<?php
/**
* Helper class for representing operations with transaction support.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup FileBackend
*/

/**
 * Delete a file at the given storage path from the backend.
 * Parameters for this operation are outlined in FileBackend::doOperations().
 */
class DeleteFileOp extends FileOp {
	protected function allowedParams() {
		return [ [ 'src' ], [ 'ignoreMissingSource' ], [ 'src' ] ];
	}

	protected function doPrecheck( array &$predicates ) {
		$status = StatusValue::newGood();
		// Check if the source file exists
		if ( !$this->fileExists( $this->params['src'], $predicates ) ) {
			if ( $this->getParam( 'ignoreMissingSource' ) ) {
				$this->doOperation = false; // no-op
				// Update file existence predicates (cache 404s)
				$predicates['exists'][$this->params['src']] = false;
				$predicates['sha1'][$this->params['src']] = false;

				return $status; // nothing to do
			} else {
				$status->fatal( 'backend-fail-notexists', $this->params['src'] );

				return $status;
			}
			// Check if a file can be placed/changed at the source
		} elseif ( !$this->backend->isPathUsableInternal( $this->params['src'] ) ) {
			$status->fatal( 'backend-fail-usable', $this->params['src'] );
			$status->fatal( 'backend-fail-delete', $this->params['src'] );

			return $status;
		}
		// Update file existence predicates
		$predicates['exists'][$this->params['src']] = false;
		$predicates['sha1'][$this->params['src']] = false;

		return $status; // safe to call attempt()
	}

	protected function doAttempt() {
		// Delete the source file
		return $this->backend->deleteInternal( $this->setFlags( $this->params ) );
	}

	public function storagePathsChanged() {
		return [ $this->params['src'] ];
	}
}