VersionMatcher.java

package net.wesjd.anvilgui.version;

import java.util.HashMap;
import java.util.Map;
import org.bukkit.Bukkit;

/**
 * Matches the server's NMS version to its {@link VersionWrapper}
 *
 * @author Wesley Smith
 * @since 1.2.1
 */
public class VersionMatcher {
    /** Maps a Minecraft version string to the corresponding revision string */
    private static final Map<String, String> VERSION_TO_REVISION = new HashMap<String, String>() {
        {
            this.put("1.20", "1_20_R1");
            this.put("1.20.1", "1_20_R1");
            this.put("1.20.2", "1_20_R2");
            this.put("1.20.3", "1_20_R3");
            this.put("1.20.4", "1_20_R3");
            this.put("1.20.5", "1_20_R4");
            this.put("1.20.6", "1_20_R4");
            this.put("1.21", "1_21_R1");
            this.put("1.21.1", "1_21_R1");
            this.put("1.21.2", "1_21_R2");
            this.put("1.21.3", "1_21_R2");
            this.put("1.21.4", "1_21_R3");
            this.put("1.21.5", "1_21_R4");
            this.put("1.21.6", "1_21_R5");
        }
    };
    /* This needs to be updated to reflect the newest available version wrapper */
    private static final String FALLBACK_REVISION = "1_21_R5";

    /**
     * Matches the server version to it's {@link VersionWrapper}
     *
     * @return The {@link VersionWrapper} for this server
     * @throws IllegalStateException If the version wrapper failed to be instantiated or is unable to be found
     */
    public VersionWrapper match() {
        String craftBukkitPackage = Bukkit.getServer().getClass().getPackage().getName();

        String rVersion;
        if (!craftBukkitPackage.contains(".v")) { // cb package not relocated (i.e. paper 1.20.5+)
            final String version = Bukkit.getBukkitVersion().split("-")[0];
            rVersion = VERSION_TO_REVISION.getOrDefault(version, FALLBACK_REVISION);
        } else {
            rVersion = craftBukkitPackage.split("\\.")[3].substring(1);
        }

        boolean isMojMap = isMojangMapped(rVersion);

        try {
            return (VersionWrapper)
                    getWrapperClass(rVersion, isMojMap).getDeclaredConstructor().newInstance();
        } catch (ClassNotFoundException exception) {
            throw new IllegalStateException("AnvilGUI does not support server version \"" + rVersion + "\"", exception);
        } catch (ReflectiveOperationException exception) {
            throw new IllegalStateException("Failed to instantiate version wrapper for version " + rVersion, exception);
        }
    }

    private Class<?> getWrapperClass(String version, boolean isMojMap) throws ClassNotFoundException {
        String pkg = getClass().getPackage().getName();
        if (isMojMap) { // if mojang-mapped server, use MojangWrapper
            try {
                return Class.forName(pkg + ".MojangWrapper" + version);
            } catch (ClassNotFoundException ignored) {
            }
        }
        // then try usual wrapper
        return Class.forName(pkg + ".Wrapper" + version);
    }

    private static boolean isMojangMapped(String version) {
        // firstly check for paper
        try {
            Class.forName("com.destroystokyo.paper.ParticleBuilder");
        } catch (ClassNotFoundException ignored) {
            return false;
        }
        // then check version
        final String[] versionNumbers = version.replace("R", "").split("_");
        int major = Integer.parseInt(versionNumbers[1]);
        int minor = versionNumbers.length > 2 ? Integer.parseInt(versionNumbers[2]) : 0;
        if (major == 20 && minor == 4) return true; // 1.20.5/6
        return major > 20; // >= 1.21
    }
}