fix(YouTube - Shorts autoplay): Fix autoplay with YT 20.12

extensions/youtube/src/main/java/app/revanced/extension/youtube/patches/ShortsAutoplayPatch.java

@@ -2,6 +2,8 @@ package app.revanced.extension.youtube.patches;
 
 import android.app.Activity;
 
+import androidx.annotation.Nullable;
+
 import java.lang.ref.WeakReference;
 import java.util.Objects;
 
@@ -76,7 +78,7 @@ public class ShortsAutoplayPatch {
     /**
      * Injection point.
      */
-    public static Enum<?> changeShortsRepeatBehavior(Enum<?> original) {
+    public static Enum<?> changeShortsRepeatBehavior(@Nullable Enum<?> original) {
         try {
             final boolean autoplay;
 
@@ -98,17 +100,35 @@ public class ShortsAutoplayPatch {
                     : ShortsLoopBehavior.REPEAT;
 
             if (behavior.ytEnumValue != null) {
-                Logger.printDebug(() -> behavior.ytEnumValue == original
+                Logger.printDebug(() -> {
-                        ? "Changing Shorts repeat behavior from: " + original.name() + " to: " + behavior.ytEnumValue
+                    String name = (original == null ? "unknown (null)" : original.name());
-                        : "Behavior setting is same as original. Using original: " + original.name()
+                    return behavior == original
-                );
+                            ? "Behavior setting is same as original. Using original: " + name
+                            : "Changing Shorts repeat behavior from: " + name + " to: " + behavior.name();
+                });
 
                 return behavior.ytEnumValue;
             }
+
+            if (original == null) {
+                // Cannot return null, as null is used to indicate Short was auto played.
+                // Unpatched app replaces null with unknown enum type (appears to fix for bad api data).
+                Enum<?> unknown = ShortsLoopBehavior.UNKNOWN.ytEnumValue;
+                Logger.printDebug(() -> "Original is null, returning: " + unknown.name());
+                return unknown;
+            }
         } catch (Exception ex) {
-            Logger.printException(() -> "changeShortsRepeatState failure", ex);
+            Logger.printException(() -> "changeShortsRepeatBehavior failure", ex);
         }
 
         return original;
     }
+
+
+    /**
+     * Injection point.
+     */
+    public static boolean isAutoPlay(Enum<?> original) {
+        return ShortsLoopBehavior.SINGLE_PLAY.ytEnumValue == original;
+    }
 }

patches/src/main/kotlin/app/revanced/patches/youtube/layout/shortsautoplay/Fingerprints.kt

@@ -1,8 +1,13 @@
 package app.revanced.patches.youtube.layout.shortsautoplay
 
 import app.revanced.patcher.fingerprint
+import app.revanced.util.getReference
+import app.revanced.util.indexOfFirstInstruction
 import com.android.tools.smali.dexlib2.AccessFlags
 import com.android.tools.smali.dexlib2.Opcode
+import com.android.tools.smali.dexlib2.iface.Method
+import com.android.tools.smali.dexlib2.iface.reference.FieldReference
+import com.android.tools.smali.dexlib2.iface.reference.MethodReference
 
 internal val reelEnumConstructorFingerprint = fingerprint {
     accessFlags(AccessFlags.STATIC, AccessFlags.CONSTRUCTOR)
@@ -20,3 +25,27 @@ internal val reelPlaybackRepeatFingerprint = fingerprint {
     parameters("L")
     strings("YoutubePlayerState is in throwing an Error.")
 }
+
+internal val reelPlaybackFingerprint = fingerprint {
+    accessFlags(AccessFlags.PUBLIC, AccessFlags.FINAL)
+    returns("V")
+    parameters("J")
+    custom { method, _ ->
+        indexOfMilliSecondsInstruction(method) >= 0 &&
+                indexOfInitializationInstruction(method) >= 0
+    }
+}
+
+private fun indexOfMilliSecondsInstruction(method: Method) =
+    method.indexOfFirstInstruction {
+        getReference<FieldReference>()?.name == "MILLISECONDS"
+    }
+
+internal fun indexOfInitializationInstruction(method: Method) =
+    method.indexOfFirstInstruction {
+        val reference = getReference<MethodReference>()
+        opcode == Opcode.INVOKE_DIRECT &&
+                reference?.name == "<init>" &&
+                reference.parameterTypes.size == 3 &&
+                reference.parameterTypes.firstOrNull() == "I"
+    }

patches/src/main/kotlin/app/revanced/patches/youtube/layout/shortsautoplay/ShortsAutoplayPatch.kt

