import { fleetSettings } from '../settings.js';
import { db } from '../db/index.js';
import { type TelemetryRequestLogEntry } from '../../telemetry-diagnostics.js';

const MAX_PAYLOAD_LENGTH = 16 * 1024;
// Bound storage even when requests claim many different, unregistered names.
export function telemetryRetention() {
    const settings = fleetSettings();
    return {
        maxAgeDays: settings.telemetryKeepDays,
        maxPerServer: settings.telemetryMaxPerServer,
        maxTotal: settings.telemetryMaxTotal
    };
}
export const telemetryCutoff = () =>
    telemetryRetention().maxAgeDays
        ? new Date(Date.now() - telemetryRetention().maxAgeDays * 86_400_000).toISOString()
        : '';
const cutoff = telemetryCutoff;
const textField = (value: unknown) => (typeof value === 'string' ? value.slice(0, 255) : null);

export function recordTelemetryRequest(input: {
    value: unknown;
    receivedAt: string;
    status: number;
    error: string | null;
    contentType: string | null;
}): void {
    // Use only the top-level JSON field, never a player's name or a substring.
    // Malformed JSON cannot be reliably attributed to an individual server.
    if (!input.value || typeof input.value !== 'object' || Array.isArray(input.value)) return;
    const body = input.value as Record<string, unknown>;
    if (typeof body.server !== 'string' || !body.server.trim() || body.server.length > 255) return;
    const payload = JSON.stringify(body);
    const handle = db();
    handle.transaction(() => {
        handle
            .prepare(
                `INSERT INTO telemetry_requests
            (server, received_at, status, error, event, map, round, player_count, content_type, payload, payload_truncated)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`
            )
            .run(
                body.server,
                input.receivedAt,
                input.status,
                input.error?.slice(0, 2000) ?? null,
                textField(body.event),
                textField(body.map),
                Number.isSafeInteger(body.round) ? (body.round as number) : null,
                Array.isArray(body.players) ? body.players.length : null,
                textField(input.contentType),
                payload.slice(0, MAX_PAYLOAD_LENGTH),
                Number(payload.length > MAX_PAYLOAD_LENGTH)
            );
        if (telemetryRetention().maxAgeDays)
            handle.prepare('DELETE FROM telemetry_requests WHERE received_at < ?').run(cutoff());
        if (telemetryRetention().maxPerServer)
            handle
                .prepare(
                    `DELETE FROM telemetry_requests WHERE server = ? AND id <= (
            SELECT id FROM telemetry_requests WHERE server = ? ORDER BY id DESC LIMIT 1 OFFSET ?
        )`
                )
                .run(body.server, body.server, telemetryRetention().maxPerServer);
        if (telemetryRetention().maxTotal)
            handle
                .prepare(
                    `DELETE FROM telemetry_requests WHERE id <= (
            SELECT id FROM telemetry_requests ORDER BY id DESC LIMIT 1 OFFSET ?
        )`
                )
                .run(telemetryRetention().maxTotal);
    })();
}

export function listTelemetryRequests(server: string): TelemetryRequestLogEntry[] {
    const rows = db()
        .prepare(
            `SELECT id, server, received_at AS receivedAt, status, error, event, map, round,
        player_count AS playerCount, content_type AS contentType, payload, payload_truncated AS payloadTruncated
        FROM telemetry_requests WHERE server = ? AND received_at >= ? ORDER BY id DESC LIMIT ?`
        )
        .all(server, cutoff(), telemetryRetention().maxPerServer || 10000) as Array<
        Omit<TelemetryRequestLogEntry, 'payloadTruncated'> & { payloadTruncated: number }
    >;
    return rows.map((row) => ({ ...row, payloadTruncated: !!row.payloadTruncated }));
}