<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\rbac;

use Yii;
use yii\base\Component;
use yii\base\InvalidParamException;

/**
 * Manager is the base class for authorization manager classes.
 *
 * Manager extends [[Component]] and implements some methods
 * that are common among authorization manager classes.
 *
 * Manager together with its concrete child classes implement the Role-Based
 * Access Control (RBAC).
 *
 * The main idea is that permissions are organized as a hierarchy of
 * [[Item]] authorization items. Items on higher level inherit the permissions
 * represented by items on lower level. And roles are simply top-level authorization items
 * that may be assigned to individual users. A user is said to have a permission
 * to do something if the corresponding authorization item is inherited by one of his roles.
 *
 * Using authorization manager consists of two aspects. First, the authorization hierarchy
 * and assignments have to be established. Manager and its child classes
 * provides APIs to accomplish this task. Developers may need to develop some GUI
 * so that it is more intuitive to end-users. Second, developers call [[Manager::checkAccess()]]
 * at appropriate places in the application code to check if the current user
 * has the needed permission for an operation.
 *
 * @property Item[] $operations Operations (name => AuthItem). This property is read-only.
 * @property Item[] $roles Roles (name => AuthItem). This property is read-only.
 * @property Item[] $tasks Tasks (name => AuthItem). This property is read-only.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @author Alexander Kochetov <creocoder@gmail.com>
 * @since 2.0
 */
abstract class Manager extends Component
{
    /**
     * @var boolean Enable error reporting for bizRules.
     */
    public $showErrors = false;

    /**
     * @var array list of role names that are assigned to all users implicitly.
     * These roles do not need to be explicitly assigned to any user.
     * When calling [[checkAccess()]], these roles will be checked first.
     * For performance reason, you should minimize the number of such roles.
     * A typical usage of such roles is to define an 'authenticated' role and associate
     * it with a biz rule which checks if the current user is authenticated.
     * And then declare 'authenticated' in this property so that it can be applied to
     * every authenticated user.
     */
    public $defaultRoles = [];

    /**
     * Creates a role.
     * This is a shortcut method to [[Manager::createItem()]].
     * @param  string $name        the item name
     * @param  string $description the item description.
     * @param  string $bizRule     the business rule associated with this item
     * @param  mixed  $data        additional data to be passed when evaluating the business rule
     * @return Item   the authorization item
     */
    public function createRole($name, $description = '', $bizRule = null, $data = null)
    {
        return $this->createItem($name, Item::TYPE_ROLE, $description, $bizRule, $data);
    }

    /**
     * Creates a task.
     * This is a shortcut method to [[Manager::createItem()]].
     * @param  string $name        the item name
     * @param  string $description the item description.
     * @param  string $bizRule     the business rule associated with this item
     * @param  mixed  $data        additional data to be passed when evaluating the business rule
     * @return Item   the authorization item
     */
    public function createTask($name, $description = '', $bizRule = null, $data = null)
    {
        return $this->createItem($name, Item::TYPE_TASK, $description, $bizRule, $data);
    }

    /**
     * Creates an operation.
     * This is a shortcut method to [[Manager::createItem()]].
     * @param  string $name        the item name
     * @param  string $description the item description.
     * @param  string $bizRule     the business rule associated with this item
     * @param  mixed  $data        additional data to be passed when evaluating the business rule
     * @return Item   the authorization item
     */
    public function createOperation($name, $description = '', $bizRule = null, $data = null)
    {
        return $this->createItem($name, Item::TYPE_OPERATION, $description, $bizRule, $data);
    }

    /**
     * Returns roles.
     * This is a shortcut method to [[Manager::getItems()]].
     * @param  mixed  $userId the user ID. If not null, only the roles directly assigned to the user
     *                        will be returned. Otherwise, all roles will be returned.
     * @return Item[] roles (name => AuthItem)
     */
    public function getRoles($userId = null)
    {
        return $this->getItems($userId, Item::TYPE_ROLE);
    }

    /**
     * Returns tasks.
     * This is a shortcut method to [[Manager::getItems()]].
     * @param  mixed  $userId the user ID. If not null, only the tasks directly assigned to the user
     *                        will be returned. Otherwise, all tasks will be returned.
     * @return Item[] tasks (name => AuthItem)
     */
    public function getTasks($userId = null)
    {
        return $this->getItems($userId, Item::TYPE_TASK);
    }

    /**
     * Returns operations.
     * This is a shortcut method to [[Manager::getItems()]].
     * @param  mixed  $userId the user ID. If not null, only the operations directly assigned to the user
     *                        will be returned. Otherwise, all operations will be returned.
     * @return Item[] operations (name => AuthItem)
     */
    public function getOperations($userId = null)
    {
        return $this->getItems($userId, Item::TYPE_OPERATION);
    }

    /**
     * Executes the specified business rule.
     * @param  string  $bizRule the business rule to be executed.
     * @param  array   $params  parameters passed to [[Manager::checkAccess()]].
     * @param  mixed   $data    additional data associated with the authorization item or assignment.
     * @return boolean whether the business rule returns true.
     *                         If the business rule is empty, it will still return true.
     */
    public function executeBizRule($bizRule, $params, $data)
    {
        return $bizRule === '' || $bizRule === null || ($this->showErrors ? eval($bizRule) != 0 : @eval($bizRule) != 0);
    }

    /**
     * Checks the item types to make sure a child can be added to a parent.
     * @param  integer               $parentType parent item type
     * @param  integer               $childType  child item type
     * @throws InvalidParamException if the item cannot be added as a child due to its incompatible type.
     */
    protected function checkItemChildType($parentType, $childType)
    {
        static $types = ['operation', 'task', 'role'];
        if ($parentType < $childType) {
            throw new InvalidParamException("Cannot add an item of type '{$types[$childType]}' to an item of type '{$types[$parentType]}'.");
        }
    }

