<?php
/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

use Alcaeus\MongoDbAdapter\TypeConverter;
use MongoDB\Collection;
use MongoDB\Driver\Cursor;
use MongoDB\Operation\Find;

/**
 * Result object for database query.
 * @link http://www.php.net/manual/en/class.mongocursor.php
 */
class MongoCursor implements Iterator
{
    /**
     * @link http://php.net/manual/en/class.mongocursor.php#mongocursor.props.slaveokay
     * @static
     * @var bool $slaveOkay
     */
    public static $slaveOkay = FALSE;

    /**
     * @var int <p>
     * Set timeout in milliseconds for all database responses. Use
     * <em>-1</em> to wait forever. Can be overridden with
     * {link http://php.net/manual/en/mongocursor.timeout.php MongoCursor::timeout()}. This does not cause the
     * MongoDB server to cancel the operation; it only instructs the driver to
     * stop waiting for a response and throw a
     * {@link http://php.net/manual/en/class.mongocursortimeoutexception.php MongoCursorTimeoutException} after a set time.
     * </p>
     */
    static $timeout = 30000;

    /**
     * @var MongoClient
     */
    private $connection;

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

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

    /**
     * @var
     */
    private $filter;

    /**
     * @var Collection
     */
    private $collection;

    /**
     * @var Cursor
     */
    private $cursor;

    /**
     * @var IteratorIterator
     */
    private $iterator;

    private $awaitData;
    private $batchSize;
    private $limit;
    private $maxTimeMS;
    private $noCursorTimeout;
    private $options = [];
    private $projection;
    private $skip;
    private $sort;
    private $tailable;

    /**
     * Create a new cursor
     * @link http://www.php.net/manual/en/mongocursor.construct.php
     * @param MongoClient $connection Database connection.
     * @param string $ns Full name of database and collection.
     * @param array $query Database query.
     * @param array $fields Fields to return.
     * @return MongoCursor Returns the new cursor
     */
    public function __construct(MongoClient $connection, $ns, array $query = array(), array $fields = array())
    {
        $this->connection = $connection;
        $this->ns = $ns;
        $this->query = $query;
        $this->projection = $fields;

        $nsParts = explode('.', $ns);
        $db = array_shift($nsParts);

        $this->collection = $connection->selectCollection($db, implode('.', $nsParts))->getCollection();
    }

    /**
     * Adds a top-level key/value pair to a query
     * @link http://www.php.net/manual/en/mongocursor.addoption.php
     * @param string $key Fieldname to add.
     * @param mixed $value Value to add.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function addOption($key, $value)
    {
        $this->errorIfOpened();
        $this->options[$key] = $value;

        return $this;
    }

    /**
     * (PECL mongo &gt;= 1.2.11)<br/>
     * Sets whether this cursor will wait for a while for a tailable cursor to return more data
     * @param bool $wait [optional] <p>If the cursor should wait for more data to become available.</p>
     * @return MongoCursor Returns this cursor.
     */
    public function awaitData($wait = true)
    {
        $this->errorIfOpened();
        $this->awaitData = $wait;

        return $this;
    }

    /**
     * Limits the number of elements returned in one batch.
     *
     * @link http://docs.php.net/manual/en/mongocursor.batchsize.php
     * @param int $batchSize The number of results to return per batch
     * @return MongoCursor Returns this cursor.
     */
    public function batchSize($batchSize)
    {
        $this->errorIfOpened();
        $this->batchSize = $batchSize;

        return $this;
    }

    /**
     * Counts the number of results for this query
     * @link http://www.php.net/manual/en/mongocursor.count.php
     * @param bool $foundOnly Send cursor limit and skip information to the count function, if applicable.
     * @return int The number of documents returned by this cursor's query.
     */
    public function count($foundOnly = false)
    {
        if ($foundOnly && $this->cursor !== null) {
            return iterator_count($this->cursor);
        }

        $options = $foundOnly ? $this->applyOptions($this->options, ['skip', 'limit']) : $this->options;

        return $this->collection->count($this->query, $options);
    }

    /**
     * Returns the current element
     * @link http://www.php.net/manual/en/mongocursor.current.php
     * @return array
     */
    public function current()
    {
        $document = $this->ensureIterator()->current();
        if ($document !== null) {
            $document = TypeConverter::convertObjectToLegacyArray($document);
        }

        return $document;
    }

    /**
     * Checks if there are documents that have not been sent yet from the database for this cursor
     * @link http://www.php.net/manual/en/mongocursor.dead.php
     * @return boolean Returns if there are more results that have not been sent to the client, yet.
     */
    public function dead()
    {
        return $this->ensureCursor()->isDead();
    }

    /**
     * Execute the query
     * @link http://www.php.net/manual/en/mongocursor.doquery.php
     * @throws MongoConnectionException if it cannot reach the database.
     * @return void
     */
    protected function doQuery()
    {
        $this->notImplemented();
    }

