/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup edtransform
 */

#include "DNA_armature_types.h"

#include "BLI_listbase.h"

#include "BKE_armature.hh"

#include "ED_armature.hh"
#include "ED_transform_snap_object_context.hh"

#include "ANIM_armature.hh"

#include "transform_snap_object.hh"

namespace blender::ed::transform {

eSnapMode snapArmature(SnapObjectContext *sctx,
                       const Object *ob_eval,
                       const float4x4 &obmat,
                       bool is_object_active)
{
  eSnapMode retval = SCE_SNAP_TO_NONE;

  if (sctx->runtime.snap_to_flag == SCE_SNAP_TO_FACE) {
    /* Currently only edge and vert. */
    return retval;
  }

  bArmature *arm = id_cast<bArmature *>(ob_eval->data);

  SnapData nearest2d(sctx, obmat);

  nearest2d.clip_planes_enable(sctx, ob_eval);

  const float *head_vec = nullptr, *tail_vec = nullptr;

  const bool is_editmode = arm->edbo != nullptr;
  const bool is_posemode = is_object_active && (ob_eval->mode & OB_MODE_POSE);
  const bool skip_selected = (is_editmode || is_posemode) &&
                             (sctx->runtime.params.snap_target_select &
                              SCE_SNAP_TARGET_NOT_SELECTED);

  if (arm->edbo) {
    for (EditBone &eBone : *arm->edbo) {
      if (animrig::bone_is_visible(arm, &eBone)) {
        const bool is_selected = (eBone.flag & (BONE_ROOTSEL | BONE_TIPSEL)) != 0;
        if (is_selected && skip_selected) {
          continue;
        }

        if (nearest2d.snap_edge(eBone.head, eBone.tail)) {
          head_vec = eBone.head;
          tail_vec = eBone.tail;
        }
      }
    }
  }
  else if (ob_eval->pose && ob_eval->pose->chanbase.first) {
    for (bPoseChannel &pchan : ob_eval->pose->chanbase) {
      if (!animrig::bone_is_visible(arm, {&pchan, pchan.bone_get(*ob_eval)})) {
        /* Skip hidden bones. */
        continue;
      }

      const bool is_selected = (pchan.flag & POSE_SELECTED) != 0;
      if (is_selected && skip_selected) {
        continue;
      }

      if (nearest2d.snap_edge(pchan.pose_head, pchan.pose_tail)) {
        head_vec = pchan.pose_head;
        tail_vec = pchan.pose_tail;
      }
    }
  }

  if (nearest2d.nearest_point.index != -2) {
    retval = sctx->runtime.snap_to_flag & SCE_SNAP_TO_EDGE;
    if (retval == SCE_SNAP_TO_NONE) {
      nearest2d.nearest_point.index = -2;
    }

    if (sctx->runtime.snap_to_flag & SCE_SNAP_TO_EDGE_ENDPOINT) {
      float dist_px_sq_edge = nearest2d.nearest_point.dist_sq;
      nearest2d.nearest_point.dist_sq = sctx->ret.dist_px_sq;
      if (nearest2d.snap_point(head_vec) || nearest2d.snap_point(tail_vec)) {
        retval = SCE_SNAP_TO_EDGE_ENDPOINT;
      }
      else if (retval) {
        nearest2d.nearest_point.dist_sq = dist_px_sq_edge;
      }
    }
  }

  if (retval) {
    nearest2d.register_result(sctx, ob_eval, &arm->id);
  }
  return retval;
}

}  // namespace blender::ed::transform
