kliedz/src/logger/level_priority.ts

Dead-simple, stateless logging utility for JavaScript and TypeScript. Pure functions. No dependencies. Just log.

import type { LogLevel } from "../types/log_level.js";
import { type LogThreshold, logThresholds } from "../types/log_threshold.js";

/**
 * Assigns a numeric priority to each log threshold level.
 * Lower numbers mean more verbose; higher means more critical.
 * "silent" is given a very high value (999) to suppress all output.
 */
export const levelPriority: Record<LogThreshold, number> = Object.fromEntries(
	logThresholds.map((level, index) =>
		level === "silent" ? [level, 999] : [level, index],
	),
) as Record<LogThreshold, number>;

/**
 * Returns the numeric priority for a given log level or threshold.
 * Throws if the level is unknown or not registered.
 *
 * @param level - Log level or threshold
 * @returns Priority number
 */
export function getPriorityFor(level: LogLevel | LogThreshold): number {
	if (!(level in levelPriority)) {
		throw new Error(`Unknown log level/threshold: "${level}"`);
	}
	return levelPriority[level];
}

/**
 * Determines whether a message with the given `level` should be logged
 * based on the user-defined `threshold`.
 *
 * @param threshold - The minimum log level required to allow output
 * @param level - The log level of the current message
 * @returns `true` if the message should be printed, `false` otherwise
 */
export function shouldLog(threshold: LogThreshold, level: LogLevel): boolean {
	return getPriorityFor(level) >= getPriorityFor(threshold);
}