Package net.fabricmc.fabric.api.permission.v1

@Experimental @NullMarked package net.fabricmc.fabric.api.permission.v1
Permission API is an api allowing mods to easily interact with each other in order to know what is and isn't allowed (aka the titular permissions). This applies to actions done by players, entities and anything else that might do actions you would want other mods to easily prevent.

By default, this api provides direct support for checking permissions for Player, Entity and CommandSourceStack, but also creation of custom contexts. To simplify access, these classes now extend the PermissionContextOwner interface allowing for access to the attached PermissionContext (which also extends that interface) as well as providing additional methods for sync and async permission checks. Custom implementations of PermissionContextOwner and PermissionContext are encouraged in places that require more flexibility or lazy evaluation.

Permission themselves are typed, which allows to support more types (aside of most common boolean permissions) allowing for more flexibility of the interactions. To create a typed permission node you can use one of the provided static factory methods from the PermissionNode interface. Permission nodes can be created at any point in time, either dynamically or statically. You can then use this object directly as an argument of PermissionContextOwner permission checking methods. Boolean permissions can also use Identifier directly, with addition for some extra utility methods on the owner object.

To define a provider, you need to register callbacks for events defined in PermissionEvents. By default, you only need to implement the PermissionEvents.ON_REQUEST event, but other ones might still be good to look into to allow better handling of them.

Example cases where you might want to use this api: - Commands that might not make sense to give to all players, but might be required for helpers/moderators/admins, - Dynamic limits for things based on external factors (for example warps, max protected area size), - Checking if non-regular in world interaction is allowed within protected area (for example transmuting blocks with a special items, summoning mounts),

Example code - Checking for command permission: 

CommandRegistrationCallback.EVENT.register((dispatcher, _, _) -> {
    dispatcher.register(literal("modcommand")
    	   // By using direct Identitier
        .requires(PermissionPredicates.require(Identifier.fromNamespaceAndPath("mymod", "command/main"), true))
        .executes(ModCommands::executeMainCommand)
        .then(literal("admin")
            // By using boolean permission node
            .requires(PermissionPredicates.require(PermissionNode.of("mymod", "command/admin"), PermissionLevel.ADMINS))
            .executes(ModCommands::executeMainCommand)
        )
});

Example code - Validating if special interaction works in claim at select position. 

// Check side (...)
var canSummonMountPermission = PermissionNode.of("mymod", "can_summon_mount");
public boolean trySummoningMount(Player player, Vec3 pos) {
    var context = player.getPermissionContext().mutable()
    				.set(PermissionContext.BLOCK_POSITION, BlockPos.containing(pos))
    				.set(PermissionContext.POSITION, pos);

    	if (!context.checkPermission(canSummonMountPermission, true)) {
    	    player.sendSystemMessage(Component.literal("You can't summon your mount here!"));
    	    return false;
    	}

    	// Mount summoning logic goes here (...)
    	return true;
}

// Protection mod / validation side (...)
var checkedPermissions = Set.of(Identifier.fromNamespaceAndPath("mymod", "can_summon_mount"), ...);

PermissionEvents.register((context, permission) -> {
		if (context.type() != PermissionContext.Type.PLAYER && context.type() != PermissionContext.Type.ENTITY) return null;

		var pos = context.get(PermissionContext.BLOCK_POSITION);
		if (pos == null) return null;

		var claim = ClaimMod.getClaimAt(pos);
		if (claim == null) return null;

     if (checkedPermissions.contains(permission.key()) && permission.codec() == Codec.BOOL) {
         return (T) Boolean.valueOf(claim.canModifyClaim(context.uuid()));
     }
     // Any other logic...
     return null;
});