Support editing the back side of signs (#6774)

* Deprecate BaseSign get/set/updateText(), add get/set/updateFaceText() which accepts true/false for front/back
* add isFrontFace() to SignChangeEvent
* add optional frontFace to Player::openSignEditor()
* add BaseSign::getFacingDegrees() and getHitboxCenter() which need to be implemented by subclasses

src/block/BaseSign.php

@@ -41,14 +41,19 @@ use pocketmine\utils\TextFormat;
 use pocketmine\world\BlockTransaction;
 use pocketmine\world\sound\DyeUseSound;
 use pocketmine\world\sound\InkSacUseSound;
+use function abs;
 use function array_map;
 use function assert;
+use function atan2;
+use function fmod;
+use function rad2deg;
 use function strlen;
 
 abstract class BaseSign extends Transparent implements WoodMaterial{
 	use WoodTypeTrait;
 
-	protected SignText $text;
+	protected SignText $text; //TODO: rename this (BC break)
+	protected SignText $backText;
 	private bool $waxed = false;
 
 	protected ?int $editorEntityRuntimeId = null;
@@ -63,6 +68,7 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		$this->woodType = $woodType;
 		parent::__construct($idInfo, $name, $typeInfo);
 		$this->text = new SignText();
+		$this->backText = new SignText();
 		$this->asItemCallback = $asItemCallback;
 	}
 
@@ -71,6 +77,7 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		$tile = $this->position->getWorld()->getTile($this->position);
 		if($tile instanceof TileSign){
 			$this->text = $tile->getText();
+			$this->backText = $tile->getBackText();
 			$this->waxed = $tile->isWaxed();
 			$this->editorEntityRuntimeId = $tile->getEditorEntityRuntimeId();
 		}
@@ -83,6 +90,7 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		$tile = $this->position->getWorld()->getTile($this->position);
 		assert($tile instanceof TileSign);
 		$tile->setText($this->text);
+		$tile->setBackText($this->backText);
 		$tile->setWaxed($this->waxed);
 		$tile->setEditorEntityRuntimeId($this->editorEntityRuntimeId);
 	}
@@ -127,11 +135,11 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		}
 	}
 
-	private function doSignChange(SignText $newText, Player $player, Item $item) : bool{
+	private function doSignChange(SignText $newText, Player $player, Item $item, bool $frontFace) : bool{
-		$ev = new SignChangeEvent($this, $player, $newText);
+		$ev = new SignChangeEvent($this, $player, $newText, $frontFace);
 		$ev->call();
 		if(!$ev->isCancelled()){
-			$this->text = $ev->getNewText();
+			$this->setFaceText($frontFace, $ev->getNewText());
 			$this->position->getWorld()->setBlock($this->position, $this);
 			$item->pop();
 			return true;
@@ -140,8 +148,9 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		return false;
 	}
 
-	private function changeSignGlowingState(bool $glowing, Player $player, Item $item) : bool{
+	private function changeSignGlowingState(bool $glowing, Player $player, Item $item, bool $frontFace) : bool{
-		if($this->text->isGlowing() !== $glowing && $this->doSignChange(new SignText($this->text->getLines(), $this->text->getBaseColor(), $glowing), $player, $item)){
+		$text = $this->getFaceText($frontFace);
+		if($text->isGlowing() !== $glowing && $this->doSignChange(new SignText($text->getLines(), $text->getBaseColor(), $glowing), $player, $item, $frontFace)){
 			$this->position->getWorld()->addSound($this->position, new InkSacUseSound());
 			return true;
 		}
@@ -168,6 +177,8 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 			return true;
 		}
 
