/*
 * 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.
 *
 * Copyright 2016, Blender Foundation.
 */

/** \file
 * \ingroup draw_engine
 *
 * Gather all screen space effects technique such as Bloom, Motion Blur, DoF, SSAO, SSR, ...
 */

#include "DRW_render.h"

#include "BKE_animsys.h"
#include "BKE_camera.h"
#include "BKE_object.h"

#include "DNA_anim_types.h"
#include "DNA_camera_types.h"
#include "DNA_screen_types.h"

#include "ED_screen.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_query.h"

#include "GPU_texture.h"
#include "eevee_private.h"

static struct {
  /* Motion Blur */
  struct GPUShader *motion_blur_sh;
} e_data = {NULL}; /* Engine data */

extern char datatoc_effect_motion_blur_frag_glsl[];

static void eevee_motion_blur_camera_get_matrix_at_time(Scene *scene,
                                                        ARegion *region,
                                                        RegionView3D *rv3d,
                                                        View3D *v3d,
                                                        Object *camera,
                                                        float time,
                                                        float r_mat[4][4])
{
  float obmat[4][4];

  /* HACK */
  Object cam_cpy = *camera;
  Camera camdata_cpy = *(Camera *)(camera->data);
  cam_cpy.data = &camdata_cpy;

  /* Reset original pointers, so direct evaluation does not attempt to flush
   * animation back to the original object: otherwise viewport with motion
   * blur enabled will always loose non-keyed changes. */
  cam_cpy.id.orig_id = NULL;
  camdata_cpy.id.orig_id = NULL;

  const DRWContextState *draw_ctx = DRW_context_state_get();

  /* Past matrix */
  /* FIXME : This is a temporal solution that does not take care of parent animations */
  /* Recalc Anim manually */
  BKE_animsys_evaluate_animdata(
      scene, &camdata_cpy.id, camdata_cpy.adt, time, ADT_RECALC_ALL, false);
  BKE_object_where_is_calc_time(draw_ctx->depsgraph, scene, &cam_cpy, time);

  /* Compute winmat */
  CameraParams params;
  BKE_camera_params_init(&params);

  if (v3d != NULL) {
    BKE_camera_params_from_view3d(&params, draw_ctx->depsgraph, v3d, rv3d);
    BKE_camera_params_compute_viewplane(&params, region->winx, region->winy, 1.0f, 1.0f);
  }
  else {
    BKE_camera_params_from_object(&params, &cam_cpy);
    BKE_camera_params_compute_viewplane(
        &params, scene->r.xsch, scene->r.ysch, scene->r.xasp, scene->r.yasp);
  }

  BKE_camera_params_compute_matrix(&params);

  /* FIXME Should be done per view (MULTIVIEW) */
  normalize_m4_m4(obmat, cam_cpy.obmat);
  invert_m4(obmat);
  mul_m4_m4m4(r_mat, params.winmat, obmat);
}

static void eevee_create_shader_motion_blur(void)
{
  e_data.motion_blur_sh = DRW_shader_create_fullscreen(datatoc_effect_motion_blur_frag_glsl, NULL);
}

int EEVEE_motion_blur_init(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data *vedata, Object *camera)
{
  EEVEE_StorageList *stl = vedata->stl;
  EEVEE_EffectsInfo *effects = stl->effects;

  const DRWContextState *draw_ctx = DRW_context_state_get();
  const Scene *scene_eval = DEG_get_evaluated_scene(draw_ctx->depsgraph);
  Scene *scene = draw_ctx->scene;

  View3D *v3d = draw_ctx->v3d;
  RegionView3D *rv3d = draw_ctx->rv3d;
  ARegion *region = draw_ctx->region;

  if (scene_eval->eevee.flag & SCE_EEVEE_MOTION_BLUR_ENABLED) {
    /* Update Motion Blur Matrices */
    if (camera && (camera->type == OB_CAMERA) && (camera->data != NULL)) {
      float persmat[4][4];
      float ctime = DEG_get_ctime(draw_ctx->depsgraph);
      float delta = scene_eval->eevee.motion_blur_shutter;
      Object *ob_camera_eval = DEG_get_evaluated_object(draw_ctx->depsgraph, camera);

