Halo Map Patcher Reference (Java)

package me.Zero2.filepatcher;

import java.awt.Font;
import java.io.File;
import java.io.RandomAccessFile;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;


public class Main {
    public static void patchFile(File file,boolean guiSuccess) { //the works
        try {
            System.out.print("Patching file \"" + file.getPath() + "\"...");
            long indexOffset = readUnsignedInt32(0x10,file); //Let's first find the index offset. You'll find this at offset 0x10 from ALL Halo full maps.
            long magic = readUnsignedInt32(indexOffset,file) - indexOffset - 0x28; //We go to the index offset, subtract 0x28 to get Magic, and then subtract Index Offset to get the Map Magic which is what we need.
            long numberOfTags = readUnsignedInt32(indexOffset + 0xC,file); //Now we need to know how many tags there are. I don't know WHY it's a long since no unmodded map has that many tags.
            long tagArrayOffset = indexOffset + 0x28; //Now we need to get to the tag array offset. It's 0x28 from the index offset.
            boolean name = false;
            boolean description = false;
            for(int i=0;i<numberOfTags;i++) { //We need to analyze every tag's name, until we get to the tag we want.
                long currentLocation = 0x20*i + tagArrayOffset;
                long nameOffset = readUnsignedInt32(currentLocation + 0x10,file) - magic;
                if(read4ByteUTF8(currentLocation,file).equals("rtsu")) { //It's the correct type, but is it the correct name?
                    if(readUTF8(nameOffset,file).equals("ui\\shell\\main_menu\\mp_map_list")) { //we've found the tag we want. Yay!
                        long namesOffset = readUnsignedInt32(currentLocation + 0x14,file) - magic + 0x1B0;
                        long boardingActionOffset = namesOffset + 0xB4;
                        changeUTF16String(boardingActionOffset,file,"Barrier",15); //changeUTF16String(long offset,File file,String changeTo,int maximumLength);
                        long chironOffset = boardingActionOffset + 0x48;
                        changeUTF16String(chironOffset,file,"The Shaft",11);
                        long gephyOffset = chironOffset + 0xA4;
                        changeUTF16String(gephyOffset,file,"Modded",13);
                        long infinityOffset = gephyOffset - 0x2C;
                        changeUTF16String(infinityOffset,file,"Crossing",8);
                        name = true;
                    }
                    if(readUTF8(nameOffset,file).equals("ui\\shell\\main_menu\\multiplayer_type_select\\mp_map_select\\map_data")) { //we've found the tag we want. Yay!
                        long descriptionOffset = readUnsignedInt32(currentLocation + 0x14,file) - magic + 0x19C;
                        long boardingActionOffset = descriptionOffset + 0x2BC;
                        changeUTF16String(boardingActionOffset,file,"Trapped!\n\n6-12 players",0x24);
                        long chironOffset = boardingActionOffset + 0x120;
                        changeUTF16String(chironOffset,file,"Your deepest grave\n\n8-16 players",0x2E);
                        long infinityOffset = chironOffset + 0x258;
                        changeUTF16String(infinityOffset,file,"In space, no one\ncan hear you scream\n\n6-12 players",0x48);
                        long gephyOffset = infinityOffset + 0x10C;
                        changeUTF16String(gephyOffset,file,"",0x32);
                        description = true;
                    }
                }
            }
            if(name && description) {
                System.out.println("Done!");
                if(guiSuccess) notification("Done!");
            }
            if(!name && !description) {
                System.out.println("Name and description tag was not found! Is this map protected?");
                if(guiSuccess) notification("The name and description tags could not be found! Protected?");
            }
            if(!name) {
                System.out.println("Names tag not found!");
                if(guiSuccess) notification("The maps' names tag wasn't found.");
            }
            if(!description) {
                System.out.println("Descriptions tag was not found!");
                if(guiSuccess) notification("The maps' descriptions tag wasn't found.");
            }
        }
        catch(Exception e) {
            e.printStackTrace();
            System.out.println("Error!");
            if(guiSuccess) notification("The map could not be opened!");
        }

    }
    public static void changeUTF16String(long offset,File file,String text, int length) throws Exception { //change string, null remaining data based on Length.
        RandomAccessFile raf = new RandomAccessFile(file, "rw");
        int reduce = 0;
        int i=0;
        for(; i<length; i++) {
            raf.seek(offset + i * 2);
            if(i+reduce<text.length()) {
                if(text.toCharArray()[i + reduce] == (char)0xA) {
                    raf.writeByte(0x0D);
                    i++;
                    if(i < length) {
                        raf.seek(offset + i*2);
                        raf.writeByte(0x0A);
                    }
                    reduce--;
                }
                else raf.writeByte(text.toCharArray()[i + reduce]);
            } else {
                raf.seek(offset + i * 2);
                raf.writeByte(0);
            }
        }
        raf.close();
    }
    public static long readUnsignedInt32(long offset, File file) throws Exception {
        RandomAccessFile raf = new RandomAccessFile(file, "r"); //loads the file for reading
        int[] b = new int[4];
        for(int i=0;i<4;i++) {
            raf.seek(offset+i);
            b[i] = raf.readByte();
            if(b[i] < 0) b[i] += Byte.MAX_VALUE*2+2;
        }
        raf.close(); //closes
        long value = b[0]; //convert to big endian
        value += b[1]*256;
        value += b[2]*256*256;
        value += b[3]*256*256*((long)256);
        return value;
    }
    public static String readUTF8(long offset, File file) throws Exception { //reads a UTF-8 string until a terminating 0
        RandomAccessFile raf = new RandomAccessFile(file, "r");
        String returnValue = "";
        boolean terminate = false;
        for(int i=0;!terminate;i++) {
            raf.seek(offset+i);
            returnValue += (char)raf.readByte();
            if(raf.readByte() == 0) terminate = true;
        }
        raf.close();
        return returnValue;
    }
    public static String read4ByteUTF8(long offset, File file) throws Exception { //reads only 4 bytes for tag class
        RandomAccessFile raf = new RandomAccessFile(file, "r"); //read only
        String returnValue = "";
        for(int i=0;i<4;i++) {
            raf.seek(offset+i);
            returnValue += (char)raf.readByte();
        }
        raf.close();
        return returnValue;
    }


    public static void main(String[] args) {
        if(args.length != 0) {
            for(String string : args) patchFile(new File(string),false);
            return;
        }
        JFileChooser dialogue = new JFileChooser();
        dialogue.showOpenDialog(null);
        try {
            if(dialogue.getSelectedFile() == null) return;
            patchFile(dialogue.getSelectedFile(),true);
        } catch (Exception e) {
            System.out.println("Failed.");
        }
    }
    public static void notification(String message) {
        final JFrame frame2 = new JFrame();
        frame2.setBounds(100, 100, 250, 100);
        frame2.setLocationRelativeTo(null);
        frame2.setTitle("Result");
        JButton label2 = new JButton(message);
        label2.setFont(Font.getFont(Font.SANS_SERIF));
        label2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent e) {
                frame2.dispose();
            }
        });
        frame2.add(label2);
        frame2.setVisible(true);
    }
}