// User CRUD. Mounted at /api/v1/auth/users by index.js (behind the auth gate).
// Flat access: any logged-in user can manage other users (spec).
import express from 'express';
import pool from '../db/pool.js';
import { hashPassword } from '../auth/passwords.js';
import { DEV_USER_ID, requireAdmin } from '../middleware/auth.js';
import { accessibleProjectIds } from '../auth/authz.js';

const router = express.Router();
const MIN_PASSWORD_LEN = 12;
const ROLES = ['admin', 'editor', 'viewer'];

function bad(res, msg) { return res.status(400).json({ error: msg }); }

// GET / — list users (real ones; dev seed hidden)
router.get('/', async (_req, res, next) => {
  try {
    const { rows } = await pool.query(
      `SELECT id, username, display_name, role, totp_enabled, last_login_at, created_at
       FROM users WHERE id <> $1 ORDER BY username`, [DEV_USER_ID]);
    res.json(rows);
  } catch (err) { next(err); }
});

// POST / — create user
router.post('/', async (req, res, next) => {
  try {
    const { username, password, display_name, role } = req.body || {};
    if (!username || typeof username !== 'string') return bad(res, 'username required');
    if (!password || password.length < MIN_PASSWORD_LEN) return bad(res, 'password must be at least ' + MIN_PASSWORD_LEN + ' chars');
    if (role !== undefined && !ROLES.includes(role)) return bad(res, "role must be one of: " + ROLES.join(', '));
    const hash = await hashPassword(password);
    const { rows } = await pool.query(
      `INSERT INTO users (username, password_hash, display_name, role)
       VALUES ($1, $2, $3, $4)
       RETURNING id, username, display_name, role, created_at`,
      [username.trim(), hash, display_name || username.trim(), role || 'admin']
    );
    res.status(201).json(rows[0]);
  } catch (err) {
    if (err.code === '23505') return res.status(409).json({ error: 'username already exists' });
    next(err);
  }
});

// POST /:id/password — admin reset another user's password
router.post('/:id/password', async (req, res, next) => {
  try {
    const { new_password } = req.body || {};
    if (!new_password || new_password.length < MIN_PASSWORD_LEN) {
      return bad(res, 'new password must be at least ' + MIN_PASSWORD_LEN + ' chars');
    }
    const hash = await hashPassword(new_password);
    const { rowCount } = await pool.query(
      `UPDATE users SET password_hash = $1, password_updated_at = NOW() WHERE id = $2 AND id <> $3`,
      [hash, req.params.id, DEV_USER_ID]);
    if (rowCount === 0) return res.status(404).json({ error: 'user not found' });
    res.status(204).end();
  } catch (err) { next(err); }
});

// DELETE /:id — delete a user, except the last real user
router.delete('/:id', async (req, res, next) => {
  try {
    if (req.params.id === DEV_USER_ID) return res.status(400).json({ error: 'cannot delete dev user' });
    const { rows } = await pool.query(
      `SELECT COUNT(*)::int AS n FROM users WHERE id <> $1`, [DEV_USER_ID]);
    if (rows[0].n <= 1) return res.status(409).json({ error: 'cannot delete last user' });
    const { rowCount } = await pool.query(`DELETE FROM users WHERE id = $1`, [req.params.id]);
    if (rowCount === 0) return res.status(404).json({ error: 'user not found' });
    res.status(204).end();
  } catch (err) { next(err); }
});

// PATCH /:id { display_name?, role?, password? } — generic update.
// password update goes through hashPassword; other fields are passed through.
router.patch('/:id', async (req, res, next) => {
  try {
    if (req.params.id === DEV_USER_ID) return res.status(400).json({ error: 'cannot edit dev user' });
    const sets = []; const vals = [];
    if (typeof req.body?.display_name === 'string') { sets.push('display_name = $' + (sets.length + 1)); vals.push(req.body.display_name); }
    if (typeof req.body?.role         === 'string') {
      if (!ROLES.includes(req.body.role)) return bad(res, "role must be one of: " + ROLES.join(', '));
      sets.push('role = $'         + (sets.length + 1)); vals.push(req.body.role);
    }
    if (typeof req.body?.password     === 'string') {
      if (req.body.password.length < MIN_PASSWORD_LEN) return bad(res, 'password must be at least ' + MIN_PASSWORD_LEN + ' chars');
      sets.push('password_hash = $' + (sets.length + 1) + ', password_updated_at = NOW()');
      vals.push(await hashPassword(req.body.password));
    }
    if (sets.length === 0) return bad(res, 'nothing to update');
    vals.push(req.params.id);
    const { rows } = await pool.query(
      `UPDATE users SET ${sets.join(', ')} WHERE id = $${vals.length} RETURNING id, username, display_name, role`,
      vals
    );
    if (rows.length === 0) return res.status(404).json({ error: 'user not found' });
    res.json(rows[0]);
  } catch (err) { next(err); }
});

