<?php

namespace SilverStripe\Security;

use BadMethodCallException;
use InvalidArgumentException;
use SilverStripe\Core\Config\Configurable;
use SilverStripe\Core\Extensible;
use SilverStripe\Core\Injector\Injectable;

/**
 * Provides access to the default admin
 */
class DefaultAdminService
{
    use Extensible;
    use Configurable;
    use Injectable;

    /**
     * Can be set to explicitly true or false, or left null.
     * If null, hasDefaultAdmin() will be inferred from environment.
     *
     * @var bool|null
     */
    protected static $has_default_admin = null;

    /**
     * @var string
     */
    protected static $default_username = null;

    /**
     * @var string
     */
    protected static $default_password = null;

    public function __construct()
    {
        $this->constructExtensions();
    }

    /**
     * Set the default admin credentials
     *
     * @param string $username
     * @param string $password
     */
    public static function setDefaultAdmin($username, $password)
    {
        // don't overwrite if already set
        if (static::hasDefaultAdmin()) {
            throw new BadMethodCallException(
                "Default admin already exists. Use clearDefaultAdmin() first."
            );
        }

        if (empty($username) || empty($password)) {
            throw new InvalidArgumentException("Default admin username / password cannot be empty");
        }

        static::$default_username = $username;
        static::$default_password = $password;
        static::$has_default_admin = true;
    }

    /**
     * @return string The default admin username
     * @throws BadMethodCallException Throws exception if there is no default admin
     */
    public static function getDefaultAdminUsername()
    {
        if (!static::hasDefaultAdmin()) {
            throw new BadMethodCallException(
                "No default admin configured. Please call hasDefaultAdmin() before getting default admin username"
            );
        }
        return static::$default_username ?: getenv('SS_DEFAULT_ADMIN_USERNAME');
    }

    /**
     * @return string The default admin password
     * @throws BadMethodCallException Throws exception if there is no default admin
     */
    public static function getDefaultAdminPassword()
    {
        if (!static::hasDefaultAdmin()) {
            throw new BadMethodCallException(
                "No default admin configured. Please call hasDefaultAdmin() before getting default admin password"
            );
        }
        return static::$default_password ?: getenv('SS_DEFAULT_ADMIN_PASSWORD');
    }

    /**
     * Check if there is a default admin
     *
     * @return bool
     */
    public static function hasDefaultAdmin()
    {
        // Check environment if not explicitly set
        if (!isset(static::$has_default_admin)) {
            return !empty(getenv('SS_DEFAULT_ADMIN_USERNAME'))
                && !empty(getenv('SS_DEFAULT_ADMIN_PASSWORD'));
        }
        return static::$has_default_admin;
    }

    /**
     * Flush the default admin credentials.
     */
    public static function clearDefaultAdmin()
    {
        static::$has_default_admin = false;
        static::$default_username = null;
        static::$default_password = null;
    }

    /**
     * @return Member|null
     */
    public function findOrCreateDefaultAdmin()
    {
        $this->extend('beforeFindOrCreateDefaultAdmin');

        // Check if we have default admins
        if (!static::hasDefaultAdmin()) {
            return null;
        }

        // Find or create ADMIN group
        Group::singleton()->requireDefaultRecords();
        $adminGroup = Permission::get_groups_by_permission('ADMIN')->first();

        if (!$adminGroup) {
            Group::singleton()->requireDefaultRecords();
            $adminGroup = Permission::get_groups_by_permission('ADMIN')->first();
        }

        // Find member
        /** @skipUpgrade */
        $admin = Member::get()
            ->filter('Email', static::getDefaultAdminUsername())
            ->first();
        // If no admin is found, create one
        if (!$admin) {
            // 'Password' is not set to avoid creating
            // persistent logins in the database. See Security::setDefaultAdmin().
            // Set 'Email' to identify this as the default admin
            $admin = Member::create();
            $admin->FirstName = _t(__CLASS__ . '.DefaultAdminFirstname', 'Default Admin');
            $admin->Email = static::getDefaultAdminUsername();
            $admin->write();
        }

        // Ensure this user is in the admin group
        if (!$admin->inGroup($adminGroup)) {
            // Add member to group instead of adding group to member
            // This bypasses the privilege escallation code in Member_GroupSet
            $adminGroup
                ->DirectMembers()
                ->add($admin);
        }

        $this->extend('afterFindOrCreateDefaultAdmin', $admin);

        return $admin;
    }

    /**
     * Check if the user is a default admin.
     * Returns false if there is no default admin.
     *
     * @param string $username
     * @return bool
     */
    public static function isDefaultAdmin($username)
    {
        return static::hasDefaultAdmin()
            && $username
            && $username === static::getDefaultAdminUsername();
    }

    /**
     * Check if the user credentials match the default admin.
     * Returns false if there is no default admin.
     *
     * @param string $username
     * @param string $password
     * @return bool
     */
    public static function isDefaultAdminCredentials($username, $password)
    {
        return static::isDefaultAdmin($username)
            && $password
            && $password === static::getDefaultAdminPassword();
    }
}