/*!
 * Copyright (c) Microsoft Corporation and contributors. All rights reserved.
 * Licensed under the MIT License.
 */

import {
	ILumberjackEngine,
	LogLevel,
	Lumber,
	LumberType,
} from "@fluidframework/server-services-telemetry";
import { serializeError } from "serialize-error";
import winston from "winston";

// Lumberjack engine based on Winston. It processes the data
// captured in a Lumber instance and sends it through Winston.
/**
 * @internal
 */
export class WinstonLumberjackEngine implements ILumberjackEngine {
	public emit(lumber: Lumber<string>) {
		try {
			const propObj: { [key: string]: any } = {};
			lumber.properties.forEach((value, key) => {
				propObj[key] = value;
			});
			const obj = {
				eventName: lumber.eventName,
				id: lumber.id,
				properties: JSON.stringify(propObj),
				type: LumberType[lumber.type],
				timestamp: new Date(lumber.timestamp).toISOString(),
				durationInMs: lumber.durationInMs,
				successful: lumber.successful,
				exception: serializeError(lumber.exception),
			};

			const level = this.getLogLevelToWinstonMapping(lumber.logLevel);
			const message = lumber.message ?? "No message provided.";

			winston.log(level, message, obj);
		} catch (err) {
			winston.error(
				`WinstonLumberjackEngine: error when emitting Lumber object. Error: ${err}`,
			);
		}
	}

	private getLogLevelToWinstonMapping(level: LogLevel | undefined) {
		switch (level) {
			case LogLevel.Error:
				return "error";
			case LogLevel.Warning:
				return "warn";
			case LogLevel.Info:
				return "info";
			case LogLevel.Verbose:
				return "verbose";
			case LogLevel.Debug:
				return "debug";
			default:
				return "info";
		}
	}
}