/**
 * Lightweight logger that suppresses output in production.
 *
 * In development (npm run dev): logs are shown with a prefix tag.
 * In production  (npm run build): all console output is suppressed
 * so logs are never exposed to the browser inspector.
 *
 * Usage:
 *   import { logger } from '$lib/core/utils/logger';
 *   logger.info('hello', someVar);
 *   logger.error('failed', err);
 */

type LogLevel = 'trace' | 'debug' | 'info' | 'warn' | 'error';

const LOG_LEVEL_RANK: Record<LogLevel, number> = {
	trace: -1,
	debug: 0,
	info: 1,
	warn: 2,
	error: 3
};

const ENV_LOG_LEVEL: LogLevel =
	(import.meta.env.PUBLIC_APP_LOG_LEVEL as LogLevel) || 'info';
const IS_DEV = import.meta.env.DEV;

function shouldLog(level: LogLevel): boolean {
	return IS_DEV && LOG_LEVEL_RANK[level] >= LOG_LEVEL_RANK[ENV_LOG_LEVEL];
}

function formatArgs(level: LogLevel, args: any[]): any[] {
	return [`[${level.toUpperCase()}]`, ...args];
}

/**
 * Extract caller location (file:line) from a stack trace.
 * Stack frame format: "    at method (file:///path/file.ts:10:20)"
 * The 3rd frame (index 2) is the caller of the method that created the Error.
 */
function getCallerLocation(): string {
	try {
		const stack = new Error().stack?.split('\n');
		if (!stack || stack.length < 3) return 'unknown';
		// stack[0] = "Error", stack[1] = "    at getCallerLocation (...)",
		// stack[2] = "    at Logger.trace (...)" — skip both
		const caller = stack[2]?.trim();
		// Extract path from common formats:
		//   "at method (file:///path/file.ts:10:20)"  or  "at file:///path/file.ts:10:20"
		const match = caller.match(/(?:\(|at\s+)([^(]+?\.\w+):(\d+)/);
		if (match) return `${match[1]}:${match[2]}`;
		return caller || 'unknown';
	} catch {
		return 'unknown';
	}
}

class Logger {
	trace(...args: any[]) {
		if (shouldLog('trace')) {
			const location = getCallerLocation();
			console.debug(`[TRACE:${location}]`, ...args);
		}
	}

	debug(...args: any[]) {
		if (shouldLog('debug')) {
			console.debug(...formatArgs('debug', args));
		}
	}

	info(...args: any[]) {
		if (shouldLog('info')) {
			console.info(...formatArgs('info', args));
		}
	}

	warn(...args: any[]) {
		if (shouldLog('warn')) {
			console.warn(...formatArgs('warn', args));
		}
	}

	error(...args: any[]) {
		if (shouldLog('error')) {
			console.error(...formatArgs('error', args));
		}
	}
}

export const logger = new Logger();