Conditionally show release notes during startup

Applications/TextMate/src/AboutWindowController.h

@@ -1,3 +1,5 @@
 @interface AboutWindowController : NSWindowController <NSWindowDelegate, NSToolbarDelegate>
++ (BOOL)shouldShowChangesWindow;
 - (void)showAboutWindow:(id)sender;
+- (void)showChangesWindow:(id)sender;
 @end

Applications/TextMate/src/AboutWindowController.mm

@@ -2,6 +2,16 @@
 #import <OakFoundation/NSString Additions.h>
 #import <updater/updater.h>
 
+static NSString* const kUserDefaultsReleaseNotesDigestKey = @"releaseNotesDigest";
+
+static NSData* Digest (NSString* someString)
+{
+	char const* str = [someString UTF8String];
+	char md[SHA_DIGEST_LENGTH];
+	CC_SHA1((unsigned char*)str, strlen(str), (unsigned char*)md);
+	return [NSData dataWithBytes:md length:sizeof(md)];
+}
+
 // ============================
 // = JavaScript Bridge Object =
 // ============================
@@ -33,6 +43,23 @@
 @end
 
 @implementation AboutWindowController
++ (BOOL)shouldShowChangesWindow
+{
+	NSURL* url = [[NSBundle mainBundle] URLForResource:@"Changes" withExtension:@"html"];
+	if(NSString* releaseNotes = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:NULL])
+	{
+		NSData* lastDigest    = [[NSUserDefaults standardUserDefaults] dataForKey:kUserDefaultsReleaseNotesDigestKey];
+		NSData* currentDigest = Digest(releaseNotes);
+		if(lastDigest)
+		{
+			if(![lastDigest isEqualToData:currentDigest])
+				return YES;
+		}
+		[[NSUserDefaults standardUserDefaults] setObject:currentDigest forKey:kUserDefaultsReleaseNotesDigestKey];
+	}
+	return NO;
+}
+
 - (id)init
 {
 	NSRect visibleRect = [[NSScreen mainScreen] visibleFrame];
@@ -88,6 +115,16 @@
 	[self showWindow:self];
 }
 
+- (void)showChangesWindow:(id)sender
+{
+	[self didClickToolbarItem:@"Changes"];
+	[self showWindow:self];
+
+	NSURL* url = [[NSBundle mainBundle] URLForResource:@"Changes" withExtension:@"html"];
+	if(NSString* releaseNotes = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:NULL])
+		[[NSUserDefaults standardUserDefaults] setObject:Digest(releaseNotes) forKey:kUserDefaultsReleaseNotesDigestKey];
+}
+
 // ====================
 // = Toolbar Delegate =
 // ====================

Applications/TextMate/src/AppController.mm

@@ -53,6 +53,12 @@ void OakOpenDocuments (NSArray* paths)
 	spellingMenu.delegate = self;
 
 	[NSApp setDelegate:self];
+
+	if([AboutWindowController shouldShowChangesWindow])
+	{
+		self.aboutWindowController = [[[AboutWindowController alloc] init] autorelease];
+		[self.aboutWindowController performSelector:@selector(showChangesWindow:) withObject:self afterDelay:0];
+	}
 }
 
 - (IBAction)newDocumentAndActivate:(id)sender