/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup gpu
 */

#include "BKE_global.h"

#include "gpu_backend.hh"
#include "mtl_backend.hh"
#include "mtl_context.hh"
#include "mtl_framebuffer.hh"
#include "mtl_index_buffer.hh"
#include "mtl_query.hh"
#include "mtl_shader.hh"
#include "mtl_uniform_buffer.hh"

#include "gpu_capabilities_private.hh"
#include "gpu_platform_private.hh"

#include <Cocoa/Cocoa.h>
#include <Metal/Metal.h>
#include <QuartzCore/QuartzCore.h>

namespace blender::gpu {

/* Global per-thread AutoReleasePool. */
thread_local NSAutoreleasePool *g_autoreleasepool = nil;
thread_local int g_autoreleasepool_depth = 0;

/* -------------------------------------------------------------------- */
/** \name Metal Backend
 * \{ */

void MTLBackend::samplers_update(){
    /* Placeholder -- Handled in MTLContext. */
};

Context *MTLBackend::context_alloc(void *ghost_window)
{
  return new MTLContext(ghost_window);
};

Batch *MTLBackend::batch_alloc()
{
  /* TODO(Metal): Implement MTLBatch. */
  return nullptr;
};

DrawList *MTLBackend::drawlist_alloc(int list_length)
{
  /* TODO(Metal): Implement MTLDrawList. */
  return nullptr;
};

FrameBuffer *MTLBackend::framebuffer_alloc(const char *name)
{
  MTLContext *mtl_context = static_cast<MTLContext *>(
      reinterpret_cast<Context *>(GPU_context_active_get()));
  return new MTLFrameBuffer(mtl_context, name);
};

IndexBuf *MTLBackend::indexbuf_alloc()
{
  return new MTLIndexBuf();
};

QueryPool *MTLBackend::querypool_alloc()
{
  return new MTLQueryPool();
};

Shader *MTLBackend::shader_alloc(const char *name)
{
  MTLContext *mtl_context = MTLContext::get();
  return new MTLShader(mtl_context, name);
};

Texture *MTLBackend::texture_alloc(const char *name)
{
  return new gpu::MTLTexture(name);
}

UniformBuf *MTLBackend::uniformbuf_alloc(int size, const char *name)
{
  return new MTLUniformBuf(size, name);
};

StorageBuf *MTLBackend::storagebuf_alloc(int size, GPUUsageType usage, const char *name)
{
  /* TODO(Metal): Implement MTLStorageBuf. */
  return nullptr;
}

VertBuf *MTLBackend::vertbuf_alloc()
{
  /* TODO(Metal): Implement MTLVertBuf. */
  return nullptr;
}

void MTLBackend::render_begin()
{
  /* All Rendering must occur within a render boundary */
  /* Track a call-count for nested calls, used to ensure we are inside an
   * autoreleasepool from all rendering path. */
  BLI_assert(g_autoreleasepool_depth >= 0);

  if (g_autoreleasepool == nil) {
    g_autoreleasepool = [[NSAutoreleasePool alloc] init];
  }
  g_autoreleasepool_depth++;
  BLI_assert(g_autoreleasepool_depth > 0);
}

void MTLBackend::render_end()
{
  /* If call-count reaches zero, drain auto release pool.
   * Ensures temporary objects are freed within a frame's lifetime. */
  BLI_assert(g_autoreleasepool != nil);
  g_autoreleasepool_depth--;
  BLI_assert(g_autoreleasepool_depth >= 0);

  if (g_autoreleasepool_depth == 0) {
    [g_autoreleasepool drain];
    g_autoreleasepool = nil;
  }
}

void MTLBackend::render_step()
{
  /* NOTE(Metal): Primarily called from main thread, but below data-structures
   * and operations are thread-safe, and GPUContext rendering coordination
   * is also thread-safe. */

  /* Flush any MTLSafeFreeLists which have previously been released by any MTLContext. */
  MTLContext::get_global_memory_manager().update_memory_pools();