    /**
     * Return an explanation of the query, often useful for optimization and debugging
     * @link http://www.php.net/manual/en/mongocursor.explain.php
     * @return array Returns an explanation of the query.
     */
    public function explain()
    {
        $this->notImplemented();
    }

    /**
     * Sets the fields for a query
     * @link http://www.php.net/manual/en/mongocursor.fields.php
     * @param array $f Fields to return (or not return).
     * @throws MongoCursorException
     * @return MongoCursor
     */
    public function fields(array $f)
    {
        $this->errorIfOpened();
        $this->projection = $f;

        return $this;
    }

    /**
     * Return the next object to which this cursor points, and advance the cursor
     * @link http://www.php.net/manual/en/mongocursor.getnext.php
     * @throws MongoConnectionException
     * @throws MongoCursorTimeoutException
     * @return array Returns the next object
     */
    public function getNext()
    {
        $this->next();

        return $this->current();
    }

    /**
     * (PECL mongo &gt;= 1.3.3)<br/>
     * @link http://www.php.net/manual/en/mongocursor.getreadpreference.php
     * @return array This function returns an array describing the read preference. The array contains the values <em>type</em> for the string
     * read preference mode (corresponding to the {@link http://www.php.net/manual/en/class.mongoclient.php MongoClient} constants), and <em>tagsets</em> containing a list of all tag set criteria. If no tag sets were specified, <em>tagsets</em> will not be present in the array.
     */
    public function getReadPreference()
    {
        $this->notImplemented();
    }

    /**
     * Checks if there are any more elements in this cursor
     * @link http://www.php.net/manual/en/mongocursor.hasnext.php
     * @throws MongoConnectionException
     * @throws MongoCursorTimeoutException
     * @return bool Returns true if there is another element
     */
    public function hasNext()
    {
        $this->notImplemented();
    }

    /**
     * Gives the database a hint about the query
     * @link http://www.php.net/manual/en/mongocursor.hint.php
     * @param array $key_pattern Indexes to use for the query.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function hint(array $key_pattern)
    {
        $this->notImplemented();
    }

    /**
     * Sets whether this cursor will timeout
     * @link http://www.php.net/manual/en/mongocursor.immortal.php
     * @param bool $liveForever If the cursor should be immortal.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function immortal($liveForever = true)
    {
        $this->errorIfOpened();
        $this->noCursorTimeout = $liveForever;

        return $this;
    }

    /**
     * Gets the query, fields, limit, and skip for this cursor
     * @link http://www.php.net/manual/en/mongocursor.info.php
     * @return array The query, fields, limit, and skip for this cursor as an associative array.
     */
    public function info()
    {
        $this->notImplemented();
    }

    /**
     * Returns the current result's _id
     * @link http://www.php.net/manual/en/mongocursor.key.php
     * @return string The current result's _id as a string.
     */
    public function key()
    {
        return $this->ensureIterator()->key();
    }

    /**
     * Limits the number of results returned
     * @link http://www.php.net/manual/en/mongocursor.limit.php
     * @param int $num The number of results to return.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function limit($num)
    {
        $this->errorIfOpened();
        $this->limit = $num;

        return $this;
    }

    /**
     * @param int $ms
     * @return $this
     * @throws MongoCursorException
     */
    public function maxTimeMS($ms)
    {
        $this->errorIfOpened();
        $this->maxTimeMs = $ms;

        return $this;
    }

    /**
     * Advances the cursor to the next result
     * @link http://www.php.net/manual/en/mongocursor.next.php
     * @throws MongoConnectionException
     * @throws MongoCursorTimeoutException
     * @return void
     */
    public function next()
    {
        $this->ensureIterator()->next();
    }

    /**
     * (PECL mongo &gt;= 1.2.0)<br/>
     * @link http://www.php.net/manual/en/mongocursor.partial.php
     * @param bool $okay [optional] <p>If receiving partial results is okay.</p>
     * @return MongoCursor Returns this cursor.
     */
    public function partial($okay = true)
    {
        $this->notImplemented();
    }

    /**
     * Clears the cursor
     * @link http://www.php.net/manual/en/mongocursor.reset.php
     * @return void
     */
    public function reset()
    {
        $this->cursor = null;
        $this->iterator = null;
    }

    /**
     * Returns the cursor to the beginning of the result set
     * @throws MongoConnectionException
     * @throws MongoCursorTimeoutException
     * @return void
     */
    public function rewind()
    {
        // Note: rewinding the cursor means recreating it internally
        $this->reset();
        $this->ensureIterator()->rewind();
    }

