Merge pull request #9 from asset-pipe/unstream

refactor: Refactor to remove streams and match js reader api changes

Author: digitalsadhu

.eslintrc

@@ -1,15 +1,14 @@
 {
   "root": true,
-  "extends": [
-    "finn",
-    "finn/node",
-    "finn-prettier"
-  ],
+  "extends": ["finn", "finn/node", "finn-prettier"],
   "parserOptions": {
-    "ecmaVersion": 2017
+    "ecmaVersion": 2017,
+    "ecmaFeatures": {
+      "experimentalObjectRestSpread": true
+    }
   },
   "env": {
     "node": true,
     "jest": true
   }
-}
+}

README.md

@@ -1,32 +1,32 @@
 <!-- TITLE/ -->
 
-<h1>asset-pipe-css-reader</h1>
+<h1>@asset-pipe/css-reader</h1>
 
 <!-- /TITLE -->
 
 
 <!-- BADGES/ -->
 
 <span class="badge-travisci"><a href="http://travis-ci.org/asset-pipe/asset-pipe-css-reader" title="Check this project's build status on TravisCI"><img src="https://img.shields.io/travis/asset-pipe/asset-pipe-css-reader/master.svg" alt="Travis CI Build Status" /></a></span>
-<span class="badge-npmversion"><a href="https://npmjs.org/package/asset-pipe-css-reader" title="View this project on NPM"><img src="https://img.shields.io/npm/v/asset-pipe-css-reader.svg" alt="NPM version" /></a></span>
+<span class="badge-npmversion"><a href="https://npmjs.org/package/@asset-pipe/css-reader" title="View this project on NPM"><img src="https://img.shields.io/npm/v/@asset-pipe/css-reader.svg" alt="NPM version" /></a></span>
 <span class="badge-daviddm"><a href="https://david-dm.org/asset-pipe/asset-pipe-css-reader" title="View the status of this project's dependencies on DavidDM"><img src="https://img.shields.io/david/asset-pipe/asset-pipe-css-reader.svg" alt="Dependency Status" /></a></span>
 <span class="badge-daviddmdev"><a href="https://david-dm.org/asset-pipe/asset-pipe-css-reader#info=devDependencies" title="View the status of this project's development dependencies on DavidDM"><img src="https://img.shields.io/david/dev/asset-pipe/asset-pipe-css-reader.svg" alt="Dev Dependency Status" /></a></span>
 
 <!-- /BADGES -->
 
 
-A module that takes any number of css feed streams (provided by asset-pipe sinks) and bundles them into a readable stream of css content.
+[![Greenkeeper badge](https://badges.greenkeeper.io/asset-pipe/asset-pipe-css-reader.svg)](https://greenkeeper.io/)
+
+A module that takes any number of css feeds and bundles them into a css bundle.
 
 This is an internal module intended for use by other modules in the [asset-pipe project](https://github.com/asset-pipe).
 
 ## Overview
 
-[![Greenkeeper badge](https://badges.greenkeeper.io/asset-pipe/asset-pipe-css-reader.svg)](https://greenkeeper.io/)
-
-Given any number of css feed streams, the reader will:
-1. Merge streams into a single stream
+Given any number of css feeds, the reader will:
+1. Merge feeds into a single feed
 2. Dedupe any items with identical id hashes keeping the last occurrence
-3. Ensure order of streams given is preserved for the final output CSS
+3. Ensure order of feeds given is preserved for the final output CSS
 
 ### Input data format
 
@@ -50,135 +50,42 @@ The following is an example of a feed file:
 ## Installation
 
 ```bash
-npm install asset-pipe-css-reader
+npm install @asset-pipe/css-reader
 ```
 
 ## Usage
 
 ### Require the reader
 ```js
-const CssReader = require('asset-pipe-css-reader')
+const cssReader = require('@asset-pipe/css-reader')
 ```
 
 ### Instantiating the reader
 
-Either pass a single stream created by an asset-pipe sink:
-```js
-const sink = new SinkFs({
-    path: '/path/to/css/feeds'
-});
-const feedStream = sink.reader('feed-a.json');
-const reader = new CssReader(feedStream)
-```
-
-Or pass an array of streams:
+Pass feeds created by an asset-pipe sink:
 ```js
 const sink = new SinkFs({
     path: '/path/to/css/feeds'
 });
-const feedStream1 = sink.reader('feed-a.json');
-const feedStream2 = sink.reader('feed-b.json');
-const reader = new CssReader([feedStream1, feedStream2])
-```
-
-### Consuming content from the reader
-
-You should wait for the reader to become ready by listening for the `pipeline ready` event.
-
-The reader is a readable stream so in order to access the data you may register a data handler
-and listen for chunks to be passed to the handler:
-```js
-reader.on('pipeline ready', () => {
-    reader.on('data', data => {
-        // ..
-    })
-})
-```
-
-You might also pipe the reader into a writeable or transform stream:
-```js
-const { writeFile } = require('fs')
-const consumer = writeFile('/path/to/save/file')
-
-reader.on('pipeline ready', () => {
-    reader.pipe(consumer)
-})
+const feed1 = JSON.parse(await sink.get('feed-a.json'));
+const feed2 = JSON.parse(await sink.get('feed-b.json'));
+const bundle = await cssReader([feed1, feed2])
 ```
 
