<?php
/**
 * MvvPerm.php
 *
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * @author      Peter Thienel <thienel@data-quest.de>
 * @license     http://www.gnu.org/licenses/gpl-2.0.html GPL version 2
 * @category    Stud.IP
 * @since       3.5
 */

class MvvPerm {

    /**
     * Permission to read the value of the designated field.
     */
    const PERM_READ = 1;

    /**
     * Permission to read and write the value of the designated field.
     */
    const PERM_WRITE = 3;

    /**
     * Permission to read, write/create and delete the value
     * of the designated field.
     */
    const PERM_CREATE = 7;

    /**
    * Permission to read, write/create and delete the value
    * of the designated field. Possibly the admin have permission to
    * particular functions.
    */
    const PERM_ADMIN = 15;

    private static $privileges = null;

    private static $roles;

    private static $user_role_institutes;

    /**
     * The actual mvv object.
     *
     * @var object
     */
    private $mvv_object;

    /**
     * to distinguish config files between different languages
     *
     * @var string
     */
    private $variant;

    /**
     * Creates a new perm object for given mvv object.
     *
     * @param ModuleManagementModel $mvv_object
     */
    public function __construct(ModuleManagementModel $mvv_object)
    {
        $this->mvv_object = $mvv_object;
    }

    /**
     * Returns a new perm object for given mvv object.
     *
     * @param ModuleManagementModel|string $mvv_object Class name or instance of
     * mvv object.
     * @return MvvPerm A new perm object.
     * @throws InvalidArgumentException
     */
    public static function get($mvv_object)
    {
        static $perm_objects;

        if (is_object($mvv_object)) {
            $index = get_class($mvv_object) . $mvv_object->id;
        } else {
            $index = $mvv_object;
        }
        if (empty($perm_objects[$index])) {
            if (!is_object($mvv_object)) {
                $mvv_class_name = (string) $mvv_object;
                $mvv_object = new $mvv_class_name;
            }

            if (!$mvv_object instanceof ModuleManagementModel) {
                throw new InvalidArgumentException('Wrong object type. Only MVV '
                        . 'objects of type ModuleManagementModel are allowed.');
            }

            $perm_objects[$index] = new MvvPerm($mvv_object);
            $perm_objects[$index]->setVariant($mvv_object->getVariant());
        }
        return $perm_objects[$index];
    }

    /**
     * Intercepts static calls to retrieve permission from configuration.
     *
     * Allowed calls are:
     *
     * MvvPerm::getFieldPermFIELD($mvv_object, $user_id, $institut_id)
     *
     * @see MvvPerm:getFieldPerm()
     * FIELD is the name of the table field.
     * $mvv_object: Class name or instance of mvv object.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * Last two arguments are optional.
     *
     * MvvPerm::havePermPERM($mvv_object, $status, $user_id, $institut_id)
     *
     * @see MvvPerm::havePerm()
     * PERM is the constant defining the permission (MvvPerm::PERM_ADMIN,
     * MvvPerm::PERM_CREATE, MvvPerm::PERM_READ, MvvPerm::PERM_WRITE)
     * $mvv_object: Class name or instance of mvv object.
     * $status: The status of mvv object defined in config. Status 'default' as
     * default.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * Last three arguments are optional
     *
     * MvvPerm::haveFieldPermFIELD($mvv_object, $perm, $user_id, $institut_id)
     *
     * @see MvvPerm::haveFieldPerm()
     * FIELD is the name of the table field.
     * $mvv_object: Class name or instance of mvv object.
     * $perm: The constant defining the permission (MvvPerm::PERM_ADMIN,
     * MvvPerm::PERM_CREATE, MvvPerm::PERM_READ, MvvPerm::PERM_WRITE).
     * Default is MvvPerm::PERM_WRITE.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * Last three arguments are optional.
     *
     * @param type $name
     * @param type $arguments
     * @return type
     * @throws InvalidArgumentException If called with unknown permission.
     * @throws BadMethodCallException If called with unknown method to
     * retrieve permission.
     */
    public static function __callStatic($name, $arguments)
    {
        $name = mb_strtolower($name);

        if (mb_strpos($name, 'haveperm') === 0) {
            $perm = 'PERM_' . mb_strtoupper(mb_substr($name, 8));
            if (defined('self::' . $perm)) {
                return self::get($arguments[0])->havePerm(
                    constant('self::' . $perm),
                    ...array_slice($arguments, 1)
                );
            } else {
                throw new InvalidArgumentException('Undefined Permission.');
            }
        }

