/**
 ******************************************************************************
 * Xenia : Xbox 360 Emulator Research Project                                 *
 ******************************************************************************
 * Copyright 2014 Ben Vanik. All rights reserved.                             *
 * Released under the BSD license - see LICENSE in the root for more details. *
 ******************************************************************************
 */

#include "xenia/gpu/gl4/gl4_graphics_system.h"

#include <algorithm>
#include <cstring>

#include "xenia/base/clock.h"
#include "xenia/base/logging.h"
#include "xenia/base/threading.h"
#include "xenia/cpu/processor.h"
#include "xenia/emulator.h"
#include "xenia/gpu/gl4/gl4_gpu_flags.h"
#include "xenia/gpu/gpu_flags.h"
#include "xenia/gpu/tracing.h"
#include "xenia/profiling.h"
#include "xenia/ui/window.h"

namespace xe {
namespace gpu {
namespace gl4 {

void InitializeIfNeeded();
void CleanupOnShutdown();

void InitializeIfNeeded() {
  static bool has_initialized = false;
  if (has_initialized) {
    return;
  }
  has_initialized = true;

  //

  atexit(CleanupOnShutdown);
}

void CleanupOnShutdown() {}

std::unique_ptr<GraphicsSystem> Create(Emulator* emulator) {
  InitializeIfNeeded();
  return std::make_unique<GL4GraphicsSystem>(emulator);
}

std::unique_ptr<ui::GraphicsContext> GL4GraphicsSystem::CreateContext(
    ui::Window* target_window) {
  // Setup the GL control that actually does the drawing.
  // We run here in the loop and only touch it (and its context) on this
  // thread. That means some sync-fu when we want to swap.
  return xe::ui::gl::GLContext::Create(target_window);
}

GL4GraphicsSystem::GL4GraphicsSystem(Emulator* emulator)
    : GraphicsSystem(emulator), worker_running_(false) {}

GL4GraphicsSystem::~GL4GraphicsSystem() = default;

X_STATUS GL4GraphicsSystem::Setup(cpu::Processor* processor,
                                  ui::Loop* target_loop,
                                  ui::Window* target_window) {
  auto result = GraphicsSystem::Setup(processor, target_loop, target_window);
  if (result) {
    return result;
  }

  display_context_ =
      reinterpret_cast<xe::ui::gl::GLContext*>(target_window->context());

  // Watch for paint requests to do our swap.
  target_window->on_painting.AddListener(
      [this](xe::ui::UIEvent* e) { Swap(e); });

  // Create rendering control.
  // This must happen on the UI thread.
  std::unique_ptr<xe::ui::GraphicsContext> processor_context;
  target_loop_->PostSynchronous([&]() {
    // Setup the GL context the command processor will do all its drawing in.
    // It's shared with the display context so that we can resolve framebuffers
    // from it.
    processor_context = display_context_->CreateShared();
    processor_context->ClearCurrent();
  });
  if (!processor_context) {
    xe::FatalError(
        "Unable to initialize GL context. Xenia requires OpenGL 4.5. Ensure "
        "you have the latest drivers for your GPU and that it supports OpenGL "
        "4.5. See http://xenia.jp/faq/ for more information.");
    return X_STATUS_UNSUCCESSFUL;
  }

  // Create command processor. This will spin up a thread to process all
  // incoming ringbuffer packets.
  command_processor_ = std::make_unique<CommandProcessor>(this);
  if (!command_processor_->Initialize(std::move(processor_context))) {
    XELOGE("Unable to initialize command processor");
    return X_STATUS_UNSUCCESSFUL;
  }
  command_processor_->set_swap_request_handler(
      [this]() { target_window_->Invalidate(); });

  // Let the processor know we want register access callbacks.
  memory_->AddVirtualMappedRange(
      0x7FC80000, 0xFFFF0000, 0x0000FFFF, this,
      reinterpret_cast<cpu::MMIOReadCallback>(MMIOReadRegisterThunk),
      reinterpret_cast<cpu::MMIOWriteCallback>(MMIOWriteRegisterThunk));

