#include <iostream>
#include <SDL3/SDL.h>

// Headers Metal usando Objective-C++
#ifdef __APPLE__
#import <Metal/Metal.h>
#import <QuartzCore/CAMetalLayer.h>
#import <Foundation/Foundation.h>
#import <AppKit/AppKit.h>
#endif

/*
 * METAL PERFORMANCE HUD - Debug FPS y métricas en tiempo real
 *
 * Para mostrar FPS y estadísticas de rendimiento, ejecutar con:
 *
 *   MTL_HUD_ENABLED=1 ./vibe5_metal
 *
 * El HUD aparece en la esquina superior derecha y muestra:
 * - FPS (Frames Per Second)
 * - CPU y GPU usage
 * - Memory usage
 * - Device info y resolución
 *
 * Atajos de teclado disponibles cuando el HUD está activo:
 * - Command+F9:  Enable/Disable HUD
 * - Command+F8:  Enable/Disable Logging
 * - Command+F11: Reset Metrics
 * - Command+F12: Show Configuration Panel
 *
 * Para activar globalmente para todas las apps Metal:
 *   launchctl setenv MTL_HUD_ENABLED 1
 *
 * Para desactivar:
 *   launchctl setenv MTL_HUD_ENABLED 0
 */

// Estructura para vértices de sprites
struct SpriteVertex {
    float position[2];  // x, y coordinates
    float texCoord[2];  // u, v texture coordinates
};

int main(int argc, char* argv[]) {
#ifdef __APPLE__
    // Configurar SDL para usar Metal
    SDL_SetHint(SDL_HINT_RENDER_DRIVER, "metal");

    // Inicializar SDL
    if (!SDL_Init(SDL_INIT_VIDEO)) {
        std::cout << "SDL_Init failed: " << SDL_GetError() << std::endl;
        return -1;
    }

    // Crear ventana
    SDL_Window* window = SDL_CreateWindow("vibe5_metal - Triangle + Gradient + Sprites", 640, 480, SDL_WINDOW_HIGH_PIXEL_DENSITY);
    if (!window) {
        std::cout << "SDL_CreateWindow failed: " << SDL_GetError() << std::endl;
        SDL_Quit();
        return -1;
    }

    // Crear renderer
    SDL_Renderer* renderer = SDL_CreateRenderer(window, nullptr);
    if (!renderer) {
        std::cout << "SDL_CreateRenderer failed: " << SDL_GetError() << std::endl;
        SDL_DestroyWindow(window);
        SDL_Quit();
        return -1;
    }

    std::cout << "SDL Window and Renderer created successfully" << std::endl;

    // Obtener Metal layer
    CAMetalLayer* metalLayer = (__bridge CAMetalLayer*)SDL_GetRenderMetalLayer(renderer);
    if (!metalLayer) {
        std::cout << "Failed to get Metal layer - SDL may not be using Metal driver" << std::endl;
        SDL_DestroyRenderer(renderer);
        SDL_DestroyWindow(window);
        SDL_Quit();
        return -1;
    }

    // Obtener device Metal del layer
    id<MTLDevice> device = metalLayer.device;
    if (!device) {
        std::cout << "Failed to get Metal device from layer" << std::endl;
        SDL_DestroyRenderer(renderer);
        SDL_DestroyWindow(window);
        SDL_Quit();
        return -1;
    }

    std::cout << "Got Metal device: " << [[device name] UTF8String] << std::endl;

    // Crear command queue
    id<MTLCommandQueue> commandQueue = [device newCommandQueue];
    if (!commandQueue) {
        std::cout << "Failed to create Metal command queue" << std::endl;
        SDL_DestroyRenderer(renderer);
        SDL_DestroyWindow(window);
        SDL_Quit();
        return -1;
    }

    // Shaders para fondo degradado
    NSString* backgroundVertexShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

vertex VertexOut background_vertex_main(uint vertexID [[vertex_id]]) {
    VertexOut out;

