From 5505a89e8aad717a0b4a7665b23a317110d38cb5 Mon Sep 17 00:00:00 2001
From: Henry Jameson <me@hjkos.com>
Date: Mon, 22 Apr 2024 23:40:39 +0300
Subject: [PATCH] implement a simple caching system for themes 3

---
 package.json                                  |  1 +
 src/boot/after_store.js                       | 26 +++++++------
 .../settings_modal/tabs/general_tab.vue       |  8 ++++
 src/i18n/en.json                              |  1 +
 src/modules/config.js                         |  1 +
 src/modules/instance.js                       |  3 +-
 src/services/style_setter/style_setter.js     | 37 ++++++++++++++++++-
 .../theme_data/theme_data_3.service.js        |  8 +++-
 8 files changed, 70 insertions(+), 15 deletions(-)

diff --git a/package.json b/package.json
index cbbcb170ea..fb157fae65 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,7 @@
     "click-outside-vue3": "4.0.1",
     "cropperjs": "1.5.13",
     "escape-html": "1.0.3",
+    "hash-sum": "^2.0.0",
     "js-cookie": "3.0.5",
     "localforage": "1.10.0",
     "parse-link-header": "2.0.0",
diff --git a/src/boot/after_store.js b/src/boot/after_store.js
index bfb671edc5..bcab7a663d 100644
--- a/src/boot/after_store.js
+++ b/src/boot/after_store.js
@@ -14,7 +14,7 @@ import { windowWidth, windowHeight } from '../services/window_utils/window_utils
 import { getOrCreateApp, getClientToken } from '../services/new_api/oauth.js'
 import backendInteractorService from '../services/backend_interactor_service/backend_interactor_service.js'
 import { CURRENT_VERSION } from '../services/theme_data/theme_data.service.js'
-import { applyTheme, applyConfig } from '../services/style_setter/style_setter.js'
+import { applyTheme, applyConfig, tryLoadCache } from '../services/style_setter/style_setter.js'
 import FaviconService from '../services/favicon_service/favicon_service.js'
 import { initServiceWorker, updateFocus } from '../services/sw/sw.js'
 
@@ -353,21 +353,25 @@ const afterStoreSetup = async ({ store, i18n }) => {
 
   await setConfig({ store })
 
-  const { customTheme, customThemeSource } = store.state.config
+  const { customTheme, customThemeSource, forceThemeRecompilation } = store.state.config
   const { theme } = store.state.instance
   const customThemePresent = customThemeSource || customTheme
 
-  if (customThemePresent) {
-    if (customThemeSource && customThemeSource.themeEngineVersion === CURRENT_VERSION) {
-      applyTheme(customThemeSource)
-    } else {
-      applyTheme(customTheme)
-    }
+  if (!forceThemeRecompilation && tryLoadCache()) {
     store.commit('setThemeApplied')
-  } else if (theme) {
-    // do nothing, it will load asynchronously
   } else {
-    console.error('Failed to load any theme!')
+    if (customThemePresent) {
+      if (customThemeSource && customThemeSource.themeEngineVersion === CURRENT_VERSION) {
+        applyTheme(customThemeSource)
+      } else {
+        applyTheme(customTheme)
+      }
+      store.commit('setThemeApplied')
+    } else if (theme) {
+      // do nothing, it will load asynchronously
+    } else {
+      console.error('Failed to load any theme!')
+    }
   }
 
   applyConfig(store.state.config)
diff --git a/src/components/settings_modal/tabs/general_tab.vue b/src/components/settings_modal/tabs/general_tab.vue
index f56fa8e0e2..424ee7e4a7 100644
--- a/src/components/settings_modal/tabs/general_tab.vue
+++ b/src/components/settings_modal/tabs/general_tab.vue
@@ -200,6 +200,14 @@
     <div class="setting-item">
       <h2>{{ $t('settings.post_look_feel') }}</h2>
       <ul class="setting-list">
+        <li>
+          <BooleanSetting
+            path="forceThemeRecompilation"
+            :expert="1"
+          >
+            {{ $t('settings.force_theme_recompilation_debug') }}
+          </BooleanSetting>
+        </li>
         <li>
           <ChoiceSetting
             id="conversationDisplay"
diff --git a/src/i18n/en.json b/src/i18n/en.json
index a011139acc..872d05d4c3 100644
--- a/src/i18n/en.json
+++ b/src/i18n/en.json
@@ -634,6 +634,7 @@
     "subject_line_email": "Like email: \"re: subject\"",
     "subject_line_mastodon": "Like mastodon: copy as is",
     "subject_line_noop": "Do not copy",
+    "force_theme_recompilation_debug": "Disable theme cahe, force recompile on each boot (DEBUG)",
     "conversation_display": "Conversation display style",
     "conversation_display_tree": "Tree-style",
     "conversation_display_tree_quick": "Tree view",
diff --git a/src/modules/config.js b/src/modules/config.js
index abb57272f4..46acae4105 100644
--- a/src/modules/config.js
+++ b/src/modules/config.js
@@ -28,6 +28,7 @@ export const defaultState = {
   theme: undefined,
   customTheme: undefined,
   customThemeSource: undefined,
+  forceThemeRecompilation: false,
   hideISP: false,
   hideInstanceWallpaper: false,
   hideShoutbox: false,
diff --git a/src/modules/instance.js b/src/modules/instance.js
index 76269eceae..a0a9e9acff 100644
--- a/src/modules/instance.js
+++ b/src/modules/instance.js
@@ -377,7 +377,8 @@ const instance = {
           commit('setInstanceOption', { name: 'themeData', value: themeData })
           // No need to apply theme if there's user theme already
           const { customTheme } = rootState.config
-          if (customTheme) return
+          const { themeApplied } = rootState.interface
+          if (customTheme || themeApplied) return
 
