#!/usr/bin/env php
<?php
// Taken from https://github.com/wikimedia/mediawiki-tools-release
/**
 * Class ExecException
 */
class ExecException extends Exception {}

/**
 * Validation on the command line arguments
 * @param array $argv
 * @return array
 */
function get_args( $argv ) {
	if ( count( $argv ) == 3 ) {
		return array( $argv[1], $argv[2] );
	} else {
		print "usage: $argv[0] oldbranch newbranch\n";
		print "  example: $argv[0] gerrit/wmf/1.20wmf2 gerrit/wmf/1.20wmf3\n";
		exit(1);
	}
}

/**
 * Wrapper around exec to throw more useful exception when
 * things go sideways
 * @param string $command
 * @throws ExecException
 * @return array
 */
function capture_output( $command ) {
	$cwd = getcwd();
	$output = array();
	exec( $command, $output, $status );
	if( $status != 0 ) {
		throw new ExecException( "Error in command: $command\nDirectory: $cwd\nStatus: $status\nOutput: "
			. print_r( $output) . "\n"
		);
	}
	return $output;
}

/**
 * Fetch an array of the change's subject for a given path, along with a bug number.
 * @param string $oldRev
 * @param string $newRev
 * @throws Exception
 * @return array
 */
function useful_git_log( $oldRev, $newRev ) {
	$gitDir = getcwd();
	$myDir = $gitDir;

	if( !is_dir( $myDir ) ) {
		return "";
	}
	chdir( $myDir );
	$retval = full_git_log_as_array( $oldRev, $newRev );
	$gitLog = array();
	foreach( $retval as $commit ) {
		$lines = array_filter( explode( "\n", $commit['message'] ) );
		$first = true;
		$subject = '';
		$bugs = array();
		foreach( $lines as $line ) {
			if( $first ) {
				$first = false;
				if( preg_match( "/\(?(Bug|RT)\s*(T?\d+)\)?\s*(.+)/i", $line, $issueRes ) ) {
					$bugs[] = $issueRes[2];
					$subject = $issueRes[3];
				} else {
					$subject = $line;
				}
			} elseif( preg_match( "/(Bug|RT):\s*(T?\d+)/i", $line, $issueRes ) ) {
				$bugs[] = $issueRes[2];
			}
		}
		// Trim down to the first bit
		$subject = trim( ltrim( trim( $subject ), '-' ) );
		$subject = preg_replace( "/    .+$/i", '', $subject );
		$gitLog[] = array(
			'hash' => substr( $commit['hash'], 1, 8 ),
			'subject' => $subject,
			'bugs' => $bugs,
		);
	}
	chdir( $gitDir );
	return $gitLog;
}

/**
 * @param string $oldRev
 * @param string $newRev
 * @return array
 * @throws Exception
 */
function full_git_log_as_array( $oldRev, $newRev ) {
	$command = "git log --format=medium --cherry-pick --right-only --no-merges $oldRev..$newRev";
	try {
		$output = capture_output( $command );
	} catch( ExecException $e ) {
		throw new Exception( "Problem with command: $command\n"
			. "******** LIKELY CAUSE: you need to run 'git fetch --all' in a sub directory"
		);
	}
	$history = array();
	foreach( $output as $line ) {
		if( strpos( $line, 'commit ' ) === 0 ) {
			if( !empty( $commit ) ) {
				array_push( $history, $commit );
				unset( $commit );
			}
			$commit['hash']   = substr( $line, strlen( 'commit' ) );
			continue;
		} elseif( strpos( $line, 'Author' ) === 0 || strpos( $line, 'Date' ) === 0 ) {
			continue;
		} else {
			if( isset( $commit['message'] ) ) {
				$commit['message'] .= "\n" . $line;
			} else {
				$commit['message'] = $line;
			}
			continue;
		}
	}
	return $history;
}

/**
 * filter_git_output - perform any extra functions needed prior to posting to
 *  a wiki page (sanitization, making obvious removals, linking bugs, etc)
 * @param array $logoutput
 * @return string
 */
function filter_git_output( $logoutput ) {
	$retval = '';
	if ( !$logoutput ) {
		return $retval;
	}

	$skipLines = array(
		'Localisation updates from',
		'COMMITMSG', // Fix for escaping fail leaving a commit summary of $COMMITMSG
		'Add (\.gitreview and )?\.gitignore',
		'Creating new WMF',
		'Commit of various live hacks', // Our catchall patch for live hacky stuff
		'Applied patches to new WMF',
		'Bump .*? for deployment',
	);
	foreach ( $logoutput as $record ) {
		foreach( $skipLines as $skip ) {
			if ( preg_match( '/' . $skip . '/i', $record['subject'] ) ) {
				continue 2;
			}
		}

		$retval .= '* ';
		if ( $record['bugs'] ) {
			$retval .= '(' . implode( ', ', $record['bugs'] ) . ') ';
		}
		$retval .= $record['subject'];
//		$retval .= " {{git|{$record['hash']}}}";
		$retval .= "\n";
	}
	return $retval;
}

/**
 * Main program flow
 * Get changes for mobile frontend
 * @param array $argv
 */
function main( $argv ) {
	list( $oldbranch, $newbranch ) = get_args( $argv );
	print filter_git_output( useful_git_log( $oldbranch, $newbranch ) );
}

main( $argv );