    /**
     * (PECL mongo &gt;= 1.2.1)<br/>
     * @link http://www.php.net/manual/en/mongocursor.setflag.php
     * @param int $flag <p>
     * Which flag to set. You can not set flag 6 (EXHAUST) as the driver does
     * not know how to handle them. You will get a warning if you try to use
     * this flag. For available flags, please refer to the wire protocol
     * {@link http://www.mongodb.org/display/DOCS/Mongo+Wire+Protocol#MongoWireProtocol-OPQUERY documentation}.
     * </p>
     * @param bool $set [optional] <p>Whether the flag should be set (<b>TRUE</b>) or unset (<b>FALSE</b>).</p>
     * @return MongoCursor
     */
    public function setFlag($flag, $set = true )
    {
        $this->notImplemented();
    }

    /**
     * (PECL mongo &gt;= 1.3.3)<br/>
     * @link http://www.php.net/manual/en/mongocursor.setreadpreference.php
     * @param string $read_preference <p>The read preference mode: MongoClient::RP_PRIMARY, MongoClient::RP_PRIMARY_PREFERRED, MongoClient::RP_SECONDARY, MongoClient::RP_SECONDARY_PREFERRED, or MongoClient::RP_NEAREST.</p>
     * @param array $tags [optional] <p>The read preference mode: MongoClient::RP_PRIMARY, MongoClient::RP_PRIMARY_PREFERRED, MongoClient::RP_SECONDARY, MongoClient::RP_SECONDARY_PREFERRED, or MongoClient::RP_NEAREST.</p>
     * @return MongoCursor Returns this cursor.
     */
    public function setReadPreference($read_preference, array $tags)
    {
        $this->notImplemented();
    }

    /**
     * Skips a number of results
     * @link http://www.php.net/manual/en/mongocursor.skip.php
     * @param int $num The number of results to skip.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function skip($num)
    {
        $this->errorIfOpened();
        $this->skip = $num;

        return $this;
    }

    /**
     * Sets whether this query can be done on a slave
     * This method will override the static class variable slaveOkay.
     * @link http://www.php.net/manual/en/mongocursor.slaveOkay.php
     * @param boolean $okay If it is okay to query the slave.
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function slaveOkay($okay = true)
    {
        $this->notImplemented();
    }

    /**
     * Use snapshot mode for the query
     * @link http://www.php.net/manual/en/mongocursor.snapshot.php
     * @throws MongoCursorException
     * @return MongoCursor Returns this cursor
     */
    public function snapshot()
    {
        $this->notImplemented();
    }

    /**
     * Sorts the results by given fields
     * @link http://www.php.net/manual/en/mongocursor.sort.php
     * @param array $fields An array of fields by which to sort. Each element in the array has as key the field name, and as value either 1 for ascending sort, or -1 for descending sort
     * @throws MongoCursorException
     * @return MongoCursor Returns the same cursor that this method was called on
     */
    public function sort(array $fields)
    {
        $this->errorIfOpened();
        $this->sort = $fields;

        return $this;
    }

    /**
     * Sets whether this cursor will be left open after fetching the last results
     * @link http://www.php.net/manual/en/mongocursor.tailable.php
     * @param bool $tail If the cursor should be tailable.
     * @return MongoCursor Returns this cursor
     */
    public function tailable($tail = true)
    {
        $this->errorIfOpened();
        $this->tailable = $tail;

        return $this;
    }

    /**
     * Sets a client-side timeout for this query
     * @link http://www.php.net/manual/en/mongocursor.timeout.php
     * @param int $ms The number of milliseconds for the cursor to wait for a response. By default, the cursor will wait forever.
     * @throws MongoCursorTimeoutException
     * @return MongoCursor Returns this cursor
     */
    public function timeout($ms)
    {
        $this->notImplemented();
    }

    /**
     * Checks if the cursor is reading a valid result.
     * @link http://www.php.net/manual/en/mongocursor.valid.php
     * @return boolean If the current result is not null.
     */
    public function valid()
    {
        return $this->ensureIterator()->valid();
    }

    private function applyOptions($options, $optionNames)
    {
        foreach ($optionNames as $option) {
            if ($this->$option === null) {
                continue;
            }

            $options[$option] = $this->$option;
        }

        return $options;
    }

    /**
     * @return Cursor
     */
    private function ensureCursor()
    {
        if ($this->cursor === null) {
            $options = $this->applyOptions($this->options, ['skip', 'limit', 'sort', 'batchSize', 'projection']);

            if ($this->tailable) {
                $options['cursorType'] = $this->awaitData ? Find::TAILABLE : Find::TAILABLE_AWAIT;
            }

            $this->cursor = $this->collection->find($this->query, $options);
        }

        return $this->cursor;
    }

    private function errorIfOpened()
    {
        if ($this->cursor === null) {
            return;
        }

        throw new MongoCursorException('cannot modify cursor after beginning iteration.');
    }

    /**
     * @return IteratorIterator
     */
    private function ensureIterator()
    {
        if ($this->iterator === null) {
            $this->iterator = new IteratorIterator($this->ensureCursor());
        }

        return $this->iterator;
    }

    protected function notImplemented()
    {
        throw new \Exception('Not implemented');
    }
}