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

namespace yii\mongodb;

use yii\base\Component;
use yii\base\InvalidConfigException;
use Yii;

/**
 * Connection represents a connection to a MongoDb server.
 *
 * Connection works together with [[Database]] and [[Collection]] to provide data access
 * to the Mongo database. They are wrappers of the [[MongoDB PHP extension]](http://us1.php.net/manual/en/book.mongo.php).
 *
 * To establish a DB connection, set [[dsn]] and then call [[open()]] to be true.
 *
 * The following example shows how to create a Connection instance and establish
 * the DB connection:
 *
 * ~~~
 * $connection = new \yii\mongodb\Connection([
 *     'dsn' => $dsn,
 * ]);
 * $connection->open();
 * ~~~
 *
 * After the Mongo connection is established, one can access Mongo databases and collections:
 *
 * ~~~
 * $database = $connection->getDatabase('my_mongo_db');
 * $collection = $database->getCollection('customer');
 * $collection->insert(['name' => 'John Smith', 'status' => 1]);
 * ~~~
 *
 * You can work with several different databases at the same server using this class.
 * However, while it is unlikely your application will actually need it, the Connection class
 * provides ability to use [[defaultDatabaseName]] as well as a shortcut method [[getCollection()]]
 * to retrieve a particular collection instance:
 *
 * ~~~
 * // get collection 'customer' from default database:
 * $collection = $connection->getCollection('customer');
 * // get collection 'customer' from database 'mydatabase':
 * $collection = $connection->getCollection(['mydatabase', 'customer']);
 * ~~~
 *
 * Connection is often used as an application component and configured in the application
 * configuration like the following:
 *
 * ~~~
 * [
 *      'components' => [
 *          'mongodb' => [
 *              'class' => '\yii\mongodb\Connection',
 *              'dsn' => 'mongodb://developer:password@localhost:27017/mydatabase',
 *          ],
 *      ],
 * ]
 * ~~~
 *
 * @property Database $database Database instance. This property is read-only.
 * @property file\Collection $fileCollection Mongo GridFS collection instance. This property is read-only.
 * @property boolean $isActive Whether the Mongo connection is established. This property is read-only.
 *
 * @author Paul Klimov <klimov.paul@gmail.com>
 * @since 2.0
 */
class Connection extends Component
{
    /**
     * @event Event an event that is triggered after a DB connection is established
     */
    const EVENT_AFTER_OPEN = 'afterOpen';

    /**
     * @var string host:port
     *
     * Correct syntax is:
     * mongodb://[username:password@]host1[:port1][,host2[:port2:],...][/dbname]
     * For example:
     * mongodb://localhost:27017
     * mongodb://developer:password@localhost:27017
     * mongodb://developer:password@localhost:27017/mydatabase
     */
    public $dsn;
    /**
     * @var array connection options.
     * for example:
     *
     * ~~~
     * [
     *     'socketTimeoutMS' => 1000, // how long a send or receive on a socket can take before timing out
     *     'journal' => true // block write operations until the journal be flushed the to disk
     * ]
     * ~~~
     *
     * @see http://www.php.net/manual/en/mongoclient.construct.php
     */
    public $options = [];
    /**
     * @var string name of the Mongo database to use by default.
     * If this field left blank, connection instance will attempt to determine it from
     * [[options]] and [[dsn]] automatically, if needed.
     */
    public $defaultDatabaseName;
    /**
     * @var \MongoClient Mongo client instance.
     */
    public $mongoClient;
    /**
     * @var Database[] list of Mongo databases
     */
    private $_databases = [];

    /**
     * Returns the Mongo collection with the given name.
     * @param string|null $name collection name, if null default one will be used.
     * @param boolean $refresh whether to reestablish the database connection even if it is found in the cache.
     * @return Database database instance.
     */
    public function getDatabase($name = null, $refresh = false)
    {
        if ($name === null) {
            $name = $this->fetchDefaultDatabaseName();
        }
        if ($refresh || !array_key_exists($name, $this->_databases)) {
            $this->_databases[$name] = $this->selectDatabase($name);
        }