  /* End existing MTLSafeFreeList and begin new list --
   * Buffers wont `free` until all associated in-flight command buffers have completed.
   * Decrement final reference count for ensuring the previous list is certainly
   * released. */
  MTLSafeFreeList *cmd_free_buffer_list =
      MTLContext::get_global_memory_manager().get_current_safe_list();
  MTLContext::get_global_memory_manager().begin_new_safe_list();
  cmd_free_buffer_list->decrement_reference();
}

bool MTLBackend::is_inside_render_boundary()
{
  return (g_autoreleasepool != nil);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Platform
 * \{ */

/* For Metal, platform_init needs to be called after MTLContext initialization. */
void MTLBackend::platform_init(MTLContext *ctx)
{
  if (GPG.initialized) {
    return;
  }

  eGPUDeviceType device = GPU_DEVICE_UNKNOWN;
  eGPUOSType os = GPU_OS_ANY;
  eGPUDriverType driver = GPU_DRIVER_ANY;
  eGPUSupportLevel support_level = GPU_SUPPORT_LEVEL_SUPPORTED;

  BLI_assert(ctx);
  id<MTLDevice> mtl_device = ctx->device;
  BLI_assert(device);

  NSString *gpu_name = [mtl_device name];
  const char *vendor = [gpu_name UTF8String];
  const char *renderer = "Metal API";
  const char *version = "1.2";
  printf("METAL API - DETECTED GPU: %s\n", vendor);

  /* macOS is the only supported platform, but check to ensure we are not building with Metal
   * enablement on another platform. */
#ifdef _WIN32
  os = GPU_OS_WIN;
#elif defined(__APPLE__)
  os = GPU_OS_MAC;
#else
  os = GPU_OS_UNIX;
#endif

  BLI_assert_msg(os == GPU_OS_MAC, "Platform must be macOS");

  /* Determine Vendor from name. */
  if (strstr(vendor, "ATI") || strstr(vendor, "AMD")) {
    device = GPU_DEVICE_ATI;
    driver = GPU_DRIVER_OFFICIAL;
  }
  else if (strstr(vendor, "NVIDIA")) {
    device = GPU_DEVICE_NVIDIA;
    driver = GPU_DRIVER_OFFICIAL;
  }
  else if (strstr(vendor, "Intel")) {
    device = GPU_DEVICE_INTEL;
    driver = GPU_DRIVER_OFFICIAL;
  }
  else if (strstr(vendor, "Apple") || strstr(vendor, "APPLE")) {
    /* Apple Silicon. */
    device = GPU_DEVICE_APPLE;
    driver = GPU_DRIVER_OFFICIAL;
  }
  else if (strstr(renderer, "Apple Software Renderer")) {
    device = GPU_DEVICE_SOFTWARE;
    driver = GPU_DRIVER_SOFTWARE;
  }
  else if (strstr(renderer, "llvmpipe") || strstr(renderer, "softpipe")) {
    device = GPU_DEVICE_SOFTWARE;
    driver = GPU_DRIVER_SOFTWARE;
  }
  else {
    printf("Warning: Could not find a matching GPU name. Things may not behave as expected.\n");
    printf("Detected configuration:\n");
    printf("Vendor: %s\n", vendor);
    printf("Renderer: %s\n", renderer);
  }

  GPG.init(device, os, driver, support_level, GPU_BACKEND_METAL, vendor, renderer, version);
}

void MTLBackend::platform_exit()
{
  BLI_assert(GPG.initialized);
  GPG.clear();
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Capabilities
 * \{ */
MTLCapabilities MTLBackend::capabilities = {};

static const char *mtl_extensions_get_null(int i)
{
  return nullptr;
}

bool supports_barycentric_whitelist(id<MTLDevice> device)
{
  NSString *gpu_name = [device name];
  BLI_assert([gpu_name length]);
  const char *vendor = [gpu_name UTF8String];

