<?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\Exception;
use yii\base\InvalidCallException;
use yii\base\InvalidParamException;

/**
 * PhpManager represents an authorization manager that stores authorization
 * information in terms of a PHP script file.
 *
 * The authorization data will be saved to and loaded from a file
 * specified by [[authFile]], which defaults to 'protected/data/rbac.php'.
 *
 * PhpManager is mainly suitable for authorization data that is not too big
 * (for example, the authorization data for a personal blog system).
 * Use [[DbManager]] for more complex authorization data.
 *
 * @property Item[] $items The authorization items of the specific type. This property is read-only.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @author Alexander Kochetov <creocoder@gmail.com>
 * @since 2.0
 */
class PhpManager extends Manager
{
    /**
     * @var string the path of the PHP script that contains the authorization data.
     * This can be either a file path or a path alias to the file.
     * Make sure this file is writable by the Web server process if the authorization needs to be changed online.
     * @see loadFromFile()
     * @see saveToFile()
     */
    public $authFile = '@app/data/rbac.php';

    private $_items = []; // itemName => item
    private $_children = []; // itemName, childName => child
    private $_assignments = []; // userId, itemName => assignment

    /**
     * Initializes the application component.
     * This method overrides parent implementation by loading the authorization data
     * from PHP script.
     */
    public function init()
    {
        parent::init();
        $this->authFile = Yii::getAlias($this->authFile);
        $this->load();
    }

    /**
     * Performs access check for the specified user.
     * @param  mixed   $userId   the user ID. This can be either an integer or a string representing
     * @param  string  $itemName the name of the operation that need access check
     *                           the unique identifier of a user. See [[\yii\web\User::id]].
     * @param  array   $params   name-value pairs that would be passed to biz rules associated
     *                           with the tasks and roles assigned to the user. A param with name 'userId' is added to
     *                           this array, which holds the value of `$userId`.
     * @return boolean whether the operations can be performed by the user.
     */
    public function checkAccess($userId, $itemName, $params = [])
    {
        if (!isset($this->_items[$itemName])) {
            return false;
        }
        /** @var Item $item */
        $item = $this->_items[$itemName];
        Yii::trace('Checking permission: ' . $item->getName(), __METHOD__);
        if (!isset($params['userId'])) {
            $params['userId'] = $userId;
        }
        if ($this->executeBizRule($item->bizRule, $params, $item->data)) {
            if (in_array($itemName, $this->defaultRoles)) {
                return true;
            }
            if (isset($this->_assignments[$userId][$itemName])) {
                /** @var Assignment $assignment */
                $assignment = $this->_assignments[$userId][$itemName];
                if ($this->executeBizRule($assignment->bizRule, $params, $assignment->data)) {
                    return true;
                }
            }
            foreach ($this->_children as $parentName => $children) {
                if (isset($children[$itemName]) && $this->checkAccess($userId, $parentName, $params)) {
                    return true;
                }
            }
        }

        return false;
    }

    /**
     * Adds an item as a child of another item.
     * @param  string               $itemName  the parent item name
     * @param  string               $childName the child item name
     * @return boolean              whether the item is added successfully
     * @throws Exception            if either parent or child doesn't exist.
     * @throws InvalidCallException if item already has a child with $itemName or if a loop has been detected.
     */
    public function addItemChild($itemName, $childName)
    {
        if (!isset($this->_items[$childName], $this->_items[$itemName])) {
            throw new Exception("Either '$itemName' or '$childName' does not exist.");
        }
        /** @var Item $child */
        $child = $this->_items[$childName];
        /** @var Item $item */
        $item = $this->_items[$itemName];
        $this->checkItemChildType($item->type, $child->type);
        if ($this->detectLoop($itemName, $childName)) {
            throw new InvalidCallException("Cannot add '$childName' as a child of '$itemName'. A loop has been detected.");
        }
        if (isset($this->_children[$itemName][$childName])) {
            throw new InvalidCallException("The item '$itemName' already has a child '$childName'.");
        }
        $this->_children[$itemName][$childName] = $this->_items[$childName];

        return true;
    }

    /**
     * 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  $childName the child item name
     * @return boolean whether the removal is successful
     */
    public function removeItemChild($itemName, $childName)
    {
        if (isset($this->_children[$itemName][$childName])) {
            unset($this->_children[$itemName][$childName]);

            return true;
        } else {
            return false;
        }
    }

    /**
     * Returns a value indicating whether a child exists within a parent.
     * @param  string  $itemName  the parent item name
     * @param  string  $childName the child item name
     * @return boolean whether the child exists
     */
    public function hasItemChild($itemName, $childName)
    {
        return isset($this->_children[$itemName][$childName]);
    }

    /**
     * Returns the children of the specified item.
     * @param  mixed  $names the parent item name. This can be either a string or an array.
     *                       The latter represents a list of item names.
     * @return Item[] all child items of the parent
     */
    public function getItemChildren($names)
    {
        if (is_string($names)) {
            return isset($this->_children[$names]) ? $this->_children[$names] : [];
        }