  // 60hz vsync timer.
  worker_running_ = true;
  worker_thread_ =
      kernel::object_ref<kernel::XHostThread>(new kernel::XHostThread(
          emulator()->kernel_state(), 128 * 1024, 0, [this]() {
            uint64_t vsync_duration = FLAGS_vsync ? 16 : 1;
            uint64_t last_frame_time = Clock::QueryGuestTickCount();
            while (worker_running_) {
              uint64_t current_time = Clock::QueryGuestTickCount();
              uint64_t elapsed = (current_time - last_frame_time) /
                                 (Clock::guest_tick_frequency() / 1000);
              if (elapsed >= vsync_duration) {
                MarkVblank();
                last_frame_time = current_time;
              }
              xe::threading::Sleep(std::chrono::milliseconds(1));
            }
            return 0;
          }));
  // As we run vblank interrupts the debugger must be able to suspend us.
  worker_thread_->set_can_debugger_suspend(true);
  worker_thread_->set_name("GL4 Vsync");
  worker_thread_->Create();

  if (FLAGS_trace_gpu_stream) {
    BeginTracing();
  }

  return X_STATUS_SUCCESS;
}

void GL4GraphicsSystem::Shutdown() {
  EndTracing();

  worker_running_ = false;
  worker_thread_->Wait(0, 0, 0, nullptr);
  worker_thread_.reset();

  command_processor_->Shutdown();

  // TODO(benvanik): remove mapped range.

  command_processor_.reset();

  GraphicsSystem::Shutdown();
}

void GL4GraphicsSystem::InitializeRingBuffer(uint32_t ptr,
                                             uint32_t page_count) {
  command_processor_->InitializeRingBuffer(ptr, page_count);
}

void GL4GraphicsSystem::EnableReadPointerWriteBack(uint32_t ptr,
                                                   uint32_t block_size) {
  command_processor_->EnableReadPointerWriteBack(ptr, block_size);
}

void GL4GraphicsSystem::RequestFrameTrace() {
  command_processor_->RequestFrameTrace(xe::to_wstring(FLAGS_trace_gpu_prefix));
}

void GL4GraphicsSystem::BeginTracing() {
  command_processor_->BeginTracing(xe::to_wstring(FLAGS_trace_gpu_prefix));
}

void GL4GraphicsSystem::EndTracing() { command_processor_->EndTracing(); }

void GL4GraphicsSystem::PlayTrace(const uint8_t* trace_data, size_t trace_size,
                                  TracePlaybackMode playback_mode) {
  command_processor_->CallInThread([this, trace_data, trace_size,
                                    playback_mode]() {
    command_processor_->set_swap_mode(SwapMode::kIgnored);

    auto trace_ptr = trace_data;
    bool pending_break = false;
    const PacketStartCommand* pending_packet = nullptr;
    while (trace_ptr < trace_data + trace_size) {
      auto type = static_cast<TraceCommandType>(xe::load<uint32_t>(trace_ptr));
      switch (type) {
        case TraceCommandType::kPrimaryBufferStart: {
          auto cmd =
              reinterpret_cast<const PrimaryBufferStartCommand*>(trace_ptr);
          //
          trace_ptr += sizeof(*cmd) + cmd->count * 4;
          break;
        }
        case TraceCommandType::kPrimaryBufferEnd: {
          auto cmd =
              reinterpret_cast<const PrimaryBufferEndCommand*>(trace_ptr);
          //
          trace_ptr += sizeof(*cmd);
          break;
        }
        case TraceCommandType::kIndirectBufferStart: {
          auto cmd =
              reinterpret_cast<const IndirectBufferStartCommand*>(trace_ptr);
          //
          trace_ptr += sizeof(*cmd) + cmd->count * 4;
          break;
        }
        case TraceCommandType::kIndirectBufferEnd: {
          auto cmd =
              reinterpret_cast<const IndirectBufferEndCommand*>(trace_ptr);
          //
          trace_ptr += sizeof(*cmd);
          break;
        }
        case TraceCommandType::kPacketStart: {
          auto cmd = reinterpret_cast<const PacketStartCommand*>(trace_ptr);
          trace_ptr += sizeof(*cmd);
          std::memcpy(memory()->TranslatePhysical(cmd->base_ptr), trace_ptr,
                      cmd->count * 4);
          trace_ptr += cmd->count * 4;
          pending_packet = cmd;
          break;
        }
        case TraceCommandType::kPacketEnd: {
          auto cmd = reinterpret_cast<const PacketEndCommand*>(trace_ptr);
          trace_ptr += sizeof(*cmd);
          if (pending_packet) {
            command_processor_->ExecutePacket(pending_packet->base_ptr,
                                              pending_packet->count);
            pending_packet = nullptr;
          }
          if (pending_break) {
            return;
          }
          break;
        }
        case TraceCommandType::kMemoryRead: {
          auto cmd = reinterpret_cast<const MemoryReadCommand*>(trace_ptr);
          trace_ptr += sizeof(*cmd);
          std::memcpy(memory()->TranslatePhysical(cmd->base_ptr), trace_ptr,
                      cmd->length);
          trace_ptr += cmd->length;
          break;
        }
        case TraceCommandType::kMemoryWrite: {
          auto cmd = reinterpret_cast<const MemoryWriteCommand*>(trace_ptr);
          trace_ptr += sizeof(*cmd);
          // ?
          trace_ptr += cmd->length;
          break;
        }
        case TraceCommandType::kEvent: {
          auto cmd = reinterpret_cast<const EventCommand*>(trace_ptr);
          trace_ptr += sizeof(*cmd);
          switch (cmd->event_type) {
            case EventType::kSwap: {
              if (playback_mode == TracePlaybackMode::kBreakOnSwap) {
                pending_break = true;
              }
              break;
            }
          }
          break;
        }
      }
    }

