import Debug from "debug";
import { setDebug } from "./debug";
const loggers = {
  debug: Debug("magicbell:debug"),
  info: Debug("magicbell:info"),
  error: Debug("magicbell:error")
};
export type LogLevel = "debug" | "info" | "error";
export type LogEvent = {
  level: LogLevel;
  message: string;
  data?: unknown;
  time: number;
};
type LogListener = (e: LogEvent) => void;
const listeners = new Set<LogListener>();
function emit(level: LogLevel, message: string, data?: unknown) {
  const evt: LogEvent = {
    level,
    message,
    data,
    time: Date.now()
  };
  for (const l of listeners) {
    try {
      l(evt);
    } catch {
      // ignore listener errors
    }
  }
}
function makeLogger(level: LogLevel) {
  const fn = loggers[level];
  return (message: string, data?: unknown) => {
    fn(message, data);
    emit(level, message, data);
  };
}
function wrap<T extends (...args: any[]) => any>(level: Exclude<keyof typeof log, "wrap">, message: string, handler: T) {
  return function (...args: Parameters<T>): ReturnType<T> {
    const logger = log[level];
    const start = Date.now();
    // only log the arguments that are consumed, vs provided.
    const input = args.slice(0, handler.length);
    logger(message, {
      args: input
    });
    const logResult = (result: any, duration: number) => {
      logger(message, {
        duration: `${duration} ms`,
        args: input,
        result
      });
      return result;
    };
    const logError = (err: any, duration: number): never => {
      logger(message, {
        duration: `${duration} ms`,
        args: input,
        error: err
      });
      throw err;
    };
    try {
      const result = handler(...args);
      if (result instanceof Promise) {
        return result.then(res => logResult(res, Date.now() - start)).catch(err => logError(err, Date.now() - start)) as ReturnType<T>;
      } else {
        return logResult(result, Date.now() - start);
      }
    } catch (err) {
      return logError(err, Date.now() - start) as ReturnType<T>;
    }
  };
}
export const log = {
  debug: makeLogger("debug"),
  info: makeLogger("info"),
  error: makeLogger("error"),
  wrap
};
export function onLog(listener: LogListener): () => void {
  listeners.add(listener);
  return () => listeners.delete(listener);
}
setDebug("onLog", onLog)