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'use strict';
const Joi = require('joi');
const Pify = require('pify');
const Redis = require('redis');
const UUID = require('uuid/v4');
const internals = {};
internals.kPostsPrefix = 'posts';
internals.kCommentsPrefix = 'comments';
internals.kMaxCommentSize = 255;
internals.kCommentsSchema = Joi.object().keys({
uuid: Joi.string().required(),
content: Joi.string().max(internals.kMaxCommentSize).required(),
timestamp: Joi.number().integer().required(),
userId: Joi.string().required(),
userName: Joi.string().required(),
userImage: Joi.string().required()
});
/**
* Handles the HTTP requests for comment related operations
*
* @class CommentsHandler
* @param {Dasein.tConfiguration} config The configuration to
* initialize.
*/
module.exports = internals.CommentsHandler = class CommentsHandler {
constructor(config) {
this._ttl = config.ttl;
this._redis = Redis.createClient(config.redis);
// Log an error if it happens.
this._redis.on('error', (err) => {
console.error(err);
});
}
/**
* Fetches all available comments
*
* @function findAll
* @memberof CommentsHandler
* @instance
* @return {generator} a koa compatible handler generator function
*/
findAll() {
const self = this;
return function * (postId) {
if (!this.state.user) {
return this.throw('Unauthorized', 401);
}
const scan = Pify(self._redis.scan.bind(self._redis));
const hgetall = Pify(self._redis.hgetall.bind(self._redis));
const commentsKey = `${internals.kCommentsPrefix}:${postId}:*`;
let keys = [];
let nextCursor = 0;
let currentKeys = null;
do {
[nextCursor, currentKeys] = yield scan(nextCursor || 0, 'MATCH', commentsKey);
keys = keys.concat(currentKeys);
} while (nextCursor > 0);
const comments = yield keys.map((key) => hgetall(key));
this.body = comments.sort((a, b) => a.timestamp - b.timestamp);
};
}
/**
* Creates a comment
*
* @function create
* @memberof CommentsHandler
* @instance
* @return {generator} a koa compatible handler generator function
*/
create() {
const self = this;
return function * (postId) {
if (!this.state.user) {
return this.throw('Unauthorized', 401);
}
const hmset = Pify(self._redis.hmset.bind(self._redis));
const hgetall = Pify(self._redis.hgetall.bind(self._redis));
const expire = Pify(self._redis.expire.bind(self._redis));
const uuid = UUID();
const timestamp = Date.now();
const user = this.state.user;
const postKey = `${internals.kPostsPrefix}:${postId}`;
const commentKey = `${internals.kCommentsPrefix}:${postId}:${uuid}`;
const comment = {
uuid,
content: this.request.body.content,
timestamp,
userId: user.screen_name,
userName: user.name,
userImage: user.profile_image_url_https
};
yield self._validate(comment).catch((err) => {
this.throw(err.message, 422);
});
yield hmset(commentKey, comment);
yield expire(commentKey, self._ttl * 100); // this is me being lazy :(
// comments will last at most 100 bumps
// but will disappear eventually
yield expire(postKey, self._ttl); // bumps the parent comment TTL
this.body = yield hgetall(commentKey);
};
}
// Validates the comment schema
_validate(comment) {
const validate = Pify(Joi.validate.bind(Joi));
return validate(comment, internals.kCommentsSchema);
}
};
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