<?php

namespace DbCopy\Driver;

class Elasticsearch implements IDriver
{
	private $_options;

	public function open(array $params): void
	{
		$params = array_merge([
			'endpoint' => null,
			'index' => null,
			'retries' => 10,
			'size' => 5000,
			'scroll_window' => '5m',
			'query' => null,
			'timeout' => 500000
		], $params);

		$params = filter_var_array($params, [
			'endpoint' => ['filter'=>FILTER_VALIDATE_URL, 'flags'=>FILTER_REQUIRE_SCALAR],
			'index' => ['filter'=>FILTER_SANITIZE_ENCODED, 'flags'=>FILTER_REQUIRE_SCALAR],
			'retries' => ['filter'=>FILTER_VALIDATE_INT, 'flags'=>FILTER_REQUIRE_SCALAR],
			'size' => ['filter'=>FILTER_VALIDATE_INT, 'flags'=>FILTER_REQUIRE_SCALAR],
			'scroll_window' => ['filter'=>FILTER_UNSAFE_RAW, 'flags'=>FILTER_REQUIRE_SCALAR],
			'query' => ['filter'=>FILTER_UNSAFE_RAW, 'flags'=>FILTER_REQUIRE_ARRAY]
		]);

		$this->_options = $params;
	}

	public function close(): void
	{
		// noop
	}

	public function get(array $params = []): \DbCopy\ICursor
	{
		$options = array_merge($this->_options, $params);
		$state = (object)[
			'scroll_id' => null,
		];

		return new \DbCopy\Cursor(function() use ($options, $state) {
			$retry_timeout = 500000;
			for ($i=0; $i<$options['retries']; $i++)
			{
				$ch = curl_init();

				if (isset($state->scroll_id))
				{
					$body = json_encode(['scroll'=>$options['scroll_window'], 'scroll_id'=>$state->scroll_id]);
					curl_setopt($ch, CURLOPT_URL, $options['endpoint'].'/_search/scroll');
					curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
					curl_setopt($ch, CURLOPT_HTTPHEADER, [
						'Content-Type: application/json',
						'Content-Length: '.strlen($body)
					]);
					curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
				}
				else
				{
					$query_string = [];
					$query_string[] = 'scroll='.$options['scroll_window'];
					$query_string[] = 'size='.$options['size'];
					if (isset($options['query']) && $options['query'] !== false)
					{
						$search_params = [];
						foreach ($options['query'] as $k=>$v)
						{
							$search_params[] = $k.':'.$v;
						}
						$query_string[] = 'q='.implode(' AND ', $search_params);
					}

					curl_setopt($ch, CURLOPT_URL, $options['endpoint'].'/'.$options['index'].'/_search?'.implode('&', $query_string));
				}

				curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
				$response = curl_exec($ch);
				curl_close($ch);

				if ($response === false)
				{
					usleep($timeout);
					$timeout = $timeout * 2;
					continue;
				}

				$response = json_decode($response, true);

				if (!isset($response['_scroll_id']))
				{
					var_dump($response);
					throw new \Exception("Elasticsearch response did not contain scroll id");
				}

				$state->scroll_id = $response['_scroll_id'];

				return array_map(function($es_arr) {
					return $es_arr['_source'];
				}, $response['hits']['hits']);
			}
			throw new \Exception("Requested failed after ".$options['retries']." retries.");
		});
	}

	public function put(array $record): void
	{
		throw new \Exception("Not implemented");
	}

}