<?php
/*
 * Permission Handler
 */

namespace Sakura;

class Permissions {

    // Fallback permission data
    private static $fallback = [

        'rid'           => 0,
        'uid'           => 0,
        'siteperms'     => '000000000000000000000000001',
        'manageperms'   => '0',
        'forumperms'    => '0',
        'rankinherit'   => '111'

    ];

    // Global permissions table
    protected static $permissions = [

        // Site permissions
        'SITE' => [

            'DEACTIVATED'           => 1,           // Is a user in this group deactivated
            'STATIC_PREMIUM'        => 2,           // Is always premium
            'ALTER_PROFILE'         => 4,           // Can alter their profile data
            'CHANGE_AVATAR'         => 8,           // Can change their avatar
            'CREATE_BACKGROUND'     => 16,          // Can create a background (different from changing)
            'CHANGE_BACKGROUND'     => 32,          // Can change their background
            'VIEW_MEMBERLIST'       => 64,          // Can view the memberlist
            'CREATE_USERPAGE'       => 128,         // Can create a userpage (different from changing)
            'CHANGE_USERPAGE'       => 256,         // Can change their userpage
            'USE_MESSAGES'          => 512,         // Can use the Private Messaging system
            'SEND_MESSAGES'         => 1024,        // Can send Private Messages to other users
            'CHANGE_EMAIL'          => 2048,        // Can change their account e-mail address
            'CHANGE_USERNAME'       => 4096,        // Can change their username
            'CHANGE_USERTITLE'      => 8192,        // Can change their usertitle
            'CHANGE_PASSWORD'       => 16384,       // Can change their password
            'CHANGE_DEFAULT_RANK'   => 32768,       // Can change their default rank
            'MANAGE_SESSIONS'       => 65536,       // Can manage their sessions
            'CREATE_REGKEYS'        => 131072,      // Can create registration keys
            'DEACTIVATE_ACCOUNT'    => 262144,      // Can deactivate their account
            'VIEW_PROFILE_DATA'     => 524288,      // Can view other's profile data
            'MANAGE_FRIENDS'        => 1048576,     // Can manage friends (add/remove)
            'REPORT_USERS'          => 2097152,     // Can report users to staff
            'OBTAIN_PREMIUM'        => 4194304,     // Can obtain the premium rank
            'JOIN_GROUPS'           => 8388608,     // Can join groups
            'CREATE_GROUP'          => 16777216,    // Can create a group
            'MULTIPLE_GROUPS'       => 33554432,    // Can create multiple groups (requires single group perm)
            'CHANGE_NAMECOLOUR'     => 67108864     // Can change their username colour

        ],

        // Forum permissions
        'FORUM' => [

            'USE_FORUM' => 1

        ],

        // Site management permissions
        'MANAGE' => [

            'USE_MANAGE' => 1

        ]

    ];

    // Checking if a user has the permissions to do a thing
    public static function check($layer, $action, $operator, $mode = 0) {

        // Check if the permission layer and the permission itself exists
        if(!array_key_exists($layer, self::$permissions) || !array_key_exists($action, self::$permissions[$layer]))
            return false;

        // Convert to the appropiate mode
        if($mode === 2)
            $operator = self::getRankPermissions($operator)[$layer];
        elseif($mode === 1)
            $operator = self::getUserPermissions($operator)[$layer];

        // Perform the bitwise AND
        if(bindec($operator) & self::$permissions[$layer][$action])
            return true;

        // Else just return false
        return false;

    }

    // Get permission data of a rank from the database
    public static function getRankPermissions($ranks) {

        // Container array
        $getRanks   = [];
        $perms      = [];

        // Get permission row for all ranks
        foreach($ranks as $rank)
            $getRanks[] = Database::fetch('permissions', false, ['rid' => [$rank, '='], 'uid' => [0 ,'=']]);

        // Check if getRanks is empty or if the rank id is 0 return the fallback
        if(empty($getRanks) || in_array(0, $ranks))
            $getRanks = [self::$fallback];

        // Go over the permission data
        foreach($getRanks as $rank) {

            // Check if perms is empty
            if(empty($perms)) {

                // Store the data of the current rank in $perms
                $perms = [

                    'SITE'      => $rank['siteperms'],
                    'MANAGE'    => $rank['manageperms'],
                    'FORUM'     => $rank['forumperms']

                ];

            } else {

                // Perform a bitwise OR on the ranks
                $perms = [

                    'SITE'      => $perms['SITE']   | $rank['siteperms'],
                    'MANAGE'    => $perms['MANAGE'] | $rank['manageperms'],
                    'FORUM'     => $perms['FORUM']  | $rank['forumperms']

                ];

            }

        }

        // Return the compiled permission strings
        return $perms;

    }

    // Get permission data for a user
    public static function getUserPermissions($uid) {

        // Get user data
        $user = Users::getUser($uid);

        // Attempt to get the permission row of a user
        $userPerms = Database::fetch('permissions', false, ['rid' => [0, '='], 'uid' => [$user['id'] ,'=']]);

        // Get their rank permissions
        $rankPerms = self::getRankPermissions(json_decode($user['ranks'], true));

        // Just return the rank permissions if no special ones are set
        if(empty($userPerms))
            return $rankPerms;

        // Split the inherit option things up
        $inheritance = str_split($userPerms['rankinherit']);

        // Override site permissions
        if(!$inheritance[0])
            $rankPerms['SITE'] = $userPerms['siteperms'];

        // Override management permissions
        if(!$inheritance[1])
            $rankPerms['MANAGE'] = $userPerms['manageperms'];

        // Override forum permissions
        if(!$inheritance[2])
            $rankPerms['FORUM'] = $userPerms['forumperms'];

        // Return permissions
        return $rankPerms;

    }

}