Generate linter args from SVN repository

generate-linter-args.php

#!/usr/local/bin/php
<?php

/**
 * Generates a structured list of files related to an
 * SVN commit or working directory, or generates the
 * diff between a particular SVN commit and its parent
 * or between the working directory and the base revision.
 *
 * Calling:
 * ./generate-linter-args.php [-rREVISION_NUMBER] --type ['changeset' or 'diff'] [file list]
 *
 *   Get current changes:
 *   ./generate-linter-args.php --type changeset
 *   ./generate-linter-args.php --type diff
 *
 *   Get changes for specific revision:
 *   ./generate-linter-args.php -r12345 --type changeset
 *   ./generate-linter-args.php -r12345 --type diff
 *
 *   Get changes for specific files in working directory
 *   ./generate-linter-args.php --type changeset "wp-content/lib/class.splines.php" "wp-content/lib/class.reticulator.php"
 *   ./generate-linter-args.php --type diff "wp-content/lib/class.splines.php" "wp-content/lib/class.reticulator.php"
 */

/**
 * Will return an item if it's a member of an array
 * or `null` if it doesn't exist within that array.
 *
 * @param Array $array Containing array
 * @param mixed $member Key to check for existence in the array
 * @return bool Whether or not $member is in $array
 */
function maybeMember( Array $array, $member ) {
	return isset( $array[ $member ] ) ? $array[ $member ] : null;
}

/**
 * Returns the shell arguments assuming they are what
 * they should be. Does not perform input validation.
 *
 * @return Array [ type of info requested, revision or null, list of filenames or blank ]
 */
function getShellArgs() {
	global $argv;

	$options = getopt( 'r::', [ 'type:' ] );

	// Which parameter to create - required
	$type = maybeMember( $options, 'type' );

	// Revision is either given or "current"
	$revision = (int) maybeMember( $options, 'r' );

	// Get the remaining args after the script name and params
	// Should be a space-separated list of filenames
	$filenames = getRealFiles( array_slice( $argv, 1 ) );

	return [ $type, $revision, $filenames ];
}

/**
 * Returns only files that exist.
 * Filters out special names that might also
 * be svn commands coming through.
 *
 * @param Array $names List of potential filenames
 * @return Array List of filenames for files that exist
 */
function getRealFiles( $names ) {
	$isIrrelevant = function( $name ) {
		return ! array_key_exists ( $name,
			[
				'commit' => true,
				'ci' => true
			] );
	};

	$files = $names;
	$files = array_filter( $files, $isIrrelevant );
	$files = array_filter( $files, 'file_exists' );

	return $files;
}

/**
 * Returns only lines that start with the specified character.
 *
 * @param string $type The letter describing which svn operation is desired
 * @return Closure produces a bool output for the passed line if it starts with $type
 */
function typeFilter( $type ) {
	return function( $line ) use ( $type ) {
		return $type === substr( $line, 0, 1 );
	};
}

/**
 * Converts the `svn status` output line into a filename
 *
 * @param string $line one line of output from `svn status`
 * @return string Trimmed version of $line without the status info prefix
 */
function statusLineToFilename( $line ) {
	return trim( substr( $line, 7 ) );
}

/**
 * Returns an array of files of a specified type
 *
 * @param Array $lines lines of output from `svn status`
 * @param string $type Which type of `svn` operation to return
 * @return Array Filenames for files that exist and match the $type predicate
 */
function filesByType( $lines, $type ) {
	return array_values( array_map( 'statusLineToFilename', array_filter( $lines, typeFilter( $type ) ) ) );
}

/**
 * Splits the output of `svn status` into a structured
 * object with added, modified, missing, and deleted files
 * as arrays.
 *
 * @param Array $lines output lines from `svn status`
 * @return stdClass Structured view of changed files
 */
function statusLinesToChangeSet( $lines ) {
	return (object) [
		"addedFiles" => array_merge(
			filesByType( $lines, 'A' ),
			filesByType( $lines, 'R' )
		),
		"deletedFiles" => filesByType( $lines, 'D' ),
		"missingFiles" => filesByType( $lines, '!' ),
		"modifiedFiles" => filesByType( $lines, 'M' )
	];
}