 ## API
 
-### Methods
-
-#### constructor
-
-Constructor takes a single stream or array of streams. Streams should be produced with an asset-pipe sink such as: 
+Reader takes an array of feeds. Feeds should be produced with an asset-pipe sink such as: 
 - [asset-pipe-sink-s3](https://github.com/asset-pipe/asset-pipe-sink-s3`)
 - [asset-pipe-sink-fs](https://github.com/asset-pipe/asset-pipe-sink-fs`)
 - [asset-pipe-sink-gcs](https://github.com/asset-pipe/asset-pipe-sink-gcs`)
 - [asset-pipe-sink-mem](https://github.com/asset-pipe/asset-pipe-sink-mem`)
 
-Examples
-```js
-new CssReader(stream)
-```
-```js
-new CssReader([stream, ...stream])
-```
-
-Returns: `Readable Stream`
-
-### Events
-
-#### file found
-
-Event produced whenever an underlying feed stream successfully reads its feed
-file from disk
-
-```js
-cssReader.on('file found', file => {})
-```
-
-Param: `file`, name of the file given to the feed stream to read from
-
-#### file not found
-
-Event produced whenever an underlying feed stream is unable to read its feed
-file from disk
-
-```js
-cssReader.on('file not found', file => {})
-```
-
-Param: `file`, name of the file given to the feed stream to read from
-
-#### pipeline ready
-
-Event produced once all feed file streams have been successfully merged into
-a pipeline
-
-```js
-cssReader.on('pipeline ready', () => {})
-```
-
-#### data
-
-Event that emits chunks of CSS content to a consumer
-
-```js
-cssReader.on('data', chunk => {})
-```
-
-Param: `chunk`, a piece of CSS text
-
-#### error
-
-Event produced whenever any of the various stages of the pipeline emit errors
-
+Example
 ```js
-cssReader.on('error', err => {})
+cssReader([feed, ...feeds])
 ```
 
-Param: `err`, Error forwarded from merged streams or otherwise emitted from the pipeline
+Returns: `string`
 
 ## Contributing
 

lib/reader.js

@@ -1,82 +1,27 @@
 'use strict';
 
-const { Readable, PassThrough, Stream } = require('readable-stream');
-const { parse } = require('JSONStream');
-const mergeStream = require('merge-stream');
-const { dedupe, sort, setOrder } = require('./util');
 const assert = require('assert');
 
-module.exports = class Reader extends Readable {
-    constructor(streams) {
-        super();
-
-        assert(
-            streams instanceof Stream || Array.isArray(streams),
-            `Expected first argument to new Reader() to be a stream or array of streams. 
-            Instead got ${typeof stream}`
-        );
-
-        if (!Array.isArray(streams)) {
-            streams = [streams];
-        }
-
-        assert(
-            streams.every(stream => stream instanceof Stream),
-            'Expected any/all arguments given to Reader constructor to be subclasses of Stream.'
-        );
-
-        assert(
-            streams.length,
-            'Expected at least one stream to be provided to new Reader(). Got none.'
-        );
-
-        const merged = mergeStream();
-
-        let count = 0;
-        streams.forEach((readStream, index) => {
-            const tmpStream = new PassThrough({ objectMode: true });
-            merged.add(tmpStream);
-
-            readStream.on('file found', file => {
-                this.emit('file found', file);
-                readStream
-                    .pipe(parse('*'))
-                    .on('error', err => {
-                        this.emit('error', err);
-                    })
-                    .pipe(setOrder(index))
-                    .pipe(tmpStream);
-
-                count++;
-                if (count === streams.length) {
-                    this.emit('pipeline ready');
-                }
-            });
-
-            readStream.on('file not found', file => {
-                this.emit('file not found', file);
-                tmpStream.end();
-
-                count++;
-                if (count === streams.length) {
-                    this.emit('pipeline ready');
-                }
-            });
-        });
-
-        this.data = merged.pipe(sort()).pipe(dedupe());
-        this.data.pause();
-
-        this.data.on('data', chunk => {
-            this.push(`${chunk.content.trim()}\n\n`);
-        });
-
-        this.data.on('end', () => {
-            this.push(null);
-        });
-    }
-
-    _read() {
-        return this.data.resume();
-    }
+module.exports = async function reader(feeds = []) {
+    assert(
+        feeds.length,
+        `Expected at least 1 feed to be given. Instead got "${feeds.length}"`
+    );
+    assert(
+        feeds.every(Array.isArray),
+        `Expected every feed to be an array. Instead got "${feeds.join(', ')}"`
+    );
+
+    feeds = [].concat(...feeds);
+
+    const feedMap = new Map();
+    feeds.forEach(feed => {
+        // because feedMap preserves order, when we get a duplicate we actually
+        // need to append to the end of the feedMap. We do that by deleting
+        // first and then adding to the feedMap
+        feedMap.delete(feed.id);
+        feedMap.set(feed.id, feed);
+    });
+    const dedupedFeeds = Array.from(feedMap.values());
+    return dedupedFeeds.map(feed => feed.content.trim()).join('\n\n');
 };