<?php

require_once "UserDAOInterface.php";

class LocalUserDAO implements UserDAOInterface {

    private string $file = "data/users.json";

    private function loadUsers() {
        if (!file_exists($this->file)) {
            return [];
        }

        $json = file_get_contents($this->file);

        if ($json === false) {
            throw new RuntimeException("Benutzerdaten konnten nicht gelesen werden.");
        }

        $users = json_decode($json, true);

        if ($users === null && json_last_error() !== JSON_ERROR_NONE) {
            throw new RuntimeException("Benutzerdaten sind fehlerhaft.");
        }

        return is_array($users) ? $users : [];
    }

    private function saveUsers($users) {
        $result = file_put_contents(
            $this->file,
            json_encode($users, JSON_PRETTY_PRINT)
        );

        if ($result === false) {
            throw new RuntimeException("Benutzerdaten konnten nicht gespeichert werden.");
        }
    }

    private function validateEmail($email) {
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException("Ungültige E-Mail-Adresse.");
        }
    }

    private function validateName($name, $fieldName) {
        if (!preg_match("/^[a-zA-ZäöüÄÖÜß -]{2,50}$/", $name)) {
            throw new InvalidArgumentException(
                $fieldName . " darf nur Buchstaben, Leerzeichen und Bindestriche enthalten."
            );
        }
    }

    private function validatePassword($password) {
        if (empty($password)) {
            throw new InvalidArgumentException("Passwort darf nicht leer sein.");
        }
    }

    public function findUser($email) {
        $this->validateEmail($email);

        $users = $this->loadUsers();

        foreach ($users as $user) {
            if (isset($user["email"]) && $user["email"] === $email) {

                if (!isset($user["vorname"]) && isset($user["username"])) {
                    $nameParts = explode(" ", $user["username"], 2);
                    $user["vorname"] = $nameParts[0] ?? "";
                    $user["nachname"] = $nameParts[1] ?? "";
                }

                return $user;
            }
        }

        return null;
    }

    public function addUser($email, $vorname, $nachname, $password) {
        $this->validateEmail($email);
        $this->validateName($vorname, "Vorname");
        $this->validateName($nachname, "Nachname");
        $this->validatePassword($password);

        $users = $this->loadUsers();

        foreach ($users as $user) {
            if (isset($user["email"]) && $user["email"] === $email) {
                throw new InvalidArgumentException("Diese E-Mail-Adresse wird bereits verwendet.");
            }
        }

        $users[] = [
            "email" => $email,
            "vorname" => $vorname,
            "nachname" => $nachname,
            "password" => $password
        ];

        $this->saveUsers($users);
    }

    public function updateUser($oldEmail, $newEmail, $vorname, $nachname, $password = null) {
        $this->validateEmail($oldEmail);
        $this->validateEmail($newEmail);
        $this->validateName($vorname, "Vorname");
        $this->validateName($nachname, "Nachname");

        $users = $this->loadUsers();

        foreach ($users as $user) {
            if (
                isset($user["email"])
                && $user["email"] === $newEmail
                && $newEmail !== $oldEmail
            ) {
                throw new InvalidArgumentException("Diese E-Mail-Adresse wird bereits verwendet.");
            }
        }

        foreach ($users as $i => $user) {
            if (isset($user["email"]) && $user["email"] === $oldEmail) {
                $users[$i]["email"] = $newEmail;
                $users[$i]["vorname"] = $vorname;
                $users[$i]["nachname"] = $nachname;

                unset($users[$i]["username"]);

                if (!empty($password)) {
                    $users[$i]["password"] = password_hash($password, PASSWORD_DEFAULT);
                }

                $this->saveUsers($users);
                return true;
            }
        }

        return false;
    }

    public function deleteUser($email) {
        $this->validateEmail($email);

        $users = $this->loadUsers();

        foreach ($users as $i => $user) {
            if (isset($user["email"]) && $user["email"] === $email) {
                unset($users[$i]);
                $users = array_values($users);
                $this->saveUsers($users);
                return true;
            }
        }

        return false;
    }
}