/**
 * Computes the changeset between two revisions
 *
 * @param int $revision Specific revision to examine
 * @return Array output from svn command
 */
function statusAcrossRevisions( $revision ) {
	if ( empty( $revision ) ) {
		$revision = getCurrentRevision();
	}

	exec( sprintf(
		'svn diff -c%d --summarize', $revision
	), $output, $exitStatus );

	if ( 0 !== $exitStatus ) {
		exit( $exitStatus );
	}

	return $output;
}

/**
 * Computes the changeset assuming we are basing the
 * comparison off of the local working copy.
 *
 * @param Array $filenames possible list of filenames to only examine
 * @return Array output from svn command
 */
function statusForWorkingCopy( $filenames ) {
	exec( sprintf( 'svn status %s 2>/dev/null',
		implode( ' ', array_map( 'escapeshellarg', $filenames ) )
	), $output, $exitStatus );

	if ( 0 !== $exitStatus ) {
		exit( $exitStatus );
	}

	return $output;
}

/**
 * Returns the current revision number for the checked-out
 * copy of the svn repository.
 *
 * @return int Revision of current local working svn repository
 */
function getCurrentRevision() {
	exec( 'svn info | grep "Revision" | awk \'{print $2}\'', $raw_revision );

	return (int) array_shift( $raw_revision );
}

/**
 * Returns the output of `svn diff` across revisions
 *
 * @param int $revision A specific svn revision to examine
 * @return Array output from svn command
 */
function createRevisionDiff( $revision ) {
	if ( empty( $revision ) ) {
		$revision = getCurrentRevision();
	}

	exec( sprintf(
		'svn diff -c%d 2>/dev/null', $revision
	), $output, $exitStatus );

	if ( 0 !== $exitStatus ) {
		exit( $exitStatus );
	}

	return $output;
}

/**
 * Returns the output of `svn diff` for the working copy
 *
 * @param Array $filenames List of filenames to only examine
 * @return Array output from svn command
 */
function createWorkingCopyDiff( $filenames ) {
	exec( sprintf( 'svn diff %s 2>/dev/null',
		implode( ' ', array_map( 'escapeshellarg', $filenames ) )
	), $output, $exitStatus );

	if ( 0 !== $exitStatus ) {
		exit( $exitStatus );
	}

	return $output;
}

/**
 * Returns the desired `svn` diff
 *
 * @param int $revision A specific revision to examine
 * @param Array $filenames Specific list of files to examine only
 * @return string Newline-terminated list of output lines for `svn diff`
 */
function createDiff( $revision, $filenames ) {
	return implode( PHP_EOL,
		empty( $revision )
			? createWorkingCopyDiff( $filenames )
			: createRevisionDiff( $revision )
	);
}

/**
 * Computes the desired changeset
 *
 * @param int $revision A specific revision to examine
 * @param Array $filenames Specific list of files to examine only
 * @return string JSON-encoded structured list of changed files for commit
 */
function listRelevantFiles( $revision, $filenames ) {
	return json_encode( statusLinesToChangeSet(
		empty( $revision )
			? statusForWorkingCopy( $filenames )
			: statusAcrossRevisions( $revision )
	) );
}

/**
 * Generates args suitable for passing into the linters
 *
 * @return int Whether or not the program was able to complete successfully
 */
function main() {
	list( $type, $revision, $filenames ) = getShellArgs();

	if ( empty( $type ) ) {
		die( 'Please choose type of information requested: "--type changeset" or "--type diff"' );
	}

	if ( 'changeset' === $type ) {
		echo listRelevantFiles( $revision, $filenames );
	}

	if ( 'diff' === $type ) {
		echo createDiff( $revision, $filenames );
	}

	echo "\n";
}

main();