/* jslint node: true */
'use strict';

//  ENiGMA½
const Log           = require('../../logger.js').log;
const ServerModule  = require('../../server_module.js').ServerModule;
const Config        = require('../../config.js').get;

//  deps
const http          = require('http');
const https         = require('https');
const _             = require('lodash');
const fs            = require('graceful-fs');
const paths         = require('path');
const mimeTypes     = require('mime-types');

const ModuleInfo = exports.moduleInfo = {
    name        : 'Web',
    desc        : 'Web Server',
    author      : 'NuSkooler',
    packageName : 'codes.l33t.enigma.web.server',
};

class Route {
    constructor(route) {
        Object.assign(this, route);

        if(this.method) {
            this.method = this.method.toUpperCase();
        }

        try {
            this.pathRegExp = new RegExp(this.path);
        } catch(e) {
            Log.debug( { route : route }, 'Invalid regular expression for route path' );
        }
    }

    isValid() {
        return (
            this.pathRegExp instanceof RegExp &&
            ( -1 !== [ 'GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'CONNECT', 'OPTIONS', 'TRACE',  ].indexOf(this.method) ) ||
            !_.isFunction(this.handler)
        );
    }

    matchesRequest(req) {
        return req.method === this.method && this.pathRegExp.test(req.url);
    }

    getRouteKey() { return `${this.method}:${this.path}`; }
}

exports.getModule = class WebServerModule extends ServerModule {
    constructor() {
        super();

        const config        = Config();
        this.enableHttp     = config.contentServers.web.http.enabled || false;
        this.enableHttps    = config.contentServers.web.https.enabled || false;

        this.routes = {};

        if(this.isEnabled() && config.contentServers.web.staticRoot) {
            this.addRoute({
                method      : 'GET',
                path        : '/static/.*$',
                handler     : this.routeStaticFile.bind(this),
            });
        }
    }

    buildUrl(pathAndQuery) {
        //
        //  Create a URL such as
        //  https://l33t.codes:44512/ + |pathAndQuery|
        //
        //  Prefer HTTPS over HTTP. Be explicit about the port
        //  only if non-standard. Allow users to override full prefix in config.
        //
        const config = Config();
        if(_.isString(config.contentServers.web.overrideUrlPrefix)) {
            return `${config.contentServers.web.overrideUrlPrefix}${pathAndQuery}`;
        }

        let schema;
        let port;
        if(config.contentServers.web.https.enabled) {
            schema  = 'https://';
            port    =  (443 === config.contentServers.web.https.port) ?
                '' :
                `:${config.contentServers.web.https.port}`;
        } else {
            schema  = 'http://';
            port    = (80 === config.contentServers.web.http.port) ?
                '' :
                `:${config.contentServers.web.http.port}`;
        }

        return `${schema}${config.contentServers.web.domain}${port}${pathAndQuery}`;
    }

    isEnabled() {
        return this.enableHttp || this.enableHttps;
    }

    createServer() {
        if(this.enableHttp) {
            this.httpServer = http.createServer( (req, resp) => this.routeRequest(req, resp) );
        }

        const config = Config();
        if(this.enableHttps) {
            const options = {
                cert    : fs.readFileSync(config.contentServers.web.https.certPem),
                key     : fs.readFileSync(config.contentServers.web.https.keyPem),
            };

            //  additional options
            Object.assign(options, config.contentServers.web.https.options || {} );

            this.httpsServer = https.createServer(options, (req, resp) => this.routeRequest(req, resp) );
        }
    }

    listen() {
        let ok = true;

        const config = Config();
        [ 'http', 'https' ].forEach(service => {
            const name = `${service}Server`;
            if(this[name]) {
                const port = parseInt(config.contentServers.web[service].port);
                if(isNaN(port)) {
                    ok = false;
                    return Log.warn( { port : config.contentServers.web[service].port, server : ModuleInfo.name }, `Invalid port (${service})` );
                }
                return this[name].listen(port);
            }
        });

        return ok;
    }

    addRoute(route) {
        route = new Route(route);

        if(!route.isValid()) {
            Log.warn( { route : route }, 'Cannot add route: missing or invalid required members' );
            return false;
        }

        const routeKey = route.getRouteKey();
        if(routeKey in this.routes) {
            Log.warn( { route : route, routeKey : routeKey }, 'Cannot add route: duplicate method/path combination exists' );
            return false;
        }

        this.routes[routeKey] = route;
        return true;
    }

    routeRequest(req, resp) {
        const route = _.find(this.routes, r => r.matchesRequest(req) );

        if(!route && '/' === req.url) {
            return this.routeIndex(req, resp);
        }

        return route ? route.handler(req, resp) : this.accessDenied(resp);
    }

    respondWithError(resp, code, bodyText, title) {
        const customErrorPage = paths.join(Config().contentServers.web.staticRoot, `${code}.html`);

        fs.readFile(customErrorPage, 'utf8', (err, data) => {
            resp.writeHead(code, { 'Content-Type' : 'text/html' } );

            if(err) {
                return resp.end(`<!doctype html>
                    <html lang="en">
                        <head>
                        <meta charset="utf-8">
                        <title>${title}</title>
                        <meta name="viewport" content="width=device-width, initial-scale=1">
                        </head>
                        <body>
                            <article>
                                <h2>${bodyText}</h2>
                            </article>
                        </body>
                    </html>`
                );
            }

            return resp.end(data);
        });
    }

    accessDenied(resp) {
        return this.respondWithError(resp, 401, 'Access denied.', 'Access Denied');
    }

    fileNotFound(resp) {
        return this.respondWithError(resp, 404, 'File not found.', 'File Not Found');
    }

    routeIndex(req, resp) {
        const filePath = paths.join(Config().contentServers.web.staticRoot, 'index.html');

        return this.returnStaticPage(filePath, resp);
    }

    routeStaticFile(req, resp) {
        const fileName = req.url.substr(req.url.indexOf('/', 1));
        const filePath = paths.join(Config().contentServers.web.staticRoot, fileName);

        return this.returnStaticPage(filePath, resp);
    }

    returnStaticPage(filePath, resp) {
        const self = this;

        fs.stat(filePath, (err, stats) => {
            if(err || !stats.isFile()) {
                return self.fileNotFound(resp);
            }

            const headers = {
                'Content-Type'      : mimeTypes.contentType(paths.basename(filePath)) || mimeTypes.contentType('.bin'),
                'Content-Length'    : stats.size,
            };

            const readStream = fs.createReadStream(filePath);
            resp.writeHead(200, headers);
            return readStream.pipe(resp);
        });
    }

    routeTemplateFilePage(templatePath, preprocessCallback, resp) {
        const self = this;

        fs.readFile(templatePath, 'utf8', (err, templateData) => {
            if(err) {
                return self.fileNotFound(resp);
            }

            preprocessCallback(templateData, (err, finalPage, contentType) => {
                if(err || !finalPage) {
                    return self.respondWithError(resp, 500, 'Internal Server Error.', 'Internal Server Error');
                }

                const headers = {
                    'Content-Type'      : contentType || mimeTypes.contentType('.html'),
                    'Content-Length'    : finalPage.length,
                };

                resp.writeHead(200, headers);
                return resp.end(finalPage);
            });
        });
    }
};