Fix issue (in most cases) of multiple monitors

Sometimes with multiple monitors and the same number of spaces
and the same space selected we won't be able to easily identify
which monitor you're on (and therefore which names we should use).
This adds in a fallback to figure out which monitor has the same
dimensions of your element and uses that.

spaces-renamer/spacesRenamer.m

@@ -10,6 +10,7 @@
 @import CoreText;
 #import "ZKSwizzle.h"
 #import <QuartzCore/QuartzCore.h>
+#import <Cocoa/Cocoa.h>
 
 static char OVERRIDDEN_STRING;
 static char OVERRIDDEN_WIDTH;
@@ -21,6 +22,14 @@
 #define listOfSpacesPlist [@"~/Library/Containers/com.alexbeals.spacesrenamer/com.alexbeals.spacesrenamer.currentspaces.plist" stringByExpandingTildeInPath]
 #define spacesPath [@"~/Library/Preferences/com.apple.spaces.plist" stringByExpandingTildeInPath]
 
+@interface Monitor : NSObject
+@property (nonatomic, strong) NSString *displayUUID;
+@property (nonatomic, strong) NSMutableArray<NSMutableDictionary *> *spaces;
+@end
+
+@implementation Monitor
+@end
+
 // Maximum online or active displays.
 //
 // SpacesRenamer uses the core graphics API to get online/active
@@ -170,7 +179,7 @@ static int getSelected(NSArray<CALayer *> *views) {
  2. Load the listOfSpacesPlist to get the current list of spaces
  3. Crosslist and return the custom names for each plist, and whether it's selected
  */
-static NSMutableArray<NSMutableArray<NSMutableDictionary *> *> *getNamesFromPlist() {
+static NSMutableArray<Monitor *> *getNamesFromPlist() {
   NSDictionary *dictOfNames = [NSDictionary dictionaryWithContentsOfFile:customNamesPlist];
   if (!dictOfNames) {
     return [NSMutableArray arrayWithCapacity:0];
@@ -187,22 +196,25 @@ static int getSelected(NSArray<CALayer *> *views) {
   for (int i = 0; i < listOfMonitors.count; i++) {
     NSArray *listOfSpaces = [listOfMonitors[i] valueForKeyPath:@"Spaces"];
     NSString *selected = [listOfMonitors[i] valueForKeyPath:@"Current Space.uuid"];
+    Monitor *monitor = [[Monitor alloc] init];
+    monitor.displayUUID = [listOfMonitors[i] valueForKeyPath:@"Display Identifier"];
 
-    NSMutableArray *monitorNames = [NSMutableArray arrayWithCapacity:listOfSpaces.count];
+    NSMutableArray *spaceNames = [NSMutableArray arrayWithCapacity:listOfSpaces.count];
     for (int j = 0; j < listOfSpaces.count; j++) {
       NSString *uuid = listOfSpaces[j][@"uuid"];
       id name = [dict objectForKey:uuid];
       NSMutableDictionary *screenDict = [NSMutableDictionary dictionary];
       screenDict[@"selected"] = @([uuid isEqualToString:selected]);
-      monitorNames[j] = screenDict;
+      spaceNames[j] = screenDict;
       if (name != nil) {
         screenDict[@"name"] = name;
       } else {
         screenDict[@"name"] = @"";
       }
-      monitorNames[j] = screenDict;
+      spaceNames[j] = screenDict;
     }
-    newNames[i] = monitorNames;
+    monitor.spaces = spaceNames;
+    newNames[i] = monitor;
   }
 
   return newNames;
@@ -316,7 +328,7 @@ - (void)setFrame:(CGRect)arg1 {
     int selected = getSelected((!unexpandedViews || !unexpandedViews.count) ? expandedViews : unexpandedViews);
 