      /* Viewport Matrix */
      /* Note: This does not have TAA jitter applied. */
      DRW_view_persmat_get(NULL, persmat, false);

      bool view_is_valid = (stl->g_data->view_updated == false);

      if (draw_ctx->evil_C != NULL) {
        struct wmWindowManager *wm = CTX_wm_manager(draw_ctx->evil_C);
        view_is_valid = view_is_valid && (ED_screen_animation_no_scrub(wm) == NULL);
      }

      /* The view is jittered by the oglrenderer. So avoid testing in this case. */
      if (!DRW_state_is_image_render()) {
        view_is_valid = view_is_valid && compare_m4m4(persmat, effects->prev_drw_persmat, FLT_MIN);
        /* WATCH: assume TAA init code runs last. */
        if (scene_eval->eevee.taa_samples == 1) {
          /* Only if TAA is disabled. If not, TAA will update prev_drw_persmat itself. */
          copy_m4_m4(effects->prev_drw_persmat, persmat);
        }
      }

      effects->motion_blur_mat_cached = view_is_valid && !DRW_state_is_image_render();

      /* Current matrix */
      if (effects->motion_blur_mat_cached == false) {
        eevee_motion_blur_camera_get_matrix_at_time(
            scene, region, rv3d, v3d, ob_camera_eval, ctime, effects->current_world_to_ndc);
      }

      /* Only continue if camera is not being keyed */
      if (DRW_state_is_image_render() ||
          compare_m4m4(persmat, effects->current_world_to_ndc, 0.0001f)) {
        /* Past matrix */
        if (effects->motion_blur_mat_cached == false) {
          eevee_motion_blur_camera_get_matrix_at_time(
              scene, region, rv3d, v3d, ob_camera_eval, ctime - delta, effects->past_world_to_ndc);

#if 0 /* for future high quality blur */
          /* Future matrix */
          eevee_motion_blur_camera_get_matrix_at_time(
              scene, region, rv3d, v3d, ob_camera_eval, ctime + delta, effects->future_world_to_ndc);
#endif
          invert_m4_m4(effects->current_ndc_to_world, effects->current_world_to_ndc);
        }

        effects->motion_blur_mat_cached = true;
        effects->motion_blur_samples = scene_eval->eevee.motion_blur_samples;

        if (!e_data.motion_blur_sh) {
          eevee_create_shader_motion_blur();
        }

        return EFFECT_MOTION_BLUR | EFFECT_POST_BUFFER;
      }
    }
  }

  return 0;
}

void EEVEE_motion_blur_cache_init(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data *vedata)
{
  EEVEE_PassList *psl = vedata->psl;
  EEVEE_StorageList *stl = vedata->stl;
  EEVEE_EffectsInfo *effects = stl->effects;
  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();

  struct GPUBatch *quad = DRW_cache_fullscreen_quad_get();

  if ((effects->enabled_effects & EFFECT_MOTION_BLUR) != 0) {
    DRW_PASS_CREATE(psl->motion_blur, DRW_STATE_WRITE_COLOR);

    DRWShadingGroup *grp = DRW_shgroup_create(e_data.motion_blur_sh, psl->motion_blur);
    DRW_shgroup_uniform_int(grp, "samples", &effects->motion_blur_samples, 1);
    DRW_shgroup_uniform_mat4(grp, "currInvViewProjMatrix", effects->current_ndc_to_world);
    DRW_shgroup_uniform_mat4(grp, "pastViewProjMatrix", effects->past_world_to_ndc);
    DRW_shgroup_uniform_texture_ref(grp, "colorBuffer", &effects->source_buffer);
    DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
    DRW_shgroup_call(grp, quad, NULL);
  }
}

void EEVEE_motion_blur_draw(EEVEE_Data *vedata)
{
  EEVEE_PassList *psl = vedata->psl;
  EEVEE_TextureList *txl = vedata->txl;
  EEVEE_FramebufferList *fbl = vedata->fbl;
  EEVEE_StorageList *stl = vedata->stl;
  EEVEE_EffectsInfo *effects = stl->effects;

  /* Motion Blur */
  if ((effects->enabled_effects & EFFECT_MOTION_BLUR) != 0) {
    GPU_framebuffer_bind(effects->target_buffer);
    DRW_draw_pass(psl->motion_blur);
    SWAP_BUFFERS();
  }
}

void EEVEE_motion_blur_free(void)
{
  DRW_SHADER_FREE_SAFE(e_data.motion_blur_sh);
}