wip(backend): Work on generating og images

packages/backend/package.json

@@ -3,8 +3,8 @@
   "version": "2.19.6",
   "description": "The freesewing.org backend",
   "private": true,
-  "main": "dist/index.js",
-  "module": "dist/index.mjs",
+  "main": "build/main.js",
+  "module": "build/main.mjs",
   "scripts": {
     "precommit": "npm run pretty && lint-staged",
     "patch": "npm version patch -m ':bookmark: v%s' && npm run build",
@@ -50,6 +50,7 @@
     "formidable": "1.2.1",
     "jsonwebtoken": "8.3.0",
     "jszip": "3.1.5",
+    "mdast-util-to-string": "2",
     "mongoose": "5.3.3",
     "mongoose-bcrypt": "1.6.0",
     "mongoose-encryption": "2.0.1",
@@ -57,11 +58,13 @@
     "passport": "0.4.0",
     "passport-jwt": "4.0.0",
     "query-string": "6.2.0",
+    "remark": "13",
+    "remark-parse": "^9.0.0",
+    "remark-plain-text": "^0.2.0",
     "rimraf": "2.6.2",
-    "sharp": "0.21.0"
+    "sharp": "^0.29.3"
   },
   "devDependencies": {
-    "backpack-core": "0.7.0",
-    "nodemon": "1.18.6"
+    "backpack-core": "0.7.0"
   }
 }

packages/backend/src/config/index.js

@@ -52,7 +52,18 @@ const config = {
       tokenUri: "https://oauth2.googleapis.com/token",
       dataUri: "https://people.googleapis.com/v1/people/me?personFields=emailAddresses,names,photos"
     }
+  },
+  og: {
+    template: ["..", "..", "artwork", "og", "template.svg"],
+    chars: {
+      title_1: 18,
+      title_2: 19,
+      title_3: 20,
+      intro: 34,
+      sub: 42
     }
+  },
+  strapi: 'https://posts.freesewing.org',
 }
 
