// This file is part of the 64k demo project.
// It implements reusable test helpers for GPU effect testing.
// Provides pixel validation utilities.

#include "effect_test_helpers.h"
#include <cassert>

// ============================================================================
// Pixel Validation Helpers
// ============================================================================

bool validate_pixels(
    const std::vector<uint8_t>& pixels, int width, int height,
    std::function<bool(uint8_t r, uint8_t g, uint8_t b, uint8_t a)> predicate) {
  const size_t pixel_count = width * height;
  for (size_t i = 0; i < pixel_count; ++i) {
    const size_t offset = i * 4; // BGRA8 = 4 bytes/pixel
    const uint8_t b = pixels[offset + 0];
    const uint8_t g = pixels[offset + 1];
    const uint8_t r = pixels[offset + 2];
    const uint8_t a = pixels[offset + 3];

    if (predicate(r, g, b, a)) {
      return true; // At least one pixel matches
    }
  }
  return false; // No pixels matched
}

bool has_rendered_content(const std::vector<uint8_t>& pixels, int width,
                          int height) {
  return validate_pixels(pixels, width, height,
                         [](uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
                           return r > 0 || g > 0 || b > 0;
                         });
}

bool all_pixels_match_color(const std::vector<uint8_t>& pixels, int width,
                            int height, uint8_t target_r, uint8_t target_g,
                            uint8_t target_b, uint8_t tolerance) {
  const size_t pixel_count = width * height;
  for (size_t i = 0; i < pixel_count; ++i) {
    const size_t offset = i * 4;
    const uint8_t b = pixels[offset + 0];
    const uint8_t g = pixels[offset + 1];
    const uint8_t r = pixels[offset + 2];

    const int diff_r = (int)(r) - (int)(target_r);
    const int diff_g = (int)(g) - (int)(target_g);
    const int diff_b = (int)(b) - (int)(target_b);

    if (diff_r * diff_r + diff_g * diff_g + diff_b * diff_b >
        tolerance * tolerance) {
      return false; // At least one pixel doesn't match
    }
  }
  return true; // All pixels match
}

uint64_t hash_pixels(const std::vector<uint8_t>& pixels) {
  // Simple FNV-1a hash
  uint64_t hash = 14695981039346656037ULL;
  for (const uint8_t byte : pixels) {
    hash ^= byte;
    hash *= 1099511628211ULL;
  }
  return hash;
}