import fs from "node:fs";
import path from "node:path";
import zlib from "node:zlib";
import { strToU8, zipSync } from "fflate";
import { CUBE_STL } from "./helpers";

/** Upload fixtures, built in code so every variation stays readable next to the test using it. */

export const stl = (): Uint8Array => fs.readFileSync(CUBE_STL);

const CRC_TABLE = Array.from({ length: 256 }, (_, n) => {
  let c = n;
  for (let k = 0; k < 8; k++) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
  return c >>> 0;
});

function crc32(buf: Buffer): number {
  let c = 0xffffffff;
  for (const byte of buf) c = CRC_TABLE[(c ^ byte) & 0xff] ^ (c >>> 8);
  return (c ^ 0xffffffff) >>> 0;
}

function pngChunk(type: string, data: Buffer): Buffer {
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length);
  const body = Buffer.concat([Buffer.from(type, "ascii"), data]);
  const crc = Buffer.alloc(4);
  crc.writeUInt32BE(crc32(body));
  return Buffer.concat([len, body, crc]);
}

/** A solid-colour RGB PNG; real enough for the server to decode and thumbnail. */
export function png([r, g, b]: [number, number, number] = [200, 80, 40], size = 64): Uint8Array {
  const ihdr = Buffer.alloc(13);
  ihdr.writeUInt32BE(size, 0);
  ihdr.writeUInt32BE(size, 4);
  ihdr[8] = 8; // bit depth
  ihdr[9] = 2; // RGB
  const row = Buffer.concat([Buffer.from([0]), Buffer.from(Array.from({ length: size }, () => [r, g, b]).flat())]);
  const raw = Buffer.concat(Array.from({ length: size }, () => row));
  return Buffer.concat([
    Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]),
    pngChunk("IHDR", ihdr),
    pngChunk("IDAT", zlib.deflateSync(raw)),
    pngChunk("IEND", Buffer.alloc(0)),
  ]);
}

const CUBE_MODEL = `<?xml version="1.0" encoding="UTF-8"?>
<model unit="millimeter" xml:lang="en-US" xmlns="http://schemas.microsoft.com/3dmanufacturing/core/2015/02">
 <resources>
  <object id="1" type="model">
   <mesh>
    <vertices>
     <vertex x="0" y="0" z="0"/><vertex x="10" y="0" z="0"/><vertex x="10" y="10" z="0"/><vertex x="0" y="10" z="0"/>
     <vertex x="0" y="0" z="10"/><vertex x="10" y="0" z="10"/><vertex x="10" y="10" z="10"/><vertex x="0" y="10" z="10"/>
    </vertices>
    <triangles>
     <triangle v1="0" v2="2" v3="1"/><triangle v1="0" v2="3" v3="2"/><triangle v1="4" v2="5" v3="6"/><triangle v1="4" v2="6" v3="7"/>
     <triangle v1="0" v2="1" v3="5"/><triangle v1="0" v2="5" v3="4"/><triangle v1="1" v2="2" v3="6"/><triangle v1="1" v2="6" v3="5"/>
     <triangle v1="2" v2="3" v3="7"/><triangle v1="2" v2="7" v3="6"/><triangle v1="3" v2="0" v3="4"/><triangle v1="3" v2="4" v3="7"/>
    </triangles>
   </mesh>
  </object>
 </resources>
 <build><item objectid="1"/></build>
</model>`;

/** A 10mm cube as a 3MF package; with `thumbnail`, it carries the embedded preview slicers write. */
export function threeMf({ thumbnail = true } = {}): Uint8Array {
  const files: Record<string, Uint8Array> = {
    "[Content_Types].xml": strToU8(
      `<?xml version="1.0" encoding="UTF-8"?><Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">` +
        `<Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>` +
        `<Default Extension="model" ContentType="application/vnd.ms-package.3dmanufacturing-3dmodel+xml"/>` +
        `<Default Extension="png" ContentType="image/png"/></Types>`,
    ),
    "_rels/.rels": strToU8(
      `<?xml version="1.0" encoding="UTF-8"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">` +
        `<Relationship Target="/3D/3dmodel.model" Id="rel0" Type="http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel"/>` +
        `</Relationships>`,
    ),
    "3D/3dmodel.model": strToU8(CUBE_MODEL),
  };
  if (thumbnail) files["Metadata/thumbnail.png"] = png([40, 120, 220]);
  return zipSync(files);
}

export const zip = (entries: Record<string, Uint8Array>): Uint8Array => zipSync(entries);

export const text = (s: string): Uint8Array => strToU8(s);

/** Writes `files` (relative path -> content) under `dir` and returns `dir`, ready for a folder pick. */
export function writeTree(dir: string, files: Record<string, Uint8Array>): string {
  for (const [rel, content] of Object.entries(files)) {
    const abs = path.join(dir, rel);
    fs.mkdirSync(path.dirname(abs), { recursive: true });
    fs.writeFileSync(abs, content);
  }
  return dir;
}

/** Shape `setFiles` takes for files that never touch disk. */
export const file = (name: string, buffer: Uint8Array, mimeType = "application/octet-stream") => ({
  name,
  mimeType,
  buffer: Buffer.from(buffer),
});