/*
 * 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.
 *
 * The Original Code is Copyright (C) 2009/2018 by the Blender Foundation.
 */

/** \file
 * \ingroup draw
 */

#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "BLI_sys_types.h"

#include "DNA_armature_types.h"
#include "DNA_scene_types.h"
#include "DNA_view3d_types.h"
#include "DNA_object_types.h"

#include "BLI_math.h"

#include "UI_resources.h"

#include "DEG_depsgraph_query.h"

#include "DRW_engine.h"
#include "DRW_render.h"

#include "GPU_shader.h"
#include "GPU_immediate.h"

#include "draw_common.h"
#include "draw_manager_text.h"

#include "draw_mode_engines.h"

/* ********************************* Lists ************************************** */
/* All lists are per viewport specific datas.
 * They are all free when viewport changes engines
 * or is free itself.
 */

/* XXX: How to show frame numbers, etc.?  Currently only doing the dots and lines */
typedef struct MPATH_PassList {
  struct DRWPass *lines;
  struct DRWPass *points;
} MPATH_PassList;

typedef struct MPATH_StorageList {
  struct MPATH_PrivateData *g_data;
} MPATH_StorageList;

typedef struct MPATH_Data {
  void *engine_type;
  DRWViewportEmptyList *fbl;
  DRWViewportEmptyList *txl;
  MPATH_PassList *psl;
  MPATH_StorageList *stl;
} MPATH_Data;

#if 0
static struct {
  GPUShader *mpath_line_sh;
  GPUShader *mpath_points_sh;
} e_data = {0};
#endif

/* *************************** Path Cache *********************************** */

/* Just convert the CPU cache to GPU cache. */
static GPUVertBuf *mpath_vbo_get(bMotionPath *mpath)
{
  if (!mpath->points_vbo) {
    GPUVertFormat format = {0};
    /* Match structure of bMotionPathVert. */
    uint pos = GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
    GPU_vertformat_attr_add(&format, "flag", GPU_COMP_I32, 1, GPU_FETCH_INT);
    mpath->points_vbo = GPU_vertbuf_create_with_format(&format);
    GPU_vertbuf_data_alloc(mpath->points_vbo, mpath->length);

    /* meh... a useless memcpy. */
    GPUVertBufRaw raw_data;
    GPU_vertbuf_attr_get_raw_data(mpath->points_vbo, pos, &raw_data);
    memcpy(
        GPU_vertbuf_raw_step(&raw_data), mpath->points, sizeof(bMotionPathVert) * mpath->length);
  }
  return mpath->points_vbo;
}

static GPUBatch *mpath_batch_line_get(bMotionPath *mpath)
{
  if (!mpath->batch_line) {
    mpath->batch_line = GPU_batch_create(GPU_PRIM_LINE_STRIP, mpath_vbo_get(mpath), NULL);
  }
  return mpath->batch_line;
}

static GPUBatch *mpath_batch_points_get(bMotionPath *mpath)
{
  if (!mpath->batch_points) {
    mpath->batch_points = GPU_batch_create(GPU_PRIM_POINTS, mpath_vbo_get(mpath), NULL);
  }
  return mpath->batch_points;
}

/* *************************** Draw Engine Entrypoints ************************** */

static void MPATH_engine_init(void *UNUSED(vedata))
{
}

static void MPATH_engine_free(void)
{
}

/* Here init all passes and shading groups
 * Assume that all Passes are NULL */
static void MPATH_cache_init(void *vedata)
{
  MPATH_PassList *psl = ((MPATH_Data *)vedata)->psl;

  {
    DRWState state = DRW_STATE_WRITE_COLOR;
    psl->lines = DRW_pass_create("Motionpath Line Pass", state);
  }

  {
    DRWState state = DRW_STATE_WRITE_COLOR;
    psl->points = DRW_pass_create("Motionpath Point Pass", state);
  }
}

static void MPATH_get_frame_range_to_draw(bAnimVizSettings *avs,
                                          bMotionPath *mpath,
                                          int current_frame,
                                          int *r_start,
                                          int *r_end,
                                          int *r_step)
{
  int start, end;

  if (avs->path_type == MOTIONPATH_TYPE_ACFRA) {
    start = current_frame - avs->path_bc;
    end = current_frame + avs->path_ac + 1;
  }
  else {
    start = avs->path_sf;
    end = avs->path_ef;
  }

  if (start > end) {
    SWAP(int, start, end);
  }

  CLAMP(start, mpath->start_frame, mpath->end_frame);
  CLAMP(end, mpath->start_frame, mpath->end_frame);

