feat: (skinchanger) fetch skins from Mojang so the module applies the chosen skin

The Online mode only scanned the current server tab list, so it could
never load an arbitrary account and did nothing out of the box. Resolve
the name to a UUID, pull the skin texture URL from the session server and
download it through the vanilla threaded image pipeline (with legacy
64x32 conversion). File mode now runs images through the same legacy
converter so non-64x64 and transparent skins render correctly.

Author: opZywl

src/main/java/net/ccbluex/liquidbounce/features/module/modules/visual/SkinChanger.kt

@@ -5,15 +5,24 @@
  */
 package net.ccbluex.liquidbounce.features.module.modules.visual
 
+import kotlinx.coroutines.launch
 import net.ccbluex.liquidbounce.event.UpdateEvent
 import net.ccbluex.liquidbounce.event.handler
 import net.ccbluex.liquidbounce.features.module.Category
 import net.ccbluex.liquidbounce.features.module.Module
 import net.ccbluex.liquidbounce.file.FileManager.dir
 import net.ccbluex.liquidbounce.utils.client.ClientUtils.LOGGER
 import net.ccbluex.liquidbounce.utils.client.chat
+import net.ccbluex.liquidbounce.utils.io.HttpClient
+import net.ccbluex.liquidbounce.utils.io.get
+import net.ccbluex.liquidbounce.utils.io.readJson
+import net.ccbluex.liquidbounce.utils.kotlin.SharedScopes
+import net.minecraft.client.renderer.IImageBuffer
+import net.minecraft.client.renderer.ImageBufferDownload
+import net.minecraft.client.renderer.ThreadDownloadImageData
 import net.minecraft.client.renderer.texture.DynamicTexture
 import net.minecraft.util.ResourceLocation
+import java.awt.image.BufferedImage
 import java.io.File
 import javax.imageio.ImageIO
 
@@ -40,11 +49,15 @@ object SkinChanger : Module("SkinChanger", Category.VISUAL, Category.SubCategory
     private var resolved: ResourceLocation? = null
     private var lastKey = ""
 
+    @Volatile
+    private var pendingKey = ""
+
     val skinLocation: ResourceLocation?
         get() = if (handleEvents()) resolved else null
 
     private fun invalidate() {
         lastKey = ""
+        pendingKey = ""
         resolved = null
     }
 
@@ -70,26 +83,68 @@ object SkinChanger : Module("SkinChanger", Category.VISUAL, Category.SubCategory
             return
         }
 
-        if (lastKey == "online:$name" && resolved != null) {
+        val key = "online:$name"
+        if (lastKey == key) {
             return
         }
 
-        lastKey = "online:$name"
+        lastKey = key
+        pendingKey = key
 
-        val playerInfoMap = mc.netHandler?.playerInfoMap ?: run {
-            resolved = null
-            return
-        }
+        SharedScopes.IO.launch {
+            runCatching {
+                val uuid = fetchUuid(name) ?: return@launch
+                val skinUrl = fetchSkinUrl(uuid) ?: return@launch
 
-        val info = synchronized(playerInfoMap) {
-            ArrayList(playerInfoMap)
-        }.firstOrNull {
-            it?.gameProfile?.name.equals(name, ignoreCase = true)
+                mc.addScheduledTask {
+                    if (pendingKey != key) return@addScheduledTask
+                    applyDownloadedSkin(key, uuid, skinUrl)
+                }
+            }.onFailure {
+                LOGGER.error("Failed to resolve skin for $name", it)
+            }
         }
+    }
 
-        resolved = info?.locationSkin
+    private fun applyDownloadedSkin(key: String, uuid: String, skinUrl: String) {
+        val location = ResourceLocation("fdp/skin-changer/$uuid")
+        val texture = ThreadDownloadImageData(
+            File(skinDir, "$uuid.png"),
+            skinUrl,
+            null,
+            object : IImageBuffer {
+                override fun parseUserSkin(image: BufferedImage?): BufferedImage? =
+                    runCatching { ImageBufferDownload().parseUserSkin(image) }.getOrNull() ?: image
+
+                override fun skinAvailable() {
+                    mc.addScheduledTask { if (pendingKey == key) resolved = location }
+                }
+            }
+        )
+        mc.textureManager.loadTexture(location, texture)
     }
 
+    private fun fetchUuid(name: String): String? =
+        HttpClient.get("https://api.mojang.com/users/profiles/minecraft/$name").use { response ->
+            if (!response.isSuccessful) return null
+            response.body.charStream().readJson().asJsonObject.get("id")?.asString?.takeIf(String::isNotBlank)
+        }
+
+    private fun fetchSkinUrl(uuid: String): String? =
+        HttpClient.get("https://sessionserver.mojang.com/session/minecraft/profile/$uuid").use { response ->
+            if (!response.isSuccessful) return null
+            val properties = response.body.charStream().readJson().asJsonObject
+                .getAsJsonArray("properties") ?: return null
+            val encoded = properties.firstOrNull {
+                it.asJsonObject.get("name")?.asString == "textures"
+            }?.asJsonObject?.get("value")?.asString ?: return null
+            val decoded = String(java.util.Base64.getDecoder().decode(encoded), Charsets.UTF_8)
+            decoded.reader().readJson().asJsonObject
+                .getAsJsonObject("textures")
+                ?.getAsJsonObject("SKIN")
+                ?.get("url")?.asString?.takeIf(String::isNotBlank)
+        }
+
     private fun resolveFile() {
         val target = fileName.trim()
         if (target.isEmpty()) {
@@ -119,7 +174,8 @@ object SkinChanger : Module("SkinChanger", Category.VISUAL, Category.SubCategory
                 return
             }
 
-            mc.textureManager.loadTexture(fileSkinLocation, DynamicTexture(image))
+            val processed = runCatching { ImageBufferDownload().parseUserSkin(image) }.getOrNull() ?: image
+            mc.textureManager.loadTexture(fileSkinLocation, DynamicTexture(processed))
             resolved = fileSkinLocation
         }.onFailure {
             LOGGER.error("Failed to load custom skin", it)