import * as fs from "node:fs";
import * as path from "node:path";

const DATA_DIR = process.env.DATA_DIR || "./data";
const LOG_PATH = path.join(DATA_DIR, "app.log");

type LogLevel = "INFO" | "WARN" | "ERROR" | "DEBUG";

function formatDate(date: Date): string {
	return date.toISOString();
}

function writeLog(
	level: LogLevel,
	message: string,
	meta?: Record<string, any>,
) {
	const timestamp = formatDate(new Date());
	const metaStr = meta ? ` ${JSON.stringify(meta)}` : "";
	const logLine = `[${timestamp}] ${level}: ${message}${metaStr}\n`;

	// Write to file
	try {
		fs.appendFileSync(LOG_PATH, logLine);
	} catch (err) {
		// Fall back to console if file write fails
		console.error("Failed to write to log file:", err);
	}

	// Also write to stdout/stderr for systemd journal
	if (level === "ERROR") {
		process.stderr.write(logLine);
	} else {
		process.stdout.write(logLine);
	}
}

export const logger = {
	info: (message: string, meta?: Record<string, any>) =>
		writeLog("INFO", message, meta),
	warn: (message: string, meta?: Record<string, any>) =>
		writeLog("WARN", message, meta),
	error: (message: string, meta?: Record<string, any>) =>
		writeLog("ERROR", message, meta),
	debug: (message: string, meta?: Record<string, any>) => {
		if (process.env.DEBUG) {
			writeLog("DEBUG", message, meta);
		}
	},
};