import com.mojang.brigadier.StringReader;
import com.mojang.brigadier.arguments.ArgumentType;
import com.mojang.brigadier.context.CommandContext;
import com.mojang.brigadier.exceptions.CommandSyntaxException;
import com.mojang.brigadier.exceptions.SimpleCommandExceptionType;
import net.minecraft.text.Text;

import java.util.ArrayList;
import java.util.Collection;
import java.util.UUID;

/**
 * Represents an ArgumentType that will return a UUID.
 */
public class UuidArgumentType implements ArgumentType<UUID> {
    public static final DynamicCommandExceptionType INVALID_UUID = new DynamicCommandExceptionType(o -> Text.literal("Invalid uuid: " + o));
    
    public static UuidArgumentType uuid() {
        return new UuidArgumentType();
    }

    public static <S> UUID getUuid(String name, CommandContext<S> context) {
        // Note that you should assume the CommandSource wrapped inside of the CommandContext will always be a generic type.
        // If you need to access the ServerCommandSource make sure you verify the source is a server command source before casting.
        return context.getArgument(name, UUID.class);
    }

    private static final Collection<String> EXAMPLES = List.of(
        "765e5d33-c991-454f-8775-b6a7a394c097", // i509VCB: Username The_1_gamers
        "069a79f4-44e9-4726-a5be-fca90e38aaf5", // Notch
        "61699b2e-d327-4a01-9f1e-0ea8c3f06bc6"  // Dinnerbone
    );

    @Override
    public UUID parse(StringReader reader) throws CommandSyntaxException {
        int argBeginning = reader.getCursor(); // The starting position of the cursor is at the beginning of the argument.
        if (!reader.canRead()) {
            reader.skip();
        }

        // Now we check the contents of the argument till either we hit the end of the
        // command line (when ''canRead'' becomes false)
        // Otherwise we go till reach reach a character that cannot compose a UUID
        while (reader.canRead() && (Character.isLetterOrDigit(reader.peek()) || reader.peek() == '-')) { // peek provides the character at the current cursor position.
            reader.skip(); // Tells the StringReader to move it's cursor to the next position.
        }

        // Now we substring the specific part we want to see using the starting cursor
        // position and the ends where the next argument starts.
        String uuidString = reader.getString().substring(argBeginning, reader.getCursor());
        try {
            UUID uuid = UUID.fromString(uuidString); // Now our actual logic.
            return uuid;
            // And we return our type, in this case the parser will consider this
            // argument to have parsed properly and then move on.
        } catch (InvalidArgumentException ex) {
            // UUIDs can throw an exception when made by a string, so we catch the exception and repackage it into a CommandSyntaxException type.
            // Create with context tells Brigadier to supply some context to tell the user where the command failed at.
            // Though normal create method could be used.
            reader.setCursor(argBeginning);
            throw INVALID_UUID.createWithContext(reader, ex.getMessage());
        }
    }

    @Override
    public Collection<String> getExamples() {
        // Brigadier has support to show examples for what the argument should look like,
        // this should contain a Collection of only the argument this type will return.
        // This is mainly used to detect ambiguity, which means an argument of this type may be parsed as another type.
        return EXAMPLES;
    }
}