+		$frontFace = $this->interactsFront($this->getHitboxCenter(), $player->getPosition(), $this->getFacingDegrees());
+
 		$dyeColor = $item instanceof Dye ? $item->getColor() : match($item->getTypeId()){
 			ItemTypeIds::BONE_MEAL => DyeColor::WHITE,
 			ItemTypeIds::LAPIS_LAZULI => DyeColor::BLUE,
@@ -176,40 +187,82 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		};
 		if($dyeColor !== null){
 			$color = $dyeColor === DyeColor::BLACK ? new Color(0, 0, 0) : $dyeColor->getRgbValue();
+			$text = $this->getFaceText($frontFace);
 			if(
-				$color->toARGB() !== $this->text->getBaseColor()->toARGB() &&
+				$color->toARGB() !== $text->getBaseColor()->toARGB() &&
-				$this->doSignChange(new SignText($this->text->getLines(), $color, $this->text->isGlowing()), $player, $item)
+				$this->doSignChange(new SignText($text->getLines(), $color, $text->isGlowing()), $player, $item, $frontFace)
 			){
 				$this->position->getWorld()->addSound($this->position, new DyeUseSound());
 				return true;
 			}
 		}elseif(match($item->getTypeId()){
-			ItemTypeIds::INK_SAC => $this->changeSignGlowingState(false, $player, $item),
+			ItemTypeIds::INK_SAC => $this->changeSignGlowingState(false, $player, $item, $frontFace),
-			ItemTypeIds::GLOW_INK_SAC => $this->changeSignGlowingState(true, $player, $item),
+			ItemTypeIds::GLOW_INK_SAC => $this->changeSignGlowingState(true, $player, $item, $frontFace),
 			ItemTypeIds::HONEYCOMB => $this->wax($player, $item),
 			default => false
 		}){
 			return true;
 		}
 
-		$player->openSignEditor($this->position);
+		$player->openSignEditor($this->position, $frontFace);
 
 		return true;
 	}
 
+	private function interactsFront(Vector3 $hitboxCenter, Vector3 $playerPosition, float $signFacingDegrees) : bool{
+		$playerCenterDiffX = $playerPosition->x - $hitboxCenter->x;
+		$playerCenterDiffZ = $playerPosition->z - $hitboxCenter->z;
+
+		$f1 = rad2deg(atan2($playerCenterDiffZ, $playerCenterDiffX)) - 90.0;
+
+		$rotationDiff = $signFacingDegrees - $f1;
+		$rotation = fmod($rotationDiff + 180.0, 360.0) - 180.0; // Normalize to [-180, 180]
+		return abs($rotation) <= 90.0;
+	}
+
+	/**
+	 * Returns the center of the sign's hitbox. Used to decide which face of the sign to open when a player interacts.
+	 */
+	protected function getHitboxCenter() : Vector3{
+		return $this->position->add(0.5, 0.5, 0.5);
+	}
+
+	/**
+	 * TODO: make this abstract (BC break)
+	 */
+	protected function getFacingDegrees() : float{
+		return 0;
+	}
+
 	/**
 	 * Returns an object containing information about the sign text.
+	 * @deprecated
+	 * @see self::getFaceText()
 	 */
 	public function getText() : SignText{
 		return $this->text;
 	}
 
-	/** @return $this */
+	/**
+	 * @deprecated
+	 * @see self::setFaceText()
+	 * @return $this
+	 */
 	public function setText(SignText $text) : self{
 		$this->text = $text;
 		return $this;
 	}
 
+	public function getFaceText(bool $frontFace) : SignText{
+		return $frontFace ? $this->text : $this->backText;
+	}
+
+	/** @return $this */
+	public function setFaceText(bool $frontFace, SignText $text) : self{
+		$frontFace ? $this->text = $text : $this->backText = $text;
+		return $this;
+	}
+
 	/**
 	 * Returns whether the sign has been waxed using a honeycomb. If true, the sign cannot be edited by a player.
 	 */
@@ -234,13 +287,21 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		return $this;
 	}
 
+	/**
+	 * @deprecated
+	 * @see self::updateFaceText()
+	 */
+	public function updateText(Player $author, SignText $text) : bool{
+		return $this->updateFaceText($author, true, $text);
+	}
+
 	/**
 	 * Called by the player controller (network session) to update the sign text, firing events as appropriate.
 	 *
 	 * @return bool if the sign update was successful.
 	 * @throws \UnexpectedValueException if the text payload is too large
 	 */
-	public function updateText(Player $author, SignText $text) : bool{
+	public function updateFaceText(Player $author, bool $frontFace, SignText $text) : bool{
 		$size = 0;
 		foreach($text->getLines() as $line){
 			$size += strlen($line);
@@ -248,15 +309,16 @@ abstract class BaseSign extends Transparent implements WoodMaterial{
 		if($size > 1000){
 			throw new \UnexpectedValueException($author->getName() . " tried to write $size bytes of text onto a sign (bigger than max 1000)");
 		}
+		$oldText = $this->getFaceText($frontFace);
 		$ev = new SignChangeEvent($this, $author, new SignText(array_map(function(string $line) : string{
 			return TextFormat::clean($line, false);
-		}, $text->getLines()), $this->text->getBaseColor(), $this->text->isGlowing()));
+		}, $text->getLines()), $oldText->getBaseColor(), $oldText->isGlowing()), $frontFace);
 		if($this->waxed || $this->editorEntityRuntimeId !== $author->getId()){
 			$ev->cancel();
 		}
 		$ev->call();
 		if(!$ev->isCancelled()){
-			$this->setText($ev->getNewText());
+			$this->setFaceText($frontFace, $ev->getNewText());
 			$this->setEditorEntityRuntimeId(null);
 			$this->position->getWorld()->setBlock($this->position, $this);
 			return true;