    /**
     * Performs access check for the specified user.
     * @param  mixed   $userId   the user ID. This should be either an integer or a string representing
     *                           the unique identifier of a user. See [[\yii\web\User::id]].
     * @param  string  $itemName the name of the operation that we are checking access to
     * @param  array   $params   name-value pairs that would be passed to biz rules associated
     *                           with the tasks and roles assigned to the user.
     * @return boolean whether the operations can be performed by the user.
     */
    abstract public function checkAccess($userId, $itemName, $params = []);

    /**
     * Creates an authorization item.
     * An authorization item represents an action permission (e.g. creating a post).
     * It has three types: operation, task and role.
     * Authorization items form a hierarchy. Higher level items inheirt permissions representing
     * by lower level items.
     * @param  string              $name        the item name. This must be a unique identifier.
     * @param  integer             $type        the item type (0: operation, 1: task, 2: role).
     * @param  string              $description description of the item
     * @param  string              $bizRule     business rule associated with the item. This is a piece of
     *                                          PHP code that will be executed when [[checkAccess()]] is called for the item.
     * @param  mixed               $data        additional data associated with the item.
     * @throws \yii\base\Exception if an item with the same name already exists
     * @return Item                the authorization item
     */
    abstract public function createItem($name, $type, $description = '', $bizRule = null, $data = null);
    /**
     * Removes the specified authorization item.
     * @param  string  $name the name of the item to be removed
     * @return boolean whether the item exists in the storage and has been removed
     */
    abstract public function removeItem($name);
    /**
     * Returns the authorization items of the specific type and user.
     * @param  mixed   $userId the user ID. Defaults to null, meaning returning all items even if
     *                         they are not assigned to a user.
     * @param  integer $type   the item type (0: operation, 1: task, 2: role). Defaults to null,
     *                         meaning returning all items regardless of their type.
     * @return Item[]  the authorization items of the specific type.
     */
    abstract public function getItems($userId = null, $type = null);
    /**
     * Returns the authorization item with the specified name.
     * @param  string $name the name of the item
     * @return Item   the authorization item. Null if the item cannot be found.
     */
    abstract public function getItem($name);
    /**
     * Saves an authorization item to persistent storage.
     * @param Item   $item    the item to be saved.
     * @param string $oldName the old item name. If null, it means the item name is not changed.
     */
    abstract public function saveItem($item, $oldName = null);

    /**
     * Adds an item as a child of another item.
     * @param  string              $itemName  the parent item name
     * @param  string              $childName the child item name
     * @throws \yii\base\Exception if either parent or child doesn't exist or if a loop has been detected.
     */
    abstract public function addItemChild($itemName, $childName);
    /**
     * Removes a child from its parent.
     * Note, the child item is not deleted. Only the parent-child relationship is removed.
     * @param  string  $itemName  the parent item name
     * @param  string  $childName the child item name
     * @return boolean whether the removal is successful
     */
    abstract public function removeItemChild($itemName, $childName);
    /**
     * Returns a value indicating whether a child exists within a parent.
     * @param  string  $itemName  the parent item name
     * @param  string  $childName the child item name
     * @return boolean whether the child exists
     */
    abstract public function hasItemChild($itemName, $childName);
    /**
     * Returns the children of the specified item.
     * @param  mixed  $itemName the parent item name. This can be either a string or an array.
     *                          The latter represents a list of item names.
     * @return Item[] all child items of the parent
     */
    abstract public function getItemChildren($itemName);

    /**
     * Assigns an authorization item to a user.
     * @param  mixed               $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string              $itemName the item name
     * @param  string              $bizRule  the business rule to be executed when [[checkAccess()]] is called
     *                                       for this particular authorization item.
     * @param  mixed               $data     additional data associated with this assignment
     * @return Assignment          the authorization assignment information.
     * @throws \yii\base\Exception if the item does not exist or if the item has already been assigned to the user
     */
    abstract public function assign($userId, $itemName, $bizRule = null, $data = null);
    /**
     * Revokes an authorization assignment from a user.
     * @param  mixed   $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string  $itemName the item name
     * @return boolean whether removal is successful
     */
    abstract public function revoke($userId, $itemName);
    /**
     * Revokes all authorization assignments from a user.
     * @param  mixed   $userId the user ID (see [[\yii\web\User::id]])
     * @return boolean whether removal is successful
     */
    abstract public function revokeAll($userId);
    /**
     * Returns a value indicating whether the item has been assigned to the user.
     * @param  mixed   $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string  $itemName the item name
     * @return boolean whether the item has been assigned to the user.
     */
    abstract public function isAssigned($userId, $itemName);
    /**
     * Returns the item assignment information.
     * @param  mixed      $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string     $itemName the item name
     * @return Assignment the item assignment information. Null is returned if
     *                             the item is not assigned to the user.
     */
    abstract public function getAssignment($userId, $itemName);
    /**
     * Returns the item assignments for the specified user.
     * @param  mixed  $userId the user ID (see [[\yii\web\User::id]])
     * @return Item[] the item assignment information for the user. An empty array will be
     *                       returned if there is no item assigned to the user.
     */
    abstract public function getAssignments($userId);
    /**
     * Saves the changes to an authorization assignment.
     * @param Assignment $assignment the assignment that has been changed.
     */
    abstract public function saveAssignment($assignment);
    /**
     * Removes all authorization data.
     */
    abstract public function clearAll();
    /**
     * Removes all authorization assignments.
     */
    abstract public function clearAssignments();
    /**
     * Saves authorization data into persistent storage.
     * If any change is made to the authorization data, please make
     * sure you call this method to save the changed data into persistent storage.
     */
    abstract public function save();
}