     // Get all of the names
-    NSMutableArray<NSMutableArray<NSMutableDictionary *> *> *names = getNamesFromPlist();
+    NSMutableArray<Monitor *> *names = getNamesFromPlist();
 
     if (names.count == 0) {
       ZKOrig(void, arg1);
@@ -327,24 +339,35 @@ - (void)setFrame:(CGRect)arg1 {
     NSMutableArray *possibleMonitors = [[NSMutableArray alloc] init];
     for (int i = 0; i < names.count; i++) {
       if (
-          names[i].count == numMonitors && // Same number of monitors
-          [names[i][selected][@"selected"] boolValue] // Same index is selected
+          names[i].spaces.count == numMonitors && // Same number of monitors
+          [names[i].spaces[selected][@"selected"] boolValue] // Same index is selected
           ) {
         [possibleMonitors addObject:[NSNumber numberWithInt:i]];
       }
     }
     // If only one monitor, good to go
-    // If more than one monitor, then just go with the same cycling as it appears to have been last time it was good to go
+    // If more than one monitor, but the sizes are different we can usually identify it
+    // Otherwise just go with the same cycling as it appears to have been last time it was good to go
     if (possibleMonitors.count == 1) {
       monitorIndex = [possibleMonitors[0] intValue];
+    } else {
+      // If the size of the bar only matches one of the monitors, then use that one
+      NSString *displayUUID = [self getDisplayUUID:arg1];
+      if (displayUUID != nil) {
+        for (int i = 0; i < names.count; i++) {
+          if ([names[i].displayUUID isEqualToString:displayUUID]) {
+            monitorIndex = i;
+          }
+        }
+      }
     }
     [possibleMonitors release];
 
     monitorIndex = monitorIndex % names.count;
 
     double unexpandedOffset = 0;
-    for (int i = 0; i < ((NSArray *)names[monitorIndex]).count; i++) {
-      NSString *name = names[monitorIndex][i][@"name"];
+    for (int i = 0; i < names[monitorIndex].spaces.count; i++) {
+      NSString *name = names[monitorIndex].spaces[i][@"name"];
       // It's overridden
       if (name != nil && ![name isEqualToString:@""]) {
         // Expanded
@@ -368,7 +391,7 @@ - (void)setFrame:(CGRect)arg1 {
     }
 
     // Make sure that it's centered in the bar when unexpanded
-    for (int i = 0; i < ((NSArray*)names[monitorIndex]).count; i++) {
+    for (int i = 0; i < names[monitorIndex].spaces.count; i++) {
       if (i < unexpandedViews.count) {
         setOffset(unexpandedViews[i], -unexpandedOffset/2, true);
       }
@@ -413,6 +436,37 @@ - (BOOL)probablyDesktopSwitcher:(CGRect)rect {
   return false;
 }
 
+// This checks the same monitors we already fetched in
+// probablyDesktopSwitcher, but this is only fallback code if both
+// screens have the same number of spaces and the same ones selected
+// which is unlikely. Therefore it's better to eat that rare double
+// cost than fetch the UUID when it's not needed.
+- (NSString *)getDisplayUUID:(CGRect)rect {
+  // Get all of the monitors
+  CGDirectDisplayID displayArray[kMaxDisplays];
+  uint32_t displayCount;
+  CGGetActiveDisplayList(kMaxDisplays, displayArray, &displayCount);
+
+  // This is only evaluated after probablyDesktopSwitcher is truthy
+  // so one of them is guaranteed to match. We only want ONE to match
+  // to feel confident using this signal though. So if we've already
+  // matched we just return nil
+  CGDirectDisplayID matchingScreen = 0;
+  for (int i = 0; i < displayCount; i++) {
+    if (CGDisplayPixelsWide(displayArray[i]) == rect.size.width) {
+      if (matchingScreen != 0) {
+        return nil;
+      } else {
+        matchingScreen = displayArray[i];
+      }
+    }
+  }
+  // Go from the CGDirectDisplayID to the Display Identifier using private APIs
+  CFUUIDRef screenUuid = CGDisplayCreateUUIDFromDisplayID(matchingScreen);
+  CFStringRef uuid = CFUUIDCreateString(nil, screenUuid);
+  return (__bridge NSString *)uuid;
+}
+
 // ===============
 // DEBUG FUNCTIONS
 // ===============