        $children = [];
        foreach ($names as $name) {
            if (isset($this->_children[$name])) {
                $children = array_merge($children, $this->_children[$name]);
            }
        }

        return $children;
    }

    /**
     * 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                 $data     additional data associated with this assignment
     * @return Assignment            the authorization assignment information.
     * @throws InvalidParamException if the item does not exist or if the item has already been assigned to the user
     */
    public function assign($userId, $itemName, $bizRule = null, $data = null)
    {
        if (!isset($this->_items[$itemName])) {
            throw new InvalidParamException("Unknown authorization item '$itemName'.");
        } elseif (isset($this->_assignments[$userId][$itemName])) {
            throw new InvalidParamException("Authorization item '$itemName' has already been assigned to user '$userId'.");
        } else {
            return $this->_assignments[$userId][$itemName] = new Assignment([
                'manager' => $this,
                'userId' => $userId,
                'itemName' => $itemName,
                'bizRule' => $bizRule,
                'data' => $data,
            ]);
        }
    }

    /**
     * Revokes an authorization assignment from a user.
     * @param  mixed   $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string  $itemName the item name
     * @return boolean whether removal is successful
     */
    public function revoke($userId, $itemName)
    {
        if (isset($this->_assignments[$userId][$itemName])) {
            unset($this->_assignments[$userId][$itemName]);

            return true;
        } else {
            return false;
        }
    }

    /**
     * Revokes all authorization assignments from a user.
     * @param  mixed   $userId the user ID (see [[\yii\web\User::id]])
     * @return boolean whether removal is successful
     */
    public function revokeAll($userId)
    {
        if (isset($this->_assignments[$userId]) && is_array($this->_assignments[$userId])) {
            foreach ($this->_assignments[$userId] as $itemName => $value)
                unset($this->_assignments[$userId][$itemName]);

            return true;
        } else {
            return false;
        }
    }

    /**
     * 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  $itemName the item name
     * @return boolean whether the item has been assigned to the user.
     */
    public function isAssigned($userId, $itemName)
    {
        return isset($this->_assignments[$userId][$itemName]);
    }

    /**
     * Returns the item assignment information.
     * @param  mixed      $userId   the user ID (see [[\yii\web\User::id]])
     * @param  string     $itemName the item name
     * @return Assignment the item assignment information. Null is returned if
     *                             the item is not assigned to the user.
     */
    public function getAssignment($userId, $itemName)
    {
        return isset($this->_assignments[$userId][$itemName]) ? $this->_assignments[$userId][$itemName] : null;
    }

    /**
     * Returns the item assignments for the specified user.
     * @param  mixed        $userId the user ID (see [[\yii\web\User::id]])
     * @return Assignment[] the item assignment information for the user. An empty array will be
     *                             returned if there is no item assigned to the user.
     */
    public function getAssignments($userId)
    {
        return isset($this->_assignments[$userId]) ? $this->_assignments[$userId] : [];
    }

    /**
     * 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 $type   the item type (0: operation, 1: task, 2: role). Defaults to null,
     *                         meaning returning all items regardless of their type.
     * @return Item[]  the authorization items of the specific type.
     */
    public function getItems($userId = null, $type = null)
    {
        if ($userId === null && $type === null) {
            return $this->_items;
        }
        $items = [];
        if ($userId === null) {
            foreach ($this->_items as $name => $item) {
                /** @var Item $item */
                if ($item->type == $type) {
                    $items[$name] = $item;
                }
            }
        } elseif (isset($this->_assignments[$userId])) {
            foreach ($this->_assignments[$userId] as $assignment) {
                /** @var Assignment $assignment */
                $name = $assignment->itemName;
                if (isset($this->_items[$name]) && ($type === null || $this->_items[$name]->type == $type)) {
                    $items[$name] = $this->_items[$name];
                }
            }
        }

        return $items;
    }

    /**
     * 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     $data        additional data associated with the item.
     * @return Item      the authorization item
     * @throws Exception if an item with the same name already exists
     */
    public function createItem($name, $type, $description = '', $bizRule = null, $data = null)
    {
        if (isset($this->_items[$name])) {
            throw new Exception('Unable to add an item whose name is the same as an existing item.');
        }

        return $this->_items[$name] = new Item([
            'manager' => $this,
            'name' => $name,
            'type' => $type,
            'description' => $description,
            'bizRule' => $bizRule,
            'data' => $data,
        ]);
    }

    /**
     * Removes the specified authorization item.
     * @param  string  $name the name of the item to be removed
     * @return boolean whether the item exists in the storage and has been removed
     */
    public function removeItem($name)
    {
        if (isset($this->_items[$name])) {
            foreach ($this->_children as &$children) {
                unset($children[$name]);
            }
            foreach ($this->_assignments as &$assignments) {
                unset($assignments[$name]);
            }
            unset($this->_items[$name]);

            return true;
        } else {
            return false;
        }
    }

    /**
     * Returns the authorization item with the specified name.
     * @param  string $name the name of the item
     * @return Item   the authorization item. Null if the item cannot be found.
     */
    public function getItem($name)
    {
        return isset($this->_items[$name]) ? $this->_items[$name] : null;
    }