    // Quad de pantalla completa en coordenadas NDC
    float2 positions[6] = {
        float2(-1.0, -1.0),  // Bottom left
        float2( 1.0, -1.0),  // Bottom right
        float2(-1.0,  1.0),  // Top left
        float2( 1.0, -1.0),  // Bottom right
        float2( 1.0,  1.0),  // Top right
        float2(-1.0,  1.0)   // Top left
    };

    // Gradiente de púrpura oscuro arriba a azul cyan abajo
    float4 colors[6] = {
        float4(0.2, 0.6, 0.8, 1.0),  // Bottom left - cyan claro
        float4(0.2, 0.6, 0.8, 1.0),  // Bottom right - cyan claro
        float4(0.3, 0.1, 0.5, 1.0),  // Top left - púrpura oscuro
        float4(0.2, 0.6, 0.8, 1.0),  // Bottom right - cyan claro
        float4(0.3, 0.1, 0.5, 1.0),  // Top right - púrpura oscuro
        float4(0.3, 0.1, 0.5, 1.0)   // Top left - púrpura oscuro
    };

    out.position = float4(positions[vertexID], 0.0, 1.0);
    out.color = colors[vertexID];

    return out;
}
)";

    NSString* backgroundFragmentShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

fragment float4 background_fragment_main(VertexOut in [[stage_in]]) {
    return in.color;
}
)";

    // Shaders para triángulo
    NSString* triangleVertexShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

vertex VertexOut triangle_vertex_main(uint vertexID [[vertex_id]]) {
    VertexOut out;

    // Triángulo simple en coordenadas normalized device coordinates
    float2 positions[3] = {
        float2( 0.0,  0.5),  // Top
        float2(-0.5, -0.5),  // Bottom left
        float2( 0.5, -0.5)   // Bottom right
    };

    float4 colors[3] = {
        float4(1, 0, 0, 1),  // Red
        float4(0, 1, 0, 1),  // Green
        float4(0, 0, 1, 1)   // Blue
    };

    out.position = float4(positions[vertexID], 0.0, 1.0);
    out.color = colors[vertexID];

    return out;
}
)";

    NSString* triangleFragmentShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

fragment float4 triangle_fragment_main(VertexOut in [[stage_in]]) {
    return in.color;
}
)";

    // Shaders para sprites con textura
    NSString* spriteVertexShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct SpriteVertexIn {
    float2 position [[attribute(0)]];
    float2 texCoord [[attribute(1)]];
};

struct SpriteVertexOut {
    float4 position [[position]];
    float2 texCoord;
};

vertex SpriteVertexOut sprite_vertex_main(SpriteVertexIn in [[stage_in]]) {
    SpriteVertexOut out;
    out.position = float4(in.position, 0.0, 1.0);
    out.texCoord = in.texCoord;
    return out;
}
)";

    NSString* spriteFragmentShaderSource = @R"(
#include <metal_stdlib>
using namespace metal;

struct SpriteVertexOut {
    float4 position [[position]];
    float2 texCoord;
};

fragment float4 sprite_fragment_main(SpriteVertexOut in [[stage_in]],
                                   texture2d<float> spriteTexture [[texture(0)]],
                                   sampler textureSampler [[sampler(0)]]) {
    float4 textureColor = spriteTexture.sample(textureSampler, in.texCoord);
    return textureColor;
}
)";

    // Compilar shaders de fondo
    NSError* error = nil;
    id<MTLLibrary> backgroundVertexLibrary = [device newLibraryWithSource:backgroundVertexShaderSource options:nil error:&error];
    if (!backgroundVertexLibrary || error) {
        if (error) {
            std::cout << "Failed to compile background vertex shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLLibrary> backgroundFragmentLibrary = [device newLibraryWithSource:backgroundFragmentShaderSource options:nil error:&error];
    if (!backgroundFragmentLibrary || error) {
        if (error) {
            std::cout << "Failed to compile background fragment shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLFunction> backgroundVertexFunction = [backgroundVertexLibrary newFunctionWithName:@"background_vertex_main"];
    id<MTLFunction> backgroundFragmentFunction = [backgroundFragmentLibrary newFunctionWithName:@"background_fragment_main"];