src/block/CeilingCenterHangingSign.php

@@ -58,4 +58,8 @@ final class CeilingCenterHangingSign extends BaseSign implements SignLikeRotatio
 			$supportBlock->getSupportType(Facing::DOWN)->hasCenterSupport() ||
 			$supportBlock->hasTypeTag(BlockTypeTags::HANGING_SIGN);
 	}
+
+	protected function getFacingDegrees() : float{
+		return $this->rotation * 22.5;
+	}
 }

src/block/CeilingEdgesHangingSign.php

@@ -30,6 +30,7 @@ use pocketmine\item\Item;
 use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\player\Player;
+use pocketmine\utils\AssumptionFailedError;
 use pocketmine\world\BlockTransaction;
 
 final class CeilingEdgesHangingSign extends BaseSign implements HorizontalFacing{
@@ -65,4 +66,14 @@ final class CeilingEdgesHangingSign extends BaseSign implements HorizontalFacing
 			$supportBlock->getSupportType(Facing::DOWN) === SupportType::FULL ||
 			(($supportBlock instanceof WallHangingSign || $supportBlock instanceof CeilingEdgesHangingSign) && Facing::axis($supportBlock->getFacing()) === Facing::axis($this->facing));
 	}
+
+	protected function getFacingDegrees() : float{
+		return match($this->facing){
+			Facing::SOUTH => 0,
+			Facing::WEST => 90,
+			Facing::NORTH => 180,
+			Facing::EAST => 270,
+			default => throw new AssumptionFailedError("Invalid facing direction: " . $this->facing),
+		};
+	}
 }

src/block/FloorSign.php

@@ -48,4 +48,8 @@ final class FloorSign extends BaseSign implements SignLikeRotation{
 		}
 		return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
 	}
+
+	protected function getFacingDegrees() : float{
+		return $this->rotation * 22.5;
+	}
 }

src/block/WallHangingSign.php

@@ -32,6 +32,7 @@ use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\player\Player;
+use pocketmine\utils\AssumptionFailedError;
 use pocketmine\world\BlockTransaction;
 
 final class WallHangingSign extends BaseSign implements HorizontalFacing{
@@ -78,4 +79,14 @@ final class WallHangingSign extends BaseSign implements HorizontalFacing{
 			($block instanceof WallHangingSign && Facing::axis(Facing::rotateY($block->getFacing(), clockwise: true)) === Facing::axis($face)) ||
 			$block->getSupportType(Facing::opposite($face)) === SupportType::FULL;
 	}
+
+	protected function getFacingDegrees() : float{
+		return match($this->facing){
+			Facing::SOUTH => 0,
+			Facing::WEST => 90,
+			Facing::NORTH => 180,
+			Facing::EAST => 270,
+			default => throw new AssumptionFailedError("Invalid facing direction: " . $this->facing),
+		};
+	}
 }

src/block/WallSign.php

@@ -30,6 +30,7 @@ use pocketmine\math\Axis;
 use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\player\Player;
+use pocketmine\utils\AssumptionFailedError;
 use pocketmine\world\BlockTransaction;
 
 final class WallSign extends BaseSign implements HorizontalFacing{
@@ -46,4 +47,25 @@ final class WallSign extends BaseSign implements HorizontalFacing{
 		$this->facing = $face;
 		return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
 	}
+
+	protected function getHitboxCenter() : Vector3{
+		[$xOffset, $zOffset] = match($this->facing){
+			Facing::NORTH => [0, 15 / 16],
+			Facing::SOUTH => [0, 1 / 16],
+			Facing::WEST => [15 / 16, 0],
+			Facing::EAST => [1 / 16, 0],
+			default => throw new AssumptionFailedError("Invalid facing direction: " . $this->facing),
+		};
+		return $this->position->add($xOffset, 0.5, $zOffset);
+	}
+
+	protected function getFacingDegrees() : float{
+		return match($this->facing){
+			Facing::SOUTH => 0,
+			Facing::WEST => 90,
+			Facing::NORTH => 180,
+			Facing::EAST => 270,
+			default => throw new AssumptionFailedError("Invalid facing direction: " . $this->facing),
+		};
+	}
 }

