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

/**
 * G Towell
 * created: Sept 2019
 * Desc:
 *   File reading in a couple of ways
 **/

/**
 * Read a file char by char and store it in a character array
 * When read complete (or array full) put on a null terminator.
 * Then print
 **/
int v1(char * filename)
{
    printf("V1\n");
    char holder[256];
    FILE *f = fopen(filename, "r");
    if (f==NULL)
    {
	printf("Cannot open file %s\n", filename);
	return -1;
    }
    int i=0;
    char c;
    while (i<255 && EOF!=(c=fgetc(f)))
    {
	holder[i++]=c;
    }
    holder[i]='\0';
    printf("%s\n", holder);
    return 1;
}

/**
 * Slightly more compact that v1, but otherwise the same
 **/
int v2(char *filename)
{
    char holder[256];
    FILE *f = fopen(filename, "r");
    if (f==NULL)
    {
	printf("Cannot open file %s\n", filename);
	return -1;
    }
    int i=0;
    while (i<255 && EOF!=(holder[i++]=fgetc(f)))
    {
    }
    if (holder[i-1]==EOF)
    {
	i--;
    }
    holder[i]='\0';
    printf("%s\n", holder);
    return 1;
}

/***
 * Doing it with pointers rather than array calc
 **/
int v3(char *filename)
{
    int mx=256;
    char holder[mx];
    FILE *f = fopen(filename, "r");
    if (f==NULL)
    {
	printf("Cannot open file %s\n", filename);
	return -1;
    }
    int i=0;
    char * p;
    p = holder;
    while (i<(mx-1) && EOF!=(*(p++)=fgetc(f)))
    {
	i++;
    }
    if (i<(mx-1))
    {
	p--;
    }
    *p='\0';
    printf("%s\n", holder);
    return 1;
}

/**
 * Danger, write off end of character array !!!
 * because not keep track of number of chars read
 **/
int v4(char *filename)
{
    int mx=10;
    char holder[mx];
    FILE *f = fopen(filename, "r");
    if (f==NULL)
    {
	printf("Cannot open file %s\n", filename);
	return -1;
    }
    char * p = holder;
    while (EOF!=(*(p++)=fgetc(f)));
    *p='\0';
    printf("%s\n", holder);
    return 1;
}

/** 
 * differs from v3 only in printing char by char
 */
int v5(char *filename)
{
    int mx=256;
    char holder[mx];
    FILE *f = fopen(filename, "r");
    if (f==NULL)
    {
	printf("Cannot open file %s\n", filename);
	return -1;
    }
    int i=0;
    char * p;
    p = holder;
    while (i<(mx-1) && EOF!=(*(p++)=fgetc(f)))
    {
	i++;
    }
    if (i<(mx-1))
    {
	p--;
    }
    *p='\0';
    p=holder;
    while (*p!='\0')
    {
	printf("%c", *(p++));
    }
    return 1;
}

/**
 * requires 2 command line args
 * 1: name of file
 * 2: which processing method
 **/
int main(int arrgc, char *argv[])
{
    char * filename = argv[1];
    //int which  = (int)strtof(argv[2], NULL);
    int which = argv[2][0];
    switch (which)
    {
    case '1':
	v1(filename);
	break;
    case '2':
	v2(filename);
	break;
    case '3':
	v3(filename);
	break;
    case '4':
	v4(filename);
	break;
    default:
	v5(filename);
	break;
    }
}