/*
 *  git-update-infoplist.m
 *  git-update-infoplist
 *
 *  Created by Ofri Wolfus on 25/05/07.
 *  Copyright 2007 Ofri Wolfus. All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without modification,
 *  are permitted provided that the following conditions are met:
 *  
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in the
 *  documentation and/or other materials provided with the distribution.
 *  3. Neither the name of Ofri Wolfus nor the names of his contributors
 *  may be used to endorse or promote products derived from this software
 *  without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 *  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * v0.3:
 * - We now check the contents of the repository directory for a git repo layout.
 * - The passed paths are now standardized before using.
 * - Paths relative to the current directory are now valid.
 * - Added -[NSString absolutePath].
 * - Added +[NSTask fullPathToExecutable:additionalSearchPaths:].
 * - A help is now displayed if no arguments are available, or if '-h' or '--help'
 *   were passed.
 *
 * v0.2:
 * - Rewrote +[NSTask fullPathToExecutable:] with pure Cocoa.
 * - Added custom executable paths.
 *
 * v0.1:
 * - Initial release
 */

#import <Foundation/Foundation.h>


@interface NSString (DPExtensions)

/*!
 * @abstract A convenient methods for creating an autoreleased string
 * from an NSData instance.
 *
 * @discussion This is the equivalent to <code>[[[NSString alloc] initWithData:data encoding:enc] autorelease]</code>.
 */
+ (id)stringWithData:(NSData *)data encoding:(NSStringEncoding)enc;

/*!
 * @abstract Returns an absolute path from the receiver.
 * @discussion The path is made by standardizing the receiver and appending it to the current directory if needed.
 */
- (NSString *)absolutePath;

@end

@implementation NSString (DPExtensions)

+ (id)stringWithData:(NSData *)data encoding:(NSStringEncoding)enc {
	return [[[NSString alloc] initWithData:data
								  encoding:enc] autorelease];
}

- (NSString *)absolutePath {
	self = [self stringByStandardizingPath];
	if (![self hasPrefix:@"/"])
		self = [[[NSFileManager defaultManager] currentDirectoryPath] stringByAppendingPathComponent:self];
	
	return self;
}

@end

@interface NSTask (DPExtensions)
+ (NSString *)fullPathToExecutable:(NSString *)execName;
+ (NSString *)fullPathToExecutable:(NSString *)execName additionalSearchPaths:(NSArray *)paths;
@end

@implementation NSTask (DPExtensions)

+ (NSString *)fullPathToExecutable:(NSString *)execName {
	return [self fullPathToExecutable:execName
						  additionalSearchPaths:[NSArray arrayWithObjects:@"/usr/local/bin",
																		  @"/usr/local/sbin",
																		  @"/opt/local/bin",
																		  @"/opt/local/sbin", nil]];
}

+ (NSString *)fullPathToExecutable:(NSString *)execName additionalSearchPaths:(NSArray *)paths {
	NSString *result = nil;
	NSPipe *pipe = [NSPipe pipe];
	NSTask *task = [[NSTask alloc] init];
	NSMutableDictionary *env = [[[NSProcessInfo processInfo] environment] mutableCopy];
	NSMutableString *path_var = [[env objectForKey:@"PATH"] mutableCopy];
	NSEnumerator *enumerator = [paths objectEnumerator];
	NSString *searchPath;
	
	// Add any additional search paths
	while ((searchPath = [enumerator nextObject])) {
		if ([path_var rangeOfString:searchPath].location == NSNotFound)
			[path_var appendFormat:@":%@", searchPath];
	}
	
	// Set the new PATH variable
	[env setObject:path_var forKey:@"PATH"];
	
	// Initialize our task
	[task setLaunchPath:@"/usr/bin/which"];
	[task setEnvironment:env];
	[task setArguments:[NSArray arrayWithObject:execName]];
	[task setStandardOutput:pipe];
	// Launch and wait
	[task launch];
	[task waitUntilExit];
	
	if ([task terminationStatus] == 0) {
		result = [NSString stringWithData:[[pipe fileHandleForReading] readDataToEndOfFile]
								 encoding:NSUTF8StringEncoding];
		result = [result stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
		// Some error occured, and we didn't get a full path
		if (![result isAbsolutePath])
			result = nil;
	}
	
