import crypto from "crypto";
import db from "./sql.mjs";
import cfg from "./config.mjs";

const RATE_LIMIT_WINDOW_MINUTES = 600; // 10 hours
const MAX_ATTEMPTS = 5;

export default new class {
    /**
     * Anonymize IP address using Hmac-SHA256 with a secret salt.
     * @param {string} ip 
     * @returns {string}
     */
    hashIP(ip) {
        if (!ip) return "unknown";
        const secret = cfg.main.invite_secret;
        if (!secret) {
            throw new Error('[FATAL] invite_secret is not configured. Set it in config.json to enable IP hashing. Refusing to use a predictable fallback salt.');
        }
        return crypto.createHmac("sha256", secret).update(ip).digest("hex");
    }

    /**
     * Get real IP from request headers or socket.
     * @param {object} req 
     * @returns {string}
     */
    getRealIP(req) {
        let ip = req.headers['cf-connecting-ip'] ||
            req.headers['true-client-ip'] ||
            req.headers['x-client-ip'] ||
            req.headers['x-real-ip'] ||
            (req.headers['x-forwarded-for'] ? req.headers['x-forwarded-for'].split(',')[0].trim() : null) ||
            req.socket.remoteAddress;

        if (!ip) return "unknown";

        // Handle IPv6 loopback and mapped IPv4
        if (ip === "::1") ip = "127.0.0.1";
        if (ip && ip.startsWith("::ffff:")) ip = ip.substring(7);

        // Basic IPv6 normalization (ensure consistent case and representation if possible)
        if (ip && ip.includes(":")) ip = ip.toLowerCase();

        if (cfg.main.development && ip === "127.0.0.1" && req.headers) {
            console.debug('[SECURITY] Local IP detected. Headers:', req.headers);
        }

        return ip;
    }

    /**
     * Record an attempt in the database.
     * @param {string} ip 
     * @param {string} username 
     * @param {string} type 'login' | 'register'
     * @param {boolean} success 
     */
    async recordAttempt(ip, username, type, success) {
        const ip_hash = this.hashIP(ip);
        
        await db`
            insert into login_attempts (ip_hash, username, type, success)
            values (${ip_hash}, ${username?.toLowerCase() || null}, ${type}, ${success})
        `.catch(err => console.error(`[SECURITY] Failed to record ${type} attempt:`, err));

        if (!success) {
            let windowMinutes = RATE_LIMIT_WINDOW_MINUTES;
            let maxAttempts = MAX_ATTEMPTS;
            let onlyFailures = true;

            if (type === 'password_reset_request') {
                windowMinutes = 1440;
                maxAttempts = 1;
                onlyFailures = false;
            } else if (type === 'password_reset_execution') {
                windowMinutes = 60;
                maxAttempts = 5;
                onlyFailures = false;
            }

            const windowStart = new Date(Date.now() - windowMinutes * 60000);

            const ipAttempts = await db`
                select count(*) as count
                from login_attempts
                where ip_hash = ${ip_hash}
                and type = ${type}
                ${onlyFailures ? db`and success = false` : db``}
                and attempted_at > ${windowStart}
            `.catch(() => [{ count: 0 }]);

            const count = +ipAttempts[0].count;
            const isBanned = count >= maxAttempts;

            console.warn(`[SECURITY] Failed ${type} attempt: user=${username}, ip_hash=${ip_hash}, ip_banned=${isBanned} (${count}/${maxAttempts})`);
        } else if (cfg.main.development) {
            console.log(`[SECURITY] Recording ${type} attempt: user=${username}, success=${success}, ip_hash=${ip_hash}`);
        }
    }

    /**
     * Clear failed attempts for a given IP and/or username.
     * @param {string} ip 
     * @param {string} username 
     */
    async clearAttempts(ip, username) {
        const ip_hash = this.hashIP(ip);
        if (cfg.main.development) console.log(`[SECURITY] Clearing attempts for user=${username}, ip_hash=${ip_hash}`);
        await db`
            delete from login_attempts
            where (ip_hash = ${ip_hash} OR username = ${username?.toLowerCase() || ''})
        `.catch(err => console.error(`[SECURITY] Failed to clear attempts:`, err));
    }

    async isRateLimited(ip, username, type) {
        const ip_hash = this.hashIP(ip);
        
        let windowMinutes = RATE_LIMIT_WINDOW_MINUTES;
        let maxAttempts = MAX_ATTEMPTS;
        let onlyFailures = true;

        if (type === 'password_reset_request') {
            windowMinutes = 1440; // 24 hours
            maxAttempts = 1;
            onlyFailures = false; // Count all attempts to prevent spam
        } else if (type === 'password_reset_execution') {
            windowMinutes = 60; // 1 hour
            maxAttempts = 5;
            onlyFailures = false; // Count all efforts
        }

        const windowStart = new Date(Date.now() - windowMinutes * 60000);

        if (cfg.main.development) console.log(`[SECURITY] Checking rate limit for ${type}: user=${username}, ip_hash=${ip_hash}`);

        // Check attempts by IP
        const ipAttempts = await db`
            select count(*) as count
            from login_attempts
            where ip_hash = ${ip_hash}
            and type = ${type}
            ${onlyFailures ? db`and success = false` : db``}
            and attempted_at > ${windowStart}
        `;

        const ipCount = +ipAttempts[0].count;
        if (ipCount >= maxAttempts) {
            console.warn(`[SECURITY] Rate limit hit for ${type}: ip_hash=${ip_hash}, attempts=${ipCount}/${maxAttempts}`);
            return true;
        }

        // Check attempts by username (if provided)
        if (username) {
            const userAttempts = await db`
                select count(*) as count
                from login_attempts
                where username = ${username.toLowerCase()}
                and type = ${type}
                ${onlyFailures ? db`and success = false` : db``}
                and attempted_at > ${windowStart}
            `;
            const userCount = +userAttempts[0].count;
            if (userCount >= maxAttempts) {
                console.warn(`[SECURITY] Rate limit hit for ${type}: user=${username}, attempts=${userCount}/${maxAttempts}`);
                return true;
            }
        }

        return false;
    }

    /**
     * Log user IP for historical tracking if enabled.
     * @param {number} userId 
     * @param {string} ip 
     */
    async logUserIP(userId, ip) {
        if (!cfg.websrv.log_user_ips || !userId || !ip) return;
        
        const { getHashUserIps } = await import("./settings.mjs");
        const finalIp = getHashUserIps() ? this.hashIP(ip) : ip;

        await db`
            insert into user_ips (user_id, ip)
            values (${userId}, ${finalIp})
            on conflict (user_id, ip) do update set last_seen = now()
        `.catch(err => console.error(`[SECURITY] Failed to log user IP:`, err));
    }
};