  /* Verify GPU support. */
  bool supported_gpu = [device supportsFamily:MTLGPUFamilyMac2];
  bool should_support_barycentrics = false;

  /* Known good configs. */
  if (strstr(vendor, "AMD") || strstr(vendor, "Apple") || strstr(vendor, "APPLE")) {
    should_support_barycentrics = true;
  }

  /* Explicit support for Intel-based platforms. */
  if ((strstr(vendor, "Intel") || strstr(vendor, "INTEL"))) {
    should_support_barycentrics = true;
  }
  return supported_gpu && should_support_barycentrics;
}

bool MTLBackend::metal_is_supported()
{
  /* Device compatibility information using Metal Feature-set tables.
   * See: https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf */

  NSOperatingSystemVersion version = [[NSProcessInfo processInfo] operatingSystemVersion];

  /* Metal Viewport requires macOS Version 10.15 onward. */
  bool supported_os_version = version.majorVersion >= 11 ||
                              (version.majorVersion == 10 ? version.minorVersion >= 15 : false);
  if (!supported_os_version) {
    printf(
        "OS Version too low to run minimum required metal version. Required at least 10.15, got "
        "%ld.%ld \n",
        (long)version.majorVersion,
        (long)version.minorVersion);
    return false;
  }

  if (@available(macOS 10.15, *)) {
    id<MTLDevice> device = MTLCreateSystemDefaultDevice();

    /* Debug: Enable low power GPU with Environment Var: METAL_FORCE_INTEL. */
    static const char *forceIntelStr = getenv("METAL_FORCE_INTEL");
    bool forceIntel = forceIntelStr ? (atoi(forceIntelStr) != 0) : false;

    if (forceIntel) {
      NSArray<id<MTLDevice>> *allDevices = MTLCopyAllDevices();
      for (id<MTLDevice> _device in allDevices) {
        if (_device.lowPower) {
          device = _device;
        }
      }
    }

    /* Metal Viewport requires argument buffer tier-2 support and Barycentric Coordinates.
     * These are available on most hardware configurations supporting Metal 2.2. */
    bool supports_argument_buffers_tier2 = ([device argumentBuffersSupport] ==
                                            MTLArgumentBuffersTier2);
    bool supports_barycentrics = [device supportsShaderBarycentricCoordinates] ||
                                 supports_barycentric_whitelist(device);
    bool supported_metal_version = [device supportsFamily:MTLGPUFamilyMac2];

    bool result = supports_argument_buffers_tier2 && supports_barycentrics &&
                  supported_os_version && supported_metal_version;

    if (!supports_argument_buffers_tier2) {
      printf("[Metal] Device does not support argument buffers tier 2\n");
    }
    if (!supports_barycentrics) {
      printf("[Metal] Device does not support barycentrics coordinates\n");
    }
    if (!supported_metal_version) {
      printf("[Metal] Device does not support metal 2.2 or higher\n");
    }

    if (result) {
      printf("Device with name %s supports metal minimum requirements\n",
             [[device name] UTF8String]);
    }

    return result;
  }
  return false;
}

void MTLBackend::capabilities_init(MTLContext *ctx)
{
  BLI_assert(ctx);
  id<MTLDevice> device = ctx->device;
  BLI_assert(device);

  /* Initialize Capabilities. */
  MTLBackend::capabilities.supports_argument_buffers_tier2 = ([device argumentBuffersSupport] ==
                                                              MTLArgumentBuffersTier2);
  MTLBackend::capabilities.supports_family_mac1 = [device supportsFamily:MTLGPUFamilyMac1];
  MTLBackend::capabilities.supports_family_mac2 = [device supportsFamily:MTLGPUFamilyMac2];
  MTLBackend::capabilities.supports_family_mac_catalyst1 = [device
      supportsFamily:MTLGPUFamilyMacCatalyst1];
  MTLBackend::capabilities.supports_family_mac_catalyst2 = [device
      supportsFamily:MTLGPUFamilyMacCatalyst2];

