package main

import (
	"io";
	"os";
	"fmt";
	"regexp";
	"xml";
	"encoding/hex";
	"bytes";
);


type Patch struct {
	Name string;
	Org string;
	Mod string;
}

type Binchg struct {
	Target string;
	Patch []Patch;
}

func main() {

	if( len(os.Args) < 3 ){
		fmt.Printf( "Argument Error!\n" );
		fmt.Printf( "\tUsage: binchg targetfile patchfile\n" );
		return;
	}

	// read patch file
	patch_file, err := os.Open( os.Args[2], os.O_RDONLY, 0 );

	if err != nil {
		patch_file.Close();
		fmt.Printf( "patch file open Error!\n" );
	} 

	// parse patch file
	var result Binchg;
	xml.Unmarshal( patch_file, &result ) ;

	// read target file
	target_file, err := os.Open( os.Args[1], os.O_RDONLY, 0 );
	if err != nil {
		target_file.Close();
		fmt.Printf( "target file open Error!\n" );
	} 

	target, err := io.ReadAll( target_file );
	if err != nil {
		target_file.Close();
		fmt.Printf( "target file read Error!\n" );
	} 

	for i := range target {
		for j, p := range result.Patch {
			var org_bin []byte;
			var mod_bin []byte;

			if false { notuse := j; j = notuse};

			r, err := regexp.Compile( " +" );
			org_bin, err = hex.DecodeString(r.ReplaceAllString( p.Org, "" ));
			if err != nil { fmt.Printf( "%v\n", err ); }

			mod_bin, err = hex.DecodeString(r.ReplaceAllString( p.Mod, "" ));
			if err != nil { fmt.Printf( "%v\n", err ); }

			if i > len( org_bin ) {
				if bytes.Compare( target[i-len(org_bin):i], org_bin ) == 0 {
					fmt.Printf( "%d:%v\n", i, p.Name );
					for k,v := range mod_bin {
						target[i-2:i][k] = v;
					}
				}
			}
		}
	}

	output_file, err := os.Open( os.Args[1] + ".patched" , os.O_WRONLY|os.O_CREAT, 0666 );
	if err != nil {
		target_file.Close();
		fmt.Printf( "open Error!\n" );
	} 

	output_file.Write( target );
	output_file.Close();

}