MacMonitor/Sources/Telemetry/Display/MMDisplayManager.m

#import "MMDisplayManager.h"
#import <IOKit/graphics/IOGraphicsLib.h>
#import <dlfcn.h>

// Private DisplayServices API signatures
typedef int (*DisplayServicesGetBrightnessFunc)(CGDirectDisplayID display, float *brightness);
typedef int (*DisplayServicesSetBrightnessFunc)(CGDirectDisplayID display, float brightness);

@implementation MMDisplayInfo

- (instancetype)initWithDisplayID:(CGDirectDisplayID)displayID
                             name:(NSString *)name
                        isBuiltin:(BOOL)isBuiltin
                           isMain:(BOOL)isMain
                         isOnline:(BOOL)isOnline
                            width:(uint32_t)width
                           height:(uint32_t)height
                      refreshRate:(double)refreshRate
                       brightness:(float)brightness {
    self = [super init];
    if (self) {
        _displayID = displayID;
        _name = [name copy] ?: @"Unknown Display";
        _isBuiltin = isBuiltin;
        _isMain = isMain;
        _isOnline = isOnline;
        _width = width;
        _height = height;
        _refreshRate = refreshRate;
        _brightness = brightness;
    }
    return self;
}

@end

@implementation MMDisplayManager {
    void *_displayServicesHandle;
    DisplayServicesGetBrightnessFunc _getBrightnessFunc;
    DisplayServicesSetBrightnessFunc _setBrightnessFunc;
}

+ (instancetype)sharedManager {
    static MMDisplayManager *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[self alloc] init];
    });
    return sharedInstance;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        [self loadDisplayServices];
    }
    return self;
}

- (void)dealloc {
    if (_displayServicesHandle) {
        dlclose(_displayServicesHandle);
        _displayServicesHandle = NULL;
    }
}

- (void)loadDisplayServices {
    _displayServicesHandle = dlopen("/System/Library/PrivateFrameworks/DisplayServices.framework/DisplayServices", RTLD_LAZY);
    if (_displayServicesHandle) {
        _getBrightnessFunc = (DisplayServicesGetBrightnessFunc)dlsym(_displayServicesHandle, "DisplayServicesGetBrightness");
        _setBrightnessFunc = (DisplayServicesSetBrightnessFunc)dlsym(_displayServicesHandle, "DisplayServicesSetBrightness");
    }
}

- (NSArray<MMDisplayInfo *> *)activeDisplays {
    uint32_t maxDisplays = 16;
    CGDirectDisplayID onlineDisplays[16];
    uint32_t displayCount = 0;
    
    CGError err = CGGetOnlineDisplayList(maxDisplays, onlineDisplays, &displayCount);
    if (err != kCGErrorSuccess || displayCount == 0) {
        return @[];
    }
    
    NSMutableArray<MMDisplayInfo *> *result = [NSMutableArray arrayWithCapacity:displayCount];
    CGDirectDisplayID mainDisplay = CGMainDisplayID();
    
    for (uint32_t i = 0; i < displayCount; i++) {
        CGDirectDisplayID dID = onlineDisplays[i];
        BOOL isBuiltin = CGDisplayIsBuiltin(dID);
        BOOL isMain = (dID == mainDisplay);
        BOOL isOnline = CGDisplayIsOnline(dID);
        
        uint32_t width = (uint32_t)CGDisplayPixelsWide(dID);
        uint32_t height = (uint32_t)CGDisplayPixelsHigh(dID);
        
        CGDisplayModeRef mode = CGDisplayCopyDisplayMode(dID);
        double refreshRate = 0.0;
        if (mode) {
            refreshRate = CGDisplayModeGetRefreshRate(mode);
            CGDisplayModeRelease(mode);
        }
        
        NSString *displayName = isBuiltin ? @"Built-in Retina Display" : [NSString stringWithFormat:@"External Display (%u)", (unsigned int)dID];
        float brightness = [self brightnessForDisplay:dID];
        
        MMDisplayInfo *info = [[MMDisplayInfo alloc] initWithDisplayID:dID
                                                                  name:displayName
                                                             isBuiltin:isBuiltin
                                                                isMain:isMain
                                                              isOnline:isOnline
                                                                 width:width
                                                                height:height
                                                           refreshRate:refreshRate
                                                            brightness:brightness];
        [result addObject:info];
    }
    
    return [result copy];
}

- (float)brightnessForDisplay:(CGDirectDisplayID)displayID {
    if (_getBrightnessFunc) {
        float b = 0.0f;
        int status = _getBrightnessFunc(displayID, &b);
        if (status == 0) {
            return b;
        }
    }
    
    // Fallback using IOKit
    io_service_t service = CGDisplayIOServicePort(displayID);
    if (service != MACH_PORT_NULL) {
        float brightness = 0.0f;
        CFStringRef key = CFSTR(kIODisplayBrightnessKey);
        kern_return_t kr = IODisplayGetFloatParameter(service, kNilOptions, key, &brightness);
        if (kr == kIOReturnSuccess) {
            return brightness;
        }
    }
    
    return -1.0f;
}

- (BOOL)setBrightness:(float)brightness forDisplay:(CGDirectDisplayID)displayID {
    if (brightness < 0.0f) brightness = 0.0f;
    if (brightness > 1.0f) brightness = 1.0f;
    
    if (_setBrightnessFunc) {
        int status = _setBrightnessFunc(displayID, brightness);
        if (status == 0) {
            return YES;
        }
    }
    
    io_service_t service = CGDisplayIOServicePort(displayID);
    if (service != MACH_PORT_NULL) {
        CFStringRef key = CFSTR(kIODisplayBrightnessKey);
        kern_return_t kr = IODisplaySetFloatParameter(service, kNilOptions, key, brightness);
        if (kr == kIOReturnSuccess) {
            return YES;
        }
    }
    
    return NO;
}

@end