        if (mb_strpos($name, 'getfieldperm') === 0) {
            $field = mb_strtolower(mb_substr($name, 12));
            return self::get($arguments[0])->getFieldPerm(
                $field,
                ...array_slice($arguments, 1)
            );
        }

        if (mb_strpos($name, 'havefieldperm') === 0) {
            $field = mb_strtolower(mb_substr($name, 13));
            return self::get($arguments[0])->haveFieldPerm(
                $field,
                ...array_slice($arguments, 1)
            );
        }

        throw new BadMethodCallException('Method '
                . get_called_class() . "::$name not found");
    }

    /**
     * Intercepts instance methods to retrieve permission from configuration.
     *
     * Allowed calls are:
     *
     * havePermPERM($status, $user_id, $institut_id)
     *
     * @see MvvPerm::havePerm()
     * PERM is the constant defining the permission (MvvPerm::PERM_ADMIN,
     * MvvPerm::PERM_CREATE, MvvPerm::PERM_READ, MvvPerm::PERM_WRITE)
     * $status: The status of mvv object defined in config. Status 'default' as
     * default.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * All three arguments are optional
     *
     * getFieldPermFIELD($user_id, $institut_id)
     *
     * @see MvvPerm::getFieldPerm()
     * FIELD is the name of the table field.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * All two arguments are optional.
     *
     *
     * haveFieldPermFIELD($perm, $user_id, $institut_id)
     *
     * @see MvvPerm::haveFieldPerm()
     * FIELD is the name of the table field.
     * $perm: The constant defining the permission (MvvPerm::PERM_ADMIN,
     * MvvPerm::PERM_CREATE, MvvPerm::PERM_READ, MvvPerm::PERM_WRITE).
     * Default is MvvPerm::PERM_WRITE.
     * $user_id: The id of an user. Id of current user as default.
     * $institut_id: The id of an institute or an array of institute ids the
     * user has a mvv related role.
     * All three arguments are optional.
     *
     *
     * @param string $name
     * @param array $arguments
     * @return mixed
     * @throws InvalidArgumentException If called with unknown permission.
     * @throws BadMethodCallException If called with unknown method to
     * reitrieve permission.
     */
    public function __call($name, $arguments)
    {
        $name = mb_strtolower($name);

        if (mb_strpos($name, 'haveperm') === 0) {
            $perm = 'PERM_' . mb_strtoupper(mb_substr($name, 8));
            if (defined('self::' . $perm)) {
                return $this->havePerm(
                    constant('self::' . $perm),
                    ...$arguments
                );
            } else {
                throw new InvalidArgumentException('Undefined Permission.');
            }
        }

        if (mb_strpos($name, 'getfieldperm') === 0) {
            $field = mb_strtolower(mb_substr($name, 12));
            return $this->getFieldPerm($field,
                    $arguments[0], $arguments[1]);
        }

        if (mb_strpos($name, 'havefieldperm') === 0) {
            $field = mb_strtolower(mb_substr($name, 13));
            return $this->haveFieldPerm($field, ...$arguments);
        }

        throw new BadMethodCallException('Method '
                . get_called_class() . "::$name not found");
    }

    /**
     * Sets the variant of an mvv object. The variant means that a different
     * configuration file is used to retrieve the permissions. It is used to
     * determines permissions for different languages of a descriptor.
     *
     * @param string $variant The suffix (part after las underscore) of the
     * file name of a config file.
     * @return $this Returns this instance for method chaining.
     */
    public function setVariant($variant)
    {
        $this->variant = trim($variant);
        return $this;
    }

