From 490d3cf2e4dbb0bd52bbe41c1024c8a30db0a217 Mon Sep 17 00:00:00 2001
From: Simon Lecoq <22963968+lowlighter@users.noreply.github.com>
Date: Fri, 26 Nov 2021 05:15:36 +0100
Subject: [PATCH] feat(metrics): improved optimizers (#680)

---
 source/app/metrics/index.mjs     | 34 +++--------------
 source/app/metrics/utils.mjs     | 65 +++++++++++++++++++++++++++++++-
 source/plugins/core/metadata.yml | 13 +++++--
 3 files changed, 80 insertions(+), 32 deletions(-)

diff --git a/source/app/metrics/index.mjs b/source/app/metrics/index.mjs
index ebb3c986..736ab872 100644
--- a/source/app/metrics/index.mjs
+++ b/source/app/metrics/index.mjs
@@ -1,8 +1,6 @@
 //Imports
 import ejs from "ejs"
-import SVGO from "svgo"
 import util from "util"
-import xmlformat from "xml-formatter"
 import * as utils from "./utils.mjs"
 
 //Setup
@@ -174,32 +172,12 @@ export default async function metrics({login, q}, {graphql, rest, plugins, conf,
     if (q["config.gemoji"])
       rendered = await imports.svg.gemojis(rendered, {rest})
     //Optimize rendering
-    if (!q.raw)
-      rendered = xmlformat(rendered, {lineSeparator:"\n", collapseContent:true})
-    if ((conf.settings?.optimize) && (!q.raw)) {
-      console.debug(`metrics/compute/${login} > optimize`)
-      if (experimental.has("--optimize")) {
-        const {error, data:optimized} = await SVGO.optimize(rendered, {
-          multipass:true,
-          plugins:SVGO.extendDefaultPlugins([
-            //Additional cleanup
-            {name:"cleanupListOfValues"},
-            {name:"removeRasterImages"},
-            {name:"removeScriptElement"},
-            //Force CSS style consistency
-            {name:"inlineStyles", active:false},
-            {name:"removeViewBox", active:false},
-          ]),
-        })
-        if (error)
-          throw new Error(`Could not optimize SVG: \n${error}`)
-        rendered = optimized
-        console.debug(`metrics/compute/${login} > optimize > success`)
-      }
-      else
-        console.debug(`metrics/compute/${login} > optimize > this feature is currently disabled due to display issues (use --optimize flag in experimental features to force enable it)`)
-
-    }
+    if ((conf.settings?.optimize === true) || (conf.settings?.optimize?.includes?.("css")))
+      rendered = await imports.svg.optimize.css(rendered)
+    if ((conf.settings?.optimize === true) || (conf.settings?.optimize?.includes?.("xml")))
+      rendered = await imports.svg.optimize.xml(rendered, q)
+    if ((conf.settings?.optimize === true) || (conf.settings?.optimize?.includes?.("svg")))
+      rendered = await imports.svg.optimize.svg(rendered, q, experimental)
     //Verify svg
     if (verify) {
       console.debug(`metrics/compute/${login} > verify SVG`)
diff --git a/source/app/metrics/utils.mjs b/source/app/metrics/utils.mjs
index 16d1a92e..4b2f42b9 100644
--- a/source/app/metrics/utils.mjs
+++ b/source/app/metrics/utils.mjs
@@ -26,6 +26,11 @@ import emoji from "emoji-name-map"
 import minimatch from "minimatch"
 import crypto from "crypto"
 import linguist from "linguist-js"
+import purgecss from "purgecss"
+import csso from "csso"
+import SVGO from "svgo"
+import xmlformat from "xml-formatter"
+
 prism_lang()
 
 //Exports
@@ -155,7 +160,7 @@ export function htmlunescape(string, u = {"&":true, "<":true, ">":true, '"':true
 
