/*
 * 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 2018, Blender Foundation.
 */

/** \file
 * \ingroup draw
 *
 * \brief Simple API to draw debug shapes in the viewport.
 */

#include "MEM_guardedalloc.h"

#include "DNA_object_types.h"

#include "BKE_object.h"

#include "BLI_link_utils.h"

#include "GPU_immediate.h"

#include "draw_debug.h"
#include "draw_manager.h"

/* --------- Register --------- */

/* Matrix applied to all points before drawing. Could be a stack if needed. */
static float g_modelmat[4][4];

void DRW_debug_modelmat_reset(void)
{
  unit_m4(g_modelmat);
}

void DRW_debug_modelmat(const float modelmat[4][4])
{
  copy_m4_m4(g_modelmat, modelmat);
}

void DRW_debug_line_v3v3(const float v1[3], const float v2[3], const float color[4])
{
  DRWDebugLine *line = MEM_mallocN(sizeof(DRWDebugLine), "DRWDebugLine");
  mul_v3_m4v3(line->pos[0], g_modelmat, v1);
  mul_v3_m4v3(line->pos[1], g_modelmat, v2);
  copy_v4_v4(line->color, color);
  BLI_LINKS_PREPEND(DST.debug.lines, line);
}

void DRW_debug_polygon_v3(const float (*v)[3], const int vert_len, const float color[4])
{
  BLI_assert(vert_len > 1);

  for (int i = 0; i < vert_len; i++) {
    DRW_debug_line_v3v3(v[i], v[(i + 1) % vert_len], color);
  }
}

void DRW_debug_m4(const float m[4][4])
{
  float v0[3] = {0.0f, 0.0f, 0.0f};
  float v1[3] = {1.0f, 0.0f, 0.0f};
  float v2[3] = {0.0f, 1.0f, 0.0f};
  float v3[3] = {0.0f, 0.0f, 1.0f};

  mul_m4_v3(m, v0);
  mul_m4_v3(m, v1);
  mul_m4_v3(m, v2);
  mul_m4_v3(m, v3);

  DRW_debug_line_v3v3(v0, v1, (float[4]){1.0f, 0.0f, 0.0f, 1.0f});
  DRW_debug_line_v3v3(v0, v2, (float[4]){0.0f, 1.0f, 0.0f, 1.0f});
  DRW_debug_line_v3v3(v0, v3, (float[4]){0.0f, 0.0f, 1.0f, 1.0f});
}

void DRW_debug_bbox(const BoundBox *bbox, const float color[4])
{
  DRW_debug_line_v3v3(bbox->vec[0], bbox->vec[1], color);
  DRW_debug_line_v3v3(bbox->vec[1], bbox->vec[2], color);
  DRW_debug_line_v3v3(bbox->vec[2], bbox->vec[3], color);
  DRW_debug_line_v3v3(bbox->vec[3], bbox->vec[0], color);

  DRW_debug_line_v3v3(bbox->vec[4], bbox->vec[5], color);
  DRW_debug_line_v3v3(bbox->vec[5], bbox->vec[6], color);
  DRW_debug_line_v3v3(bbox->vec[6], bbox->vec[7], color);
  DRW_debug_line_v3v3(bbox->vec[7], bbox->vec[4], color);

  DRW_debug_line_v3v3(bbox->vec[0], bbox->vec[4], color);
  DRW_debug_line_v3v3(bbox->vec[1], bbox->vec[5], color);
  DRW_debug_line_v3v3(bbox->vec[2], bbox->vec[6], color);
  DRW_debug_line_v3v3(bbox->vec[3], bbox->vec[7], color);
}

void DRW_debug_m4_as_bbox(const float m[4][4], const float color[4], const bool invert)
{
  BoundBox bb;
  const float min[3] = {-1.0f, -1.0f, -1.0f}, max[3] = {1.0f, 1.0f, 1.0f};
  float project_matrix[4][4];
  if (invert) {
    invert_m4_m4(project_matrix, m);
  }
  else {
    copy_m4_m4(project_matrix, m);
  }

