git.r.bdr.sh - rbdr/dasein/blob - lib/handlers/comments.js

   1 'use strict';
   2
   3 const Joi = require('joi');
   4 const Pify = require('pify');
   5 const Redis = require('redis');
   6 const UUID = require('uuid/v4');
   7
   8 const internals = {};
   9
  10 internals.kPostsPrefix = 'posts';
  11 internals.kCommentsPrefix = 'comments';
  12 internals.kMaxCommentSize = 255;
  13
  14 internals.kCommentsSchema = Joi.object().keys({
  15   uuid: Joi.string().required(),
  16   content: Joi.string().max(internals.kMaxCommentSize).required(),
  17   timestamp: Joi.number().integer().required(),
  18   userId: Joi.string().required(),
  19   userName: Joi.string().required(),
  20   userImage: Joi.string().required()
  21 });
  22
  23 /**
  24  * Handles the HTTP requests for comment related operations
  25  *
  26  * @class CommentsHandler
  27  * @param {Dasein.tConfiguration} config The configuration to
  28  * initialize.
  29  */
  30 module.exports = internals.CommentsHandler = class CommentsHandler {
  31   constructor(config) {
  32
  33     this._ttl = config.ttl;
  34     this._redis = Redis.createClient(config.redis);
  35
  36     // Log an error if it happens.
  37     this._redis.on('error', (err) => {
  38
  39       console.error(err);
  40     });
  41   }
  42
  43   /**
  44    * Fetches all available comments
  45    *
  46    * @function findAll
  47    * @memberof CommentsHandler
  48    * @instance
  49    * @return {generator} a koa compatible handler generator function
  50    */
  51   findAll() {
  52
  53     const self = this;
  54
  55     return function * (postId) {
  56
  57       if (!this.state.user) {
  58         return this.throw('Unauthorized', 401);
  59       }
  60
  61       const scan = Pify(self._redis.scan.bind(self._redis));
  62       const hgetall = Pify(self._redis.hgetall.bind(self._redis));
  63
  64       const commentsKey = `${internals.kCommentsPrefix}:${postId}:*`;
  65       let keys = [];
  66       let nextCursor = 0;
  67       let currentKeys = null;
  68
  69       do {
  70         [nextCursor, currentKeys] = yield scan(nextCursor || 0, 'MATCH', commentsKey);
  71         keys = keys.concat(currentKeys);
  72       } while (nextCursor > 0);
  73
  74       const comments = yield keys.map((key) => hgetall(key));
  75
  76       this.body = comments.sort((a, b) => a.timestamp - b.timestamp);
  77     };
  78   }
  79
  80   /**
  81    * Creates a comment
  82    *
  83    * @function create
  84    * @memberof CommentsHandler
  85    * @instance
  86    * @return {generator} a koa compatible handler generator function
  87    */
  88   create() {
  89
  90     const self = this;
  91
  92     return function * (postId) {
  93
  94       if (!this.state.user) {
  95         return this.throw('Unauthorized', 401);
  96       }
  97
  98       const hmset = Pify(self._redis.hmset.bind(self._redis));
  99       const hgetall = Pify(self._redis.hgetall.bind(self._redis));
 100       const expire = Pify(self._redis.expire.bind(self._redis));
 101
 102       const uuid = UUID();
 103       const timestamp = Date.now();
 104       const user = this.state.user;
 105
 106       const postKey = `${internals.kPostsPrefix}:${postId}`;
 107       const commentKey = `${internals.kCommentsPrefix}:${postId}:${uuid}`;
 108
 109       const comment = {
 110         uuid,
 111         content: this.request.body.content,
 112         timestamp,
 113         userId: user.screen_name,
 114         userName: user.name,
 115         userImage: user.profile_image_url_https
 116       };
 117
 118       yield self._validate(comment).catch((err) => {
 119
 120         this.throw(err.message, 422);
 121       });
 122
 123       yield hmset(commentKey, comment);
 124       yield expire(commentKey, self._ttl * 100); // this is me being lazy :(
 125                                                  // comments will last at most 100 bumps
 126                                                  // but will disappear eventually
 127       yield expire(postKey, self._ttl); // bumps the parent comment TTL
 128
 129       this.body = yield hgetall(commentKey);
 130     };
 131   }
 132
 133   // Validates the comment schema
 134
 135   _validate(comment) {
 136
 137     const validate = Pify(Joi.validate.bind(Joi));
 138     return validate(comment, internals.kCommentsSchema);
 139   }
 140 };