    command_processor_->set_swap_mode(SwapMode::kNormal);
    command_processor_->IssueSwap(0, 1280, 720);
  });
}

void GL4GraphicsSystem::ClearCaches() {
  command_processor_->CallInThread(
      [&]() { command_processor_->ClearCaches(); });
}

void GL4GraphicsSystem::MarkVblank() {
  SCOPE_profile_cpu_f("gpu");

  // Increment vblank counter (so the game sees us making progress).
  command_processor_->increment_counter();

  // TODO(benvanik): we shouldn't need to do the dispatch here, but there's
  //     something wrong and the CP will block waiting for code that
  //     needs to be run in the interrupt.
  DispatchInterruptCallback(0, 2);
}

void GL4GraphicsSystem::Swap(xe::ui::UIEvent* e) {
  if (!command_processor_) {
    return;
  }
  // Check for pending swap.
  auto& swap_state = command_processor_->swap_state();
  {
    std::lock_guard<std::mutex> lock(swap_state.mutex);
    if (swap_state.pending) {
      swap_state.pending = false;
      std::swap(swap_state.front_buffer_texture,
                swap_state.back_buffer_texture);
    }
  }

  if (!swap_state.front_buffer_texture) {
    // Not yet ready.
    return;
  }

  // Blit the frontbuffer.
  display_context_->blitter()->BlitTexture2D(
      swap_state.front_buffer_texture,
      Rect2D(0, 0, swap_state.width, swap_state.height),
      Rect2D(0, 0, target_window_->width(), target_window_->height()),
      GL_LINEAR);
}

uint32_t GL4GraphicsSystem::ReadRegister(uint32_t addr) {
  uint32_t r = addr & 0xFFFF;

  switch (r) {
    case 0x3C00:  // ?
      return 0x08100748;
    case 0x3C04:  // ?
      return 0x0000200E;
    case 0x6530:  // Scanline?
      return 0x000002D0;
    case 0x6544:  // ? vblank pending?
      return 1;
    case 0x6584:  // Screen res - 1280x720
      return 0x050002D0;
  }

  assert_true(r < RegisterFile::kRegisterCount);
  return register_file_.values[r].u32;
}

void GL4GraphicsSystem::WriteRegister(uint32_t addr, uint32_t value) {
  uint32_t r = addr & 0xFFFF;

  switch (r) {
    case 0x0714:  // CP_RB_WPTR
      command_processor_->UpdateWritePointer(value);
      break;
    case 0x6110:  // ? swap related?
      XELOGW("Unimplemented GPU register %.4X write: %.8X", r, value);
      return;
    default:
      XELOGW("Unknown GPU register %.4X write: %.8X", r, value);
      break;
  }

  assert_true(r < RegisterFile::kRegisterCount);
  register_file_.values[r].u32 = value;
}

}  // namespace gl4
}  // namespace gpu
}  // namespace xe