// A synthetic imported course, laid out as the importer leaves it in <dataDir>/courses/<id>. Nothing here is real material.
import { mkdirSync, symlinkSync, writeFileSync } from "node:fs";
import { dirname, join } from "node:path";
import { LARGE_FILE_BYTES } from "../src/server/media-refs";
import { tempDir } from "./helpers";

export const VIDEO = "media/01 Intro – Übersicht.mp4";
export const VIDEO2 = "media/[2] Next step.mp4";
export const BIG_PDF = "decks/big deck.pdf";
/** Fake MP4 bytes: the server only streams them, nothing decodes them. */
export const videoBytes = (n = 4096, seed = 7) => new Uint8Array(n).map((_, i) => (i * seed) % 256);

export interface ImportFixtureOpts {
  id?: string;
  kind?: string;
  manifestId?: string;
  root?: string;
  visibility?: string;
  /** Extra hostile bits: a symlink to outside, a .git dir, a nested .gitignore that hides a lesson. */
  hostile?: boolean;
}

function put(dir: string, rel: string, content: string | Uint8Array) {
  mkdirSync(dirname(join(dir, rel)), { recursive: true });
  writeFileSync(join(dir, rel), content);
}

export function manifestYaml(o: ImportFixtureOpts = {}): string {
  const id = o.manifestId ?? o.id ?? "imp";
  return [
    "schema: 1",
    `id: ${id}`,
    "title: Imported Course",
    `visibility: ${o.visibility ?? "restricted"}`,
    ...(o.root ? [`root: ${o.root}`] : []),
    "cover: media/cover.jpg",
    "source:",
    `  kind: ${o.kind ?? "video-folder"}`,
    "  origin: /import/synthetic",
    "decks:",
    "  - id: d1",
    `    file: ${BIG_PDF}`,
    "    attachTo: l1",
    "modules:",
    "  - id: m1",
    "    title: Videos",
    "    lessons:",
    "      - id: l1",
    "        title: Intro",
    "        type: video",
    `        file: "${VIDEO}"`,
    "        transcript: transcripts/l1.md",
    "      - id: l2",
    "        title: Next step",
    "        type: video",
    `        file: "${VIDEO2}"`,
    "      - id: notes",
    "        title: Reading",
    "        type: text",
    "        file: code/S01 - Basics/README.md",
    "",
  ].join("\n");
}

/** Writes the course into `<dataDir>/courses/<id>` and returns that folder. */
export function makeImportedCourse(dataDir: string, o: ImportFixtureOpts = {}): string {
  const id = o.id ?? "imp";
  const dir = join(dataDir, "courses", id);
  mkdirSync(dir, { recursive: true });
  put(dir, "stcourse.yaml", manifestYaml(o));
  put(dir, VIDEO, videoBytes(4096, 7));
  put(dir, VIDEO2, videoBytes(2048, 11));
  put(dir, "media/cover.jpg", new Uint8Array([0xff, 0xd8, 0xff, 0xe0, 0, 0x10, 0x4a, 0x46, 0x49, 0x46, 0, 1, 0xff, 0xd9]));
  put(dir, BIG_PDF, new Uint8Array(LARGE_FILE_BYTES + 100).fill(0x25));
  put(dir, "transcripts/l1.md", "# Intro\n\n[0:00] Hello.\n");
  put(dir, "code/S01 - Basics/README.md", "# Basics\n\nRead me.\n");
  if (o.hostile) {
    // the companion code repo's own .gitignore hides Markdown: the lesson must still be committed
    put(dir, "code/S01 - Basics/.gitignore", "*.md\n");
    put(dir, "code/.git/config", "[core]\n");
    const outside = join(tempDir(), "secret.txt");
    writeFileSync(outside, "outside\n");
    symlinkSync(outside, join(dir, "code/leak.txt"));
  }
  return dir;
}