    // Compilar shaders de triángulo
    id<MTLLibrary> triangleVertexLibrary = [device newLibraryWithSource:triangleVertexShaderSource options:nil error:&error];
    if (!triangleVertexLibrary || error) {
        if (error) {
            std::cout << "Failed to compile triangle vertex shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLLibrary> triangleFragmentLibrary = [device newLibraryWithSource:triangleFragmentShaderSource options:nil error:&error];
    if (!triangleFragmentLibrary || error) {
        if (error) {
            std::cout << "Failed to compile triangle fragment shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLFunction> triangleVertexFunction = [triangleVertexLibrary newFunctionWithName:@"triangle_vertex_main"];
    id<MTLFunction> triangleFragmentFunction = [triangleFragmentLibrary newFunctionWithName:@"triangle_fragment_main"];

    // Compilar shaders de sprites
    id<MTLLibrary> spriteVertexLibrary = [device newLibraryWithSource:spriteVertexShaderSource options:nil error:&error];
    if (!spriteVertexLibrary || error) {
        if (error) {
            std::cout << "Failed to compile sprite vertex shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLLibrary> spriteFragmentLibrary = [device newLibraryWithSource:spriteFragmentShaderSource options:nil error:&error];
    if (!spriteFragmentLibrary || error) {
        if (error) {
            std::cout << "Failed to compile sprite fragment shader: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    id<MTLFunction> spriteVertexFunction = [spriteVertexLibrary newFunctionWithName:@"sprite_vertex_main"];
    id<MTLFunction> spriteFragmentFunction = [spriteFragmentLibrary newFunctionWithName:@"sprite_fragment_main"];

    // Crear pipeline de fondo
    MTLRenderPipelineDescriptor* backgroundPipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
    backgroundPipelineDescriptor.vertexFunction = backgroundVertexFunction;
    backgroundPipelineDescriptor.fragmentFunction = backgroundFragmentFunction;
    backgroundPipelineDescriptor.colorAttachments[0].pixelFormat = metalLayer.pixelFormat;

    id<MTLRenderPipelineState> backgroundPipelineState = [device newRenderPipelineStateWithDescriptor:backgroundPipelineDescriptor error:&error];
    if (!backgroundPipelineState || error) {
        if (error) {
            std::cout << "Failed to create background render pipeline: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    // Crear pipeline de triángulo
    MTLRenderPipelineDescriptor* trianglePipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
    trianglePipelineDescriptor.vertexFunction = triangleVertexFunction;
    trianglePipelineDescriptor.fragmentFunction = triangleFragmentFunction;
    trianglePipelineDescriptor.colorAttachments[0].pixelFormat = metalLayer.pixelFormat;

    id<MTLRenderPipelineState> trianglePipelineState = [device newRenderPipelineStateWithDescriptor:trianglePipelineDescriptor error:&error];
    if (!trianglePipelineState || error) {
        if (error) {
            std::cout << "Failed to create triangle render pipeline: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    // Crear pipeline de sprites con alpha blending
    MTLRenderPipelineDescriptor* spritePipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
    spritePipelineDescriptor.vertexFunction = spriteVertexFunction;
    spritePipelineDescriptor.fragmentFunction = spriteFragmentFunction;
    spritePipelineDescriptor.colorAttachments[0].pixelFormat = metalLayer.pixelFormat;

    // Configurar alpha blending
    spritePipelineDescriptor.colorAttachments[0].blendingEnabled = YES;
    spritePipelineDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperationAdd;
    spritePipelineDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperationAdd;
    spritePipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha;
    spritePipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorSourceAlpha;
    spritePipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOneMinusSourceAlpha;
    spritePipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactorOneMinusSourceAlpha;

