<?php declare(strict_types=1);

namespace FeedReaderCentral;

use BitBadger\PDODocument\{DocumentException, Field, Patch};

/**
 * Security functions
 */
class Security
{
    /** @var int Run as a single user requiring no password */
    public const SINGLE_USER = 0;

    /** @var int Run as a single user requiring a password */
    public const SINGLE_USER_WITH_PASSWORD = 1;

    /** @var int Require users to provide e-mail address and password */
    public const MULTI_USER = 2;

    /** @var string The e-mail address for the single user */
    public const SINGLE_USER_EMAIL = 'solouser@example.com';

    /** @var string The password for the single user with no password */
    public const SINGLE_USER_PASSWORD = 'no-password-required';

    /** @var string The password algorithm to use for our passwords */
    public const PW_ALGORITHM = PASSWORD_DEFAULT;

    /**
     * Verify a user's password
     *
     * @param User $user The user information retrieved from the database
     * @param string $password The password provided by the user
     * @param string|null $returnTo The URL to which the user should be redirected
     * @throws DocumentException if any is encountered
     */
    private static function verifyPassword(User $user, string $password, ?string $returnTo): void
    {
        if (password_verify($password, $user->password)) {
            if (password_needs_rehash($user->password, self::PW_ALGORITHM)) {
                Patch::byId(Table::USER, $user->id, ['password' => password_hash($password, self::PW_ALGORITHM)]);
            }
            $_SESSION[Key::USER_ID]    = $user->id;
            $_SESSION[Key::USER_EMAIL] = $user->email;
            frc_redirect($returnTo ?? '/');
        }
    }

    /**
     * Log on a user with e-mail address and password
     *
     * @param string $email The e-mail address for the user (cannot be the single-user mode user)
     * @param string $password The password provided by the user
     * @param string|null $returnTo The URL to which the user should be redirected
     * @throws DocumentException If any is encountered
     */
    public static function logOnUser(string $email, string $password, ?string $returnTo): void {
        if (SECURITY_MODEL == self::SINGLE_USER_WITH_PASSWORD) {
            $dbEmail = self::SINGLE_USER_EMAIL;
        } else {
            if ($email == self::SINGLE_USER_EMAIL) {
                add_error('Invalid credentials; log on unsuccessful');
                return;
            }
            $dbEmail = $email;
        }
        $user = User::findByEmail($dbEmail);
        if ($user) self::verifyPassword($user, $password, $returnTo);
        add_error('Invalid credentials; log on unsuccessful');
    }

    /**
     * Update the password for the given user
     *
     * @param string $email The e-mail address of the user whose password should be updated
     * @param string $password The new password for this user
     * @throws DocumentException If any is encountered
     */
    public static function updatePassword(string $email, string $password): void {
        Patch::byFields(Table::USER, [Field::EQ('email', $email)],
            ['password' => password_hash($password, self::PW_ALGORITHM)]);
    }

    /**
     * Log on the single user
     *
     * @throws DocumentException If any is encountered
     */
    private static function logOnSingleUser(): void {
        $user = User::findByEmail(self::SINGLE_USER_EMAIL);
        if (!$user) {
            User::add(self::SINGLE_USER_EMAIL, self::SINGLE_USER_PASSWORD);
            $user = User::findByEmail(self::SINGLE_USER_EMAIL);
        }
        self::verifyPassword($user, self::SINGLE_USER_PASSWORD, $_GET['returnTo']);
    }

    /**
     * Verify that user is logged on
     *
     * @param bool $redirectIfAnonymous Whether to redirect the request if there is no user logged on
     * @throws DocumentException If any is encountered
     */
    public static function verifyUser(bool $redirectIfAnonymous = true): void {
        if (key_exists(Key::USER_ID, $_SESSION)) return;

        if (SECURITY_MODEL == self::SINGLE_USER) self::logOnSingleUser();

        if (SECURITY_MODEL != self::SINGLE_USER_WITH_PASSWORD && SECURITY_MODEL != self::MULTI_USER) {
            die('Unrecognized security model (' . SECURITY_MODEL . ')');
        }

        if ($redirectIfAnonymous) {
            header("Location: /user/log-on?returnTo={$_SERVER['REQUEST_URI']}", true, 307);
            die();
        }
    }
}