/*
 * 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_state.h"

#include "gpu_context_private.hh"

#include "gpu_state_private.hh"

using namespace blender::gpu;

#define SET_STATE(_prefix, _state, _value) \
  do { \
    StateManager *stack = Context::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)
{
  StateManager *stack = Context::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)
{
  StateManager *stack = Context::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)
{
  StateManager *stack = Context::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)
{
  StateManager *stack = Context::get()->state_manager;
  auto &state = stack->mutable_state;
  copy_v2_fl2(state.depth_range, near, far);
}

/**
 * \note By convention, this is set as needed and not reset back to 1.0.
 * This means code that draws lines must always set the line width beforehand,
 * but is not expected to restore it's previous value.
 */
void GPU_line_width(float width)
{
  width = max_ff(1.0f, width * PIXELSIZE);
  SET_MUTABLE_STATE(line_width, width);
}

void GPU_point_size(float size)
{
  StateManager *stack = Context::get()->state_manager;
  auto &state = stack->mutable_state;
  /* Keep the sign of point_size since it represents the enable state. */
  state.point_size = size * ((state.point_size > 0.0) ? 1.0f : -1.0f);
}

/* Programmable point size
 * - shaders set their own point size when enabled
 * - use GPU_point_size when disabled */
/* TODO: remove and use program point size everywhere. */
void GPU_program_point_size(bool enable)
{
  StateManager *stack = Context::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)
{
  Context::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};
  Context::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};
  Context::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 = Context::get()->state_manager->state;
  return (eGPUBlend)state.blend;
}

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

uint GPU_stencil_mask_get()
{
  const GPUStateMutable &state = Context::get()->state_manager->mutable_state;
  return state.stencil_write_mask;
}

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

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

/* NOTE: Already premultiplied by U.pixelsize. */
float GPU_line_width_get()
{
  const GPUStateMutable &state = Context::get()->state_manager->mutable_state;
  return state.line_width;
}

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

void GPU_viewport_size_get_f(float coords[4])
{
  int viewport[4];
  Context::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])
{
  Context::get()->active_fb->viewport_get(coords);
}

bool GPU_depth_mask_get()
{
  const GPUState &state = Context::get()->state_manager->state;
  return (state.write_mask & GPU_WRITE_DEPTH) != 0;
}

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

/** \} */

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

void GPU_flush()
{
  Context::get()->flush();
}

void GPU_finish()
{
  Context::get()->finish();
}

void GPU_apply_state()
{
  Context::get()->state_manager->apply_state();
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name BGL workaround
 *
 * bgl makes direct GL calls that makes our state tracking out of date.
 * This flag make it so that the pyGPU calls will not override the state set by
 * bgl functions.
 * \{ */

void GPU_bgl_start()
{
  Context *ctx = Context::get();
  if (!(ctx && ctx->state_manager)) {
    return;
  }
  StateManager &state_manager = *(Context::get()->state_manager);
  if (state_manager.use_bgl == false) {
    /* Expected by many addons (see T80169, T81289).
     * This will reset the blend function. */
    GPU_blend(GPU_BLEND_NONE);

    /* Equivalent of setting the depth func `glDepthFunc(GL_LEQUAL)`
     * Needed since Python scripts may enable depth test.
     * Without this block the depth test function is undefined. */
    {
      eGPUDepthTest depth_test_real = GPU_depth_test_get();
      eGPUDepthTest depth_test_temp = GPU_DEPTH_LESS_EQUAL;
      if (depth_test_real != depth_test_temp) {
        GPU_depth_test(depth_test_temp);
        state_manager.apply_state();
        GPU_depth_test(depth_test_real);
      }
    }

    state_manager.apply_state();
    state_manager.use_bgl = true;
  }
}

/* Just turn off the bgl safeguard system. Can be called even without GPU_bgl_start. */
void GPU_bgl_end()
{
  Context *ctx = Context::get();
  if (!(ctx && ctx->state_manager)) {
    return;
  }
  StateManager &state_manager = *ctx->state_manager;
  if (state_manager.use_bgl == true) {
    state_manager.use_bgl = false;
    /* Resync state tracking. */
    state_manager.force_state();
  }
}

bool GPU_bgl_get()
{
  return Context::get()->state_manager->use_bgl;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Synchronization Utils
 * \{ */

void GPU_memory_barrier(eGPUBarrier barrier)
{
  Context::get()->state_manager->issue_barrier(barrier);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Default State
 * \{ */

StateManager::StateManager()
{
  /* 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.clip_distances = 0;
  state.polygon_smooth = false;
  state.line_smooth = false;

  mutable_state.depth_range[0] = 0.0f;
  mutable_state.depth_range[1] = 1.0f;
  mutable_state.point_size = -1.0f; /* Negative is not using point size. */
  mutable_state.line_width = 1.0f;
  mutable_state.stencil_write_mask = 0x00;
  mutable_state.stencil_compare_mask = 0x00;
  mutable_state.stencil_reference = 0x00;
}

/** \} */
