// api_v1/scanner/scanPhotosUser.js
const path = require('path');
const fsp = require('fs/promises');
const scanPhoto = require('./scanPhoto');
const { log } = require('./logger');
const { WEB_ROOT, SUPPORTED_EXTS } = require('../config');

// ---------------------------------------------------------
// ETA CALCULATOR
// ---------------------------------------------------------
function computeETA(startTime, current, total) {
  if (current === 0) return "calcolo...";

  const elapsed = (Date.now() - startTime) / 1000; // sec
  const rate = current / elapsed;
  const remaining = (total - current) / rate;

  const m = Math.floor(remaining / 60);
  const s = Math.floor(remaining % 60);

  return `${m}m ${s}s`;
}

// ---------------------------------------------------------
// PRIMA PASSATA: conta TUTTI i file reali (ricorsiva)
// ---------------------------------------------------------
async function countFilesUser(rootDir) {
  let count = 0;

  async function walk(dir) {
    let entries = [];
    try {
      entries = await fsp.readdir(dir, { withFileTypes: true });
    } catch {
      return;
    }

    for (const e of entries) {
      const abs = path.join(dir, e.name);

      if (e.isDirectory()) {
        await walk(abs);
      } else {
        const ext = path.extname(e.name).toLowerCase();
        if (SUPPORTED_EXTS.has(ext)) {
          count++;
        }
      }
    }
  }

  await walk(rootDir);
  return count;
}

// ---------------------------------------------------------
// SECONDA PASSATA: scansiona SOLO le cartelle vere
// ---------------------------------------------------------
async function scanPhotosUser(userName, db) {
  log(`🔵 Inizio scan TUTTE le cartelle per user=${userName}`);

  const photosRoot = path.resolve(__dirname, '..', '..', WEB_ROOT, 'photos');
  const userDir = path.join(photosRoot, userName, 'original');
  const statusPath = path.join(photosRoot, "scan_status.json");

  let entries = [];
  try {
    entries = await fsp.readdir(userDir, { withFileTypes: true });
  } catch {
    log(`❌ Nessuna directory per utente ${userName}`);
    return [];
  }

  // 🔥 Filtra SOLO cartelle vere dentro "original"
  const folders = entries.filter(e => e.isDirectory()).map(e => e.name);

  // ---------------------------------------------------------
  // 🔥 RIMOZIONE CARTELLE CANCELLATE DAL FILESYSTEM
  // ---------------------------------------------------------
  const createDeleteFolderFunctions = require('./deleteFolder');
  const { deleteFolderForUser } = createDeleteFolderFunctions(db);

  const dbFolders = await db('photos')
    .where({ user: userName })
    .distinct('cartella')
    .pluck('cartella');

  for (const dbFolder of dbFolders) {
    if (!folders.includes(dbFolder)) {
      log(`🗑️ Cartella rimossa dal filesystem: ${dbFolder}`);
      await deleteFolderForUser(userName, dbFolder);
    }
  }

  // 🔥 PRIMA PASSATA: conta i file reali
  const TOTAL_FILES = await countFilesUser(userDir);
  const CURRENT = { value: 0 };
  const start = Date.now();

  log(`📊 File totali da scansionare: ${TOTAL_FILES}`);

  // Scrivi stato iniziale
  await fsp.writeFile(
    statusPath,
    JSON.stringify({
      current: 0,
      total: TOTAL_FILES,
      percent: 0,
      eta: "calcolo..."
    }, null, 2)
  );

  const allNewFiles = [];

  // 🔥 SECONDA PASSATA: UNA SOLA SCANSIONE PER CARTELLA
  for (const cartella of folders) {
    log(`📁 Scan cartella utente: ${cartella}`);

    const newFiles = await scanPhoto(
      cartella,
      userName,
      db,
      CURRENT,
      TOTAL_FILES,
      start,
      async () => {
        // 🔥 Callback di aggiornamento progresso
        await fsp.writeFile(
          statusPath,
          JSON.stringify({
            current: CURRENT.value,
            total: TOTAL_FILES,
            percent: Math.round((CURRENT.value / TOTAL_FILES) * 100),
            eta: computeETA(start, CURRENT.value, TOTAL_FILES)
          }, null, 2)
        );
      }
    );

    if (newFiles?.length) {
      allNewFiles.push(...newFiles);
    }
  }

  // Stato finale
  await fsp.writeFile(
    statusPath,
    JSON.stringify({
      current: TOTAL_FILES,
      total: TOTAL_FILES,
      percent: 100,
      eta: "0m 0s"
    }, null, 2)
  );

  log(`🟣 Scan COMPLETATO per user=${userName}. Nuovi file totali: ${allNewFiles.length}`);

  return allNewFiles;
}

module.exports = scanPhotosUser;