import * as bodyParser from "body-parser";
import * as cors from 'cors';
import * as express from "express";
import { initialize } from "express-openapi";
import { readFile } from "fs/promises";
import { assignIn } from 'lodash';
import { join } from "path";
import "reflect-metadata";
import { Logger } from 'winston';
import { IoSocketServer } from "../lib/communication/IoSocketServer";
import { getLinkedDispatcher } from "../lib/dispatcher/getLinkedDispatcher";
import { getBackendAccesors } from './getBackendAccessors';

/**
 * Function to generate the Base Api Documentation
 * @param title The Title of the API
 * @param version The Version
 * @param basePath A Basepath for the API
 */
function _genApiDoc(title: string, version: string, basePath: string, definitions: any = {}){
    // Default API Doc 
    const apiDoc = {
        swagger: '2.0',
        basePath: basePath || '/v1',
        info: {
            title,
            version
        },
        definitions,
        paths: {}
    };

    return apiDoc;
}

/**
 * Function to start a Open-API-Server
 * @param options Options for the Server
 */
export async function startBackend(options: {
    port?: number,
    backendPort?: number,
    basePath?: string,
    logger?: Logger,
} = {}) {
    const app: express.Application = (express as any)();

    // Define the Default Options
    const defaults = {
        port: 3001,
        backendPort: 3002,
        basePath: '/api'
    }
    // Mix the Options.
    const opts = assignIn(defaults, options);

    app.use(bodyParser.json());
    app.use(cors());

    let _definition = {};

    try {
        // Extract the Elements provided in the API-Document.
        _definition = JSON.parse(await readFile(join(__dirname, 'apidoc.json'), {
            encoding: 'utf8'
        })).definitions;
    } catch(e){
        if (opts.logger) {
            opts.logger.error('cant parse apidoc.json');
        }
    }

    initialize({
        apiDoc: _genApiDoc('Backend API', '1.0.0', opts.basePath, _definition),
        app,
        paths: './dist/open-api',
        routesGlob: '**/*.{ts,js}',
        routesIndexFileRegExp: /(?:index)?\.[tj]s$/,
        dependencies: {
            _dispatcher: getLinkedDispatcher(
                {
                    communicator: new IoSocketServer(opts.backendPort, 'generic', 'generic')
                }
            )
        },
    });

    app.use(((err, req, res, next) => {
        res.status(err.status).json(err);
    }) as express.ErrorRequestHandler);

    const server = app.listen(opts.port);

    const accessor = getBackendAccesors(app);

    if (options.logger) {
        options.logger.info('Server Running on http://localhost:' + opts.port.toString() + opts.basePath);
        options.logger.info('API Documentation available on http://localhost:' + opts.port.toString() + opts.basePath + '/api-docs');
        options.logger.debug('Checkout http://localhost:3000/docs')
    }

    return {
        app,
        // Accessor for the Server
        accessor,
        // Function to extract the Definitions.
        definitionUri: opts.basePath + '/api-docs',
        // Function to Close the Server
        close() {
            server.close();
        }
    }
}