From a2ffd046d61fb6424825f183af195ce1df2e156f Mon Sep 17 00:00:00 2001
From: Chocobozzz <me@florianbigard.com>
Date: Fri, 25 Oct 2019 10:57:23 +0200
Subject: Speedup theme injection

---
 client/src/app/core/theme/theme.service.ts | 91 ++++++++++++++++++++++++++----
 1 file changed, 80 insertions(+), 11 deletions(-)

(limited to 'client/src/app/core/theme/theme.service.ts')

diff --git a/client/src/app/core/theme/theme.service.ts b/client/src/app/core/theme/theme.service.ts
index 012488075..b312e8f7a 100644
--- a/client/src/app/core/theme/theme.service.ts
+++ b/client/src/app/core/theme/theme.service.ts
@@ -4,13 +4,21 @@ import { ServerService } from '@app/core/server'
 import { environment } from '../../../environments/environment'
 import { PluginService } from '@app/core/plugins/plugin.service'
 import { ServerConfigTheme } from '@shared/models'
+import { peertubeLocalStorage } from '@app/shared/misc/peertube-local-storage'
 
 @Injectable()
 export class ThemeService {
 
+  private static KEYS = {
+    LAST_ACTIVE_THEME: 'last_active_theme'
+  }
+
   private oldThemeName: string
   private themes: ServerConfigTheme[] = []
 
+  private themeFromLocalStorage: ServerConfigTheme
+  private themeDOMLinksFromLocalStorage: HTMLLinkElement[] = []
+
   constructor (
     private auth: AuthService,
     private pluginService: PluginService,
@@ -18,22 +26,30 @@ export class ThemeService {
   ) {}
 
   initialize () {
+    // Try to load from local storage first, so we don't have to wait network requests
+    this.loadAndSetFromLocalStorage()
+
     this.server.configLoaded
         .subscribe(() => {
-          this.injectThemes()
+          const themes = this.server.getConfig().theme.registered
+
+          this.removeThemeFromLocalStorageIfNeeded(themes)
+          this.injectThemes(themes)
 
           this.listenUserTheme()
         })
   }
 
-  private injectThemes () {
-    this.themes = this.server.getConfig().theme.registered
+  private injectThemes (themes: ServerConfigTheme[], fromLocalStorage = false) {
+    this.themes = themes
 
     console.log('Injecting %d themes.', this.themes.length)
 
-    const head = document.getElementsByTagName('head')[0]
+    const head = this.getHeadElement()
 
     for (const theme of this.themes) {
+      // Already added this theme?
+      if (fromLocalStorage === false && this.themeFromLocalStorage && this.themeFromLocalStorage.name === theme.name) continue
 
       for (const css of theme.css) {
         const link = document.createElement('link')
@@ -45,12 +61,16 @@ export class ThemeService {
         link.setAttribute('title', theme.name)
         link.setAttribute('disabled', '')
 
+        if (fromLocalStorage === true) this.themeDOMLinksFromLocalStorage.push(link)
+
         head.appendChild(link)
       }
     }
   }
 
   private getCurrentTheme () {
+    if (this.themeFromLocalStorage) return this.themeFromLocalStorage.name
+
     if (this.auth.isLoggedIn()) {
       const theme = this.auth.getUser().theme
       if (theme !== 'instance-default') return theme
@@ -70,13 +90,7 @@ export class ThemeService {
   }
 
   private updateCurrentTheme () {
-    if (this.oldThemeName) {
-      const oldTheme = this.getTheme(this.oldThemeName)
-      if (oldTheme) {
-        console.log('Removing scripts of old theme %s.', this.oldThemeName)
-        this.pluginService.removePlugin(oldTheme)
-      }
-    }
+    if (this.oldThemeName) this.removeThemePlugins(this.oldThemeName)
 
     const currentTheme = this.getCurrentTheme()
 
@@ -90,12 +104,20 @@ export class ThemeService {
       this.pluginService.addPlugin(theme, true)
 
       this.pluginService.reloadLoadedScopes()
+
+      peertubeLocalStorage.setItem(ThemeService.KEYS.LAST_ACTIVE_THEME, JSON.stringify(theme))
+    } else {
+      peertubeLocalStorage.removeItem(ThemeService.KEYS.LAST_ACTIVE_THEME)
     }
 
     this.oldThemeName = currentTheme
   }
 
   private listenUserTheme () {
+    // We don't need them anymore
+    this.themeFromLocalStorage = undefined
+    this.themeDOMLinksFromLocalStorage = []
+
     if (!this.auth.isLoggedIn()) {
       this.updateCurrentTheme()
     }
@@ -104,6 +126,53 @@ export class ThemeService {
       .subscribe(() => this.updateCurrentTheme())
   }
 
+  private loadAndSetFromLocalStorage () {
+    const lastActiveThemeString = peertubeLocalStorage.getItem(ThemeService.KEYS.LAST_ACTIVE_THEME)
+    if (!lastActiveThemeString) return
+
+    try {
+      const lastActiveTheme = JSON.parse(lastActiveThemeString)
+      this.themeFromLocalStorage = lastActiveTheme
+
+      this.injectThemes([ lastActiveTheme ], true)
+      this.updateCurrentTheme()
+    } catch (err) {
+      console.error('Cannot parse last active theme.', err)
+      return
+    }
+  }
+
+  private removeThemePlugins (themeName: string) {
+    const oldTheme = this.getTheme(themeName)
+    if (oldTheme) {
+      console.log('Removing scripts of old theme %s.', themeName)
+      this.pluginService.removePlugin(oldTheme)
+    }
+  }
+
+  private removeThemeFromLocalStorageIfNeeded (themes: ServerConfigTheme[]) {
+    if (!this.themeFromLocalStorage) return
+
+    const loadedTheme = themes.find(t => t.name === this.themeFromLocalStorage.name)
+    if (!loadedTheme || loadedTheme.version !== this.themeFromLocalStorage.version) {
+      // Need to remove this theme: we loaded an old version or a theme that does not exist anymore
+      this.removeThemePlugins(this.themeFromLocalStorage.name)
+      this.oldThemeName = undefined
+
+      const head = this.getHeadElement()
+      for (const htmlLinkElement of this.themeDOMLinksFromLocalStorage) {
+        head.removeChild(htmlLinkElement)
+      }
+
+      this.themeFromLocalStorage = undefined
+      this.themeDOMLinksFromLocalStorage = []
+    }
+  }
+
+  private getHeadElement () {
+    return document.getElementsByTagName('head')[0]
+  }
+
   private getTheme (name: string) {
     return this.themes.find(t => t.name === name)
   }
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