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

#include "display/mesh/mesh.h"
#include "display/texture/texture.h"
#include "assert/assert.h"

errorret_t meshInitDolphin(
  meshdolphin_t *mesh,
  const meshprimitivetypedolphin_t primitiveType,
  const int32_t vertexCount,
  const meshvertex_t *vertices
) {
  assertNotNull(mesh, "Mesh cannot be null.");
  assertNotNull(vertices, "Vertices cannot be null.");
  assertTrue(vertexCount > 0, "Vertex count must be greater than 0.");

  mesh->primitiveType = primitiveType;
  mesh->vertexCount = vertexCount;
  mesh->vertices = vertices;

  errorOk();
}

errorret_t meshDrawDolphin(
  const meshdolphin_t *mesh,
  const int32_t vertexOffset,
  const int32_t vertexCount
) {
  assertNotNull(mesh, "Mesh cannot be NULL.");
  assertTrue(vertexOffset >= 0, "Vertex offset must be >= 0");
  assertTrue(vertexCount > 0, "Vertex count must be > 0");
  assertTrue(
    vertexOffset + vertexCount <= mesh->vertexCount,
    "Requested vertex range is invalid"
  );
  assertTrue(vertexCount <= UINT16_MAX, "Vertex count exceeds GX limit");

  // Matches vertex format described in displaydolphin.c
  assertTrue(sizeof(color_t) == 4, "color_t must be exactly 4 bytes");
  assertTrue(offsetof(meshvertex_t, color) == 0, "color offset wrong");
  assertTrue(offsetof(meshvertex_t, uv) == 4, "uv offset wrong");
  assertTrue(offsetof(meshvertex_t, pos) == 12, "pos offset wrong");

  textureDolphinUploadTEV();

  DCFlushRange(
    (void*)&mesh->vertices[vertexOffset],
    sizeof(meshvertex_t) * vertexCount
  );

  const uint8_t stride = (uint8_t)sizeof(meshvertex_t);
  GX_SetArray(GX_VA_POS, (void*)&mesh->vertices[vertexOffset].pos[0], stride);
  GX_SetArray(GX_VA_CLR0, (void*)&mesh->vertices[vertexOffset].color.r, stride);
  GX_SetArray(GX_VA_TEX0, (void*)&mesh->vertices[vertexOffset].uv[0], stride);
  
  GX_Begin(mesh->primitiveType, GX_VTXFMT0, (uint16_t)vertexCount);
  for(uint16_t i = 0; i < (uint16_t)vertexCount; ++i) {
    GX_Position1x16(i);
    GX_Color1x16(i);
    GX_TexCoord1x16(i);
  }
  GX_End();

  errorOk();
}

int32_t meshGetVertexCountDolphin(const meshdolphin_t *mesh) {
  assertNotNull(mesh, "Mesh cannot be NULL.");
  return mesh->vertexCount;
}

errorret_t meshDisposeDolphin(meshdolphin_t *mesh) {
  errorOk();
}