    /**
     * Retrieves the permission for the table or object.
     * Returns the (max) perm the given or current user has globally.
     * If the institute is set, checks for the perm in the context of this institute.
     *
     * @param object|string $object An mvv object or its class name.
     * @param string $status Constrain the permission to this status of the object.
     * @param string $user_id The ID of the user. If not set the ID of the
     * current user.
     * @param string|array $institut_id The ID(s) of institute(s)
     * if the user role is defined for institutes.
     * @param string $variant The optional variant of the object table (e.g. to
     * support different languages)
     * @return int The perm defined in class MVVPlugin.
     * @throws InvalidArgumentException If the object is not of type
     * ApplicationSimpleOrMap.
     */
    public final static function getPerm($object, $status = null,
            $user_id = null, $institut_id = null, $variant = null)
    {
        if (is_object($object)) {
            $mvv_object = $object;
        } else {
            $mvv_object = new $object;
        }
        if (!$mvv_object instanceof ModuleManagementModel) {
            throw new InvalidArgumentException('Wrong object type. Only MVV '
                        . 'objects of type ModuleManagementModel are allowed.');
        }
        $user_id = is_null($user_id) ? $GLOBALS['user']->id : $user_id;
        if ($GLOBALS['perm']->get_perm($user_id) == 'root' ) {
            return self::PERM_ADMIN;
        }
        if (is_null($institut_id)) {
            $inst_ids = [];
            foreach ($mvv_object->getResponsibleInstitutes() as $inst) {
                if ($inst) {
                    $inst_ids[] = $inst->getId();
                    // the user have permission if he is assigned to the faculty
                    $inst_ids[] = $inst->fakultaets_id;
                }
            }
        } else {
            $inst_ids = [];
            foreach (Institute::findMany((array) $institut_id) as $inst) {
                $inst_ids[] = $inst->getId();
                // the user have permission if he is assigned to the faculty
                $inst_ids[] = $inst->fakultaets_id;
            }
        }
        $table_meta = $mvv_object->getTableMetadata();
        $institut_ids = array_unique($inst_ids);
        $status = $status ?: $mvv_object->getStatus();
        $roles = self::getRoles($user_id);
        $variant = $variant ?: $mvv_object->getVariant();
        $mvv_table = $table_meta['table'] . ($variant ? '_' . $variant : '');
        self::getPrivileges($mvv_table);
        $perm = 0;
        foreach ($roles as $role) {
            if ($role->rolename === 'MVVAdmin') {
                return self::PERM_ADMIN;
            }
            if (count($institut_ids)) {
                $institutes_assigned_role = RolePersistence::getAssignedRoleInstitutes($user_id, $role->roleid);
                // count($institutes_assigned_role) === 0 means global role.
                if (count($institutes_assigned_role) === 0
                        || count(array_intersect($institut_ids, $institutes_assigned_role))) {
                    if (!$status) {
                        $priv = intval(self::$privileges[$mvv_table]['default_table'][$role->rolename] ?? 0);
                    } else {
                        $priv = intval(self::$privileges[$mvv_table]['table'][$status][$role->rolename] ?? 0);
                    }
                } else {
                    $priv = 0;
                }
            } else {
                if (!$status) {
                    $priv = intval(self::$privileges[$mvv_table]['default_table'][$role->rolename] ?? 0);
                } else {
                    $priv = intval(self::$privileges[$mvv_table]['table'][$status][$role->rolename] ?? 0);
                }
            }

            if ($priv > $perm) {
                $perm = $priv;
            }
        }
        return $perm;
    }

    /**
     * Accepts the id of the user, an institute id and the status of this object
     * as optional arguments. Returns whether the user has the given permission
     * to this object.
     *
     * The status of this object is defined in the configuration file
     *
     * @param int $perm The permission to check against.
     * @param string $status The status of the object defined in config.
     * @param string $user_id The id of the user.
     * @param string|array $institut_id The id of an institute or an array of
     * institute ids the user has a mvv related role.
     * @return bool
     */
    public final function havePerm($perm, $status = null,
            $user_id = null, $institut_id = null)
    {
        $user_perm = self::getPerm($this->mvv_object, $status, $user_id,
                $institut_id, $this->variant);
        return ($user_perm >= $perm);
    }

    /**
     * Returns whether the given user has at least the given permission to this
     * object with the actual status. The user_id is optional. Default is the
     * id of the current user.
     *
     * @param int $perm The permission to check against.
     * @param type $user_id The id of an user.
     * @return bool True if the permission is granted.
     */
    public function haveObjectPerm($perm, $user_id = null)
    {
        $institute_ids = SimpleORMapCollection::createFromArray(
                $this->mvv_object->getResponsibleInstitutes())->pluck('id');
        return $this->havePerm($perm, $this->mvv_object->getStatus(), $user_id,
                $institute_ids);
    }

    /**
     * Returns whether the actual user has at least the given permission to
     * the datafield entry.
     *
     * @param $datafield_id The id of a datafield.
     * @param int $perm
     * @return bool True if permission is granted.
     */
    public function haveDfEntryPerm($datafield_id, $perm)
    {
        $field = 'datafields';
        $field_perm = $this->getFieldPerm([$field, $datafield_id]);
        return $field_perm >= $perm;
    }