	// Clean up
	[path_var release];
	[env release];
	[task release];
	
	return result;
}

@end

BOOL directoryIsGitRepo(NSString *path) {
	NSArray *contents = [[NSFileManager defaultManager] directoryContentsAtPath:path];
	
	if (contents &&
		[contents containsObject:@"HEAD"] &&
		[contents containsObject:@"branches"] &&
		[contents containsObject:@"config"] &&
		[contents containsObject:@"description"] &&
		[contents containsObject:@"hooks"] &&
		[contents containsObject:@"info"] &&
		[contents containsObject:@"objects"] &&
		[contents containsObject:@"refs"])
	{
		return YES;
	}
	
	return NO;
}

void printHelp(void) {
	puts("usage: git-info-plist REPO_PATH PLIST_PATH\n\n"
		 "The first argument is a path to the Git repository. It may point to a bare repository,\n"
		 "a \"regular\" repository or to the .git repository inside a repository.\n"
		 "The second argument is a path to a plist file to which git-update-infoplist will write\n"
		 "the commit ID.\n\n"
		 "git-info-plist also accepts two optional environment variables:\n"
		 "  COMMIT_KEY_NAME   The name of the key to write the commit ID.\n"
		 "                    The default is \"DPGitCommit\"\n"
		 "  GIT_LOG_PATH      A full path to the git-log executable. If git-info-plist fails to\n"
		 "                    locate the git-log executable, use this variable to point it to it.\n"
		 "                    Alternatively, this can be used to force the use of a given executable\n"
		 "                    if more than one are available. Note: The default search paths together\n"
		 "                    with /usr/local/bin, /usr/local/sbin, /opt/local/bin and \n"
		 "                    /opt/local/sbin are searched for the git-log executable.\n");
}

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	NSProcessInfo *pinfo = [NSProcessInfo processInfo];
	NSArray *args = [pinfo arguments];
	
	if ([args count] < 3 || [args containsObject:@"-h"] || [args containsObject:@"--help"]) {
		printHelp();
		return 0;
	}
	
	NSString *repoPath = [[args objectAtIndex:1] absolutePath];
	NSString *plistPath = [[args objectAtIndex:2] absolutePath];
	NSMutableDictionary *plist = [NSMutableDictionary dictionaryWithContentsOfFile:plistPath];
	
	// Make sure our repository is a real repo
	repoPath = directoryIsGitRepo(repoPath)	? repoPath
											: [repoPath stringByAppendingPathComponent:@".git"];
	if (!directoryIsGitRepo(repoPath)) {
		printf("Error: The passed repository does not appear to be a git repository.");
		return EXIT_FAILURE;
	}
	
	// Something went wrong with loading our plist
	if (!plist) {
		printf("Error: Can't load plist from %s.\n", [plistPath UTF8String]);
		return EXIT_FAILURE;
	}
	
	NSPipe *pipe = [NSPipe pipe];
	NSTask *gitLog = [[NSTask alloc] init];
	NSMutableDictionary *env = [NSMutableDictionary dictionaryWithDictionary:[pinfo environment]];
	NSString *gitLogPath = [env objectForKey:@"GIT_LOG_PATH"] ?: [NSTask fullPathToExecutable:@"git-log"];
	
	// Make sure we found git-log
	if (!gitLogPath) {
		printf("Error: Can't find the git-log exectable.\n");
		return EXIT_FAILURE;
	}
	
	// Let git-log know where the repo is located
	[env setObject:repoPath forKey:@"GIT_DIR"];
	
	// Initialize our task
	[gitLog setLaunchPath:gitLogPath];
	[gitLog setArguments:[NSArray arrayWithObjects:@"-1",
								 @"--pretty=format:%H", nil]];
	[gitLog setEnvironment:env];
	[gitLog setStandardOutput:pipe];
	[gitLog setStandardError:pipe];
	// Launch and wait for its termination
	[gitLog launch];
	[gitLog waitUntilExit];
	
	// Get the output of git-log
	NSString *output = [NSString stringWithData:[[pipe fileHandleForReading] readDataToEndOfFile]
									   encoding:NSUTF8StringEncoding];
	// An error had occured and git-log exited with non-zero value
	if ([gitLog terminationStatus] != 0) {
		// Log the error message of git-log if one was provided
		if ([output length] > 0)
			printf("%s", [output UTF8String]);
		
		return EXIT_FAILURE;
	}
	
	// Modify the dictionary,
	[plist setObject:[output stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]
			  forKey:[env objectForKey:@"COMMIT_KEY_NAME"] ?: @"DPGitCommit"];
	// and write it back to disk
	if (![plist writeToFile:plistPath atomically:YES]) {
		printf("Error: Can't write plist to %s.\n", [plistPath UTF8String]);
		return EXIT_FAILURE;
	}
	
    [pool release];
    return 0;
}