import { isProKey } from "../services/keys.js";
import logger from "../services/logger.js";
import { queryWithRetry, connectWithRetry } from "../services/db.js";
const FREE_TIER_LIMIT = 100;
const PRO_TIER_LIMIT = 5000;
// In-memory cache, periodically synced to PostgreSQL
let usage = new Map();
// Write-behind buffer for batching DB writes (Audit #10)
const dirtyKeys = new Set();
const retryCount = new Map();
const MAX_RETRIES = 3;
const FLUSH_INTERVAL_MS = 5000;
const FLUSH_THRESHOLD = 50;
function getMonthKey() {
    const d = new Date();
    return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, "0")}`;
}
export async function loadUsageData() {
    try {
        const result = await queryWithRetry("SELECT key, count, month_key FROM usage");
        usage = new Map();
        for (const row of result.rows) {
            usage.set(row.key, { count: row.count, monthKey: row.month_key });
        }
        logger.info(`Loaded usage data for ${usage.size} keys from PostgreSQL`);
    }
    catch (error) {
        logger.info("No existing usage data found, starting fresh");
        usage = new Map();
    }
}
// Batch flush dirty entries to DB (Audit #10 + #12)
async function flushDirtyEntries() {
    if (dirtyKeys.size === 0)
        return;
    const keysToFlush = [...dirtyKeys];
    const client = await connectWithRetry();
    try {
        await client.query("BEGIN");
        for (const key of keysToFlush) {
            const record = usage.get(key);
            if (!record)
                continue;
            try {
                await client.query(`INSERT INTO usage (key, count, month_key) VALUES ($1, $2, $3)
           ON CONFLICT (key) DO UPDATE SET count = $2, month_key = $3`, [key, record.count, record.monthKey]);
                dirtyKeys.delete(key);
                retryCount.delete(key);
            }
            catch (error) {
                // Audit #12: retry logic for failed writes
                const retries = (retryCount.get(key) || 0) + 1;
                if (retries >= MAX_RETRIES) {
                    logger.error({ key: key.slice(0, 8) + "...", retries }, "CRITICAL: Usage write failed after max retries, data may diverge");
                    dirtyKeys.delete(key);
                    retryCount.delete(key);
                }
                else {
                    retryCount.set(key, retries);
                    logger.warn({ key: key.slice(0, 8) + "...", retries }, "Usage write failed, will retry");
                }
            }
        }
        await client.query("COMMIT");
    }
    catch (error) {
        await client.query("ROLLBACK").catch(() => { });
        logger.error({ err: error }, "Failed to flush usage batch");
        // Keep all keys dirty for retry
    }
    finally {
        client.release();
    }
}
// Periodic flush
setInterval(flushDirtyEntries, FLUSH_INTERVAL_MS);
// Flush on process exit
process.on("SIGTERM", () => { flushDirtyEntries().catch(() => { }); });
process.on("SIGINT", () => { flushDirtyEntries().catch(() => { }); });
export function usageMiddleware(req, res, next) {
    const keyInfo = req.apiKeyInfo;
    const key = keyInfo?.key || "unknown";
    const monthKey = getMonthKey();
    if (isProKey(key)) {
        const record = usage.get(key);
        if (record && record.monthKey === monthKey && record.count >= PRO_TIER_LIMIT) {
            res.status(429).json({ error: "Pro tier limit reached (5,000/month). Contact support for higher limits." });
            return;
        }
        trackUsage(key, monthKey);
        next();
        return;
    }
    const record = usage.get(key);
    if (record && record.monthKey === monthKey && record.count >= FREE_TIER_LIMIT) {
        res.status(429).json({ error: "Free tier limit reached (100/month). Upgrade to Pro at https://docfast.dev/#pricing for 5,000 PDFs/month." });
        return;
    }
    trackUsage(key, monthKey);
    next();
}
function trackUsage(key, monthKey) {
    const record = usage.get(key);
    if (!record || record.monthKey !== monthKey) {
        usage.set(key, { count: 1, monthKey });
    }
    else {
        record.count++;
    }
    dirtyKeys.add(key);
    // Flush immediately if threshold reached
    if (dirtyKeys.size >= FLUSH_THRESHOLD) {
        flushDirtyEntries().catch((err) => logger.error({ err }, "Threshold flush failed"));
    }
}
export function getUsageStats(apiKey) {
    const stats = {};
    if (apiKey) {
        const record = usage.get(apiKey);
        if (record) {
            const masked = apiKey.slice(0, 8) + "...";
            stats[masked] = { count: record.count, month: record.monthKey };
        }
    }
    return stats;
}