        return $this->_databases[$name];
    }

    /**
     * Returns [[defaultDatabaseName]] value, if it is not set,
     * attempts to determine it from [[dsn]] value.
     * @return string default database name
     * @throws \yii\base\InvalidConfigException if unable to determine default database name.
     */
    protected function fetchDefaultDatabaseName()
    {
        if ($this->defaultDatabaseName === null) {
            if (isset($this->options['db'])) {
                $this->defaultDatabaseName = $this->options['db'];
            } elseif (preg_match('/^mongodb:\\/\\/.+\\/(.+)$/s', $this->dsn, $matches)) {
                $this->defaultDatabaseName = $matches[1];
            } else {
                throw new InvalidConfigException("Unable to determine default database name from dsn.");
            }
        }

        return $this->defaultDatabaseName;
    }

    /**
     * Selects the database with given name.
     * @param string $name database name.
     * @return Database database instance.
     */
    protected function selectDatabase($name)
    {
        $this->open();

        return Yii::createObject([
            'class' => 'yii\mongodb\Database',
            'mongoDb' => $this->mongoClient->selectDB($name)
        ]);
    }

    /**
     * Returns the Mongo collection with the given name.
     * @param string|array $name collection name. If string considered as the name of the collection
     * inside the default database. If array - first element considered as the name of the database,
     * second - as name of collection inside that database
     * @param boolean $refresh whether to reload the collection instance even if it is found in the cache.
     * @return Collection Mongo collection instance.
     */
    public function getCollection($name, $refresh = false)
    {
        if (is_array($name)) {
            list ($dbName, $collectionName) = $name;

            return $this->getDatabase($dbName)->getCollection($collectionName, $refresh);
        } else {
            return $this->getDatabase()->getCollection($name, $refresh);
        }
    }

    /**
     * Returns the Mongo GridFS collection.
     * @param string|array $prefix collection prefix. If string considered as the prefix of the GridFS
     * collection inside the default database. If array - first element considered as the name of the database,
     * second - as prefix of the GridFS collection inside that database, if no second element present
     * default "fs" prefix will be used.
     * @param boolean $refresh whether to reload the collection instance even if it is found in the cache.
     * @return file\Collection Mongo GridFS collection instance.
     */
    public function getFileCollection($prefix = 'fs', $refresh = false)
    {
        if (is_array($prefix)) {
            list ($dbName, $collectionPrefix) = $prefix;
            if (!isset($collectionPrefix)) {
                $collectionPrefix = 'fs';
            }

            return $this->getDatabase($dbName)->getFileCollection($collectionPrefix, $refresh);
        } else {
            return $this->getDatabase()->getFileCollection($prefix, $refresh);
        }
    }

    /**
     * Returns a value indicating whether the Mongo connection is established.
     * @return boolean whether the Mongo connection is established
     */
    public function getIsActive()
    {
        return is_object($this->mongoClient) && $this->mongoClient->getConnections() != [];
    }

    /**
     * Establishes a Mongo connection.
     * It does nothing if a Mongo connection has already been established.
     * @throws Exception if connection fails
     */
    public function open()
    {
        if ($this->mongoClient === null) {
            if (empty($this->dsn)) {
                throw new InvalidConfigException($this->className() . '::dsn cannot be empty.');
            }
            $token = 'Opening MongoDB connection: ' . $this->dsn;
            try {
                Yii::trace($token, __METHOD__);
                Yii::beginProfile($token, __METHOD__);
                $options = $this->options;
                $options['connect'] = true;
                if ($this->defaultDatabaseName !== null) {
                    $options['db'] = $this->defaultDatabaseName;
                }
                $this->mongoClient = new \MongoClient($this->dsn, $options);
                $this->initConnection();
                Yii::endProfile($token, __METHOD__);
            } catch (\Exception $e) {
                Yii::endProfile($token, __METHOD__);
                throw new Exception($e->getMessage(), (int) $e->getCode(), $e);
            }
        }
    }

    /**
     * Closes the currently active DB connection.
     * It does nothing if the connection is already closed.
     */
    public function close()
    {
        if ($this->mongoClient !== null) {
            Yii::trace('Closing MongoDB connection: ' . $this->dsn, __METHOD__);
            $this->mongoClient = null;
            $this->_databases = [];
        }
    }

    /**
     * Initializes the DB connection.
     * This method is invoked right after the DB connection is established.
     * The default implementation triggers an [[EVENT_AFTER_OPEN]] event.
     */
    protected function initConnection()
    {
        $this->trigger(self::EVENT_AFTER_OPEN);
    }
}