import * as fs from "fs";
import * as path from "path";
import { EventEmitter } from "events";
import { DownloadJob } from "./types";

const DATA_DIR = path.join(__dirname, "..", "data");
const JOBS_FILE = path.join(DATA_DIR, "jobs.json");

if (!fs.existsSync(DATA_DIR)) {
  fs.mkdirSync(DATA_DIR, { recursive: true });
}
if (!fs.existsSync(JOBS_FILE)) {
  fs.writeFileSync(JOBS_FILE, "[]", "utf-8");
}

// Fired every time a job is created or updated, so the SSE route can push
// live status to the frontend without polling the file.
export const jobEvents = new EventEmitter();

function readAll(): DownloadJob[] {
  const raw = fs.readFileSync(JOBS_FILE, "utf-8");
  try {
    return JSON.parse(raw) as DownloadJob[];
  } catch {
    return [];
  }
}

function writeAll(jobs: DownloadJob[]): void {
  fs.writeFileSync(JOBS_FILE, JSON.stringify(jobs, null, 2), "utf-8");
}

export function listJobs(): DownloadJob[] {
  return readAll().sort((a, b) => (a.createdAt < b.createdAt ? 1 : -1));
}

export function getJob(id: string): DownloadJob | undefined {
  return readAll().find((j) => j.id === id);
}

export function createJob(title: string, sourceUrl: string): DownloadJob {
  const now = new Date().toISOString();
  const job: DownloadJob = {
    id: `job_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`,
    title,
    sourceUrl,
    status: "queued",
    progress: 0,
    bytesReceived: 0,
    bytesTotal: null,
    filePath: null,
    error: null,
    createdAt: now,
    updatedAt: now,
  };
  const jobs = readAll();
  jobs.push(job);
  writeAll(jobs);
  jobEvents.emit("update", job);
  return job;
}

export function updateJob(id: string, patch: Partial<DownloadJob>): DownloadJob | undefined {
  const jobs = readAll();
  const idx = jobs.findIndex((j) => j.id === id);
  if (idx === -1) return undefined;
  jobs[idx] = { ...jobs[idx], ...patch, updatedAt: new Date().toISOString() };
  writeAll(jobs);
  jobEvents.emit("update", jobs[idx]);
  return jobs[idx];
}