import type {Mesh, MeshAttributes} from '@loaders.gl/schema';
import {getMeshBoundingBox} from '@loaders.gl/schema-utils';
import {parseOBJMeshes} from './parse-obj-meshes';
import {getOBJSchema} from './get-obj-schema';

export function parseOBJ(text: string, options?): Mesh {
  const {meshes} = parseOBJMeshes(text);

  // @ts-expect-error
  const vertexCount = meshes.reduce((s, mesh) => s + mesh.header.vertexCount, 0);
  // TODO - render objects separately
  const attributes = mergeAttributes(meshes, vertexCount);

  const header = {
    vertexCount,
    // @ts-ignore Need to export Attributes type
    boundingBox: getMeshBoundingBox(attributes)
  };

  const schema = getOBJSchema(attributes, {
    mode: 4,
    boundingBox: header.boundingBox
  });

  return {
    // Data return by this loader implementation
    loaderData: {
      header: {}
    },

    // Normalised data
    schema,
    header,
    mode: 4, // TRIANGLES
    topology: 'point-list',

    attributes
  };
}

// eslint-disable-next-line max-statements
function mergeAttributes(meshes, vertexCount): MeshAttributes {
  const positions = new Float32Array(vertexCount * 3);
  let normals;
  let colors;
  let uvs;
  let i = 0;

  for (const mesh of meshes) {
    const {POSITION, NORMAL, COLOR_0, TEXCOORD_0} = mesh.attributes;

    positions.set(POSITION.value, i * 3);

    if (NORMAL) {
      normals = normals || new Float32Array(vertexCount * 3);
      normals.set(NORMAL.value, i * 3);
    }
    if (COLOR_0) {
      colors = colors || new Float32Array(vertexCount * 3);
      colors.set(COLOR_0.value, i * 3);
    }
    if (TEXCOORD_0) {
      uvs = uvs || new Float32Array(vertexCount * 2);
      uvs.set(TEXCOORD_0.value, i * 2);
    }

    i += POSITION.value.length / 3;
  }

  const attributes: MeshAttributes = {};
  attributes.POSITION = {value: positions, size: 3};

  if (normals) {
    attributes.NORMAL = {value: normals, size: 3};
  }
  if (colors) {
    attributes.COLOR_0 = {value: colors, size: 3};
  }
  if (uvs) {
    attributes.TEXCOORD_0 = {value: uvs, size: 2};
  }

  return attributes;
}