Learn_System/backend/src/controllers/studentMaterialsController.js

'use strict';
/* Student-owned personal materials ("Мои материалы").
 * A user keeps copies of items saved from live lessons; the copies are
 * independent of the session lifecycle. */
const db = require('../db/db');

const KINDS = ['board', 'note', 'link', 'image'];

/* GET /api/materials — list the current user's saved materials + their collections */
function list(req, res) {
  const uid = req.user.id;
  const materials = db.prepare(`
    SELECT id, kind, title, body, url, source_session_id, source_title, collection_id, tags, created_at
      FROM student_materials
     WHERE user_id = ?
     ORDER BY created_at DESC, id DESC
  `).all(uid);
  const collections = db.prepare(`
    SELECT c.id, c.name, c.color, c.sort_order,
           (SELECT COUNT(*) FROM student_materials m WHERE m.collection_id = c.id) AS count
      FROM material_collections c
     WHERE c.user_id = ?
     ORDER BY c.sort_order, c.id
  `).all(uid);
  res.json({ materials, collections });
}

/* Validate that a collection id belongs to the user; returns null if unset/invalid. */
function ownCollectionId(raw, uid) {
  if (raw === null || raw === '' || raw === undefined) return null;
  const cid = Number(raw);
  if (!Number.isFinite(cid)) return null;
  const own = db.prepare('SELECT 1 FROM material_collections WHERE id = ? AND user_id = ?').get(cid, uid);
  return own ? cid : null;
}

/* POST /api/materials — save a new item to the current user's collection.
   Body: { kind, title?, body?, url?, sourceSessionId?, sourceTitle? } */
function create(req, res) {
  const b = req.body || {};
  const kind = String(b.kind || '');
  if (!KINDS.includes(kind)) return res.status(400).json({ error: 'invalid kind' });

  const title = String(b.title || '').slice(0, 300);
  const body  = b.body != null ? String(b.body).slice(0, 60000) : null;
  const url   = b.url != null ? String(b.url).slice(0, 2000) : null;
  if ((kind === 'note') && !body) return res.status(400).json({ error: 'body required for note' });
  if ((kind === 'board' || kind === 'image' || kind === 'link') && !url)
    return res.status(400).json({ error: 'url required' });

  // Soft reference to the source session (kept readable via source_title even
  // after the session is deleted). Only store the id if the session exists.
  let sourceSessionId = Number(b.sourceSessionId);
  if (!Number.isFinite(sourceSessionId)) sourceSessionId = null;
  else if (!db.prepare('SELECT 1 FROM classroom_sessions WHERE id = ?').get(sourceSessionId)) sourceSessionId = null;
  const sourceTitle = b.sourceTitle != null ? String(b.sourceTitle).slice(0, 300) : null;
  const collectionId = ownCollectionId(b.collection_id, req.user.id);
  const tags = b.tags != null ? String(b.tags).slice(0, 500) : null;

  const r = db.prepare(`
    INSERT INTO student_materials (user_id, kind, title, body, url, source_session_id, source_title, collection_id, tags)
    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
  `).run(req.user.id, kind, title, body, url, sourceSessionId, sourceTitle, collectionId, tags);
  res.status(201).json({ id: Number(r.lastInsertRowid) });
}

/* PATCH /api/materials/:id — rename / edit one of the current user's items.
   Editable: title, body. (collection_id/tags wired in a later phase.) */
function update(req, res) {
  const row = db.prepare('SELECT user_id FROM student_materials WHERE id = ?').get(req.params.id);
  if (!row) return res.status(404).json({ error: 'not found' });
  if (row.user_id !== req.user.id) return res.status(403).json({ error: 'forbidden' });
  const b = req.body || {};
  const fields = [], args = [];
  if (b.title !== undefined) { fields.push('title = ?'); args.push(String(b.title || '').slice(0, 300)); }
  if (b.body  !== undefined) { fields.push('body = ?');  args.push(b.body != null ? String(b.body).slice(0, 60000) : null); }
  if (b.collection_id !== undefined) { fields.push('collection_id = ?'); args.push(ownCollectionId(b.collection_id, req.user.id)); }
  if (b.tags !== undefined) { fields.push('tags = ?'); args.push(b.tags != null ? String(b.tags).slice(0, 500) : null); }
  if (!fields.length) return res.json({ ok: true });
  args.push(req.params.id);
  db.prepare(`UPDATE student_materials SET ${fields.join(', ')} WHERE id = ?`).run(...args);
  res.json({ ok: true });
}

/* DELETE /api/materials/:id — remove one of the current user's items */
function remove(req, res) {
  const row = db.prepare('SELECT user_id FROM student_materials WHERE id = ?').get(req.params.id);
  if (!row) return res.status(404).json({ error: 'not found' });
  if (row.user_id !== req.user.id) return res.status(403).json({ error: 'forbidden' });
  db.prepare('DELETE FROM student_materials WHERE id = ?').run(req.params.id);
  res.json({ ok: true });
}

/* ── Collections (folders) ──────────────────────────────────────────── */

/* POST /api/materials/collections — create a folder */
function createCollection(req, res) {
  const name = String((req.body && req.body.name) || '').trim().slice(0, 120);
  if (!name) return res.status(400).json({ error: 'name required' });
  const color = req.body && req.body.color ? String(req.body.color).slice(0, 20) : null;
  const r = db.prepare(
    'INSERT INTO material_collections (user_id, name, color, sort_order) VALUES (?, ?, ?, ?)'
  ).run(req.user.id, name, color, Number(req.body && req.body.sortOrder) || 0);
  res.status(201).json({ id: Number(r.lastInsertRowid) });
}

/* PATCH /api/materials/collections/:id — rename / recolor / reorder */
function updateCollection(req, res) {
  const row = db.prepare('SELECT user_id FROM material_collections WHERE id = ?').get(req.params.id);
  if (!row) return res.status(404).json({ error: 'not found' });
  if (row.user_id !== req.user.id) return res.status(403).json({ error: 'forbidden' });
  const b = req.body || {};
  const fields = [], args = [];
  if (b.name !== undefined)      { fields.push('name = ?');       args.push(String(b.name || '').trim().slice(0, 120)); }
  if (b.color !== undefined)     { fields.push('color = ?');      args.push(b.color ? String(b.color).slice(0, 20) : null); }
  if (b.sortOrder !== undefined) { fields.push('sort_order = ?'); args.push(Number(b.sortOrder) || 0); }
  if (!fields.length) return res.json({ ok: true });
  args.push(req.params.id);
  db.prepare(`UPDATE material_collections SET ${fields.join(', ')} WHERE id = ?`).run(...args);
  res.json({ ok: true });
}

/* DELETE /api/materials/collections/:id — delete folder (materials kept, uncategorised) */
function deleteCollection(req, res) {
  const row = db.prepare('SELECT user_id FROM material_collections WHERE id = ?').get(req.params.id);
  if (!row) return res.status(404).json({ error: 'not found' });
  if (row.user_id !== req.user.id) return res.status(403).json({ error: 'forbidden' });
  db.prepare('DELETE FROM material_collections WHERE id = ?').run(req.params.id); // ON DELETE SET NULL
  res.json({ ok: true });
}

module.exports = { list, create, update, remove, createCollection, updateCollection, deleteCollection };