src/block/tile/Sign.php

@@ -70,16 +70,18 @@ class Sign extends Spawnable{
 	}
 
 	protected SignText $text;
+	protected SignText $backText;
 	private bool $waxed = false;
 
 	protected ?int $editorEntityRuntimeId = null;
 
 	public function __construct(World $world, Vector3 $pos){
 		$this->text = new SignText();
+		$this->backText = new SignText();
 		parent::__construct($world, $pos);
 	}
 
-	private function readTextTag(CompoundTag $nbt, bool $lightingBugResolved) : void{
+	private function readTextTag(CompoundTag $nbt, bool $lightingBugResolved) : SignText{
 		$baseColor = new Color(0, 0, 0);
 		$glowingText = false;
 		if(($baseColorTag = $nbt->getTag(self::TAG_TEXT_COLOR)) instanceof IntTag){
@@ -90,19 +92,27 @@ class Sign extends Spawnable{
 			//see https://bugs.mojang.com/browse/MCPE-117835
 			$glowingText = $glowingTextTag->getValue() !== 0;
 		}
-		$this->text = SignText::fromBlob(mb_scrub($nbt->getString(self::TAG_TEXT_BLOB), 'UTF-8'), $baseColor, $glowingText);
+		return SignText::fromBlob(mb_scrub($nbt->getString(self::TAG_TEXT_BLOB), 'UTF-8'), $baseColor, $glowingText);
+	}
+
+	private function writeTextTag(SignText $text) : CompoundTag{
+		return CompoundTag::create()
+			->setString(self::TAG_TEXT_BLOB, rtrim(implode("\n", $text->getLines()), "\n"))
+			->setInt(self::TAG_TEXT_COLOR, Binary::signInt($text->getBaseColor()->toARGB()))
+			->setByte(self::TAG_GLOWING_TEXT, $text->isGlowing() ? 1 : 0)
+			->setByte(self::TAG_PERSIST_FORMATTING, 1);
 	}
 
 	public function readSaveData(CompoundTag $nbt) : void{
 		$frontTextTag = $nbt->getTag(self::TAG_FRONT_TEXT);
 		if($frontTextTag instanceof CompoundTag){
-			$this->readTextTag($frontTextTag, true);
+			$this->text = $this->readTextTag($frontTextTag, true);
 		}elseif($nbt->getTag(self::TAG_TEXT_BLOB) instanceof StringTag){ //MCPE 1.2 save format
 			$lightingBugResolved = false;
 			if(($lightingBugResolvedTag = $nbt->getTag(self::TAG_LEGACY_BUG_RESOLVE)) instanceof ByteTag){
 				$lightingBugResolved = $lightingBugResolvedTag->getValue() !== 0;
 			}
-			$this->readTextTag($nbt, $lightingBugResolved);
+			$this->text = $this->readTextTag($nbt, $lightingBugResolved);
 		}else{
 			$text = [];
 			for($i = 0; $i < SignText::LINE_COUNT; ++$i){
@@ -113,22 +123,14 @@ class Sign extends Spawnable{
 			}
 			$this->text = new SignText($text);
 		}
+		$backTextTag = $nbt->getTag(self::TAG_BACK_TEXT);
+		$this->backText = $backTextTag instanceof CompoundTag ? $this->readTextTag($backTextTag, true) : new SignText();
 		$this->waxed = $nbt->getByte(self::TAG_WAXED, 0) !== 0;
 	}
 
 	protected function writeSaveData(CompoundTag $nbt) : void{
-		$nbt->setTag(self::TAG_FRONT_TEXT, CompoundTag::create()
+		$nbt->setTag(self::TAG_FRONT_TEXT, $this->writeTextTag($this->text));
-			->setString(self::TAG_TEXT_BLOB, rtrim(implode("\n", $this->text->getLines()), "\n"))
+		$nbt->setTag(self::TAG_BACK_TEXT, $this->writeTextTag($this->backText));
-			->setInt(self::TAG_TEXT_COLOR, Binary::signInt($this->text->getBaseColor()->toARGB()))
-			->setByte(self::TAG_GLOWING_TEXT, $this->text->isGlowing() ? 1 : 0)
-			->setByte(self::TAG_PERSIST_FORMATTING, 1)
-		);
-		$nbt->setTag(self::TAG_BACK_TEXT, CompoundTag::create()
-			->setString(self::TAG_TEXT_BLOB, "")
-			->setInt(self::TAG_TEXT_COLOR, Binary::signInt(0xff_00_00_00))
-			->setByte(self::TAG_GLOWING_TEXT, 0)
-			->setByte(self::TAG_PERSIST_FORMATTING, 1)
-		);
 
