<?php
/**
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Google\Cloud\Core\Iam;

/**
 * IAM Manager
 *
 * This class is not meant to be used directly. It should be accessed
 * through other objects which support IAM.
 *
 * Policies can be created using the {@see \Google\Cloud\Core\Iam\PolicyBuilder}
 * to help ensure their validity.
 *
 * Example:
 * ```
 * // IAM policies are obtained via resources which implement IAM.
 * // In this example, we'll use PubSub topics to demonstrate
 * // how IAM policies are managed.
 *
 * use Google\Cloud\Spanner\SpannerClient;
 *
 * $spanner = new SpannerClient(['projectId' => 'my-project']);
 * $instance = $spanner->instance('my-new-instance');
 *
 * $iam = $instance->iam();
 * ```
 */
class Iam
{
    /**
     * @var IamConnectionInterface
     */
    private $connection;

    /**
     * @var string
     */
    private $resource;

    /**
     * @var array
     */
    private $policy;

    /**
     * @var array
     */
    private $args;

    /**
     * @var array
     */
    private $options;

    /**
     * @param IamConnectionInterface $connection
     * @param string $resource
     * @param array $options [optional] {
     *     Configuration Options
     *
     *     @type string|null $parent The parent request parameter for the policy.
     *           If set, policy data will be sent as `request.{$parent}`.
     *           Otherwise, policy will be sent in request root. **Defaults to**
     *           `policy`.
     *     @type array $args Arbitrary data to be sent with the request.
     * }
     * @access private
     */
    public function __construct(IamConnectionInterface $connection, $resource, array $options = [])
    {
        $options += [
            'parent' => 'policy',
            'args' => []
        ];

        $this->connection = $connection;
        $this->resource = $resource;
        $this->options = $options;
    }

    /**
     * Get the existing IAM policy for this resource.
     *
     * If a policy has already been retrieved from the API, it will be returned.
     * To fetch a fresh copy of the policy, use
     * {@see \Google\Cloud\Core\Iam\Iam::reload()}.
     *
     * Example:
     * ```
     * $policy = $iam->policy();
     * ```
     *
     * @param  array $options Configuration Options
     * @param  int   $options['requestedPolicyVersion'] Specify the policy version to
     *     request from the server. Please see
     *     [policy versioning](https://cloud.google.com/iam/docs/policies#versions)
     *     for more information.
     * @return array An array of policy data
     */
    public function policy(array $options = [])
    {
        if (!$this->policy) {
            $this->reload($options);
        }

        return $this->policy;
    }

    /**
     * Set the IAM policy for this resource.
     *
     * Bindings with invalid roles, or non-existent members will raise a server
     * error.
     *
     * Example:
     * ```
     * $oldPolicy = $iam->policy();
     * $oldPolicy['bindings'][0]['members'] = 'user:test@example.com';
     *
     * $policy = $iam->setPolicy($oldPolicy);
     * ```
     *
     * @param  array|PolicyBuilder $policy The new policy, as an array or an
     *         instance of {@see \Google\Cloud\Core\Iam\PolicyBuilder}.
     * @param  array $options Configuration Options
     * @return array An array of policy data
     * @throws \InvalidArgumentException If the given policy is not an array or PolicyBuilder.
     */
    public function setPolicy($policy, array $options = [])
    {
        if ($policy instanceof PolicyBuilder) {
            $policy = $policy->result();
        }

        if (!is_array($policy)) {
            throw new \InvalidArgumentException('Given policy data must be an array or an instance of PolicyBuilder.');
        }

        $request = [];
        if ($this->options['parent']) {
            $parent = $this->options['parent'];
            $request[$parent] = $policy;
        } else {
            $request = $policy;
        }

        return $this->policy = $this->connection->setPolicy([
            'resource' => $this->resource
        ] + $request + $options + $this->options['args']);
    }

    /**
     * Test if the current user has the given permissions on this resource.
     *
     * Invalid permissions will raise a BadRequestException.
     *
     * Example:
     * ```
     * $allowedPermissions = $iam->testPermissions([
     *     'pubsub.topics.publish',
     *     'pubsub.topics.attachSubscription'
     * ]);
     * ```
     *
     * @param  array $permissions A list of permissions to test
     * @param  array $options Configuration Options
     * @return array A subset of $permissions, with only those allowed included.
     */
    public function testPermissions(array $permissions, array $options = [])
    {
        $res = $this->connection->testPermissions([
            'permissions' => $permissions,
            'resource' => $this->resource
        ] + $options + $this->options['args']);

        return (isset($res['permissions'])) ? $res['permissions'] : [];
    }

    /**
     * Refresh the IAM policy for this resource.
     *
     * Example:
     * ```
     * $policy = $iam->reload();
     * ```
     *
     * @param  array $options Configuration Options
     * @return array An array of policy data
     */
    public function reload(array $options = [])
    {
        return $this->policy = $this->connection->getPolicy([
            'resource' => $this->resource
        ] + $options + $this->options['args']);
    }
}