    // Configurar vertex descriptor para sprites
    MTLVertexDescriptor* spriteVertexDescriptor = [[MTLVertexDescriptor alloc] init];
    spriteVertexDescriptor.attributes[0].format = MTLVertexFormatFloat2;  // position
    spriteVertexDescriptor.attributes[0].offset = 0;
    spriteVertexDescriptor.attributes[0].bufferIndex = 0;
    spriteVertexDescriptor.attributes[1].format = MTLVertexFormatFloat2;  // texCoord
    spriteVertexDescriptor.attributes[1].offset = 8;
    spriteVertexDescriptor.attributes[1].bufferIndex = 0;
    spriteVertexDescriptor.layouts[0].stride = sizeof(SpriteVertex);
    spriteVertexDescriptor.layouts[0].stepFunction = MTLVertexStepFunctionPerVertex;

    spritePipelineDescriptor.vertexDescriptor = spriteVertexDescriptor;

    id<MTLRenderPipelineState> spritePipelineState = [device newRenderPipelineStateWithDescriptor:spritePipelineDescriptor error:&error];
    if (!spritePipelineState || error) {
        if (error) {
            std::cout << "Failed to create sprite render pipeline: " << [[error localizedDescription] UTF8String] << std::endl;
        }
        return -1;
    }

    // Cargar textura de sprite
    NSString* texturePath = @"data/ball.png";
    NSImage* image = [[NSImage alloc] initWithContentsOfFile:texturePath];
    if (!image) {
        std::cout << "Failed to load texture image: data/ball.png" << std::endl;
        return -1;
    }

    // Obtener representación como bitmap
    NSBitmapImageRep* bitmap = [[NSBitmapImageRep alloc] initWithData:[image TIFFRepresentation]];
    if (!bitmap) {
        std::cout << "Failed to create bitmap from image" << std::endl;
        return -1;
    }

    // Crear descriptor de textura Metal
    MTLTextureDescriptor* textureDescriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm
                                                                                                 width:[bitmap pixelsWide]
                                                                                                height:[bitmap pixelsHigh]
                                                                                             mipmapped:NO];

    // Crear textura Metal
    id<MTLTexture> spriteTexture = [device newTextureWithDescriptor:textureDescriptor];
    if (!spriteTexture) {
        std::cout << "Failed to create Metal texture" << std::endl;
        return -1;
    }

    // Copiar datos de imagen a textura Metal
    MTLRegion region = MTLRegionMake2D(0, 0, [bitmap pixelsWide], [bitmap pixelsHigh]);
    [spriteTexture replaceRegion:region
               mipmapLevel:0
                 withBytes:[bitmap bitmapData]
               bytesPerRow:[bitmap bytesPerRow]];

    // Crear sampler con filtro NEAREST para evitar blur
    MTLSamplerDescriptor* samplerDescriptor = [[MTLSamplerDescriptor alloc] init];
    samplerDescriptor.minFilter = MTLSamplerMinMagFilterNearest;
    samplerDescriptor.magFilter = MTLSamplerMinMagFilterNearest;
    samplerDescriptor.sAddressMode = MTLSamplerAddressModeClampToEdge;
    samplerDescriptor.tAddressMode = MTLSamplerAddressModeClampToEdge;

    id<MTLSamplerState> textureSampler = [device newSamplerStateWithDescriptor:samplerDescriptor];
    if (!textureSampler) {
        std::cout << "Failed to create Metal sampler" << std::endl;
        return -1;
    }

    // Crear vertex buffer para sprites
    id<MTLBuffer> spriteVertexBuffer = [device newBufferWithLength:1024 options:MTLResourceCPUCacheModeDefaultCache];
    if (!spriteVertexBuffer) {
        std::cout << "Failed to create sprite vertex buffer" << std::endl;
        return -1;
    }

    std::cout << "Metal pipelines created successfully (background + triangle + sprites)" << std::endl;
    std::cout << "Sprite texture loaded: " << [bitmap pixelsWide] << "x" << [bitmap pixelsHigh] << std::endl;

