import * as bunyan from 'bunyan';
import { WriteStream } from 'fs';

import { Middleware } from './middleware';
import { Request, Response } from '../http';
import { getLogger } from '../system';


/**
 * Logs requests and responses as JSON.
 *
 * @export
 * @class JSONLogger
 * @extends {Middleware}
 */
export class JSONLogger extends Middleware {

    /**
     * Reference to underlying bunyan logger.
     *
     * @private
     * @type {bunyan}
     * @memberof JSONLogger
     */
    private log: bunyan;

    /**
     * Reference to underlying log level.
     *
     * @private
     * @type {string}
     * @memberof JSONLogger
     */
    private level: string;

    /**
     * Creates an instance of JSONLogger.
     * @param {string} name
     * @param {string} [level='info']
     * @memberof JSONLogger
     */
    constructor(name: string, level: string='info') {
        super();
        this.log = getLogger(name, level);
    }

    /**
     * Add a NodeJS.WriteStream stream to the list of log targets.
     *
     * @param {NodeJS.WriteStream} stream
     * @memberof JSONLogger
     */
    addStream(stream: NodeJS.WriteStream) {
        let writeStream: bunyan.Stream = {
            level: this.level as bunyan.LogLevel,
            stream: stream
        };
        this.log.addStream(writeStream as bunyan.Stream);
    }

    /**
     * Logs selected request values as JSON.
     *
     * @param {Request} req
     * @param {Response} res
     * @memberof JSONLogger
     */
    processRequest = async (req: Request, res: Response) => {
        let msg = {
            id: req.id,
            path: req.path,
            query: req.query,
            params: req.params,
            method: req.method,
            body: req.body,
        };
        this.log.info(msg);
    }

    /**
     * Logs selected response values as JSON.
     *
     * @param {Request} req
     * @param {Response} res
     * @returns {Promise<any>}
     * @memberof JSONLogger
     */
    processResponse = async (req: Request, res: Response) => {
        let msg = {
            id: req.id,
            code: res.code,
            body: res.body
        };
        this.log.info(msg);
    }
}