// Structured JSON logger with traceId support
import { randomUUID } from "crypto";

const LOG_LEVELS = { debug: 0, info: 1, warn: 2, error: 3 };
const CURRENT_LEVEL = LOG_LEVELS[process.env.LOG_LEVEL || "info"] ?? LOG_LEVELS.info;

function formatLog(level, message, data = {}) {
  const entry = {
    ts: new Date().toISOString(),
    level,
    msg: message,
    ...data,
  };
  if (!entry.traceId) {
    entry.traceId = randomUUID().slice(0, 8);
  }
  return JSON.stringify(entry);
}

function createLogger(module) {
  function log(level, message, data = {}) {
    if (LOG_LEVELS[level] < CURRENT_LEVEL) return;
    const line = formatLog(level, message, { module, ...data });
    if (level === "error") {
      console.error(line);
    } else if (level === "warn") {
      console.warn(line);
    } else {
      console.log(line);
    }
  }

  return {
    debug: (msg, data) => log("debug", msg, data),
    info: (msg, data) => log("info", msg, data),
    warn: (msg, data) => log("warn", msg, data),
    error: (msg, data) => log("error", msg, data),
    child: (extra) => createLogger(`${module}:${extra.sub || "child"}`),
  };
}

export { createLogger };