[Ready for Testing] Folder-Syncing

src/main/java/ru/bclib/api/dataexchange/SyncFileHash.java

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+package ru.bclib.api.dataexchange;
+
+import net.minecraft.network.FriendlyByteBuf;
+import ru.bclib.api.dataexchange.handler.AutoSyncID;
+import ru.bclib.api.dataexchange.handler.DataExchange;
+
+import java.io.File;
+import java.util.Objects;
+
+/**
+ * Calculates a hash based on the contents of a File.
+ * <p>
+ * A File-Hash contains the md5-sum of the File, as well as its size and byte-values from defined positions
+ * <p>
+ * You can compare instances using {@link #equals(Object)} to determine if two files are
+ * identical.
+ */
+public class SyncFileHash extends AutoSyncID {
+    public final FileHash hash;
+
+    SyncFileHash(String modID, File file, byte[] md5, int size, int value) {
+        this(modID, file.getName(), md5, size, value);
+    }
+
+    SyncFileHash(String modID, String uniqueID, byte[] md5, int size, int value) {
+        this(modID, uniqueID, new FileHash(md5, size, value));
+    }
+    
+    SyncFileHash(String modID, File file, FileHash hash) {
+        this(modID, file.getName(), hash);
+    }
+    
+    SyncFileHash(String modID, String uniqueID, FileHash hash) {
+        super(modID, uniqueID);
+        this.hash = hash;
+    }
+
+   
+    final static DataExchange.NeedTransferPredicate NEED_TRANSFER = (clientHash, serverHash, content)-> !clientHash.equals(serverHash);
+    
+    @Override
+    public String toString() {
+        return super.toString()+": "+hash.toString();
+    }
+    
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof SyncFileHash)) return false;
+        if (!super.equals(o)) return false;
+        SyncFileHash that = (SyncFileHash) o;
+        return hash.equals(that.hash);
+    }
+    
+    @Override
+    public int hashCode() {
+        return Objects.hash(super.hashCode(), hash);
+    }
+    
+    /**
+     * Serializes the Object to a buffer
+     * @param buf The buffer to write to
+     */
+    public void serialize(FriendlyByteBuf buf) {
+        hash.serialize(buf);
+        DataHandler.writeString(buf, modID);
+        DataHandler.writeString(buf, uniqueID);
+    }
+
+    /**
+     *Deserialize a Buffer to a new {@link SyncFileHash}-Object
+     * @param buf Thea buffer to read from
+     * @return The received String
+     */
+    public static SyncFileHash deserialize(FriendlyByteBuf buf){
+        final FileHash hash = FileHash.deserialize(buf);
+        final String modID = DataHandler.readString(buf);
+        final String uniqueID = DataHandler.readString(buf);
+
+        return new SyncFileHash(modID, uniqueID, hash);
+    }
+
+    /**
+     * Create a new {@link SyncFileHash}.
+     * <p>
+     * Will call {@link #create(String, File, String)} using the name of the File as {@code uniqueID}.
+     * @param modID ID of the calling Mod
+     * @param file The input file
+     *
+     * @return A new Instance. You can compare instances using {@link #equals(Object)} to determine if two files are
+     * identical. Will return {@code null} when an error occurs or the File does not exist
+     */
+    public static SyncFileHash create(String modID, File file){
+        return create(modID, file, file.getName());
+    }
+
+    /**
+     * Create a new {@link SyncFileHash}.
+     * @param modID ID of the calling Mod
+     * @param file The input file
+     * @param uniqueID The unique ID that is used for this File (see {@link SyncFileHash#uniqueID} for Details.
+     * @return A new Instance. You can compare instances using {@link #equals(Object)} to determine if two files are
+     * identical. Will return {@code null} when an error occurs or the File does not exist
+     */
+    public static SyncFileHash create(String modID, File file, String uniqueID){
+        return new SyncFileHash(modID, uniqueID, FileHash.create(file));
+    }
+}