  *r_start = start;
  *r_end = end;
  *r_step = max_ii(avs->path_step, 1);
}

static void MPATH_cache_motion_path(MPATH_PassList *psl,
                                    Object *ob,
                                    bPoseChannel *pchan,
                                    bAnimVizSettings *avs,
                                    bMotionPath *mpath)
{
  const DRWContextState *draw_ctx = DRW_context_state_get();
  struct DRWTextStore *dt = DRW_text_cache_ensure();
  int txt_flag = DRW_TEXT_CACHE_GLOBALSPACE | DRW_TEXT_CACHE_ASCII;
  int cfra = (int)DEG_get_ctime(draw_ctx->depsgraph);
  bool sel = (pchan) ? (pchan->bone->flag & BONE_SELECTED) : (ob->base_flag & BASE_SELECTED);
  bool show_keyframes = (avs->path_viewflag & MOTIONPATH_VIEW_KFRAS) != 0;

  int sfra, efra, stepsize;
  MPATH_get_frame_range_to_draw(avs, mpath, cfra, &sfra, &efra, &stepsize);

  int len = efra - sfra;
  if (len == 0) {
    return;
  }
  int start_index = sfra - mpath->start_frame;

  bool use_custom_col = (mpath->flag & MOTIONPATH_FLAG_CUSTOM) != 0;

  /* draw curve-line of path */
  /* Draw lines only if line drawing option is enabled */
  if (mpath->flag & MOTIONPATH_FLAG_LINES) {
    DRWShadingGroup *shgrp = DRW_shgroup_create(mpath_line_shader_get(), psl->lines);
    DRW_shgroup_uniform_int_copy(shgrp, "frameCurrent", cfra);
    DRW_shgroup_uniform_int_copy(shgrp, "frameStart", sfra);
    DRW_shgroup_uniform_int_copy(shgrp, "frameEnd", efra);
    DRW_shgroup_uniform_int_copy(shgrp, "cacheStart", mpath->start_frame);
    DRW_shgroup_uniform_int_copy(shgrp, "lineThickness", mpath->line_thickness);
    DRW_shgroup_uniform_bool_copy(shgrp, "selected", sel);
    DRW_shgroup_uniform_bool_copy(shgrp, "useCustomColor", use_custom_col);
    DRW_shgroup_uniform_vec2(shgrp, "viewportSize", DRW_viewport_size_get(), 1);
    DRW_shgroup_uniform_block(shgrp, "globalsBlock", G_draw.block_ubo);
    if (use_custom_col) {
      DRW_shgroup_uniform_vec3(shgrp, "customColor", mpath->color, 1);
    }
    /* Only draw the required range. */
    DRW_shgroup_call_range(shgrp, mpath_batch_line_get(mpath), NULL, start_index, len);
  }

  /* Draw points. */
  DRWShadingGroup *shgrp = DRW_shgroup_create(mpath_points_shader_get(), psl->points);
  DRW_shgroup_uniform_int_copy(shgrp, "frameCurrent", cfra);
  DRW_shgroup_uniform_int_copy(shgrp, "cacheStart", mpath->start_frame);
  DRW_shgroup_uniform_int_copy(shgrp, "pointSize", max_ii(mpath->line_thickness - 1, 1));
  DRW_shgroup_uniform_int_copy(shgrp, "stepSize", stepsize);
  DRW_shgroup_uniform_bool_copy(shgrp, "showKeyFrames", show_keyframes);
  DRW_shgroup_uniform_bool_copy(shgrp, "useCustomColor", use_custom_col);
  DRW_shgroup_uniform_block(shgrp, "globalsBlock", G_draw.block_ubo);
  if (use_custom_col) {
    DRW_shgroup_uniform_vec3(shgrp, "customColor", mpath->color, 1);
  }
  /* Only draw the required range. */
  DRW_shgroup_call_range(shgrp, mpath_batch_points_get(mpath), NULL, start_index, len);