@@ -2,21 +2,32 @@ package app.revanced.patches.youtube.layout.shortsautoplay
 
 import app.revanced.patcher.extensions.InstructionExtensions.addInstruction
 import app.revanced.patcher.extensions.InstructionExtensions.addInstructions
+import app.revanced.patcher.extensions.InstructionExtensions.addInstructionsWithLabels
 import app.revanced.patcher.extensions.InstructionExtensions.getInstruction
 import app.revanced.patcher.patch.bytecodePatch
+import app.revanced.patcher.util.proxy.mutableTypes.MutableMethod.Companion.toMutable
 import app.revanced.patches.all.misc.resources.addResources
 import app.revanced.patches.shared.misc.mapping.resourceMappingPatch
 import app.revanced.patches.shared.misc.settings.preference.SwitchPreference
 import app.revanced.patches.youtube.misc.extension.sharedExtensionPatch
 import app.revanced.patches.youtube.misc.playservice.is_19_34_or_greater
+import app.revanced.patches.youtube.misc.playservice.is_20_09_or_greater
 import app.revanced.patches.youtube.misc.playservice.versionCheckPatch
 import app.revanced.patches.youtube.misc.settings.PreferenceScreen
 import app.revanced.patches.youtube.misc.settings.settingsPatch
 import app.revanced.patches.youtube.shared.mainActivityOnCreateFingerprint
 import app.revanced.util.findInstructionIndicesReversedOrThrow
 import app.revanced.util.getReference
+import app.revanced.util.indexOfFirstInstructionOrThrow
+import com.android.tools.smali.dexlib2.AccessFlags
+import com.android.tools.smali.dexlib2.Opcode
+import com.android.tools.smali.dexlib2.builder.MutableMethodImplementation
 import com.android.tools.smali.dexlib2.iface.instruction.OneRegisterInstruction
+import com.android.tools.smali.dexlib2.iface.instruction.ReferenceInstruction
+import com.android.tools.smali.dexlib2.iface.reference.FieldReference
 import com.android.tools.smali.dexlib2.iface.reference.MethodReference
+import com.android.tools.smali.dexlib2.immutable.ImmutableMethod
+import com.android.tools.smali.dexlib2.immutable.ImmutableMethodParameter
 
 private const val EXTENSION_CLASS_DESCRIPTOR = "Lapp/revanced/extension/youtube/patches/ShortsAutoplayPatch;"
 
@@ -98,5 +109,84 @@ val shortsAutoplayPatch = bytecodePatch(
                 )
             }
         }
+
+        // As of YouTube 20.09, Google has removed the code for 'Autoplay' and 'Pause' from this method.
+        // Manually restore the removed 'Autoplay' code.
+        if (is_20_09_or_greater) {
+            // Variable names are only a rough guess of what these methods do.
+            val userActionMethodIndex = indexOfInitializationInstruction(reelPlaybackFingerprint.method)
+            val userActionMethodReference = reelPlaybackFingerprint.method
+                .getInstruction<ReferenceInstruction>(userActionMethodIndex).reference as MethodReference
+            val reelSequenceControllerMethodIndex = reelPlaybackFingerprint.method
+                .indexOfFirstInstructionOrThrow(userActionMethodIndex, Opcode.INVOKE_VIRTUAL)
+            val reelSequenceControllerMethodReference = reelPlaybackFingerprint.method
+                .getInstruction<ReferenceInstruction>(reelSequenceControllerMethodIndex).reference as MethodReference
+
+            reelPlaybackRepeatFingerprint.method.apply {
+                // Find the first call modified by extension code above.
+                val extensionReturnResultIndex = indexOfFirstInstructionOrThrow {
+                    opcode == Opcode.INVOKE_STATIC &&
+                            getReference<MethodReference>()?.definingClass == EXTENSION_CLASS_DESCRIPTOR
+                } + 1
+                val enumRegister = getInstruction<OneRegisterInstruction>(extensionReturnResultIndex).registerA
+                val getReelSequenceControllerIndex = indexOfFirstInstructionOrThrow(extensionReturnResultIndex) {
+                    val reference = getReference<FieldReference>()
+                    opcode == Opcode.IGET_OBJECT &&
+                            reference?.definingClass == definingClass &&
+                            reference.type == reelSequenceControllerMethodReference.definingClass
+                }
+                val getReelSequenceControllerReference =
+                    getInstruction<ReferenceInstruction>(getReelSequenceControllerIndex).reference
+
+                // Add a helper method to avoid finding multiple free registers.
+                // If enum is autoplay then method performs autoplay and returns null,
+                // otherwise returns the same enum.
+                val helperClass = definingClass
+                val helperName = "patch_handleAutoPlay"
+                val helperReturnType = "Ljava/lang/Enum;"
+                val helperMethod = ImmutableMethod(
+                    helperClass,
+                    helperName,
+                    listOf(ImmutableMethodParameter("Ljava/lang/Enum;", null, null)),
+                    helperReturnType,
+                    AccessFlags.PRIVATE.value,
+                    null,
+                    null,
+                    MutableMethodImplementation(7),
+                ).toMutable().apply {
+                    addInstructionsWithLabels(
+                        0,
+                        """
+                            invoke-static { p1 }, $EXTENSION_CLASS_DESCRIPTOR->isAutoPlay(Ljava/lang/Enum;)Z
+                            move-result v0
+                            if-eqz v0, :ignore
+                            new-instance v0, ${userActionMethodReference.definingClass}
+                            const/4 v1, 0x3
+                            const/4 v2, 0x0
+                            invoke-direct { v0, v1, v2, v2 }, $userActionMethodReference
+                            iget-object v3, p0, $getReelSequenceControllerReference
+                            invoke-virtual { v3, v0 }, $reelSequenceControllerMethodReference
+                            const/4 v4, 0x0
+                            return-object v4
+                            :ignore
+                            return-object p1
+                        """
+                    )
+                }
+                reelPlaybackRepeatFingerprint.classDef.methods.add(helperMethod)
+
+                addInstructionsWithLabels(
+                    extensionReturnResultIndex + 1,
+                    """
+                        invoke-direct { p0, v$enumRegister }, $helperClass->$helperName(Ljava/lang/Enum;)$helperReturnType
+                        move-result-object v$enumRegister
+                        if-nez v$enumRegister, :ignore
+                        return-void     # Autoplay was performed.
+                        :ignore
+                        nop
+                    """
+                )
+            }
+        }
     }
 }