// GET /:id/access — effective per-project access for one user (admin only).
// Reuses authz.accessibleProjectIds (MAX over direct user grant + every group the
// user belongs to). `via` is 'direct' for a user grant, 'group:<name>' otherwise.
// When the effective level comes from several sources we report the direct grant
// if present, else the first contributing group.
router.get('/:id/access', requireAdmin, async (req, res, next) => {
  try {
    const { rows: urows } = await pool.query(
      `SELECT id, role FROM users WHERE id = $1`, [req.params.id]);
    if (urows.length === 0) return res.status(404).json({ error: 'user not found' });
    const target = urows[0];

    const { rows: groups } = await pool.query(
      `SELECT g.id, g.name
         FROM user_groups ug JOIN groups g ON g.id = ug.group_id
        WHERE ug.user_id = $1 ORDER BY g.name`, [target.id]);

    // Admins bypass scoping — every project at 'edit', via their role.
    const access = await accessibleProjectIds(target);
    if (access.all) {
      const { rows: projects } = await pool.query(
        `SELECT id, name FROM projects ORDER BY name`);
      return res.json({
        projects: projects.map(p => ({
          project_id: p.id, project_name: p.name, level: 'edit', via: 'direct',
        })),
        groups,
      });
    }

    const ids = [...access.ids];
    if (ids.length === 0) return res.json({ projects: [], groups });

    // Resolve names + the source of each grant. groupNameById lets us label a
    // group-sourced grant; a direct user grant always wins the `via` label.
    const groupNameById = new Map(groups.map(g => [g.id, g.name]));
    const { rows: grants } = await pool.query(
      `SELECT pa.project_id, pa.subject_type, pa.subject_id, pa.level, p.name AS project_name
         FROM project_access pa JOIN projects p ON p.id = pa.project_id
        WHERE (pa.subject_type = 'user'  AND pa.subject_id = $1)
           OR (pa.subject_type = 'group' AND pa.subject_id IN (
                SELECT group_id FROM user_groups WHERE user_id = $1
              ))`,
      [target.id]);

    const byProject = new Map();
    for (const g of grants) {
      const eff = access.levelByProject.get(g.project_id);  // already the MAX
      const via = g.subject_type === 'user'
        ? 'direct'
        : 'group:' + (groupNameById.get(g.subject_id) || g.subject_id);
      const prev = byProject.get(g.project_id);
      // Keep a row only if it carries the effective level; prefer a direct grant
      // when both a direct and a group grant hit the same level.
      if (g.level === eff && (!prev || (prev.via !== 'direct' && via === 'direct'))) {
        byProject.set(g.project_id, {
          project_id: g.project_id, project_name: g.project_name, level: eff, via,
        });
      }
    }

    res.json({
      projects: [...byProject.values()].sort((a, b) => a.project_name.localeCompare(b.project_name)),
      groups,
    });
  } catch (err) { next(err); }
});

// POST /:id/totp/disable — admin clears a locked-out user's 2FA WITHOUT their
// password (the self-service /auth/totp/disable needs the victim's own). Mirrors
// that handler's SQL but targets :id and skips the password check. Dev user blocked.
router.post('/:id/totp/disable', requireAdmin, async (req, res, next) => {
  try {
    if (req.params.id === DEV_USER_ID) return res.status(400).json({ error: 'cannot edit dev user' });
    const { rowCount } = await pool.query(
      `UPDATE users SET totp_enabled = FALSE, totp_secret = NULL, totp_last_counter = 0
         WHERE id = $1 AND id <> $2`,
      [req.params.id, DEV_USER_ID]);
    if (rowCount === 0) return res.status(404).json({ error: 'user not found' });
    await pool.query(`DELETE FROM user_recovery_codes WHERE user_id = $1`, [req.params.id]);
    res.status(204).end();
  } catch (err) { next(err); }
});

export default router;