const path = require('path');
const fs   = require('fs');
const db   = require('../db/db');
const { audit } = require('../utils/audit');

const AVATARS_DIR = path.join(__dirname, '../../uploads/avatars');

/* ── POST /api/avatar/request ── student submits a new avatar ───────────── */
function requestAvatar(req, res) {
    if (!req.file) return res.status(400).json({ error: 'Файл не загружен' });

    // Cancel any previous pending request from this user (replace it)
    const prev = db.prepare(
        "SELECT filename FROM avatar_requests WHERE user_id=? AND status='pending'"
    ).get(req.user.id);
    if (prev) {
        // Delete old file
        try { fs.unlinkSync(path.join(AVATARS_DIR, prev.filename)); } catch {}
        db.prepare("DELETE FROM avatar_requests WHERE user_id=? AND status='pending'").run(req.user.id);
    }

    db.prepare(`
        INSERT INTO avatar_requests (user_id, filename, status, created_at)
        VALUES (?, ?, 'pending', datetime('now'))
    `).run(req.user.id, req.file.filename);

    res.json({ ok: true, filename: req.file.filename });
}

/* ── GET /api/avatar/my-status ── student polls their request status ────── */
function myStatus(req, res) {
    const row = db.prepare(`
        SELECT ar.id, ar.filename, ar.status, ar.reject_msg, ar.created_at, ar.reviewed_at
        FROM avatar_requests ar
        WHERE ar.user_id = ?
        ORDER BY ar.created_at DESC LIMIT 1
    `).get(req.user.id);

    const user = db.prepare('SELECT avatar_url FROM users WHERE id=?').get(req.user.id);
    res.json({ request: row || null, current_avatar: user?.avatar_url || null });
}

/* ── GET /api/avatar/pending ── moderator sees all pending requests ──────── */
function getPending(req, res) {
    const rows = db.prepare(`
        SELECT ar.id, ar.filename, ar.status, ar.created_at,
               u.id AS user_id, u.name AS user_name, u.email AS user_email,
               u.avatar_url AS current_avatar
        FROM avatar_requests ar
        JOIN users u ON u.id = ar.user_id
        WHERE ar.status = 'pending'
        ORDER BY ar.created_at ASC
    `).all();
    res.json(rows);
}

/* ── POST /api/avatar/:id/approve ── moderator approves ─────────────────── */
function approveAvatar(req, res) {
    const row = db.prepare('SELECT * FROM avatar_requests WHERE id=?').get(req.params.id);
    if (!row) return res.status(404).json({ error: 'Заявка не найдена' });
    if (row.status !== 'pending') return res.status(400).json({ error: 'Заявка уже обработана' });

    // Remove old avatar file if exists
    const user = db.prepare('SELECT avatar_url FROM users WHERE id=?').get(row.user_id);
    if (user?.avatar_url) {
        try { fs.unlinkSync(path.join(AVATARS_DIR, user.avatar_url)); } catch {}
    }

    db.prepare('UPDATE users SET avatar_url=? WHERE id=?').run(row.filename, row.user_id);
    db.prepare(`
        UPDATE avatar_requests SET status='approved', reviewer_id=?, reviewed_at=datetime('now')
        WHERE id=?
    `).run(req.user.id, row.id);

    audit(req, 'avatar.approve', `user:${row.user_id}`, row.filename);
    res.json({ ok: true });
}

/* ── POST /api/avatar/:id/reject ── moderator rejects ───────────────────── */
function rejectAvatar(req, res) {
    const row = db.prepare('SELECT * FROM avatar_requests WHERE id=?').get(req.params.id);
    if (!row) return res.status(404).json({ error: 'Заявка не найдена' });
    if (row.status !== 'pending') return res.status(400).json({ error: 'Заявка уже обработана' });

    const msg = (req.body.reason || '').toString().slice(0, 200).trim();

    // Delete uploaded file
    try { fs.unlinkSync(path.join(AVATARS_DIR, row.filename)); } catch {}

    db.prepare(`
        UPDATE avatar_requests
        SET status='rejected', reviewer_id=?, reject_msg=?, reviewed_at=datetime('now')
        WHERE id=?
    `).run(req.user.id, msg || null, row.id);

    audit(req, 'avatar.reject', `user:${row.user_id}`, msg || '');
    res.json({ ok: true });
}

/* ── DELETE /api/avatar/me ── student removes their approved avatar ──────── */
function removeAvatar(req, res) {
    const user = db.prepare('SELECT avatar_url FROM users WHERE id=?').get(req.user.id);
    if (user?.avatar_url) {
        if (!/^preset_\d{2}\.png$/.test(user.avatar_url)) {
            try { fs.unlinkSync(path.join(AVATARS_DIR, user.avatar_url)); } catch {}
        }
        db.prepare('UPDATE users SET avatar_url=NULL WHERE id=?').run(req.user.id);
    }
    res.json({ ok: true });
}

/* ── GET /api/avatar/presets ── list available preset avatars ─────────────── */
function listPresets(_req, res) {
    const files = fs.readdirSync(AVATARS_DIR)
        .filter(f => /^preset_\d{2}\.png$/.test(f))
        .sort();
    res.json({ presets: files });
}

/* ── POST /api/avatar/preset ── set avatar to a preset (no moderation) ────── */
function setPreset(req, res) {
    const filename = String(req.body.filename || '');
    if (!/^preset_\d{2}\.png$/.test(filename)) {
        return res.status(400).json({ error: 'Некорректный пресет' });
    }
    if (!fs.existsSync(path.join(AVATARS_DIR, filename))) {
        return res.status(404).json({ error: 'Пресет не найден' });
    }

    // Remove old uploaded avatar file (but never delete preset files)
    const user = db.prepare('SELECT avatar_url FROM users WHERE id=?').get(req.user.id);
    if (user?.avatar_url && !/^preset_\d{2}\.png$/.test(user.avatar_url)) {
        try { fs.unlinkSync(path.join(AVATARS_DIR, user.avatar_url)); } catch {}
    }

    // Cancel any pending moderation request from this user
    const prev = db.prepare(
        "SELECT filename FROM avatar_requests WHERE user_id=? AND status='pending'"
    ).get(req.user.id);
    if (prev) {
        try { fs.unlinkSync(path.join(AVATARS_DIR, prev.filename)); } catch {}
        db.prepare("DELETE FROM avatar_requests WHERE user_id=? AND status='pending'").run(req.user.id);
    }

    db.prepare('UPDATE users SET avatar_url=? WHERE id=?').run(filename, req.user.id);
    res.json({ ok: true, avatar_url: filename });
}

module.exports = { requestAvatar, myStatus, getPending, approveAvatar, rejectAvatar, removeAvatar, listPresets, setPreset };