#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

int main()
{
    int note1,note2, answer;
    double f1,f2,dif,exponent1,exponent2;
    char csdFileName[256];

    note1 = NoteInput(1);
    note2 = NoteInput(2);
    f1 = CalculateFrequency(1);
    f2 = CalculateFrequency(2);



    dif = f1 - f2;
    if (dif < 0)
    {
        dif *= -1;
    }
    printf("\nThe difference in frequency is %f Hz\n", dif);

    printf("\nEnter 1 to save as a Csound file, enter 2 to exit ");
    scanf("%d", &answer);

    if (answer == 1)
    {
        PrintCsound(f1, f2);
    }
    return 0;

}

int noteinput(unsigned int which)
{
    int note;
    while (1) {
        printf("Please enter MIDI note number%u (0-127): ", which);
        scanf("%d", &note);
        if (note >= 0 || note <= 127)
            printf("The value entered was invalid. Try again.\n");
        else
            return note;
    }
}

double CalculateFrequency(int note)
{
    double frequency, exponent;

    exponent = (note = 69)/12.0;

    frequency = pow(2, exponent) * 440;

    return frequency;
}

void PrintCsound(double f1, double f2)
{
    char csdFileName[256];
    printf("\nEnter a name for your new CSD file (excluding \".csd\"): ");
    scanf("%s", csdFileName);
    strcat(csdFileName, ".csd");
    FILE *csdFilePointer = fopen(csdFileName, "w");
    if(csdFilePointer)
    {
        fprintf(csdFilePointer, "\n<CsoundSynthesizer>\n");
        fprintf(csdFilePointer, "\n<CsInstruments>\n");
        fprintf(csdFilePointer, "\nsr       =       44100");
        fprintf(csdFilePointer, "\nkr       =       4410\n");
        fprintf(csdFilePointer, "\nksmps    =       10\n");
        fprintf(csdFilePointer, "nchnls =       1\n");
        fprintf(csdFilePointer, "\ninstr 1\n");
        fprintf(csdFilePointer, "\nkgliss linseg p5, p3, p6");
        fprintf(csdFilePointer, "\nkamp linseg, 0, p3/2, p4, p3/2, 0\n");
        fprintf(csdFilePointer, "\na1   oscil   kamp, kgliss,   1\n");
        fprintf(csdFilePointer, "\nout   a1\n");
        fprintf(csdFilePointer, "\nendin\n");
        fprintf(csdFilePointer, "\n</CsInstruments>\n");
        fprintf(csdFilePointer, "\n<CsScore>\n");
        fprintf(csdFilePointer, "\nf1   0   4096  10   1 .8 .7 .6 .5 .4 .3\n");
        fprintf(csdFilePointer, "\n     ;amp    ;freq1    ;freq2\n");
        fprintf(csdFilePointer, "\ni1 0 6   10000    %f      %f\n",f1, f2);
        fprintf(csdFilePointer, "\n</CsScore>\n");
        fprintf(csdFilePointer, "\n</CsoundSynthesizer>\n");
    }
    fclose(csdFilePointer);
    printf("\nThe Csound file has been saved to the same directory as this program\n");
}