Channels: Add support for multi-image community posts (#4412)

This PR adds a CSS-only image carousel for community posts with more than
one image attached.

Closes issue 3522

5 files changed, 167 insertions, 7 deletions

diff --git a/assets/css/carousel.css b/assets/css/carousel.css
new file mode 100644
index 00000000..4bae92e5
--- /dev/null
+++ b/assets/css/carousel.css
@@ -0,0 +1,119 @@
+/*
+Copyright (c) 2024 by Jennifer (https://codepen.io/jwjertzoch/pen/JjyGeRy)
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without restriction,
+ including without limitation the rights to use, copy, modify,
+merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall
+be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+.carousel {
+    margin: 0 auto;
+    overflow: hidden;
+    text-align: center;
+}
+
+.slides {
+    width: 100%;
+    display: flex;
+    overflow-x: scroll;
+    scrollbar-width: none;
+    scroll-snap-type: x mandatory;
+    scroll-behavior: smooth;
+}
+
+.slides::-webkit-scrollbar {
+    display: none;
+}
+
+.slides-item {
+    align-items: center;
+    border-radius: 10px;
+    display: flex;
+    flex-shrink: 0;
+    font-size: 100px;
+    height: 600px;
+    justify-content: center;
+    margin: 0 1rem;
+    position: relative;
+    scroll-snap-align: start;
+    transform: scale(1);
+    transform-origin: center center;
+    transition: transform .5s;
+    width: 100%;
+}
+
+.carousel__nav {
+    padding: 1.25rem .5rem;
+}
+
+.slider-nav {
+    align-items: center;
+    background-color: #ddd;
+    border-radius: 50%;
+    color: #000;
+    display: inline-flex;
+    height: 1.5rem;
+    justify-content: center;
+    padding: .5rem;
+    position: relative;
+    text-decoration: none;
+    width: 1.5rem;
+}
+
+.skip-link {
+    height: 1px;
+    overflow: hidden;
+    position: absolute;
+    top: auto;
+    width: 1px;
+}
+
+.skip-link:focus {
+    align-items: center;
+    background-color: #000;
+    color: #fff;
+    display: flex;
+    font-size: 30px;
+    height: 30px;
+    justify-content: center;
+    opacity: .8;
+    text-decoration: none;
+    width: 50%;
+    z-index: 1;
+}
+
+.light-theme .slider-nav {
+    background-color: #ddd;
+}
+
+.dark-theme .slider-nav  {
+    background-color: #0005;
+}
+
+@media (prefers-color-scheme: light) {
+    .no-theme .slider-nav {
+        background-color: #ddd;
+    }
+}
+
+@media (prefers-color-scheme: dark) {
+    .no-theme .slider-nav {
+        background-color: #0005;
+    }
+}
diff --git a/locales/en-US.json b/locales/en-US.json
index da83767c..10887612 100644
--- a/locales/en-US.json
+++ b/locales/en-US.json
@@ -493,5 +493,8 @@
     "channel_tab_playlists_label": "Playlists",
     "channel_tab_community_label": "Community",
     "channel_tab_channels_label": "Channels",
-    "toggle_theme": "Toggle Theme"
+    "toggle_theme": "Toggle Theme",
+    "carousel_slide": "Slide {{current}} of {{total}}",
+    "carousel_skip": "Skip the Carousel",
+    "carousel_go_to": "Go to slide `x`"
 }
diff --git a/src/invidious/frontend/comments_youtube.cr b/src/invidious/frontend/comments_youtube.cr
index ecc0bc1b..aecac87f 100644
--- a/src/invidious/frontend/comments_youtube.cr
+++ b/src/invidious/frontend/comments_youtube.cr
@@ -107,6 +107,36 @@ module Invidious::Frontend::Comments
               </div>
               END_HTML
             end
+          when "multiImage"
+            html << <<-END_HTML
+              <section class="carousel">
+              <a class="skip-link" href="#skip-#{child["commentId"]}">#{translate(locale, "carousel_skip")}</a>
+              <div class="slides">
+              END_HTML
+            image_array = attachment["images"].as_a
+
+            image_array.each_index do |i|
+              html << <<-END_HTML
+                  <div class="slides-item slide-#{i + 1}" id="#{child["commentId"]}-slide-#{i + 1}" aria-label="#{translate(locale, "carousel_slide", {"current" => (i + 1).to_s, "total" => image_array.size.to_s})}" tabindex="0">
+                    <img loading="lazy" src="/ggpht#{URI.parse(image_array[i][1]["url"].as_s).request_target}" alt="" />
+                  </div>
+                END_HTML
+            end
+
+            html << <<-END_HTML
+              </div>
+              <div class="carousel__nav">
+              END_HTML
+            attachment["images"].as_a.each_index do |i|
+              html << <<-END_HTML
+                  <a class="slider-nav" href="##{child["commentId"]}-slide-#{i + 1}" aria-label="#{translate(locale, "carousel_go_to", (i + 1).to_s)}" tabindex="-1" aria-hidden="true">#{i + 1}</a>
+                END_HTML
+            end
+            html << <<-END_HTML
+              </div>
+              <div id="skip-#{child["commentId"]}"></div>
+            </section>
+            END_HTML
           else nil # Ignore
           end
         end
diff --git a/src/invidious/helpers/i18n.cr b/src/invidious/helpers/i18n.cr
index 76e477a4..23a1aafc 100644
--- a/src/invidious/helpers/i18n.cr
+++ b/src/invidious/helpers/i18n.cr
@@ -78,7 +78,7 @@ def load_all_locales
   return locales
 end
 
