// Minimal audio/visual synchronization test tool
// Plays simple drum beat with synchronized screen flashes

#include "audio/audio.h"
#include "audio/audio_engine.h"
#include "audio/synth.h"
#include "generated/assets.h"  // Note: uses main demo asset bundle
#include "gpu/demo_effects.h"
#include "gpu/gpu.h"
#include "platform/platform.h"
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>

// External declarations from generated files
extern float GetDemoDuration();
extern void LoadTimeline(MainSequence& main_seq, const GpuContext& ctx);

// Inline peak meter effect for debugging audio-visual sync
#include "gpu/effects/post_process_helper.h"
class PeakMeterEffect : public PostProcessEffect {
 public:
  PeakMeterEffect(const GpuContext& ctx)
      : PostProcessEffect(ctx) {
    const char* shader_code = R"(
      struct VertexOutput {
        @builtin(position) position: vec4<f32>,
        @location(0) uv: vec2<f32>,
      };

      struct Uniforms {
        peak_value: f32,
        _pad0: f32,
        _pad1: f32,
        _pad2: f32,
      };

      @group(0) @binding(0) var inputSampler: sampler;
      @group(0) @binding(1) var inputTexture: texture_2d<f32>;
      @group(0) @binding(2) var<uniform> uniforms: Uniforms;

      @vertex
      fn vs_main(@builtin(vertex_index) vertexIndex: u32) -> VertexOutput {
        var output: VertexOutput;
        var pos = array<vec2<f32>, 3>(
          vec2<f32>(-1.0, -1.0),
          vec2<f32>(3.0, -1.0),
          vec2<f32>(-1.0, 3.0)
        );
        output.position = vec4<f32>(pos[vertexIndex], 0.0, 1.0);
        output.uv = pos[vertexIndex] * 0.5 + 0.5;
        return output;
      }

      @fragment
      fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
        let color = textureSample(inputTexture, inputSampler, input.uv);

        // Draw red horizontal bar in middle of screen
        // Bar height: 5% of screen height
        // Bar width: proportional to peak_value (0.0 to 1.0)
        let bar_height = 0.05;
        let bar_center_y = 0.5;
        let bar_y_min = bar_center_y - bar_height * 0.5;
        let bar_y_max = bar_center_y + bar_height * 0.5;

        // Bar extends from left (0.0) to peak_value position
        let bar_x_max = uniforms.peak_value;

        // Check if current pixel is inside the bar
        let in_bar_y = input.uv.y >= bar_y_min && input.uv.y <= bar_y_max;
        let in_bar_x = input.uv.x <= bar_x_max;

        if (in_bar_y && in_bar_x) {
          // Red bar
          return vec4<f32>(1.0, 0.0, 0.0, 1.0);
        } else {
          // Original color
          return color;
        }
      }
    )";

    pipeline_ = create_post_process_pipeline(device_, format_, shader_code);
    uniforms_ = gpu_create_buffer(
        device_, 16, WGPUBufferUsage_Uniform | WGPUBufferUsage_CopyDst);
  }

  void update_bind_group(WGPUTextureView input_view) {
    pp_update_bind_group(device_, pipeline_, &bind_group_, input_view, uniforms_);
  }

  void render(WGPURenderPassEncoder pass, float time, float beat,
              float peak_value, float aspect_ratio) {
    (void)time;
    (void)beat;
    (void)aspect_ratio;

    float uniforms[4] = {peak_value, 0.0f, 0.0f, 0.0f};
    wgpuQueueWriteBuffer(queue_, uniforms_.buffer, 0, uniforms, sizeof(uniforms));

    wgpuRenderPassEncoderSetPipeline(pass, pipeline_);
    wgpuRenderPassEncoderSetBindGroup(pass, 0, bind_group_, 0, nullptr);
    wgpuRenderPassEncoderDraw(pass, 3, 1, 0, 0);
  }
};

#if !defined(STRIP_ALL)
static void print_usage(const char* prog_name) {
  printf("Usage: %s [OPTIONS]\n", prog_name);
  printf("\nMinimal audio/visual synchronization test tool.\n");
  printf("Plays a simple drum beat with synchronized screen flashes.\n");
  printf("\nOptions:\n");
  printf("  --help              Show this help message and exit\n");
  printf("  --fullscreen        Run in fullscreen mode\n");
  printf("  --resolution WxH    Set window resolution (e.g., 1024x768)\n");
  printf("  --tempo             Enable tempo variation test mode\n");
  printf("                      (alternates between acceleration and deceleration)\n");
  printf("  --log-peaks FILE    Log audio peaks at each beat (32 samples for 16s)\n");
  printf("  --log-peaks-fine    Log at each frame for fine analysis (~960 samples)\n");
  printf("                      (use with --log-peaks for millisecond resolution)\n");
  printf("\nExamples:\n");
  printf("  %s --fullscreen\n", prog_name);
  printf("  %s --resolution 1024x768 --tempo\n", prog_name);
  printf("  %s --log-peaks peaks.txt\n", prog_name);
  printf("  %s --log-peaks peaks.txt --log-peaks-fine\n", prog_name);
  printf("\nControls:\n");
  printf("  ESC                 Exit the demo\n");
  printf("  F                   Toggle fullscreen\n");
}
#endif