    // Main loop
    bool quit = false;
    SDL_Event e;

    while (!quit) {
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_EVENT_QUIT) {
                quit = true;
            }
        }

        // Obtener drawable del Metal layer
        id<CAMetalDrawable> drawable = [metalLayer nextDrawable];
        if (!drawable) {
            continue;
        }

        // Crear render pass descriptor
        MTLRenderPassDescriptor* renderPassDescriptor = [MTLRenderPassDescriptor renderPassDescriptor];
        renderPassDescriptor.colorAttachments[0].texture = drawable.texture;
        renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
        renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0.0, 0.0, 0.0, 1.0);
        renderPassDescriptor.colorAttachments[0].storeAction = MTLStoreActionStore;

        // Crear command buffer
        id<MTLCommandBuffer> commandBuffer = [commandQueue commandBuffer];
        if (!commandBuffer) {
            continue;
        }

        // Crear render command encoder
        id<MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];
        if (!renderEncoder) {
            continue;
        }

        // 1. Dibujar fondo degradado primero
        [renderEncoder setRenderPipelineState:backgroundPipelineState];
        [renderEncoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:6];

        // 2. Dibujar triángulo encima
        [renderEncoder setRenderPipelineState:trianglePipelineState];
        [renderEncoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:3];

        // 3. Dibujar sprite con alpha blending
        [renderEncoder setRenderPipelineState:spritePipelineState];

        // Configurar textura y sampler
        [renderEncoder setFragmentTexture:spriteTexture atIndex:0];
        [renderEncoder setFragmentSamplerState:textureSampler atIndex:0];

        // Crear sprite centrado con un tamaño pequeño
        SpriteVertex spriteVertices[6];  // 2 triángulos para formar un quad

        // Sprite centrado de 64x64 pixels en pantalla de 640x480
        float spriteSize = 64.0f;
        float windowWidth = 640.0f;
        float windowHeight = 480.0f;

        // Convertir a coordenadas NDC
        float halfWidth = (spriteSize / windowWidth);   // 0.1 en NDC
        float halfHeight = (spriteSize / windowHeight); // 0.133 en NDC

        // Primer triángulo (bottom-left, bottom-right, top-left)
        spriteVertices[0] = {{-halfWidth, -halfHeight}, {0.0f, 1.0f}}; // bottom-left
        spriteVertices[1] = {{ halfWidth, -halfHeight}, {1.0f, 1.0f}}; // bottom-right
        spriteVertices[2] = {{-halfWidth,  halfHeight}, {0.0f, 0.0f}}; // top-left

        // Segundo triángulo (bottom-right, top-right, top-left)
        spriteVertices[3] = {{ halfWidth, -halfHeight}, {1.0f, 1.0f}}; // bottom-right
        spriteVertices[4] = {{ halfWidth,  halfHeight}, {1.0f, 0.0f}}; // top-right
        spriteVertices[5] = {{-halfWidth,  halfHeight}, {0.0f, 0.0f}}; // top-left

        // Copiar vértices al buffer
        void* spriteData = [spriteVertexBuffer contents];
        memcpy(spriteData, spriteVertices, sizeof(spriteVertices));

        // Configurar vertex buffer y dibujar
        [renderEncoder setVertexBuffer:spriteVertexBuffer offset:0 atIndex:0];
        [renderEncoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:6];

        [renderEncoder endEncoding];

        // Presentar drawable
        [commandBuffer presentDrawable:drawable];
        [commandBuffer commit];
    }

    // Cleanup
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    std::cout << "vibe5_metal finished successfully" << std::endl;
    return 0;

#else
    std::cout << "This example requires macOS and Metal support" << std::endl;
    return -1;
#endif
}