#include <iostream>
#include <fstream>
#include <string>
#include <map>

using namespace std;

unsigned long int get32le(fstream* input){
    unsigned char b1=input->get();
    unsigned char b2=input->get();
    unsigned char b3=input->get();
    unsigned char b4=input->get();
    long int i1=b1;
    long int i2=b2;
    long int i3=b3;
    long int i4=b4;
    return i1 | (i2<<8) | (i3<<16) | (i4<<24);}

int main(int argc, char** argv){
    if (argc <= 1){
        cout << "Instrument Reorderer for FamiTracker\n"
             << "Usage: reinst [filename] ([listname])\n"
             << "Description: Reads a text file containing space-delimited hexadecimal numbers,\n"
             << "             so that the ordering of the FamiTracker module's instruments,\n"
             << "             including those not created, matches the text file.\n"
             << "Options:\n"
             << "[filename]: Name of the FTM\n"
             << "[listname]: Name of the reorder list. Defaults to \"reinst.txt\" if not present"
             << endl;}
    else{
        int version;
        fstream instlist((argc >= 3) ? (argv[2]) : ("reinst.txt"), ios::in);
        if (!instlist){
            cerr << "Cannot open instrument list!" << endl;
            exit(1);}
        fstream ftm(argv[1], ios::in | ios::out | ios::binary);
        if (!ftm){
            cerr << "Cannot open FamiTracker module!" << endl;
            exit(1);}
        fstream* ftmP = &ftm;
        int* permute = new int[65];
        for (int i=0;i<=0x40;i++){
            permute[i]=i;}
        for (int i=0;i<0x40;i++){
            if (instlist){
                string str;
                instlist >> str;
                if (str!="") permute[stoi(str,NULL,16)]=i;}}
        ftm.seekg(0x2A);
        ftm.seekg(get32le(ftmP)+0x14,ios_base::cur);
        ftm.seekg(get32le(ftmP)+0x14,ios_base::cur);
        int pos=get32le(ftmP);
        pos+=0x10+ftm.tellg();
        int songs=ftm.get()+1;
        int zero=0;
        while (zero<songs) if (ftm.get()=='\0') zero++;
        int headerpos=ftm.tellg();
        ftm.seekg(pos); // seeks through "INSTRUMENT      " for normally created FTMs
        version=get32le(ftmP);
        ftm.seekg(0x4,ios_base::cur);
        int instcount=get32le(ftmP);
        for (int i=0;i<instcount;i++){
            int newinst=permute[ftm.peek()];
            ftm.seekp(ftm.tellg(),ios_base::beg);
            ftm.write(reinterpret_cast<char*>(&newinst),1);
            ftm.seekg(0x3,ios_base::cur);
            switch(ftm.get()){
                case 1: // 2A03
                    ftm.seekg(0x9E+0x30*(version>=2)+0x60*(version>=6),ios_base::cur); break;
                case 2: // VRC6
                    ftm.seekg(0xE,ios_base::cur); break;
                case 3: // VRC7
                    ftm.seekg(0xC,ios_base::cur); break;
                case 4: // FDS
                    ftm.seekg(0x6C,ios_base::cur);
                    for (int j=0;j<3;j++) ftm.seekg(ftm.get()+0xC,ios_base::cur); break;
                case 5: // N163
                    ftm.seekg(0xE,ios_base::cur);
                    int wavecount=get32le(ftmP);
                    ftm.seekg(0x4,ios_base::cur);
                    ftm.seekg(wavecount*get32le(ftmP),ios_base::cur); break;}
            ftm.seekg(get32le(ftmP),ios_base::cur);}
        ftm.seekg(0x14,ios_base::cur);
        ftm.seekg(get32le(ftmP)+0x14,ios_base::cur);
        ftm.seekg(get32le(ftmP)+0x10,ios_base::cur); // seeks through "PATTERNS        " for normally created FTMs
        version=get32le(ftmP);
        int patsize=get32le(ftmP)+ftm.tellg();
        while (ftm.tellg()<patsize){
            int track=get32le(ftmP);
            int channel=get32le(ftmP);
            ftm.seekg(0x4,ios_base::cur);
            int rowcount=get32le(ftmP);
            for(int i=0;i<rowcount;i++){
                ftm.seekg(0x6,ios_base::cur);
                int newinst2=permute[ftm.peek()];
                ftm.seekp(ftm.tellg(),ios_base::beg);
                ftm.write(reinterpret_cast<char*>(&newinst2),1);
                int pos2=ftm.tellg();
                ftm.seekg(headerpos+(songs+1)*channel+track+1);
                ftm.seekg(pos2+3+2*ftm.get());}}}
    return 0;}