int main(int argc, char** argv) {
  // Parse command-line
  PlatformState platform_state;
  bool fullscreen_enabled = false;
  bool tempo_test_enabled = false;
  int width = 1280;
  int height = 720;
  const char* log_peaks_file = nullptr;
  bool log_peaks_fine = false;

#if !defined(STRIP_ALL)
  // Early exit for invalid options
  for (int i = 1; i < argc; ++i) {
    if (strcmp(argv[i], "--help") == 0) {
      print_usage(argv[0]);
      return 0;
    } else if (strcmp(argv[i], "--fullscreen") == 0) {
      fullscreen_enabled = true;
    } else if (strcmp(argv[i], "--tempo") == 0) {
      tempo_test_enabled = true;
    } else if (strcmp(argv[i], "--resolution") == 0) {
      if (i + 1 < argc) {
        const char* res_str = argv[++i];
        int w, h;
        if (sscanf(res_str, "%dx%d", &w, &h) == 2) {
          width = w;
          height = h;
        } else {
          fprintf(stderr, "Error: Invalid resolution format '%s' (expected WxH, e.g., 1024x768)\n\n", res_str);
          print_usage(argv[0]);
          return 1;
        }
      } else {
        fprintf(stderr, "Error: --resolution requires an argument (e.g., 1024x768)\n\n");
        print_usage(argv[0]);
        return 1;
      }
    } else if (strcmp(argv[i], "--log-peaks") == 0) {
      if (i + 1 < argc) {
        log_peaks_file = argv[++i];
      } else {
        fprintf(stderr, "Error: --log-peaks requires a filename argument\n\n");
        print_usage(argv[0]);
        return 1;
      }
    } else if (strcmp(argv[i], "--log-peaks-fine") == 0) {
      log_peaks_fine = true;
    } else {
      fprintf(stderr, "Error: Unknown option '%s'\n\n", argv[i]);
      print_usage(argv[0]);
      return 1;
    }
  }
#else
  (void)argc;
  (void)argv;
  fullscreen_enabled = true;
#endif

  // Initialize platform, GPU, audio
  platform_state = platform_init(fullscreen_enabled, width, height);
  gpu_init(&platform_state);

  // Add peak meter visualization effect (renders as final post-process)
#if !defined(STRIP_ALL)
  const GpuContext* gpu_ctx = gpu_get_context();
  auto* peak_meter = new PeakMeterEffect(*gpu_ctx);
  gpu_add_custom_effect(peak_meter, 0.0f, 99999.0f, 999); // High priority = renders last
#endif

  audio_init();

  static AudioEngine g_audio_engine;
  g_audio_engine.init();

  // Music time tracking with optional tempo variation
  static float g_music_time = 0.0f;
  static double g_last_physical_time = 0.0;
  static float g_tempo_scale = 1.0f;

  auto fill_audio_buffer = [&](double t) {
    const float dt = (float)(t - g_last_physical_time);
    g_last_physical_time = t;

    // Calculate tempo scale if --tempo flag enabled
    if (tempo_test_enabled) {
      // Each bar = 2 seconds at 120 BPM (4 beats)
      const float bar_duration = 2.0f;
      const int bar_number = (int)(t / bar_duration);
      const float bar_progress = fmodf((float)t, bar_duration) / bar_duration;  // 0.0-1.0 within bar

      if (bar_number % 2 == 0) {
        // Even bars: Ramp from 1.0x → 1.5x
        g_tempo_scale = 1.0f + (0.5f * bar_progress);
      } else {
        // Odd bars: Ramp from 1.0x → 0.66x
        g_tempo_scale = 1.0f - (0.34f * bar_progress);
      }
    } else {
      g_tempo_scale = 1.0f;  // No tempo variation
    }

    g_music_time += dt * g_tempo_scale;

    g_audio_engine.update(g_music_time);
    audio_render_ahead(g_music_time, dt * g_tempo_scale);
  };

