'use strict';

var _ = require('lodash');

var BaseServer = require('./BaseServer');

var Func = require('./Func');

var Host = function Host(config) {

BaseServer.call(this, config);

this.functions = Object.create(null);

if (this.config.functions) {

_.forOwn(this.config.functions, function(func, name) {

this.addFunction(name, func);

}, this);

}

};

Host.prototype = Object.create(BaseServer.prototype);

Host.prototype.constructor = Host;

Host.prototype.defaultConfig = _.defaults({

functions: null,

requestDataLimit: '10mb'

}, BaseServer.prototype.defaultConfig);

Host.prototype.getSerializableConfig = function getSerializableConfig() {

var serializableConfig = BaseServer.prototype.getSerializableConfig.call(this);

// Convert `functions` to an array of names

return _.mapValues(serializableConfig, function(val, key) {

if (key === 'functions' && val) {

return Object.keys(val);

}

return val;

});

};

Host.prototype.addFunction = function addFunction(name, func) {

if (this.functions[name] !== undefined) {

throw new Error('A function has already been defined with the name "' + name + '"');

}

this.functions[name] = new Func(name, func);

return this.functions[name];

};

Host.prototype.bindListener = function bindListener(listener) {

BaseServer.prototype.bindListener.call(this, listener);

listener.param('function', function functionLookup(req, res, next, funcName) {

var func = this.functions[funcName];

if (!func) {

this.logger.info('Request for unknown function "' + funcName + '"');

return res.status(404).end('Not found. Unknown function "' + funcName + '"');

}

res.locals.func = func;

next();

}.bind(this));

listener.post('/function/:function', function callFunction(req, res) {

var func = res.locals.func;

this.logger.info('Calling function "' + func.name + '"');

var data = req.body;

var context = {

name: func.name,

host: func,

req: req,

res: res

};

func.call(context, data, this.functionCallbackFactory(context, func));

}.bind(this));

};

Host.prototype.functionCallbackFactory = function functionCallbackFactory(context, func) {

var called = false;

return function functionCallback(err, output) {

if (called) {

err = new Error('Function "' + func.name + '" called its callback more than once');

return this.logger.error(err.stack);

}

// Prevent the callback from being called a second time

called = true;

var res = context.res;

if (err) {

if (!(err instanceof Error)) {

err = new Error(err);

}

this.logger.error('Function: ' + func.name, err.stack);

return res.status(500).end(err.stack);

}

this.logger.info('Function: ' + func.name + ' completed');

res.end(output.toString());

}.bind(this);

};

module.exports = Host;