/**
 * Copyright (c) 2026 Dominic Masters
 *
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "triprism.h"
#include "assert/assert.h"

mesh_t TRIPRISM_MESH_SIMPLE;
meshvertex_t TRIPRISM_MESH_SIMPLE_VERTICES[TRIPRISM_VERTEX_COUNT];

errorret_t triPrismInit() {
  triPrismBuffer(
    TRIPRISM_MESH_SIMPLE_VERTICES,
    0.0f, 0.0f,   /* p0: bottom-left */
    1.0f, 0.0f,   /* p1: bottom-right */
    0.5f, 1.0f,   /* p2: apex */
    0.0f, 1.0f    /* minZ, maxZ */
    #if MESH_ENABLE_COLOR
      , COLOR_WHITE_4B
    #endif
  );
  errorChain(meshInit(
    &TRIPRISM_MESH_SIMPLE,
    TRIPRISM_PRIMITIVE_TYPE,
    TRIPRISM_VERTEX_COUNT,
    TRIPRISM_MESH_SIMPLE_VERTICES
  ));
  errorOk();
}

void triPrismBuffer(
  meshvertex_t *vertices,
  const float_t x0, const float_t y0,
  const float_t x1, const float_t y1,
  const float_t x2, const float_t y2,
  const float_t minZ,
  const float_t maxZ
  #if MESH_ENABLE_COLOR
    , const color_t color
  #endif
) {
  assertNotNull(vertices, "Vertices cannot be NULL");

  /* Helper macro: write one vertex then advance index. */
  int32_t vi = 0;
  #if MESH_ENABLE_COLOR
    #define PRISM_VERT(px, py, pz, u, v) \
      vertices[vi].color    = color; \
      vertices[vi].pos[0]   = (px); \
      vertices[vi].pos[1]   = (py); \
      vertices[vi].pos[2]   = (pz); \
      vertices[vi].uv[0]    = (u);  \
      vertices[vi].uv[1]    = (v);  \
      vi++;
  #else
    #define PRISM_VERT(px, py, pz, u, v) \
      vertices[vi].pos[0]   = (px); \
      vertices[vi].pos[1]   = (py); \
      vertices[vi].pos[2]   = (pz); \
      vertices[vi].uv[0]    = (u);  \
      vertices[vi].uv[1]    = (v);  \
      vi++;
  #endif

  /* --- Front face (z = maxZ), CCW from +Z --- */
  PRISM_VERT(x0, y0, maxZ,  0.0f, 0.0f)
  PRISM_VERT(x1, y1, maxZ,  1.0f, 0.0f)
  PRISM_VERT(x2, y2, maxZ,  0.5f, 1.0f)

  /* --- Back face (z = minZ), CCW from -Z (reverse winding) --- */
  PRISM_VERT(x2, y2, minZ,  0.5f, 1.0f)
  PRISM_VERT(x1, y1, minZ,  1.0f, 0.0f)
  PRISM_VERT(x0, y0, minZ,  0.0f, 0.0f)

  /* --- Side face 0: edge p0->p1 --- */
  PRISM_VERT(x0, y0, minZ,  0.0f, 0.0f)
  PRISM_VERT(x1, y1, minZ,  1.0f, 0.0f)
  PRISM_VERT(x1, y1, maxZ,  1.0f, 1.0f)

  PRISM_VERT(x0, y0, minZ,  0.0f, 0.0f)
  PRISM_VERT(x1, y1, maxZ,  1.0f, 1.0f)
  PRISM_VERT(x0, y0, maxZ,  0.0f, 1.0f)

  /* --- Side face 1: edge p1->p2 --- */
  PRISM_VERT(x1, y1, minZ,  0.0f, 0.0f)
  PRISM_VERT(x2, y2, minZ,  1.0f, 0.0f)
  PRISM_VERT(x2, y2, maxZ,  1.0f, 1.0f)

  PRISM_VERT(x1, y1, minZ,  0.0f, 0.0f)
  PRISM_VERT(x2, y2, maxZ,  1.0f, 1.0f)
  PRISM_VERT(x1, y1, maxZ,  0.0f, 1.0f)

  /* --- Side face 2: edge p2->p0 --- */
  PRISM_VERT(x2, y2, minZ,  0.0f, 0.0f)
  PRISM_VERT(x0, y0, minZ,  1.0f, 0.0f)
  PRISM_VERT(x0, y0, maxZ,  1.0f, 1.0f)

  PRISM_VERT(x2, y2, minZ,  0.0f, 0.0f)
  PRISM_VERT(x0, y0, maxZ,  1.0f, 1.0f)
  PRISM_VERT(x2, y2, maxZ,  0.0f, 1.0f)

  #undef PRISM_VERT
}