// Decodes every PNG under a directory with pngdecode.c and with macOS ImageIO (which yields
// exact non-premultiplied samples on macOS) and requires byte-identical results.
// Usage: png_parity DATA_DIR
#import <Foundation/Foundation.h>
#import <ImageIO/ImageIO.h>
#import <QuartzCore/QuartzCore.h>
#include "pngdecode.h"

int main(int argc, char **argv) {
    @autoreleasepool {
        NSString *root = @(argv[1]);
        long checked = 0, fallback = 0, mismatched = 0, skipped = 0;
        double tw = 0, ti = 0; long px = 0;
        for (NSString *rel in [NSFileManager.defaultManager enumeratorAtPath:root]) {
            if (![rel hasSuffix:@".png"]) continue;
            NSData *data = [NSData dataWithContentsOfFile:[root stringByAppendingPathComponent:rel]];
            uint8_t *mine; int w, h, ch;
            double t0 = CACurrentMediaTime();
            int ok = fx_png_decode(data.bytes, data.length, &mine, &w, &h, &ch);
            double t1 = CACurrentMediaTime();
            if (!ok) { fallback++; continue; }
            CGImageSourceRef src = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
            CGImageRef img = CGImageSourceCreateImageAtIndex(src, 0, NULL);
            CFDataRef ref = CGDataProviderCopyData(CGImageGetDataProvider(img));
            double t2 = CACurrentMediaTime();
            tw += t1 - t0; ti += t2 - t1; px += (long)w * h;
            size_t bpp = CGImageGetBitsPerPixel(img) / 8, row = CGImageGetBytesPerRow(img);
            CGImageAlphaInfo a = CGImageGetAlphaInfo(img);
            if (CGImageGetBitsPerComponent(img) != 8 || (CGImageGetBitmapInfo(img) & kCGBitmapByteOrderMask) ||
                a == kCGImageAlphaPremultipliedLast || a == kCGImageAlphaPremultipliedFirst || a == kCGImageAlphaFirst ||
                a == kCGImageAlphaNoneSkipFirst) { skipped++; goto next; }
            // Compare the channels AppKit would expose (drop ImageIO's padding byte for RGBX).
            for (int y = 0; y < h && !mismatched; y++)
                for (int x = 0; x < w; x++) {
                    const uint8_t *r = CFDataGetBytePtr(ref) + y * row + x * bpp, *m = mine + ((size_t)y * w + x) * ch;
                    if (memcmp(r, m, ch)) {
                        NSLog(@"MISMATCH %@ at %d,%d ch=%d", rel, x, y, ch);
                        mismatched++;
                        break;
                    }
                }
            checked++;
        next:
            CFRelease(ref); CGImageRelease(img); CFRelease(src); free(mine);
        }
        NSLog(@"checked %ld identical-format images, %ld mismatched, %ld skipped (ImageIO layout), %ld fallback to ImageIO",
              checked, mismatched, skipped, fallback);
        NSLog(@"%.0f Mpx: wuffs %.2fs (%.0f Mpx/s), ImageIO %.2fs (%.0f Mpx/s)", px / 1e6, tw, px / 1e6 / tw, ti, px / 1e6 / ti);
        return mismatched ? 1 : 0;
    }
}