 		$nbt->setByte(self::TAG_WAXED, $this->waxed ? 1 : 0);
 	}
@@ -141,6 +143,10 @@ class Sign extends Spawnable{
 		$this->text = $text;
 	}
 
+	public function getBackText() : SignText{ return $this->backText; }
+
+	public function setBackText(SignText $backText) : void{ $this->backText = $backText; }
+
 	public function isWaxed() : bool{ return $this->waxed; }
 
 	public function setWaxed(bool $waxed) : void{ $this->waxed = $waxed; }
@@ -162,19 +168,8 @@ class Sign extends Spawnable{
 	}
 
 	protected function addAdditionalSpawnData(CompoundTag $nbt) : void{
-		$nbt->setTag(self::TAG_FRONT_TEXT, CompoundTag::create()
+		$nbt->setTag(self::TAG_FRONT_TEXT, $this->writeTextTag($this->text));
-			->setString(self::TAG_TEXT_BLOB, rtrim(implode("\n", $this->text->getLines()), "\n"))
+		$nbt->setTag(self::TAG_BACK_TEXT, $this->writeTextTag($this->backText));
-			->setInt(self::TAG_TEXT_COLOR, Binary::signInt($this->text->getBaseColor()->toARGB()))
-			->setByte(self::TAG_GLOWING_TEXT, $this->text->isGlowing() ? 1 : 0)
-			->setByte(self::TAG_PERSIST_FORMATTING, 1) //TODO: not sure what this is used for
-		);
-		//TODO: this is not yet used by the server, but needed to rollback any client-side changes to the back text
-		$nbt->setTag(self::TAG_BACK_TEXT, CompoundTag::create()
-			->setString(self::TAG_TEXT_BLOB, "")
-			->setInt(self::TAG_TEXT_COLOR, Binary::signInt(0xff_00_00_00))
-			->setByte(self::TAG_GLOWING_TEXT, 0)
-			->setByte(self::TAG_PERSIST_FORMATTING, 1)
-		);
 		$nbt->setByte(self::TAG_WAXED, $this->waxed ? 1 : 0);
 		$nbt->setLong(self::TAG_LOCKED_FOR_EDITING_BY, $this->editorEntityRuntimeId ?? -1);
 	}

src/event/block/SignChangeEvent.php

@@ -35,11 +35,15 @@ use pocketmine\player\Player;
 class SignChangeEvent extends BlockEvent implements Cancellable{
 	use CancellableTrait;
 
+	private SignText $oldText;
+
 	public function __construct(
 		private BaseSign $sign,
 		private Player $player,
-		private SignText $text
+		private SignText $text,
+		private bool $frontFace = true
 	){
+		$this->oldText = $this->sign->getFaceText($this->frontFace);
 		parent::__construct($sign);
 	}
 
@@ -55,7 +59,7 @@ class SignChangeEvent extends BlockEvent implements Cancellable{
 	 * Returns the text currently on the sign.
 	 */
 	public function getOldText() : SignText{
-		return $this->sign->getText();
+		return $this->oldText;
 	}
 
 	/**
@@ -71,4 +75,6 @@ class SignChangeEvent extends BlockEvent implements Cancellable{
 	public function setNewText(SignText $text) : void{
 		$this->text = $text;
 	}
+
+	public function isFrontFace() : bool{ return $this->frontFace; }
 }

src/network/mcpe/handler/InGamePacketHandler.php

@@ -756,6 +756,43 @@ class InGamePacketHandler extends PacketHandler{
 		return true; //this packet is useless
 	}
 