    /**
     * Retrieves the permission for the table or object.
     * Returns the (max) perm the given or current user have globally.
     * If the institute is set, checks for the perm in the context of this institute.
     *
     * @param string|array Name of field or an array with name of field and
     * related entry (usefull in the case of relations to datafields).
     * @param string $user_id Optional. The ID of the user. If not set the ID of
     * the current user.
     * @param string|array $institut_id Optional. The id of an institute or an
     * array of institute ids the user has a mvv related role.
     * @return int The perm defined in class MVVPlugin.
     */
    public final function getFieldPerm($field, $user_id = null, $institut_id = null)
    {
        $user_id = is_null($user_id) ? $GLOBALS['user']->id : $user_id;
        if ($GLOBALS['perm']->get_perm($user_id) == 'root' ) {
            return self::PERM_CREATE;
        }
        $roles = self::getRoles($user_id);
        $table_meta = $this->mvv_object->getTableMetadata();
        $mvv_table = $table_meta['table']
                . ($this->variant ? '_' . $this->variant : '');
        if (is_null($institut_id)) {
            $institut_ids = array_map(function ($ins) {
                return $ins ? $ins->getId() : null;
            }, $this->mvv_object->getResponsibleInstitutes());
        } else {
            $institut_ids = is_array($institut_id) ? $institut_id : [$institut_id];
        }
        $status = $this->mvv_object->getStatus();
        self::getPrivileges($mvv_table);

        $perm = 0;
        foreach ($roles as $role) {
            if ($role->rolename === 'MVVAdmin') {
                return self::PERM_CREATE;
            }
            if (count($institut_ids)) {
                $institutes_assigned_role = RolePersistence::getAssignedRoleInstitutes($user_id, $role->roleid);
                // count($institutes_assigned_role) === 0 means global role.
                if (
                    count($institutes_assigned_role) === 0
                    || count(array_intersect($institut_ids, $institutes_assigned_role))
                ) {
                    $priv = is_array($field)
                            ? self::$privileges[$mvv_table]['fields'][$field[0]][$field[1]][$status][$role->rolename] ?? null
                            : self::$privileges[$mvv_table]['fields'][$field][$status][$role->rolename] ?? null;
                    if (is_null($priv)) {
                        $priv = is_array($field)
                                ? self::$privileges[$mvv_table]['fields'][$field[0]]['default'][$status][$role->rolename] ?? null
                                : self::$privileges[$mvv_table]['fields'][$field]['default'][$role->rolename] ?? null;
                    }
                    if (is_null($priv)) {
                        $priv = self::$privileges[$mvv_table]['default_fields'][$role->rolename] ?? null;
                    }
                } else {
                    $priv = 0;
                }
            } else {
                $priv = is_array($field)
                        ? self::$privileges[$mvv_table]['fields'][$field[0]][$field[1]][$status][$role->rolename] ?? null
                        : self::$privileges[$mvv_table]['fields'][$field][$status][$role->rolename] ?? null;
                if (is_null($priv)) {
                    $priv = is_array($field)
                            ? self::$privileges[$mvv_table]['fields'][$field[0]]['default'][$status][$role->rolename] ?? null
                            : self::$privileges[$mvv_table]['fields'][$field]['default'][$role->rolename] ?? null;
                }
                if (is_null($priv)) {
                    $priv = self::$privileges[$mvv_table]['default_fields'][$role->rolename] ?? null;
                }
            }
            $priv = intval($priv);
            if ($priv > $perm) {
                $perm = $priv;
            }
        }
        return $perm;
    }

    /**
     * Returns true if the user have at least the given permission status.
     *
     * @param string $field The name of the table field.
     * @param int $perm The optional (default PERM_WRITE) permission status.
     * @param string $user_id Optional. The ID of the user. If not set the ID of
     * the current user.
     * @param string|array $institut_id Optional. The id of an institute or an array of
     * institute ids the user has a mvv related role.
     * @return bool True if the permission is at least the given permission.
     */
    public final function haveFieldPerm($field, $perm = null, $user_id = null, $institut_id = null)
    {
        $perm = intval($perm) ?: MvvPerm::PERM_WRITE;
        $user_perm = $this->getFieldPerm($field, $user_id, $institut_id);
        return ($user_perm >= $perm);
    }