  // Pre-fill audio buffer
  g_audio_engine.update(g_music_time);
  audio_render_ahead(g_music_time, 1.0f / 60.0f);
  audio_start();

  int last_width = platform_state.width;
  int last_height = platform_state.height;
  const float demo_duration = GetDemoDuration();

#if !defined(STRIP_ALL)
  // Open peak log file if requested
  FILE* peak_log = nullptr;
  if (log_peaks_file) {
    peak_log = fopen(log_peaks_file, "w");
    if (peak_log) {
      fprintf(peak_log, "# Audio peak log from test_demo\n");
      fprintf(peak_log, "# Mode: %s\n", log_peaks_fine ? "fine (per-frame)" : "beat-aligned");
      fprintf(peak_log, "# To plot with gnuplot:\n");
      fprintf(peak_log, "#   gnuplot -p -e \"set xlabel 'Time (s)'; set ylabel 'Peak'; plot '%s' using 2:3 with lines title 'Raw Peak'\"\n", log_peaks_file);
      if (log_peaks_fine) {
        fprintf(peak_log, "# Columns: frame_number clock_time raw_peak beat_number\n");
      } else {
        fprintf(peak_log, "# Columns: beat_number clock_time raw_peak\n");
      }
      fprintf(peak_log, "#\n");
    } else {
      fprintf(stderr, "Warning: Could not open log file '%s'\n", log_peaks_file);
    }
  }
  int last_beat_logged = -1;
  int frame_number = 0;
#endif

  // Main loop
  while (!platform_should_close(&platform_state)) {
    platform_poll(&platform_state);

    // Handle resize
    if (platform_state.width != last_width ||
        platform_state.height != last_height) {
      last_width = platform_state.width;
      last_height = platform_state.height;
      gpu_resize(last_width, last_height);
    }

    const double physical_time = platform_state.time;

    // Auto-exit at end (based on physical time for reliability)
    if (demo_duration > 0.0f && physical_time >= demo_duration) {
#if !defined(STRIP_ALL)
      printf("test_demo finished at %.2f seconds.\n", physical_time);
#endif
      break;
    }

    fill_audio_buffer(physical_time);

    // Audio-visual synchronization: Use audio playback time (not physical time!)
    // This accounts for ring buffer latency automatically (no hardcoded constants)
    const float audio_time = audio_get_playback_time();

    // Audio/visual sync parameters
    const float aspect_ratio = platform_state.aspect_ratio;
    // Peak is measured at audio playback time, so it matches audio_time
    const float raw_peak = audio_get_realtime_peak();
    const float visual_peak = fminf(raw_peak * 8.0f, 1.0f);

    // Beat calculation uses AUDIO TIME (what's being heard), not physical time
    const float beat_time = audio_time * 120.0f / 60.0f;
    const int beat_number = (int)beat_time;
    const float beat = fmodf(beat_time, 1.0f);

#if !defined(STRIP_ALL)
    // Log peak (either per-frame or per-beat)
    if (peak_log) {
      if (log_peaks_fine) {
        // Log every frame for fine-grained analysis
        fprintf(peak_log, "%d %.6f %.6f %d\n", frame_number, audio_time, raw_peak, beat_number);
      } else if (beat_number != last_beat_logged) {
        // Log only at beat boundaries
        fprintf(peak_log, "%d %.6f %.6f\n", beat_number, audio_time, raw_peak);
        last_beat_logged = beat_number;
      }
    }
    frame_number++;

    // Debug output every 0.5 seconds (based on audio time for consistency)
    static float last_print_time = -1.0f;
    if (audio_time - last_print_time >= 0.5f) {
      if (tempo_test_enabled) {
        printf("[AudioT=%.2f, PhysT=%.2f, MusicT=%.2f, Beat=%d, Frac=%.2f, Peak=%.2f, Tempo=%.2fx]\n",
               audio_time, (float)physical_time, g_music_time, beat_number, beat, visual_peak, g_tempo_scale);
      } else {
        printf("[AudioT=%.2f, Beat=%d, Frac=%.2f, Peak=%.2f]\n",
               audio_time, beat_number, beat, visual_peak);
      }
      last_print_time = audio_time;
    }
#endif

    gpu_draw(visual_peak, aspect_ratio, audio_time, beat);
    audio_update();
  }

  // Shutdown
#if !defined(STRIP_ALL)
  if (peak_log) {
    fclose(peak_log);
    printf("Peak log written to '%s'\n", log_peaks_file);
  }
#endif

  audio_shutdown();
  gpu_shutdown();
  platform_shutdown(&platform_state);
  return 0;
}