-def translate(locale : String?, key : String, text : String | Nil = nil) : String
+def translate(locale : String?, key : String, text : String | Hash(String, String) | Nil = nil) : String
   # Log a warning if "key" doesn't exist in en-US locale and return
   # that key as the text, so this is more or less transparent to the user.
   if !LOCALES["en-US"].has_key?(key)
@@ -101,10 +101,12 @@ def translate(locale : String?, key : String, text : String | Nil = nil) : Strin
     match_length = 0
 
     raw_data.as_h.each do |hash_key, value|
-      if md = text.try &.match(/#{hash_key}/)
-        if md[0].size >= match_length
-          translation = value.as_s
-          match_length = md[0].size
+      if text.is_a?(String)
+        if md = text.try &.match(/#{hash_key}/)
+          if md[0].size >= match_length
+            translation = value.as_s
+            match_length = md[0].size
+          end
         end
       end
     end
@@ -114,8 +116,13 @@ def translate(locale : String?, key : String, text : String | Nil = nil) : Strin
     raise "Invalid translation \"#{raw_data}\""
   end
 
-  if text
+  if text.is_a?(String)
     translation = translation.gsub("`x`", text)
+  elsif text.is_a?(Hash(String, String))
+    # adds support for multi string interpolation. Based on i18next https://www.i18next.com/translation-function/interpolation#basic
+    text.each_key do |hash_key|
+      translation = translation.gsub("{{#{hash_key}}}", text[hash_key])
+    end
   end
 
   return translation
diff --git a/src/invidious/views/template.ecr b/src/invidious/views/template.ecr
index 5623bf77..9904b4fc 100644
--- a/src/invidious/views/template.ecr
+++ b/src/invidious/views/template.ecr
@@ -21,6 +21,7 @@
     <link rel="stylesheet" href="/css/grids-responsive-min.css?v=<%= ASSET_COMMIT %>">
     <link rel="stylesheet" href="/css/ionicons.min.css?v=<%= ASSET_COMMIT %>">
     <link rel="stylesheet" href="/css/default.css?v=<%= ASSET_COMMIT %>">
+    <link rel="stylesheet" href="/css/carousel.css?v=<%= ASSET_COMMIT %>">
     <script src="/js/_helpers.js?v=<%= ASSET_COMMIT %>"></script>
 </head>