
    }

    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);

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

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

            return $user ?: null;

        } catch (PDOException $e) {
            throw new RuntimeException("Benutzer konnte nicht geladen werden.");
        }
    }

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

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

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

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

            $db->commit();

        } catch (PDOException $e) {
            if (isset($db) && $db->inTransaction()) {
                $db->rollBack();
            }

            if ($e->getCode() === "23000") {
                throw new InvalidArgumentException("Diese E-Mail-Adresse wird bereits verwendet.");
            }

            throw new RuntimeException("Benutzer konnte nicht gespeichert werden.");
        }
    }

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

            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);
            $command->execute($params);

            return $command->rowCount() > 0;

        } catch (PDOException $e) {
            if ($e->getCode() === "23000") {
                throw new InvalidArgumentException("Diese E-Mail-Adresse wird bereits verwendet.");
            }

            throw new RuntimeException("Benutzer konnte nicht aktualisiert werden.");
        }
    }

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

            $sql = "DELETE FROM users WHERE email = :email";
            $command = $db->prepare($sql);

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

            return $command->rowCount() > 0;

        } catch (PDOException $e) {
            throw new RuntimeException("Benutzer konnte nicht gelöscht werden.");
        }
    }
}