/**
 * @file audit.js
 * @description Server mode's audit trail (docs/SERVER-MODE.md): every read by
 * an admin or analyst of a session that a MEMBER owns — the session page, its
 * transcript, its events, its cost — is written to `audit_log` with who read
 * it, whose it was and which path. `auditGuard` runs on `/api` after the
 * scope guard; it never blocks a request, and it is a no-op in local mode and
 * for a member (who can only read their own). An admin's account change on
 * the Users page is written here too (`recordAccountChange`).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const sql = (q) => require("../db").db.prepare(q);

// Paths that name one session's content.
const SESSION_PATHS = [
  /^\/sessions\/(?!facets\/?$)([^/]+)/i,
  /^\/pricing\/cost\/([^/]+)/i,
  /^\/workflows\/session\/([^/]+)/i,
];

function auditGuard(req, res, next) {
  const u = req.user;
  if (!u || u.role === "developer" || (req.method !== "GET" && req.method !== "HEAD"))
    return next();
  const p = require("./auth").apiPath(req);
  for (const re of SESSION_PATHS) {
    const m = re.exec(p);
    if (!m) continue;
    try {
      const { sessionOwners } = require("./scope");
      const id = m[1];
      for (const owner of sessionOwners(id)) {
        if (owner === u.id) continue;
        const ownerRole = sql("SELECT role FROM users WHERE id = ?").get(owner)?.role;
        if (ownerRole !== "developer") continue;
        sql(
          "INSERT INTO audit_log (user_id, owner_id, session_id, method, path) VALUES (?, ?, ?, ?, ?)"
        ).run(u.id, owner, id, req.method, req.originalUrl.slice(0, 500));
      }
    } catch (err) {
      console.warn("[audit] could not record:", err.message);
    }
    break;
  }
  return next();
}

/** The newest entries, with user names. */
function listAudit(limit = 100) {
  const n = Math.min(Math.max(Number(limit) || 100, 1), 1000);
  return sql(
    `SELECT a.id, a.at, a.method, a.path, a.session_id,
            r.username AS reader, o.username AS owner
       FROM audit_log a
       LEFT JOIN users r ON r.id = a.user_id
       LEFT JOIN users o ON o.id = a.owner_id
      ORDER BY a.id DESC LIMIT ?`
  ).all(n);
}

/** An admin's account change from the Users page: who, on whom, what (never
 *  a password). `owner_id` is the account changed; `path` carries the action. */
function recordAccountChange(actorId, targetId, method, action) {
  sql(
    "INSERT INTO audit_log (user_id, owner_id, session_id, method, path) VALUES (?, ?, NULL, ?, ?)"
  ).run(actorId, targetId, method, String(action).slice(0, 500));
}

module.exports = { auditGuard, listAudit, recordAccountChange };