  /* Common Global Capabilities. */
  GCaps.max_texture_size = ([device supportsFamily:MTLGPUFamilyApple3] ||
                            MTLBackend::capabilities.supports_family_mac1) ?
                               16384 :
                               8192;
  GCaps.max_texture_3d_size = 2048;
  GCaps.max_texture_layers = 2048;
  GCaps.max_textures = (MTLBackend::capabilities.supports_family_mac1) ?
                           128 :
                           (([device supportsFamily:MTLGPUFamilyApple4]) ? 96 : 31);
  if (GCaps.max_textures <= 32) {
    BLI_assert(false);
  }
  GCaps.max_samplers = (MTLBackend::capabilities.supports_argument_buffers_tier2) ? 1024 : 16;

  GCaps.max_textures_vert = GCaps.max_textures;
  GCaps.max_textures_geom = 0; /* N/A geometry shaders not supported. */
  GCaps.max_textures_frag = GCaps.max_textures;

  /* Conservative uniform data limit is 4KB per-stage -- This is the limit of setBytes.
   * MTLBuffer path is also supported but not as efficient. */
  GCaps.max_uniforms_vert = 1024;
  GCaps.max_uniforms_frag = 1024;

  GCaps.max_batch_indices = 1 << 31;
  GCaps.max_batch_vertices = 1 << 31;
  GCaps.max_vertex_attribs = 31;
  GCaps.max_varying_floats = 60;

  /* Feature support */
  GCaps.mem_stats_support = false;
  GCaps.shader_image_load_store_support = ([device supportsFamily:MTLGPUFamilyApple3] ||
                                           MTLBackend::capabilities.supports_family_mac1 ||
                                           MTLBackend::capabilities.supports_family_mac2);
  /* TODO(Metal): Add support? */
  GCaps.shader_draw_parameters_support = false;
  GCaps.compute_shader_support = false; /* TODO(Metal): Add compute support. */
  GCaps.shader_storage_buffer_objects_support =
      false; /* TODO(Metal): implement Storage Buffer support. */

  /* Maximum buffer bindings: 31. Consider required slot for uniforms/UBOs/Vertex attributes.
   * Can use argument buffers if a higher limit is required. */
  GCaps.max_shader_storage_buffer_bindings = 24;

  if (GCaps.compute_shader_support) {
    GCaps.max_work_group_count[0] = 65535;
    GCaps.max_work_group_count[1] = 65535;
    GCaps.max_work_group_count[2] = 65535;

    /* In Metal, total_thread_count is 512 or 1024, such that
     * threadgroup `width*height*depth <= total_thread_count` */
    uint max_threads_per_threadgroup_per_dim = ([device supportsFamily:MTLGPUFamilyApple4] ||
                                                MTLBackend::capabilities.supports_family_mac1) ?
                                                   1024 :
                                                   512;
    GCaps.max_work_group_size[0] = max_threads_per_threadgroup_per_dim;
    GCaps.max_work_group_size[1] = max_threads_per_threadgroup_per_dim;
    GCaps.max_work_group_size[2] = max_threads_per_threadgroup_per_dim;
  }

  GCaps.transform_feedback_support = true;

  /* OPENGL Related workarounds -- none needed for Metal. */
  GCaps.extensions_len = 0;
  GCaps.extension_get = mtl_extensions_get_null;
  GCaps.mip_render_workaround = false;
  GCaps.depth_blitting_workaround = false;
  GCaps.use_main_context_workaround = false;
  GCaps.broken_amd_driver = false;

  /* Metal related workarounds. */
  /* Minimum per-vertex stride is 4 bytes in Metal.
   * A bound vertex buffer must contribute at least 4 bytes per vertex. */
  GCaps.minimum_per_vertex_stride = 4;
}

/** \} */

}  // blender::gpu