/* SPDX-FileCopyrightText: 2016 by Mike Erwin. All rights reserved.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup gpu
 *
 * This interface allow GPU to manage GL objects for multiple context and threads.
 */

#pragma once

#include "BKE_global.hh"

#include "GPU_batch.hh"
#include "GPU_context.hh"
#include "GPU_texture_pool.hh"

#include "gpu_debug_private.hh"
#include "gpu_framebuffer_private.hh"
#include "gpu_immediate_private.hh"
#include "gpu_shader_private.hh"
#include "gpu_state_private.hh"

#include <pthread.h>

struct GPUMatrixState;

namespace blender::gpu {

class Context {
 public:
  /** State management */
  Shader *shader = nullptr;
  FrameBuffer *active_fb = nullptr;
  GPUMatrixState *matrix_state = nullptr;
  StateManager *state_manager = nullptr;
  Immediate *imm = nullptr;

  /**
   * All 4 window frame-buffers.
   * None of them are valid in an off-screen context.
   * Right frame-buffers are only available if using stereo rendering.
   * Front frame-buffers contains (in principle, but not always) the last frame color.
   * Default frame-buffer is back_left.
   */
  FrameBuffer *back_left = nullptr;
  FrameBuffer *front_left = nullptr;
  FrameBuffer *back_right = nullptr;
  FrameBuffer *front_right = nullptr;

  DebugStack debug_stack;
  bool debug_is_capturing = false;

  /* GPUContext counter used to assign a unique ID to each GPUContext.
   * NOTE(Metal): This is required by the Metal Backend, as a bug exists in the global OS shader
   * cache wherein compilation of identical source from two distinct threads can result in an
   * invalid cache collision, result in a broken shader object. Appending the unique context ID
   * onto compiled sources ensures the source hashes are different. */
  static int context_counter;
  int context_id = 0;

  /* Used as a stack. Each render_begin/end pair will push pop from the stack. */
  Vector<StorageBuf *> printf_buf;

  /** Dummy VBO to feed the procedural batches. */
  VertBuf *dummy_vbo = nullptr;
  /** Dummy batches for procedural geometry rendering. */
  Batch *procedural_points_batch = nullptr;
  Batch *procedural_lines_batch = nullptr;
  Batch *procedural_triangles_batch = nullptr;
  Batch *procedural_triangle_strips_batch = nullptr;

  /** Texture pool used to recycle temporary texture (or render target) memory. */
  TexturePool *texture_pool = nullptr;

  /** Global state to avoid setting the srgb builtin uniform for every shader bind. */
  int shader_builtin_srgb_transform = 0;
  bool shader_builtin_srgb_is_dirty = false;

 protected:
  /** Thread on which this context is active. */
  pthread_t thread_;
  bool is_active_;
  /** Avoid including GHOST headers. Can be nullptr for off-screen contexts. */
  void *ghost_window_;

 public:
  Context();
  virtual ~Context();

  static Context *get();

  virtual void activate() = 0;
  virtual void deactivate() = 0;
  virtual void begin_frame() = 0;
  virtual void end_frame() = 0;

  /* Will push all pending commands to the GPU. */
  virtual void flush() = 0;
  /* Will wait until the GPU has finished executing all command. */
  virtual void finish() = 0;

  virtual void memory_statistics_get(int *r_total_mem, int *r_free_mem) = 0;

  virtual void debug_group_begin(const char * /*name*/, int /*index*/){};
  virtual void debug_group_end(){};

  /* Returns true if capture successfully started. */
  virtual bool debug_capture_begin(const char *title) = 0;
  virtual void debug_capture_end() = 0;
  virtual void *debug_capture_scope_create(const char *name) = 0;
  virtual bool debug_capture_scope_begin(void *scope) = 0;
  virtual void debug_capture_scope_end(void *scope) = 0;

  /* Consider all buffers slot empty after these call for error checking.
   * But doesn't really free them. */
  virtual void debug_unbind_all_ubo() = 0;
  virtual void debug_unbind_all_ssbo() = 0;

  bool is_active_on_thread();

  VertBuf *dummy_vbo_get();
  Batch *procedural_points_batch_get();
  Batch *procedural_lines_batch_get();
  Batch *procedural_triangles_batch_get();
  Batch *procedural_triangle_strips_batch_get();

  /* When using `--debug-gpu`, assert that the shader fragments write to all the writable
   * attachments of the bound frame-buffer. */
  void assert_framebuffer_shader_compatibility(Shader *sh)
  {
    if (!(G.debug & G_DEBUG_GPU)) {
      return;
    }

    if (!(state_manager->state.write_mask & eGPUWriteMask::GPU_WRITE_COLOR)) {
      return;
    }

    uint16_t fragment_output_bits = sh->fragment_output_bits;
    uint16_t fb_attachments_bits = active_fb->get_color_attachments_bitset();

    if ((fb_attachments_bits & ~fragment_output_bits) != 0) {
      std::string msg;
      msg = msg + "Shader (" + sh->name_get() + ") does not write to all frame-buffer (" +
            active_fb->name_get() + ") color attachments";
      BLI_assert_msg(false, msg.c_str());
      std::cerr << msg << std::endl;
    }
  }

 protected:
  /**
   * Derived classes should call this from the destructor,
   * as freeing textures and frame-buffers may need the derived context to be valid.
   */
  void free_resources();
};

/* Syntactic sugar. */
static inline GPUContext *wrap(Context *ctx)
{
  return reinterpret_cast<GPUContext *>(ctx);
}
static inline Context *unwrap(GPUContext *ctx)
{
  return reinterpret_cast<Context *>(ctx);
}
static inline const Context *unwrap(const GPUContext *ctx)
{
  return reinterpret_cast<const Context *>(ctx);
}

}  // namespace blender::gpu