/**
 * Structured logging via Winston.
 *
 * One root logger is created at module load. Each domain gets a child logger
 * that adds a `domain` field to every log entry so log lines can be filtered
 * and routed independently.
 *
 * A custom format reads the current request context from AsyncLocalStorage and
 * injects `requestId` into every log entry automatically — no manual threading needed.
 *
 * Optional env vars:
 *   LOG_LEVEL  — winston level (default: "info"; use "debug" for verbose output)
 *   NODE_ENV   — when "development", logs are pretty-printed; otherwise JSON
 */
import { createLogger, format, transports } from 'winston';

import { getContext } from '$lib/server/context';

import { env } from '$env/dynamic/private';

const level = env.LOG_LEVEL ?? 'info';

// Injects requestId from AsyncLocalStorage into every log entry.
const requestContextFormat = format((info) => {
	const ctx = getContext();
	if (ctx) info['requestId'] = ctx.requestId;
	return info;
});

const productionFormat = format.combine(
	requestContextFormat(),
	format.timestamp(),
	format.errors({ stack: true }),
	format.json(),
);

const developmentFormat = format.combine(
	requestContextFormat(),
	format.timestamp({ format: 'HH:mm:ss' }),
	format.errors({ stack: true }),
	format.colorize(),
	format.printf(({ timestamp, level, message, domain, requestId, ...rest }) => {
		const domainTag = domain ? `[${domain}] ` : '';
		const rid = requestId ? `(${requestId}) ` : '';
		const extra = Object.keys(rest).length ? ' ' + JSON.stringify(rest) : '';
		return `${timestamp} ${level} ${domainTag}${rid}${message}${extra}`;
	}),
);

const root = createLogger({
	level,
	format: env.NODE_ENV === 'development' ? developmentFormat : productionFormat,
	transports: [new transports.Console()],
});

const child = (domain: string) => root.child({ domain });

// --- Domain loggers ---

const serverLogger = child('server');
const authLogger = child('auth');
const gitLogger = child('git');
const k8sLogger = child('k8s');

export { authLogger, gitLogger, k8sLogger, root as logger, serverLogger };