/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup gpu
 */

#ifndef GPU_STANDALONE
#  include "DNA_userdef_types.h"
#  define PIXELSIZE (U.pixelsize)
#else
#  define PIXELSIZE (1.0f)
#endif

#include "BLI_math_vector.h"
#include "BLI_utildefines.h"

#include "BKE_global.h"

#include "GPU_extensions.h"
#include "GPU_glew.h"
#include "GPU_state.h"

#include "gpu_context_private.hh"

#include "gpu_state_private.hh"

using namespace blender::gpu;

#define SET_STATE(_prefix, _state, _value) \
  do { \
    GPUStateManager *stack = GPU_context_active_get()->state_manager; \
    auto &state_object = stack->_prefix##state; \
    state_object._state = (_value); \
  } while (0)

#define SET_IMMUTABLE_STATE(_state, _value) SET_STATE(, _state, _value)
#define SET_MUTABLE_STATE(_state, _value) SET_STATE(mutable_, _state, _value)

/* -------------------------------------------------------------------- */
/** \name Immutable state Setters
 * \{ */

void GPU_blend(eGPUBlend blend)
{
  SET_IMMUTABLE_STATE(blend, blend);
}

void GPU_face_culling(eGPUFaceCullTest culling)
{
  SET_IMMUTABLE_STATE(culling_test, culling);
}

void GPU_front_facing(bool invert)
{
  SET_IMMUTABLE_STATE(invert_facing, invert);
}

void GPU_provoking_vertex(eGPUProvokingVertex vert)
{
  SET_IMMUTABLE_STATE(provoking_vert, vert);
}

void GPU_depth_test(eGPUDepthTest test)
{
  SET_IMMUTABLE_STATE(depth_test, test);
}

void GPU_stencil_test(eGPUStencilTest test)
{
  SET_IMMUTABLE_STATE(stencil_test, test);
}

void GPU_line_smooth(bool enable)
{
  SET_IMMUTABLE_STATE(line_smooth, enable);
}

void GPU_polygon_smooth(bool enable)
{
  SET_IMMUTABLE_STATE(polygon_smooth, enable);
}

void GPU_logic_op_xor_set(bool enable)
{
  SET_IMMUTABLE_STATE(logic_op_xor, enable);
}

void GPU_write_mask(eGPUWriteMask mask)
{
  SET_IMMUTABLE_STATE(write_mask, mask);
}

void GPU_color_mask(bool r, bool g, bool b, bool a)
{
  GPUStateManager *stack = GPU_context_active_get()->state_manager;
  auto &state = stack->state;
  uint32_t write_mask = state.write_mask;
  SET_FLAG_FROM_TEST(write_mask, r, (uint32_t)GPU_WRITE_RED);
  SET_FLAG_FROM_TEST(write_mask, g, (uint32_t)GPU_WRITE_GREEN);
  SET_FLAG_FROM_TEST(write_mask, b, (uint32_t)GPU_WRITE_BLUE);
  SET_FLAG_FROM_TEST(write_mask, a, (uint32_t)GPU_WRITE_ALPHA);
  state.write_mask = write_mask;
}

void GPU_depth_mask(bool depth)
{
  GPUStateManager *stack = GPU_context_active_get()->state_manager;
  auto &state = stack->state;
  uint32_t write_mask = state.write_mask;
  SET_FLAG_FROM_TEST(write_mask, depth, (uint32_t)GPU_WRITE_DEPTH);
  state.write_mask = write_mask;
}

void GPU_shadow_offset(bool enable)
{
  SET_IMMUTABLE_STATE(shadow_bias, enable);
}

void GPU_clip_distances(int distances_enabled)
{
  SET_IMMUTABLE_STATE(clip_distances, distances_enabled);
}

void GPU_state_set(eGPUWriteMask write_mask,
                   eGPUBlend blend,
                   eGPUFaceCullTest culling_test,
                   eGPUDepthTest depth_test,
                   eGPUStencilTest stencil_test,
                   eGPUStencilOp stencil_op,
                   eGPUProvokingVertex provoking_vert)
{
  GPUStateManager *stack = GPU_context_active_get()->state_manager;
  auto &state = stack->state;
  state.write_mask = (uint32_t)write_mask;
  state.blend = (uint32_t)blend;
  state.culling_test = (uint32_t)culling_test;
  state.depth_test = (uint32_t)depth_test;
  state.stencil_test = (uint32_t)stencil_test;
  state.stencil_op = (uint32_t)stencil_op;
  state.provoking_vert = (uint32_t)provoking_vert;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Mutable State Setters
 * \{ */

void GPU_depth_range(float near, float far)
{
  GPUStateManager *stack = GPU_context_active_get()->state_manager;
  auto &state = stack->mutable_state;
  copy_v2_fl2(state.depth_range, near, far);
}

void GPU_line_width(float width)
{
  SET_MUTABLE_STATE(line_width, width * PIXELSIZE);
}

void GPU_point_size(float size)
{
  SET_MUTABLE_STATE(point_size, size * PIXELSIZE);
}

