surface.js

/**
 * Surface
 * Copyright 2014 Zed Gu
 * License: MIT
 */
'use strict';

/**
 * Dependencies
 */
var path = require('path');
var util = require('util');
var Kow = require('koa-ovenware');
var debug = require('debug')('surface:debug');

var render = require('./render');
var context = require('./context');

/**
 * Global
 */
var defaultSetting = {
  root: './lib',
  prefix: false,
  prefixPattern: /^\/api\/v?\d{1,3}(\.\d{1,3}){0,2}/i,
  ctrl: 'controllers',
  model: 'models',
  format: 'json',
  nosniff: true,
  authenticate: false,
  options: 'Accept,Content-Type',
  origin: '*',
  routes: {
    'index': {
      method: 'get',
      path: ''
    },
    'create': {
      method: 'post',
      path: ''
    },
    'get': {
      method: 'get',
      path: '/:id'
    },
    'update': {
      method: 'put',
      path: '/:id'
    },
    'del': {
      method: 'delete',
      path: '/:id'
    }
  },
  aliases: {
    'index': ''
  },
  fields: {
    path: 'request',
    status: 'code',
    message: 'msg',
    data: 'data'
  }
};

/**
 * Expose
 */
module.exports = Surface;

/**
 * Surface Constructor.
 * @param {Object} app     koa().
 * @param {Object} options Config object.
 * @api public
 */
function Surface(app, options) {
  if (!(this instanceof Surface)) {
    return new Surface(app, options);
  }

  this.conf = setting(options);

  this.middleware(app);
  context(app, this);
}

var surface = Surface.prototype;

surface.load = function(app, options) {
  var kp = Kow.prototype;
  var conf = this.conf;

  kp.preprocess = function(fn, path) {
    function *authFn(next) {
      if (yield conf.authenticate.bind(this)()) {
        yield fn.bind(this)();
      } else {
        yield conf.deny.bind(this)();
      }
      yield next;
    }

    function *Fn(next) {
      yield fn.bind(this)();
      yield next;
    }

    if (conf.authenticate) {
      if (conf.authenticatePattern && !conf.authenticatePattern.test(path)) {
        return Fn;
      }
      return authFn;
    }
    return Fn;
  };

  var kow = Kow(app, options);
  this.kow = kow;
  this.ctrls = kow.ctrls;
  this.models = kow.models;
};

/**
 * middleware of Surface
 * @return {Generator} middleware for koa
 */
surface.middleware = function(app) {
  var conf = this.conf;
  var fields = conf.fields;

  app.use(function() {
    if (conf.options) {
      return function *SurfaceOPTIONS(next) {
        yield *next;
        if (this.method === 'OPTIONS') {
          this.set('Access-Control-Allow-Methods', this.res.getHeader('Allow') + ', OPTIONS');
          this.set('Access-Control-Allow-Headers', conf.options);
          this.remove('Allow');
        }
      };
    } else {
      return function *SurfaceOPTIONS(next) {
        yield *next;
        if (this.method === 'OPTIONS') {
          this.remove('Allow');
          this.status = 404;
        }
      };
    }
  }());

  if (conf.nosniff) {
    app.use(function *SurfaceNosniff(next) {
      yield *next;
      this.set('X-Content-Type-Options', 'nosniff');
    });
  }

  if (conf.origin) {
    app.use(function *SurfaceOrigin(next) {
      yield *next;
      this.set('Access-Control-Allow-Origin', conf.origin);
    });
  }

  this.load(app, this.conf);

  var router = this.kow.router || app.router;
  // app.router for koa-router 4.x
  // this.kow.router for koa-router 5.x
  if (router.allowedMethods) {
    app.use(router.allowedMethods());
  }

  app.use(function *Surface(next) {
    yield next;

    if (this.skip_surface) {
      debug('%s : \nNot format by Surface via skip API', this.path);
      return;
    }

    if (conf.prefix && !conf.prefixPattern.test(this.path)) {
      debug('%s : \nNot format by Surface via prefix setting: %s', this.url, conf.prefixPattern);
      return;
    }

    var status = this.res.statusCode;
    if (status === 204 || status === 205 || status === 304) {
      return;
    }

    /**
     * ctx.toJSON().response.string for <= koa@0.12.2,
     * see https://github.com/koajs/koa/pull/353
     * and https://github.com/koajs/koa/commit/eb443d1bee748b3429d5308757573ec083e7e899#diff-d86a59ede7d999db4b7bc43cb25a1c11R477
     */
    var msg = this.res.statusMessage || this.toJSON().response.string || this.toJSON().response.message;
    var format = render.checkFormat.bind(this)(conf.format);

    this.body = render.format(format, this.path, status, msg, this.body, fields);
    this.type = format;
    this.res.statusCode = status;
  });
};

/**
 * Set conf
 * @param  {Object} options Options objest
 * @return {Object}         Formated conf object
 * @api private
 */
function setting(options) {
  var conf = {};

  if (options === null || typeof options !== 'object') {
    options = {};
  }

  for (var key in defaultSetting) {
    conf[key] = options[key] === undefined ? defaultSetting[key] : options[key];
  }

  conf.format = defaultFormat(['json', 'xml'].indexOf(conf.format.toLowerCase()));

  var prefix = conf.prefix;
  if ((typeof prefix === 'string' || util.isRegExp(prefix)) && !options.prefixPattern) {
    conf.prefixPattern = util.isRegExp(prefix) ? prefix : new RegExp(prefix);
  }

  if (conf.authenticate) {
    conf.deny = options.deny;
    conf.authenticatePattern = options.authenticatePattern || conf.prefixPattern;

    if (conf.authenticate.constructor.name !== 'GeneratorFunction') {
      console.error('authenticate should be a GeneratorFunction');
      conf.authenticate = false;
    }
    if (conf.deny.constructor.name !== 'GeneratorFunction') {
      console.error('deny should be a GeneratorFunction');
    }
  }

  return conf;
}

function defaultFormat(index) {
  var d = [['json', 'xml'], ['xml', 'json']];
  index = index === -1 ? 0 : index;

  return d[index];
}