+	/**
+	 * @throws PacketHandlingException
+	 */
+	private function updateSignText(CompoundTag $nbt, string $tagName, bool $frontFace, BaseSign $block, Vector3 $pos) : bool{
+		$textTag = $nbt->getTag($tagName);
+		if(!$textTag instanceof CompoundTag){
+			throw new PacketHandlingException("Invalid tag type " . get_debug_type($textTag) . " for tag \"$tagName\" in sign update data");
+		}
+		$textBlobTag = $textTag->getTag(Sign::TAG_TEXT_BLOB);
+		if(!$textBlobTag instanceof StringTag){
+			throw new PacketHandlingException("Invalid tag type " . get_debug_type($textBlobTag) . " for tag \"" . Sign::TAG_TEXT_BLOB . "\" in sign update data");
+		}
+
+		try{
+			$text = SignText::fromBlob($textBlobTag->getValue());
+		}catch(\InvalidArgumentException $e){
+			throw PacketHandlingException::wrap($e, "Invalid sign text update");
+		}
+
+		$oldText = $block->getFaceText($frontFace);
+		if($text->getLines() === $oldText->getLines()){
+			return false;
+		}
+
+		try{
+			if(!$block->updateFaceText($this->player, $frontFace, $text)){
+				foreach($this->player->getWorld()->createBlockUpdatePackets([$pos]) as $updatePacket){
+					$this->session->sendDataPacket($updatePacket);
+				}
+				return false;
+			}
+			return true;
+		}catch(\UnexpectedValueException $e){
+			throw PacketHandlingException::wrap($e);
+		}
+	}
+
 	public function handleBlockActorData(BlockActorDataPacket $packet) : bool{
 		$pos = new Vector3($packet->blockPosition->getX(), $packet->blockPosition->getY(), $packet->blockPosition->getZ());
 		if($pos->distanceSquared($this->player->getLocation()) > 10000){
@@ -767,29 +804,9 @@ class InGamePacketHandler extends PacketHandler{
 		if(!($nbt instanceof CompoundTag)) throw new AssumptionFailedError("PHPStan should ensure this is a CompoundTag"); //for phpstorm's benefit
 
 		if($block instanceof BaseSign){
-			$frontTextTag = $nbt->getTag(Sign::TAG_FRONT_TEXT);
+			if(!$this->updateSignText($nbt, Sign::TAG_FRONT_TEXT, true, $block, $pos)){
-			if(!$frontTextTag instanceof CompoundTag){
+				//only one side can be updated at a time
-				throw new PacketHandlingException("Invalid tag type " . get_debug_type($frontTextTag) . " for tag \"" . Sign::TAG_FRONT_TEXT . "\" in sign update data");
+				$this->updateSignText($nbt, Sign::TAG_BACK_TEXT, false, $block, $pos);
-			}
-			$textBlobTag = $frontTextTag->getTag(Sign::TAG_TEXT_BLOB);
-			if(!$textBlobTag instanceof StringTag){
-				throw new PacketHandlingException("Invalid tag type " . get_debug_type($textBlobTag) . " for tag \"" . Sign::TAG_TEXT_BLOB . "\" in sign update data");
-			}
-
-			try{
-				$text = SignText::fromBlob($textBlobTag->getValue());
-			}catch(\InvalidArgumentException $e){
-				throw PacketHandlingException::wrap($e, "Invalid sign text update");
-			}
-
-			try{
-				if(!$block->updateText($this->player, $text)){
-					foreach($this->player->getWorld()->createBlockUpdatePackets([$pos]) as $updatePacket){
-						$this->session->sendDataPacket($updatePacket);
-					}
-				}
-			}catch(\UnexpectedValueException $e){
-				throw PacketHandlingException::wrap($e);
 			}
 
 			return true;

src/player/Player.php

@@ -2838,13 +2838,12 @@ class Player extends Human implements CommandSender, ChunkListener, IPlayer{
 
 	/**
 	 * Opens the player's sign editor GUI for the sign at the given position.
-	 * TODO: add support for editing the rear side of the sign (not currently supported due to technical limitations)
 	 */
-	public function openSignEditor(Vector3 $position) : void{
+	public function openSignEditor(Vector3 $position, bool $frontFace = true) : void{
 		$block = $this->getWorld()->getBlock($position);
 		if($block instanceof BaseSign){
 			$this->getWorld()->setBlock($position, $block->setEditorEntityRuntimeId($this->getId()));
-			$this->getNetworkSession()->onOpenSignEditor($position, true);
+			$this->getNetworkSession()->onOpenSignEditor($position, $frontFace);
 		}else{
 			throw new \InvalidArgumentException("Block at this position is not a sign");
 		}