  /* Draw frame numbers at each framestep value */
  bool show_kf_no = (avs->path_viewflag & MOTIONPATH_VIEW_KFNOS) != 0;
  if ((avs->path_viewflag & (MOTIONPATH_VIEW_FNUMS)) || (show_kf_no && show_keyframes)) {
    int i;
    uchar col[4], col_kf[4];
    UI_GetThemeColor3ubv(TH_TEXT_HI, col);
    UI_GetThemeColor3ubv(TH_VERTEX_SELECT, col_kf);
    col[3] = col_kf[3] = 255;

    bMotionPathVert *mpv;
    bMotionPathVert *mpv_start = mpath->points + start_index;
    for (i = 0, mpv = mpv_start; i < len; i += stepsize, mpv += stepsize) {
      int frame = sfra + i;
      char numstr[32];
      size_t numstr_len;
      bool is_keyframe = (mpv->flag & MOTIONPATH_VERT_KEY) != 0;

      if ((show_keyframes && show_kf_no && is_keyframe) ||
          ((avs->path_viewflag & MOTIONPATH_VIEW_FNUMS) && (i == 0))) {
        numstr_len = sprintf(numstr, " %d", frame);
        DRW_text_cache_add(
            dt, mpv->co, numstr, numstr_len, 0, 0, txt_flag, (is_keyframe) ? col_kf : col);
      }
      else if (avs->path_viewflag & MOTIONPATH_VIEW_FNUMS) {
        bMotionPathVert *mpvP = (mpv - stepsize);
        bMotionPathVert *mpvN = (mpv + stepsize);
        /* only draw framenum if several consecutive highlighted points don't occur on same point
         */
        if ((equals_v3v3(mpv->co, mpvP->co) == 0) || (equals_v3v3(mpv->co, mpvN->co) == 0)) {
          numstr_len = sprintf(numstr, " %d", frame);
          DRW_text_cache_add(dt, mpv->co, numstr, numstr_len, 0, 0, txt_flag, col);
        }
      }
    }
  }
}

/* Add geometry to shading groups. Execute for each objects */
static void MPATH_cache_populate(void *vedata, Object *ob)
{
  MPATH_PassList *psl = ((MPATH_Data *)vedata)->psl;
  const DRWContextState *draw_ctx = DRW_context_state_get();

  if (draw_ctx->v3d->overlay.flag & V3D_OVERLAY_HIDE_MOTION_PATHS) {
    return;
  }

  if (ob->type == OB_ARMATURE) {
    if (DRW_pose_mode_armature(ob, draw_ctx->obact)) {
      for (bPoseChannel *pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
        if (pchan->mpath) {
          MPATH_cache_motion_path(psl, ob, pchan, &ob->pose->avs, pchan->mpath);
        }
      }
    }
  }
  else {
    if (ob->mpath) {
      MPATH_cache_motion_path(psl, ob, NULL, &ob->avs, ob->mpath);
    }
  }
}

/* Draw time! Control rendering pipeline from here */
static void MPATH_draw_scene(void *vedata)
{
  MPATH_PassList *psl = ((MPATH_Data *)vedata)->psl;
  DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();

  if (DRW_pass_is_empty(psl->lines) && DRW_pass_is_empty(psl->points)) {
    /* Nothing to draw. */
    return;
  }

  MULTISAMPLE_SYNC_ENABLE(dfbl, dtxl);

  DRW_draw_pass(psl->lines);
  DRW_draw_pass(psl->points);

  MULTISAMPLE_SYNC_DISABLE_NO_DEPTH(dfbl, dtxl);
}

/* *************************** Draw Engine Defines ****************************** */

static const DrawEngineDataSize MPATH_data_size = DRW_VIEWPORT_DATA_SIZE(MPATH_Data);

DrawEngineType draw_engine_motion_path_type = {
    NULL,
    NULL,
    N_("MotionPath"),
    &MPATH_data_size,
    &MPATH_engine_init,
    &MPATH_engine_free,
    &MPATH_cache_init,
    &MPATH_cache_populate,
    NULL,
    NULL,
    &MPATH_draw_scene,
    NULL,
    NULL,
};