    /**
     * Returns 'readonly' if the given user has no access to the given field.
     *
     * @param string $field The name of the table field.
     * @param int $perm Optional. The permission. Defaults to MvvPerm:PERM_WRITE.
     * @param string $user_id Optional. The ID of the user. If not set the ID of
     * the current user.
     * @param string|array $institut_id The id of an institute or an array of
     * institute ids the user has a mvv related role.
     * @return string 'readonly' if the permission is not granted.
     */
    public function disable($field, $perm = null, $user_id = null, $institut_id = null)
    {
        $perm = intval($perm) ?: MvvPerm::PERM_WRITE;
        return $this->haveFieldPerm($field, $perm, $user_id, $institut_id)
                ? '' : ' readonly ';
    }

    /**
     *
     *
     * @param string $user_id
     * @return
     */
    public static function getRoles($user_id)
    {
        if (!isset(self::$roles[$user_id])) {
            self::$roles[$user_id] = array_filter(
                RolePersistence::getAssignedRoles($user_id),
                function ($role) {
                    return stripos($role->rolename, 'mvv') === 0;
                }
            );
        }
        return self::$roles[$user_id];
    }

    /**
     * Retrieves all privileges from config files.
     */
    private static function getPrivileges($mvv_table)
    {
        if (self::$privileges === null) {
            $cache = \Studip\Cache\Factory::getCache();
            self::$privileges = unserialize($cache->read(MVV::CACHE_KEY . '/privileges')) ?: [];
        }

        if (self::$privileges[$mvv_table] === null) {
            $config_dir = $GLOBALS['STUDIP_BASE_PATH'] . '/config/mvvconfig';
            if ($config_dir) {
                $config_file = $config_dir . '/' . $mvv_table . '.php';
                if (filetype($config_file) === 'file') {
                    // TODO: This should be refactored in a way that $config_file returns an array
                    include $config_file; // Defines $privileges
                    self::$privileges[$mvv_table] = $privileges ?? [];
                }
                $cache = \Studip\Cache\Factory::getCache();
                $cache->write(MVV::CACHE_KEY . '/privileges', serialize(self::$privileges));
            }
        }
        return isset(self::$privileges[$mvv_table]);
    }

    public static function refreshPrivileges($mvv_table)
    {
        self::$privileges[$mvv_table] = null;
        return self::getPrivileges($mvv_table);
    }

    /**
     * Returns all ids of institutes the user is assigned with at least one role.
     * Have the user at least one role globally an empty array is returned.
     *
     * @param string $user_id Optional. The ID of the user. If not set the ID of
     * the current user.
     * @param array $mvv_roles Optional. An array of roles. All Mvv-Roles if not set.
     * @return array An array of institute ids or an empty array.
     */
    public static function getOwnInstitutes($user_id = null, $mvv_roles = null)
    {
        $user_id = $user_id ?: $GLOBALS['user']->id;
        $roles = [];
        if (is_null($mvv_roles)) {
            $roles = self::getRoles($user_id);
        } else {
            foreach (self::getRoles($user_id) as $role) {
                if (in_array($role->rolename, (array) $mvv_roles)) {
                    $roles[] = $role;
                }
            }
        }

        if (!isset(self::$user_role_institutes[$user_id])) {
            $institutes = [];
            foreach ($roles as $role) {

                // don't check system roles or roles not related to MVV
                if (stripos($role->rolename, 'MVV') !== 0) continue;

                if ($GLOBALS['perm']->have_perm('root', $user_id)) {
                    $institutes = [];
                    break;
                }
                $institutes_assigned_role = RolePersistence::getAssignedRoleInstitutes($user_id, $role->roleid);
                if (count($institutes_assigned_role) === 0) {
                    // this role is globally defined for this user
                    $institutes = [];
                    break;
                }
                $institutes = array_merge((array) $institutes, array_filter(
                    $institutes_assigned_role, function ($inst) {
                        return $inst != '';
                    }));
            }

            if (count($institutes)) {
                $stmt = DBManager::get()->prepare('SELECT DISTINCT(Institut_id) '
                        . 'FROM Institute WHERE Institut_id IN (:inst_ids) '
                        . 'OR fakultaets_id IN (:inst_ids)');
                $stmt->execute(['inst_ids' => $institutes]);
                self::$user_role_institutes[$user_id] = $stmt->fetchAll(PDO::FETCH_COLUMN);
            } else {
                self::$user_role_institutes[$user_id] = [];
            }
        }
        return self::$user_role_institutes[$user_id];
    }

}