#include<stdio.h>
#include<ctype.h>
#include<string.h>

#define		FILENAME	20
#define		MAXLINE		200
#define		DAYLENGTH	4

#define		PREFIX		"nip"
#define		SUFFIX		".txt"

void reverse(char s[])
{
	int c, i, j;

	for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
		c = s[i];
		s[i] = s[j];
		s[j] = c;
	}
}

void itoa (int n, char s[])
{
	int i = 0;

	do {
		s[i++] = n % 10 + '0';
	} while ((n /= 10) > 0);
	s[i] = '\0';
	reverse(s);
}	

int getDay(char line[])
{
	char dayString[DAYLENGTH];
	int i, j; 
	i = j = 0;

	while (!isspace(line[i++]));	//	move beyond first field
	while (isspace(line[i++]));	//	move beyond white space to second field
	while (!isspace(line[i++]));	//	move beyond second field
	while (isspace(line[i++]));	//	move beyond white space to julian day field that we're after
	--i;	//	back up one - when we reached the first no-space, 'i' was still incremented;
	while (!isspace(line[i]))
		dayString[j++] = line[i++];	//	copy julian day as a string
	dayString[i] = '\0';		//	null terminate 

	return (atoi(dayString));
}

void makeFileName(int currentDay, char sepFileName[])
{
	char dayString[DAYLENGTH];
	itoa(currentDay, dayString);

	strcpy(sepFileName, PREFIX);	
	strcat(sepFileName, dayString);
	strcat(sepFileName, SUFFIX);
}

void separate(char fileName[])
{
	FILE *tempFile, *newFile;
	char line[MAXLINE], sepFileName[FILENAME];
	int currentDay, lineDay;
	currentDay = lineDay = 0;

	printf("Separating %s:\n", fileName);	
	tempFile = fopen(fileName, "r");
	if (tempFile) {
		fgets(line, MAXLINE, tempFile);
		currentDay = getDay(line);
		makeFileName(currentDay, sepFileName);
		newFile = fopen(sepFileName, "a");
		while (!feof(tempFile)) {
			lineDay = getDay(line);
			if (lineDay == currentDay)
				fputs(line, newFile);
			else {	//	reached the next julian day in the file
				fclose(newFile);	//	close previous day's file
				currentDay = lineDay;	//	set new currentDay
				makeFileName(currentDay, sepFileName);						
				newFile = fopen(sepFileName, "a");
				fputs(line, newFile);
			}
			fgets(line, MAXLINE, tempFile);	//	read in the next line
		}
	}		
	else
		printf("\tCouldn't open %s.\n\n", fileName);
}

int main()
{
	FILE *fileList;
	char fileName[FILENAME];

	system("ls *.temp > temp_file_list");
	fileList = fopen("temp_file_list", "r");

	if (fileList) {
		fscanf(fileList, "%s", fileName);
		do {
			separate(fileName);
			fscanf(fileList, "%s", fileName);
		} while (!feof(fileList)); 
	}

	return 0;
}