  BKE_boundbox_init_from_minmax(&bb, min, max);
  for (int i = 0; i < 8; i++) {
    mul_project_m4_v3(project_matrix, bb.vec[i]);
  }
  DRW_debug_bbox(&bb, color);
}

void DRW_debug_sphere(const float center[3], const float radius, const float color[4])
{
  float size_mat[4][4];
  DRWDebugSphere *sphere = MEM_mallocN(sizeof(DRWDebugSphere), "DRWDebugSphere");
  /* Bake all transform into a Matrix4 */
  scale_m4_fl(size_mat, radius);
  copy_m4_m4(sphere->mat, g_modelmat);
  translate_m4(sphere->mat, center[0], center[1], center[2]);
  mul_m4_m4m4(sphere->mat, sphere->mat, size_mat);

  copy_v4_v4(sphere->color, color);
  BLI_LINKS_PREPEND(DST.debug.spheres, sphere);
}

/* --------- Render --------- */

static void drw_debug_draw_lines(void)
{
  int count = BLI_linklist_count((LinkNode *)DST.debug.lines);

  if (count == 0) {
    return;
  }

  GPUVertFormat *vert_format = immVertexFormat();
  uint pos = GPU_vertformat_attr_add(vert_format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
  uint col = GPU_vertformat_attr_add(vert_format, "color", GPU_COMP_F32, 4, GPU_FETCH_FLOAT);

  immBindBuiltinProgram(GPU_SHADER_3D_FLAT_COLOR);

  immBegin(GPU_PRIM_LINES, count * 2);

  while (DST.debug.lines) {
    void *next = DST.debug.lines->next;

    immAttr4fv(col, DST.debug.lines->color);
    immVertex3fv(pos, DST.debug.lines->pos[0]);

    immAttr4fv(col, DST.debug.lines->color);
    immVertex3fv(pos, DST.debug.lines->pos[1]);

    MEM_freeN(DST.debug.lines);
    DST.debug.lines = next;
  }
  immEnd();

  immUnbindProgram();
}

static void drw_debug_draw_spheres(void)
{
  int count = BLI_linklist_count((LinkNode *)DST.debug.spheres);

  if (count == 0) {
    return;
  }

  float one = 1.0f;
  GPUVertFormat vert_format = {0};
  uint mat = GPU_vertformat_attr_add(
      &vert_format, "InstanceModelMatrix", GPU_COMP_F32, 16, GPU_FETCH_FLOAT);
  uint col = GPU_vertformat_attr_add(&vert_format, "color", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
  uint siz = GPU_vertformat_attr_add(&vert_format, "size", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);

  GPUVertBuf *inst_vbo = GPU_vertbuf_create_with_format(&vert_format);

  GPU_vertbuf_data_alloc(inst_vbo, count);

  int v = 0;
  while (DST.debug.spheres) {
    void *next = DST.debug.spheres->next;

    GPU_vertbuf_attr_set(inst_vbo, mat, v, DST.debug.spheres->mat[0]);
    GPU_vertbuf_attr_set(inst_vbo, col, v, DST.debug.spheres->color);
    GPU_vertbuf_attr_set(inst_vbo, siz, v, &one);
    v++;

    MEM_freeN(DST.debug.spheres);
    DST.debug.spheres = next;
  }

  GPUBatch *empty_sphere = DRW_cache_empty_sphere_get();

  GPUBatch *draw_batch = GPU_batch_create(GPU_PRIM_LINES, empty_sphere->verts[0], NULL);
  GPU_batch_instbuf_set(draw_batch, inst_vbo, true);
  GPU_batch_program_set_builtin(draw_batch, GPU_SHADER_INSTANCE_VARIYING_COLOR_VARIYING_SIZE);

  float persmat[4][4];
  DRW_view_persmat_get(NULL, persmat, false);
  GPU_batch_uniform_mat4(draw_batch, "ViewProjectionMatrix", persmat);

  GPU_batch_draw(draw_batch);
  GPU_batch_discard(draw_batch);
}

void drw_debug_draw(void)
{
  drw_debug_draw_lines();
  drw_debug_draw_spheres();
}

void drw_debug_init(void)
{
  DRW_debug_modelmat_reset();
}