// scanner/scanCartella.js
const path = require('path');
const fsp = require('fs/promises');
const processFile = require('./processFile');
const { sha256 } = require('./utils');
const { SUPPORTED_EXTS } = require('../config');

async function scanCartella(userName, cartella, absCartella, previousIndexTree) {
  const changes = [];

  async function walk(currentAbs, relPath = '') {
    console.log(`[SCAN] Entrato in cartella: ${currentAbs}`);

    let entries = [];
    try {
      entries = await fsp.readdir(currentAbs, { withFileTypes: true });
    } catch (err) {
      console.error(`[SCAN] Impossibile leggere: ${currentAbs} - ${err.message}`);
      return;
    }

    for (const e of entries) {
      const absPath = path.join(currentAbs, e.name);

      if (e.isDirectory()) {
        await walk(absPath, path.join(relPath, e.name));
        continue;
      }

      const ext = path.extname(e.name).toLowerCase();
      if (!SUPPORTED_EXTS.has(ext)) continue;

      const fileRelPath = relPath ? `${relPath}/${e.name}` : e.name;
      console.log(`[SCAN] FILE TROVATO → ${fileRelPath}`);

      const id = sha256(`${userName}/${cartella}/${fileRelPath}`);

      let st;
      try {
        st = await fsp.stat(absPath);
      } catch {
        continue;
      }

      const hash = sha256(`${st.size}-${st.mtimeMs}`);
      const prev = previousIndexTree?.[userName]?.[cartella]?.[id];

      console.log(`[SCAN] CHECK → id=${id}, hash=${hash}, prevHash=${prev?.hash}`);

      // 🔥 NON facciamo più SKIP qui.
      //    Anche se il file è invariato, lo passiamo a scanPhoto.js
      //    così può rimuovere l'ID da idsIndex.
      if (prev && prev.hash === hash) {
        console.log(`[SCAN] FILE INVARIATO (passato a scanPhoto) → ${fileRelPath}`);

        const meta = {
          id,
          user: userName,
          cartella,
          path: `/photos/${userName}/original/${cartella}/${fileRelPath}`,
          _indexHash: hash,
          unchanged: true
        };

        changes.push(meta);
        continue;
      }

      console.log(`[SCAN] PROCESSING → ${userName}/${cartella}/${fileRelPath}`);

      const meta = await processFile(
        userName,
        cartella,
        fileRelPath,
        absPath,
        ext,
        st
      );

      meta.id = id;
      meta.path = `/photos/${userName}/original/${cartella}/${fileRelPath}`;
      meta._indexHash = hash;

      changes.push(meta);
    }
  }

  await walk(absCartella);
  return changes;
}

module.exports = scanCartella;