<?php

namespace DbCopy;
use DbCopy\Driver\IDriver;

class Copy
{
	private $_options;

	private $_src = null, $_srcParams = [];
	private $_dst = null, $_dstParams = [];
	private $_transform = null;

	private $_status_lastUpdate, $_status_lastCount;

	public function __construct(array $params = [])
	{
		$this->_options = array_merge([
			'limit' => null,
			'batch' => 2500,
			'status_interval' => 5
		], $params);
	}

	public static function create(array $params = []): Copy
	{
		return new Copy($params);
	}

	public function source(IDriver $source, array $params = []): Copy
	{
		$this->_src = $source;
		$this->_srcParams = $params;
		return $this;
	}

	public function destination(IDriver $destination, array $params = []): Copy
	{
		$this->_dst = $destination;
		$this->_dstParams = $params;
		return $this;
	}

	public function transform(callable $callback): Copy
	{
		$this->_transform = $callback;
		return $this;
	}

	public function execute(): int
	{
		$cursor = $this->_src->get($this->_srcParams);
		$transform = $this->_transform;
		$count = 0;

		for (;;)
		{
			// Read records
			$records = [];
			$batchSize = 0;
			while ($record = $cursor->get())
			{
				$records[] = $record;
				$batchSize++;
				if ($batchSize == $this->_options['batch'] ||
					$count + $batchSize == $this->_options['limit'])
					break;
			}

			if ($batchSize == 0)
			{
				// Done copying!
				return $count;
			}

			// Transform records if applicable
			if (is_callable($transform))
			{
				foreach ($records as &$record)
				{
					$record = $transform($record);
				}
				unset($record);
				$records = array_filter($records);
			}

			// Write records
			if (method_exists($this->_dst, 'putBatch') && $this->_options['batch'] > 1)
			{
				$this->_dst->putBatch($records, $this->_dstParams);
			}
			else
			{
				// Otherwise write one by one
				foreach ($records as $record)
				{
					$this->_dst->put($record, $this->_dstParams);
				}
			}

			$count += sizeof($records);

			if (isset($this->_options['status_interval']) &&
				$this->_status_lastUpdate + $this->_options['status_interval'] < time())
			{
				$processed = $count - $this->_status_lastCount;
				$pps = round($processed / (time() - $this->_status_lastUpdate), 0);
				echo "Complete: ".$count."; Records/sec: ".$pps.PHP_EOL;
				$this->_status_lastUpdate = time();
				$this->_status_lastCount = $count;
			}
		}

		return $count;
	}

}