From 0155262ddd081c8677654619a09e814088fdd8b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Gonz=C3=A1lez?= <me@alegon.dev>
Date: Sun, 25 May 2025 20:29:33 +0200
Subject: [PATCH] feat(app/minecraft_skins): save current custom external skin
 when equipping skins

---
 packages/app-lib/src/api/minecraft_skins.rs | 53 +++++++++++++++++++--
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/packages/app-lib/src/api/minecraft_skins.rs b/packages/app-lib/src/api/minecraft_skins.rs
index 199515166..dc1a3a922 100644
--- a/packages/app-lib/src/api/minecraft_skins.rs
+++ b/packages/app-lib/src/api/minecraft_skins.rs
@@ -102,7 +102,7 @@ impl Skin {
     }
 }
 
-#[derive(Deserialize, Serialize, Debug)]
+#[derive(Deserialize, Serialize, Debug, PartialEq, Eq)]
 #[serde(rename_all = "snake_case")]
 pub enum SkinSource {
     /// A default Minecraft skin, which may be assigned to players at random by default.
@@ -256,7 +256,9 @@ pub async fn get_available_skins() -> crate::Result<Vec<Skin>> {
 }
 
 /// Adds a custom skin to the app database and equips it for the currently selected
-/// Minecraft profile.
+/// Minecraft profile. If the currently equipped skin is custom but not managed by
+/// the app (i.e., it was set externally by another launcher, the Minecraft website,
+/// etc.), that skin will be added as a custom skin to the app database as well.
 #[tracing::instrument]
 pub async fn add_and_equip_custom_skin(
     texture_blob: Bytes,
@@ -275,9 +277,11 @@ pub async fn add_and_equip_custom_skin(
         .await?
         .ok_or(ErrorKind::NoCredentialsError)?;
 
-    // We have to equip the skin first, as it's the Mojang API backend who knows
-    // how to compute the texture key we require, which we can then read from the
-    // updated player profile
+    save_current_custom_external_skin(&state, &selected_credentials).await?;
+
+    // We have to equip the new skin before storing it, as it's the Mojang API backend
+    // who knows how to compute the texture key we require, which we can then read from
+    // the updated player profile
     mojang_api::MinecraftSkinOperation::equip(
         &selected_credentials,
         stream::iter([Ok::<_, String>(Bytes::clone(&texture_blob))]),
@@ -366,6 +370,10 @@ pub async fn set_default_cape(cape: Option<Cape>) -> crate::Result<()> {
 ///
 /// This function does not check that the passed skin, if custom, exists in the app database,
 /// giving the caller complete freedom to equip any skin at any time.
+///
+/// If the currently equipped skin is a custom skin that is not managed by the app (i.e., it was
+/// set externally by another launcher, the Minecraft website, etc.), that skin will be added as
+/// a custom skin to the app database, in order to allow the app to manage it later.
 #[tracing::instrument]
 pub async fn equip_skin(skin: Skin) -> crate::Result<()> {
     let state = State::get().await?;
@@ -374,6 +382,8 @@ pub async fn equip_skin(skin: Skin) -> crate::Result<()> {
         .await?
         .ok_or(ErrorKind::NoCredentialsError)?;
 
+    save_current_custom_external_skin(&state, &selected_credentials).await?;
+
     let profile =
         selected_credentials.online_profile().await.ok_or_else(|| {
             ErrorKind::OnlineMinecraftProfileUnavailable {
@@ -485,6 +495,39 @@ async fn sync_cape(
     Ok(())
 }
 
+/// Stores the currently equipped skin as a custom skin, if it is a custom skin that is not
+/// managed by the app (i.e., it was externally set).
+async fn save_current_custom_external_skin(
+    state: &State,
+    selected_credentials: &Credentials,
+) -> crate::Result<()> {
+    if let Some(current_external_skin) = get_available_skins()
+        .await?
+        .into_iter()
+        .find(|skin| skin.is_equipped)
+        .filter(|skin| skin.source == SkinSource::CustomExternal)
+    {
+        CustomMinecraftSkin::add(
+            selected_credentials.offline_profile.id,
+            &current_external_skin.texture_key,
+            &current_external_skin
+                .resolve_texture()
+                .await?
+                .try_fold(vec![], async |mut texture_blob, chunk| {
+                    texture_blob.extend_from_slice(&chunk);
+                    Ok(texture_blob)
+                })
+                .await?,
+            current_external_skin.variant,
+            current_external_skin.cape_id,
+            &state.pool,
+        )
+        .await?;
+    }
+
+    Ok(())
+}
+
 fn texture_blob_to_data_url(texture_blob: Vec<u8>) -> Arc<Url> {
     let data = if is_png(&texture_blob) {
         Cow::Owned(texture_blob)