           // New theme presets don't have 'theme' property, they use 'source'
           const themeSource = themeData.source
diff --git a/src/services/style_setter/style_setter.js b/src/services/style_setter/style_setter.js
index 95198ec7c9..17682bd40f 100644
--- a/src/services/style_setter/style_setter.js
+++ b/src/services/style_setter/style_setter.js
@@ -1,6 +1,6 @@
 import { hex2rgb } from '../color_convert/color_convert.js'
 import { generatePreset } from '../theme_data/theme_data.service.js'
-import { init } from '../theme_data/theme_data_3.service.js'
+import { init, getChecksum } from '../theme_data/theme_data_3.service.js'
 import { convertTheme2To3 } from '../theme_data/theme2_to_theme3.js'
 import { getCssRules } from '../theme_data/css_utils.js'
 import { defaultState } from '../../modules/config.js'
@@ -87,9 +87,37 @@ export const generateTheme = async (input, callbacks) => {
   return { lazyProcessFunc: processChunk }
 }
 
-export const applyTheme = async (input) => {
+export const tryLoadCache = () => {
+  const json = localStorage.getItem('pleroma-fe-theme-cache')
+  if (!json) return null
+  let cache
+  try {
+    cache = JSON.parse(json)
+  } catch (e) {
+    console.error('Failed to decode theme cache:', e)
+    return false
+  }
+  if (cache.checksum === getChecksum()) {
+    const styleSheet = new CSSStyleSheet()
+    const lazyStyleSheet = new CSSStyleSheet()
+
+    cache.data[0].forEach(rule => styleSheet.insertRule(rule, 'index-max'))
+    cache.data[1].forEach(rule => lazyStyleSheet.insertRule(rule, 'index-max'))
+
+    document.adoptedStyleSheets = [styleSheet, lazyStyleSheet]
+
+    return true
+  } else {
+    console.warn('Checksum doesn\'t match, cache not usable, clearing')
+    localStorage.removeItem('pleroma-fe-theme-cache')
+  }
+}
+
+export const applyTheme = async (input, onFinish = (data) => {}) => {
   const styleSheet = new CSSStyleSheet()
+  const styleArray = []
   const lazyStyleSheet = new CSSStyleSheet()
+  const lazyStyleArray = []
 
   const { lazyProcessFunc } = await generateTheme(
     input,
@@ -97,8 +125,10 @@ export const applyTheme = async (input) => {
       onNewRule (rule, isLazy) {
         if (isLazy) {
           lazyStyleSheet.insertRule(rule, 'index-max')
+          lazyStyleArray.push(rule)
         } else {
           styleSheet.insertRule(rule, 'index-max')
+          styleArray.push(rule)
         }
       },
       onEagerFinished () {
@@ -106,6 +136,9 @@ export const applyTheme = async (input) => {
       },
       onLazyFinished () {
         document.adoptedStyleSheets = [styleSheet, lazyStyleSheet]
+        const cache = { checksum: getChecksum(), data: [styleArray, lazyStyleArray] }
+        onFinish(cache)
+        localStorage.setItem('pleroma-fe-theme-cache', JSON.stringify(cache))
       }
     }
   )
diff --git a/src/services/theme_data/theme_data_3.service.js b/src/services/theme_data/theme_data_3.service.js
index 7457ab99c7..844e951a6a 100644
--- a/src/services/theme_data/theme_data_3.service.js
+++ b/src/services/theme_data/theme_data_3.service.js
@@ -1,4 +1,5 @@
 import { convert, brightness } from 'chromatism'
+import sum from 'hash-sum'
 import { flattenDeep } from 'lodash'
 import {
   alphaBlend,
@@ -142,8 +143,12 @@ componentsContext.keys().forEach(key => {
   components[component.name] = component
 })
 
+const checksum = sum(components)
+
 const ruleToSelector = genericRuleToSelector(components)
 
+export const getChecksum = () => checksum
+
 export const init = (extraRuleset, ultimateBackgroundColor) => {
   const staticVars = {}
   const stacked = {}
@@ -463,6 +468,7 @@ export const init = (extraRuleset, ultimateBackgroundColor) => {
   return {
     lazy: result.filter(x => typeof x === 'function'),
     eager: result.filter(x => typeof x !== 'function'),
-    staticVars
+    staticVars,
+    checksum
   }
 }