import fs from "node:fs";
import factory from "../../web/app/src/vendor/blender/web_engine.js";

const wasmBinary = fs.readFileSync(new URL("../../web/app/src/vendor/blender/web_engine.wasm", import.meta.url));
const blend = fs.readFileSync(new URL("../../tests/files/web/basic_scene.blend", import.meta.url));
const expected = JSON.parse(fs.readFileSync(new URL("../../tests/golden/W-079/basic-scene-decimate.json", import.meta.url), "utf8"));

function readSnapshot(engine, handle) {
  const dataOut = engine._malloc(4);
  const lengthOut = engine._malloc(4);
  try {
    if (engine._web_engine_get_scene_snapshot(handle, dataOut, lengthOut) !== 0) throw new Error("golden snapshot request failed");
    const pointer = engine.HEAPU32[dataOut >>> 2];
    const length = engine.HEAPU32[lengthOut >>> 2];
    return JSON.parse(new TextDecoder().decode(engine.HEAPU8.slice(pointer, pointer + length)));
  }
  finally {
    engine._free(dataOut);
    engine._free(lengthOut);
  }
}

function open(engine, handle) {
  const pointer = engine._malloc(blend.byteLength);
  engine.HEAPU8.set(blend, pointer);
  const result = engine._web_engine_open_blend(handle, pointer, blend.byteLength);
  engine._free(pointer);
  if (result !== 0) throw new Error(`golden fixture open failed: ${engine.UTF8ToString(engine._web_engine_last_error_message())}`);
}

function apply(engine, handle, command) {
  const bytes = new TextEncoder().encode(JSON.stringify(command));
  const pointer = engine._malloc(bytes.byteLength);
  engine.HEAPU8.set(bytes, pointer);
  const result = engine._web_engine_apply_command(handle, pointer, bytes.byteLength);
  engine._free(pointer);
  if (result !== 0) throw new Error(`golden command failed: ${engine.UTF8ToString(engine._web_engine_last_error_message())}`);
}

function sourceSummary(snapshot) {
  const meshById = new Map(snapshot.meshes.map((mesh) => [mesh.id, mesh]));
  return {
    frame: [snapshot.frame.start, snapshot.frame.end],
    objects: snapshot.nodes.map((node) => {
      const mesh = node.dataId ? meshById.get(node.dataId) : undefined;
      return { name: node.name, type: node.type, vertices: mesh?.vertexCount ?? 0, polygons: mesh?.faceCount ?? 0, materials: mesh?.materialSlotIds?.length ?? 0 };
    }).sort((left, right) => left.name.localeCompare(right.name)),
  };
}

const sourceEngine = await factory({ wasmBinary });
const sourceHandle = sourceEngine._web_engine_create();
open(sourceEngine, sourceHandle);
const source = sourceSummary(readSnapshot(sourceEngine, sourceHandle));
sourceEngine._web_engine_destroy(sourceHandle);

const collapse = {};
for (const ratio of [1, 0.9, 0.8, 0.75, 0.7, 0.65, 0.5, 0.25]) {
  const engine = await factory({ wasmBinary });
  const handle = engine._web_engine_create();
  open(engine, handle);
  const snapshot = readSnapshot(engine, handle);
  const mesh = snapshot.meshes.find((candidate) => candidate.id === "mesh:Cube.001");
  apply(engine, handle, { type: "decimateMesh", meshId: mesh.id, profile: { schemaVersion: 1, sourceMeshRevision: snapshot.revision, attributePolicy: "PRESERVE", mode: "COLLAPSE", ratio, triangulate: false, useSymmetry: false } });
  const output = readSnapshot(engine, handle).meshes.find((candidate) => candidate.id === mesh.id);
  collapse[String(ratio)] = { vertices: output.vertexCount, triangles: output.triangleCount ?? Math.floor((output.indices?.length ?? 0) / 3) };
  engine._web_engine_destroy(handle);
}

const actual = { fixture: expected.fixture, source, collapse };
if (JSON.stringify(actual) !== JSON.stringify(expected)) {
  throw new Error(`Blender golden mismatch\nexpected=${JSON.stringify(expected)}\nactual=${JSON.stringify(actual)}`);
}
console.log(`blender-golden-ok fixture=${expected.fixture} ratios=${Object.keys(collapse).join(",")}`);