48 lines
1.9 KiB
TypeScript
48 lines
1.9 KiB
TypeScript
 
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type LogLevel = "debug" | "info" | "warn" | "error";
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type LogFields = Record<string, unknown>;
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const LEVEL_ORDER: Record<LogLevel, number> = { debug: 0, info: 1, warn: 2, error: 3 };
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function resolveMinLevel(): LogLevel {
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const configured = process.env.LOG_LEVEL?.toLowerCase();
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if (configured === "debug" || configured === "info" || configured === "warn" || configured === "error") {
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return configured;
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}
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return process.env.NODE_ENV === "production" ? "info" : "debug";
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}
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const MIN_LEVEL = resolveMinLevel();
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function formatFields(fields?: LogFields): string {
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if (!fields) return "";
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const parts = Object.entries(fields)
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.filter(([, value]) => value !== undefined)
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.map(([key, value]) => `${key}=${typeof value === "string" ? value : JSON.stringify(value)}`);
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return parts.length > 0 ? ` ${parts.join(" ")}` : "";
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}
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function write(level: LogLevel, scope: string, message: string, fields?: LogFields): void {
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if (LEVEL_ORDER[level] < LEVEL_ORDER[MIN_LEVEL]) return;
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const line = `${new Date().toISOString()} ${level.toUpperCase().padEnd(5)} [${scope}] ${message}${formatFields(fields)}`;
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if (level === "error") console.error(line);
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else if (level === "warn") console.warn(line);
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else console.log(line);
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}
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export interface Logger {
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debug(message: string, fields?: LogFields): void;
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info(message: string, fields?: LogFields): void;
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warn(message: string, fields?: LogFields): void;
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error(message: string, fields?: LogFields): void;
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}
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/** Scoped logger. `scope` is the bracketed tag, e.g. createLogger("scheduler") -> "[scheduler]". */
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export function createLogger(scope: string): Logger {
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return {
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debug: (message, fields) => write("debug", scope, message, fields),
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info: (message, fields) => write("info", scope, message, fields),
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warn: (message, fields) => write("warn", scope, message, fields),
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error: (message, fields) => write("error", scope, message, fields),
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};
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}
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