    /**
     * Saves an authorization item to persistent storage.
     * @param  Item                  $item    the item to be saved.
     * @param  string                $oldName the old item name. If null, it means the item name is not changed.
     * @throws InvalidParamException if an item with the same name already taken
     */
    public function saveItem($item, $oldName = null)
    {
        if ($oldName !== null && ($newName = $item->getName()) !== $oldName) { // name changed
            if (isset($this->_items[$newName])) {
                throw new InvalidParamException("Unable to change the item name. The name '$newName' is already used by another item.");
            }
            if (isset($this->_items[$oldName]) && $this->_items[$oldName] === $item) {
                unset($this->_items[$oldName]);
                $this->_items[$newName] = $item;
                if (isset($this->_children[$oldName])) {
                    $this->_children[$newName] = $this->_children[$oldName];
                    unset($this->_children[$oldName]);
                }
                foreach ($this->_children as &$children) {
                    if (isset($children[$oldName])) {
                        $children[$newName] = $children[$oldName];
                        unset($children[$oldName]);
                    }
                }
                foreach ($this->_assignments as &$assignments) {
                    if (isset($assignments[$oldName])) {
                        $assignments[$newName] = $assignments[$oldName];
                        unset($assignments[$oldName]);
                    }
                }
            }
        }
    }

    /**
     * Saves the changes to an authorization assignment.
     * @param Assignment $assignment the assignment that has been changed.
     */
    public function saveAssignment($assignment)
    {
    }

    /**
     * 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.
     */
    public function save()
    {
        $items = [];
        foreach ($this->_items as $name => $item) {
            /** @var Item $item */
            $items[$name] = [
                'type' => $item->type,
                'description' => $item->description,
                'bizRule' => $item->bizRule,
                'data' => $item->data,
            ];
            if (isset($this->_children[$name])) {
                foreach ($this->_children[$name] as $child) {
                    /** @var Item $child */
                    $items[$name]['children'][] = $child->getName();
                }
            }
        }

        foreach ($this->_assignments as $userId => $assignments) {
            foreach ($assignments as $name => $assignment) {
                /** @var Assignment $assignment */
                if (isset($items[$name])) {
                    $items[$name]['assignments'][$userId] = [
                        'bizRule' => $assignment->bizRule,
                        'data' => $assignment->data,
                    ];
                }
            }
        }

        $this->saveToFile($items, $this->authFile);
    }

    /**
     * Loads authorization data.
     */
    public function load()
    {
        $this->clearAll();

        $items = $this->loadFromFile($this->authFile);

        foreach ($items as $name => $item) {
            $this->_items[$name] = new Item([
                'manager' => $this,
                'name' => $name,
                'type' => $item['type'],
                'description' => $item['description'],
                'bizRule' => $item['bizRule'],
                'data' => $item['data'],
            ]);
        }

        foreach ($items as $name => $item) {
            if (isset($item['children'])) {
                foreach ($item['children'] as $childName) {
                    if (isset($this->_items[$childName])) {
                        $this->_children[$name][$childName] = $this->_items[$childName];
                    }
                }
            }
            if (isset($item['assignments'])) {
                foreach ($item['assignments'] as $userId => $assignment) {
                    $this->_assignments[$userId][$name] = new Assignment([
                        'manager' => $this,
                        'userId' => $userId,
                        'itemName' => $name,
                        'bizRule' => $assignment['bizRule'],
                        'data' => $assignment['data'],
                    ]);
                }
            }
        }
    }

    /**
     * Removes all authorization data.
     */
    public function clearAll()
    {
        $this->clearAssignments();
        $this->_children = [];
        $this->_items = [];
    }

    /**
     * Removes all authorization assignments.
     */
    public function clearAssignments()
    {
        $this->_assignments = [];
    }

    /**
     * Checks whether there is a loop in the authorization item hierarchy.
     * @param  string  $itemName  parent item name
     * @param  string  $childName the name of the child item that is to be added to the hierarchy
     * @return boolean whether a loop exists
     */
    protected function detectLoop($itemName, $childName)
    {
        if ($childName === $itemName) {
            return true;
        }
        if (!isset($this->_children[$childName], $this->_items[$itemName])) {
            return false;
        }
        foreach ($this->_children[$childName] as $child) {
            /** @var Item $child */
            if ($this->detectLoop($itemName, $child->getName())) {
                return true;
            }
        }

        return false;
    }

    /**
     * Loads the authorization data from a PHP script file.
     * @param  string $file the file path.
     * @return array  the authorization data
     * @see saveToFile()
     */
    protected function loadFromFile($file)
    {
        if (is_file($file)) {
            return require($file);
        } else {
            return [];
        }
    }

    /**
     * Saves the authorization data to a PHP script file.
     * @param array  $data the authorization data
     * @param string $file the file path.
     * @see loadFromFile()
     */
    protected function saveToFile($data, $file)
    {
        file_put_contents($file, "<?php\nreturn " . var_export($data, true) . ";\n", LOCK_EX);
    }
}