 export default config

packages/backend/src/controllers/og.js

@@ -0,0 +1,186 @@
+import config from "../config";
+import { log } from "../utils";
+import sharp from 'sharp';
+import fs from "fs";
+import path from "path";
+import axios from 'axios'
+import remark from 'remark'
+import remarkParse from 'remark-parse'
+import toString from 'mdast-util-to-string'
+import { Buffer } from 'buffer'
+
+// Sites for which we generate images
+const sites = ['dev', 'org']
+// Langauges for which we generate images
+const languages = ['en', 'fr', 'de', 'es', 'nl' ]
+
+// Load template once at startup
+const template = fs.readFileSync(
+  path.resolve(...config.og.template),
+  'utf-8'
+)
+
+/* Turns markdown into a syntax tree */
+/* Helper method to extract intro from markdown */
+const introFromMarkdown = async (md, slug) => {
+  const tree = await remark().use(remarkParse).parse(md)
+  if (tree.children[0].type !== 'paragraph')
+    console.log('Markdown does not start with paragraph', slug)
+
+  return toString(tree.children[0])
+}
+
+/* Helper method to load dev blog post */
+const loadDevBlogPost = async (slug) => {
+  const result = await axios.get(
+    `${config.strapi}/blogposts?_locale=en&dev_eq=true&slug_eq=${slug}`
+  )
+  if (result.data) return {
+    title: titleAsLines(result.data[0].title),
+    intro: introAsLines(await introFromMarkdown(result.data[0].body, slug)),
+    sub: [
+      result.data[0].author.displayname,
+      new Date(result.data[0].published_at).toString().split(' ').slice(0,4).join(' '),
+    ],
+    lead: 'Developer Blog',
+  }
+
+  return false
+}
+
+/* Find longest possible place to split a string */
+const splitLine = (line, chars) => {
+  const words = line.split(' ')
+  if (words[0].length > chars) {
+    // Force a word break
+    return [ line.slice(0, chars-1)+'-', line.slice(chars-1) ]
+  }
+  // Glue chunks together until it's too long
+  let firstLine = ''
+  let max = false
+  for (const word of words) {
+    if (!max && `${firstLine}${word}`.length <= chars) firstLine += `${word} `
+    else max = true
+  }
+
+  return [ firstLine, words.join(' ').slice(firstLine.length) ]
+}
+
+/* Divide title into lines to fit on image */
+const titleAsLines = title => {
+  // Does it fit on one line?
+  if (title.length <= config.og.chars.title_1) return [title]
+  // Does it fit on two lines?
+  let lines = splitLine(title, config.og.chars.title_1)
+  if (lines[1].length <= config.og.chars.title_2) return lines
+  // Three lines it is
+  return [ lines[0], ...splitLine(lines[1], config.og.chars.title_2) ]
+}
+
+/* Divive intro into lines to fit on image */
+const introAsLines = intro => {
+  // Does it fit on one line?
+  if (intro.length <= config.og.chars.intro) return [intro]
+  // Two lines it is
+  return splitLine(intro, config.og.chars.intro)
+}
+// Get title and intro
+const getMetaData = {
+  dev: async (page) => {
+    const data = {}
+    const chunks = page.split('/')
+    if (chunks.length === 0) return {
+      title: 'FreeSewing FIXME',
+      intro: "FreeSewing's fixme",
+      sub: ['freesewing.dev', '/fixme'],
+    }
+    if (chunks.length === 1) {
+      if (chunks[0] === 'blog') return {
+        title: titleAsLines('FreeSewing Development Blog'),
+        intro: introAsLines("FreeSewing's blog for developers and contributors"),
+        sub: ['freesewing.dev', '/blog'],
+      }
+    }
+    if (chunks.length === 2 && chunks[0] === 'blog') {
+      return await loadDevBlogPost(chunks[1])
+    }
+  },
+  org: page => ({})
+}
+
+/* Hide unused placeholders */
+const hidePlaceholders = list => {
+  let svg = template
+  for (const i of list) {
+    svg = svg
+      .replace(`${i}title_1`, '')
+      .replace(`${i}title_2`, '')
+      .replace(`${i}title_3`, '')
+      .replace(`${i}intro_1`, '')
+      .replace(`${i}intro_2`, '')
+  }
+
+  return svg
+}
+
+/* Place text in SVG template */
+const decorateSvg = data => {
+  let svg
+  // Single title line
+  if (data.title.length === 1) {
+    svg = hidePlaceholders([2,3])
+      .replace(`1title_1`, data.title[0])
+      .replace(`1intro_1`, data.intro[0] || '')
+      .replace(`1intro_2`, data.intro[1] || '')
+  }
+  // Double title line
+  else if (data.title.length === 2) {
+    svg = hidePlaceholders([1,3])
+      .replace(`2title_1`, data.title[0])
+      .replace(`2title_2`, data.title[1])
+      .replace(`2intro_1`, data.intro[0] || '')
+      .replace(`2intro_2`, data.intro[1] || '')
+  }
+  // Triple title line
+  else if (data.title.length === 3) {
+    svg = hidePlaceholders([1,2])
+      .replace(`3title_1`, data.title[0])
+      .replace(`3title_2`, data.title[1])
+      .replace(`3title_3`, data.title[2])
+      .replace(`3intro_1`, data.intro[0] || '')
+      .replace(`3intro_2`, data.intro[1] || '')
+  }
+
+  return svg
+    .replace('sub_1', data.sub[0])
+    .replace('sub_2', data.sub[1])
+    .replace('lead_1', data.lead)
+}
+
+/* This generates open graph images */
+
+function OgController() { }
+
+OgController.prototype.image = async function (req, res) {
+  // Extract path parameters
+  const { lang='en', site='dev' } = req.params
+  const page = req.params["0"]
+  if (sites.indexOf(site) === -1) return res.send({error: 'sorry'})
+  if (languages.indexOf(lang) === -1) return res.send({error: 'sorry'})
+
+  // Load meta data
+  const data = await getMetaData[site](page)
+  // Inject into SVG
+  const svg = decorateSvg(data)
+  // Turn into PNG
+  sharp(Buffer.from(svg, 'utf-8'))
+    .resize({ width: 1200 })
+    .toBuffer((err, data, info) => {
+      if (err) console.log(err)
+      return res.type('png').send(data)
+    })
+}
+
+
+
+export default OgController;

packages/backend/src/routes/index.js

@@ -5,5 +5,6 @@ import model from "./model";
 import referral from "./referral";
 import user from "./user";
 import auth from "./auth";
+import og from "./og";
 
-export default { comment, user, draft, model, referral, confirmation, auth }
+export default { comment, user, draft, model, referral, confirmation, auth, og }

packages/backend/src/routes/og.js

@@ -0,0 +1,11 @@
+import Controller from "../controllers/og";
+
+// Note: Og = Open graph. See https://ogp.me/
+const Og = new Controller();
+
+export default (app, passport) => {
+
+  // Load open graph image (requires no authentication)
+  app.get("/og-img/:lang/:site/*", Og.image);
+
+}