/**
 * queue.mjs — Job queue management
 * Handles jobs_queue.json read/write/update
 * Uses in-memory cache to avoid redundant disk I/O within a run.
 */
import { readFileSync, writeFileSync, existsSync, mkdirSync } from 'fs';
import { dirname, resolve } from 'path';
import { fileURLToPath } from 'url';

const __dir = dirname(fileURLToPath(import.meta.url));
const QUEUE_PATH = `${__dir}/../data/jobs_queue.json`;
const LOG_PATH = `${__dir}/../data/applications_log.json`;

/**
 * Load and validate a JSON config file. Throws with a clear message on failure.
 */
export function loadConfig(filePath) {
  const resolved = resolve(filePath);
  if (!existsSync(resolved)) {
    throw new Error(`Config file not found: ${resolved}\nCopy the matching .example.json and fill in your values.`);
  }
  let raw;
  try {
    raw = readFileSync(resolved, 'utf8');
  } catch (e) {
    throw new Error(`Cannot read config file ${resolved}: ${e.message}`);
  }
  try {
    return JSON.parse(raw);
  } catch (e) {
    throw new Error(`Invalid JSON in ${resolved}: ${e.message}`);
  }
}

function ensureDir(path) {
  const dir = dirname(path);
  if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
}

// --- In-memory caches (populated on first read, invalidated on write) ---
let _queueCache = null;
let _logCache = null;

export function loadQueue() {
  if (_queueCache) return _queueCache;
  ensureDir(QUEUE_PATH);
  _queueCache = existsSync(QUEUE_PATH) ? JSON.parse(readFileSync(QUEUE_PATH, 'utf8')) : [];
  return _queueCache;
}

export function saveQueue(jobs) {
  ensureDir(QUEUE_PATH);
  writeFileSync(QUEUE_PATH, JSON.stringify(jobs, null, 2));
  _queueCache = jobs;
}

function loadLog() {
  if (_logCache) return _logCache;
  ensureDir(LOG_PATH);
  _logCache = existsSync(LOG_PATH) ? JSON.parse(readFileSync(LOG_PATH, 'utf8')) : [];
  return _logCache;
}

function saveLog(log) {
  writeFileSync(LOG_PATH, JSON.stringify(log, null, 2));
  _logCache = log;
}

export function appendLog(entry) {
  const log = loadLog();
  log.push({ ...entry, logged_at: new Date().toISOString() });
  saveLog(log);
}

/**
 * After AI filtering, deduplicate jobs that exist on multiple tracks.
 * For each group sharing the same original job URL, keep the highest-scoring copy.
 * Marks losers as status='duplicate'. Call this after collect completes.
 */
export function dedupeAfterFilter() {
  _queueCache = null;
  const queue = loadQueue();

  // Group by URL (canonical dedup key)
  const byUrl = {};
  for (const job of queue) {
    if (!job.url) continue;
    if (!byUrl[job.url]) byUrl[job.url] = [];
    byUrl[job.url].push(job);
  }

  let deduped = 0;
  for (const jobs of Object.values(byUrl)) {
    if (jobs.length < 2) continue;
    // Keep the one with highest filter_score; if tied, prefer 'new' over 'filtered'
    jobs.sort((a, b) => {
      const sa = a.filter_score ?? -1;
      const sb = b.filter_score ?? -1;
      if (sb !== sa) return sb - sa;
      if (a.status === 'new' && b.status !== 'new') return -1;
      return 1;
    });
    // Mark losers as duplicate
    for (const loser of jobs.slice(1)) {
      loser.status = 'duplicate';
      loser.status_updated_at = new Date().toISOString();
      deduped++;
    }
  }

  if (deduped > 0) saveQueue(queue);
  return deduped;
}

export function isAlreadyApplied(jobId) {
  const log = loadLog();
  return log.some(e => e.id === jobId && e.status === 'applied');
}

export function getJobsByStatus(status) {
  const queue = loadQueue();
  if (Array.isArray(status)) return queue.filter(j => status.includes(j.status));
  return queue.filter(j => j.status === status);
}

export function updateJobStatus(id, status, extra = {}) {
  const queue = loadQueue();
  const idx = queue.findIndex(j => j.id === id);
  if (idx === -1) return;
  queue[idx] = {
    ...queue[idx],
    ...extra,
    status,
    status_updated_at: new Date().toISOString(),
  };
  saveQueue(queue);
  return queue[idx];
}

export function addJobs(newJobs) {
  // Always read fresh from disk to avoid clobbering concurrent writes (e.g. filter scoring)
  _queueCache = null;
  const queue = loadQueue();

  // Dedup key: same job.id + same track = skip (duplicate search hit for same track)
  // Same job.id but different track = allow (will be deduped after AI filter, keeping best score)
  const existingKeys = new Set(queue.map(j => `${j.track || 'ae'}::${j.id}`));
  let added = 0;

  for (const job of newJobs) {
    const track = job.track || 'ae';
    const key = `${track}::${job.id}`;
    if (existingKeys.has(key)) continue;
    existingKeys.add(key);

    // If this job.id already exists on a different track, give this copy a composite id
    // so filter batch custom_ids don't collide
    const idConflict = queue.some(j => j.id === job.id && (j.track || 'ae') !== track);
    const queueId = idConflict ? `${job.id}_${track}` : job.id;

    queue.push({
      ...job,
      id: queueId,
      original_id: job.id,
      status: 'new',
      found_at: new Date().toISOString(),
      status_updated_at: new Date().toISOString(),
      pending_question: null,
      applied_at: null,
      notes: null,
    });
    added++;
  }

  saveQueue(queue);
  return added;
}