/* Programmable point size
 * - shaders set their own point size when enabled
 * - use glPointSize when disabled */
/* TODO remove and use program point size everywhere */
void GPU_program_point_size(bool enable)
{
  GPUStateManager *stack = GPU_context_active_get()->state_manager;
  auto &state = stack->mutable_state;
  /* Set point size sign negative to disable. */
  state.point_size = fabsf(state.point_size) * (enable ? 1 : -1);
}

void GPU_scissor_test(bool enable)
{
  GPU_context_active_get()->active_fb->scissor_test_set(enable);
}

void GPU_scissor(int x, int y, int width, int height)
{
  int scissor_rect[4] = {x, y, width, height};
  GPU_context_active_get()->active_fb->scissor_set(scissor_rect);
}

void GPU_viewport(int x, int y, int width, int height)
{
  int viewport_rect[4] = {x, y, width, height};
  GPU_context_active_get()->active_fb->viewport_set(viewport_rect);
}

void GPU_stencil_reference_set(uint reference)
{
  SET_MUTABLE_STATE(stencil_reference, (uint8_t)reference);
}

void GPU_stencil_write_mask_set(uint write_mask)
{
  SET_MUTABLE_STATE(stencil_write_mask, (uint8_t)write_mask);
}

void GPU_stencil_compare_mask_set(uint compare_mask)
{
  SET_MUTABLE_STATE(stencil_compare_mask, (uint8_t)compare_mask);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name State Getters
 * \{ */

eGPUBlend GPU_blend_get()
{
  GPUState &state = GPU_context_active_get()->state_manager->state;
  return (eGPUBlend)state.blend;
}

eGPUWriteMask GPU_write_mask_get()
{
  GPUState &state = GPU_context_active_get()->state_manager->state;
  return (eGPUWriteMask)state.write_mask;
}

uint GPU_stencil_mask_get()
{
  GPUStateMutable &state = GPU_context_active_get()->state_manager->mutable_state;
  return state.stencil_write_mask;
}

eGPUDepthTest GPU_depth_test_get()
{
  GPUState &state = GPU_context_active_get()->state_manager->state;
  return (eGPUDepthTest)state.depth_test;
}

eGPUStencilTest GPU_stencil_test_get()
{
  GPUState &state = GPU_context_active_get()->state_manager->state;
  return (eGPUStencilTest)state.stencil_test;
}

void GPU_scissor_get(int coords[4])
{
  GPU_context_active_get()->active_fb->scissor_get(coords);
}

void GPU_viewport_size_get_f(float coords[4])
{
  int viewport[4];
  GPU_context_active_get()->active_fb->viewport_get(viewport);
  for (int i = 0; i < 4; i++) {
    coords[i] = viewport[i];
  }
}

void GPU_viewport_size_get_i(int coords[4])
{
  GPU_context_active_get()->active_fb->viewport_get(coords);
}

bool GPU_depth_mask_get(void)
{
  GPUState &state = GPU_context_active_get()->state_manager->state;
  return (state.write_mask & GPU_WRITE_DEPTH) != 0;
}

bool GPU_mipmap_enabled(void)
{
  /* TODO(fclem) this used to be a userdef option. */
  return true;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Context Utils
 * \{ */

void GPU_flush(void)
{
  glFlush();
}

void GPU_finish(void)
{
  glFinish();
}

void GPU_unpack_row_length_set(uint len)
{
  glPixelStorei(GL_UNPACK_ROW_LENGTH, len);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Default OpenGL State
 *
 * This is called on startup, for opengl offscreen render.
 * Generally we should always return to this state when
 * temporarily modifying the state for drawing, though that are (undocumented)
 * exceptions that we should try to get rid of.
 * \{ */

GPUStateManager::GPUStateManager(void)
{
  /* Set default state. */
  state.write_mask = GPU_WRITE_COLOR;
  state.blend = GPU_BLEND_NONE;
  state.culling_test = GPU_CULL_NONE;
  state.depth_test = GPU_DEPTH_NONE;
  state.stencil_test = GPU_STENCIL_NONE;
  state.stencil_op = GPU_STENCIL_OP_NONE;
  state.provoking_vert = GPU_VERTEX_LAST;
  state.logic_op_xor = false;
  state.invert_facing = false;
  state.shadow_bias = false;
  state.polygon_smooth = false;
  state.clip_distances = 0;

  mutable_state.depth_range[0] = 0.0f;
  mutable_state.depth_range[1] = 1.0f;
  mutable_state.point_size = 1.0f;
  mutable_state.line_width = 1.0f;
  mutable_state.stencil_write_mask = 0x00;
  mutable_state.stencil_compare_mask = 0x00;
  mutable_state.stencil_reference = 0x00;
}

/** \} */