 /**Chartist */
 export async function chartist() {
-  const css = `<style>${await fs.readFile(paths.join(__module(import.meta.url), "../../../node_modules", "node-chartist/dist/main.css")).catch(_ => "")}</style>`
+  const css = `<style data-optimizable="true">${await fs.readFile(paths.join(__module(import.meta.url), "../../../node_modules", "node-chartist/dist/main.css")).catch(_ => "")}</style>`
   return (await nodechartist(...arguments))
     .replace(/class="ct-chart-line">/, `class="ct-chart-line">${css}`)
 }
@@ -510,6 +515,64 @@ export const svg = {
       rendered = rendered.replace(new RegExp(emoji, "g"), gemoji)
     return rendered
   },
+  /**Optimizers */
+  optimize:{
+    /**CSS optimizer */
+    async css(rendered) {
+      //Extract styles
+      console.debug("metrics/svg/optimize/css > optimizing")
+      const regex = /<style data-optimizable="true">(?<style>[\s\S]*?)<\/style>/
+      const cleaned = "<!-- (optimized css) -->"
+      const css = []
+      while (regex.test(rendered)) {
+        const style = htmlunescape(rendered.match(regex)?.groups?.style ?? "")
+        rendered = rendered.replace(regex, cleaned)
+        css.push({raw:style})
+      }
+      const content = [{raw:rendered, extension:"html"}]
+
+      //Purge CSS
+      const purged = await new purgecss.PurgeCSS().purge({content, css})
+      const optimized = `<style>${csso.minify(purged.map(({css}) => css).join("\n")).css}</style>`
+      return rendered.replace(cleaned, optimized)
+    },
+    /**XML optimizer */
+    async xml(rendered, {raw = false} = {}) {
+      console.debug("metrics/svg/optimize/xml > optimizing")
+      if (raw) {
+        console.debug("metrics/svg/optimize/xml > skipped as raw option is enabled")
+        return rendered
+      }
+      return xmlformat(rendered, {lineSeparator:"\n", collapseContent:true})
+    },
+    /**SVG optimizer */
+    async svg(rendered, {raw = false} = {}, experimental = new Set()) {
+      console.debug("metrics/svg/optimize/svg > optimizing")
+      if (raw) {
+        console.debug("metrics/svg/optimize/svg > skipped as raw option is enabled")
+        return rendered
+      }
+      if (!experimental.has("--optimize")) {
+        console.debug("metrics/svg/optimize/svg > this feature require experimental feature flag --optimize-svg")
+        return rendered
+      }
+      const {error, data:optimized} = await SVGO.optimize(rendered, {
+        multipass:true,
+        plugins:SVGO.extendDefaultPlugins([
+          //Additional cleanup
+          {name:"cleanupListOfValues"},
+          {name:"removeRasterImages"},
+          {name:"removeScriptElement"},
+          //Force CSS style consistency
+          {name:"inlineStyles", active:false},
+          {name:"removeViewBox", active:false},
+        ]),
+      })
+      if (error)
+        throw new Error(`Could not optimize SVG: \n${error}`)
+      return optimized
+    }
+  }
 }
 
 /**Wait */
diff --git a/source/plugins/core/metadata.yml b/source/plugins/core/metadata.yml
index e01779d5..763ad86d 100644
--- a/source/plugins/core/metadata.yml
+++ b/source/plugins/core/metadata.yml
@@ -106,8 +106,14 @@ inputs:
   # Some templates may not support this option
   optimize:
     description: SVG optimization
-    type: boolean
-    default: yes
+    type: array
+    default: css, xml
+    format:
+      - comma-separated
+    values:
+      - css  # Purge and minify CSS styles
+      - xml  # Pretty-print XML
+      - svg  # Optimize SVG with SVGO (experimental, require --optimize-svg flag)
 
   # Setup additional templates from remote repositories
   setup_community_templates:
@@ -280,13 +286,14 @@ inputs:
     default: no
 
   # Experimental features
+  # Note that no backward compatibility are guaranteed for these features
   experimental_features:
     description: Experimental features
     type: array
     format: space-separated
     default: ""
     values:
-      - --optimize
+      - --optimize-svg
 
   # Use mocked data to bypass external APIs
   use_mocked_data: