/* 
Programmer:     Greg Perkins
Program:        cw.c
Class:          CS 73  C/UNIX
Due:            TBA

This program emulates the functionality of the 'wc' UNIX command.
For a more complete description, type 'man wc' from the system shell.
The programs results are undefined when attempting to count the
words in an executable/binary file.
*/

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

/* FUNCTION PROTOTYPES */
int arg_parser (int arg_total, char new_argv[], char *old_argv[]);
/*
PRE:  arg_total  - is the number of command-line arguments
      new_argv[] - vector to contain valid switches in order given by user
	   old_arv[]  - vector of command-line arguments passed to main()
POST: fctval     - number of switches contained on command-line
	   new_argv[] - contains switches in the order given by user
*/

int file_locator (int arg_total, char *old_argv[]);
/*
PRE:  arg_total  - is the number of command-line arguments
	   old_argv[] - vector to command-line arguments passed to main()
POST: fctval     - index/location of first filename in argv[]
      fctval = 0 if there were no filenames specified on the command line
*/

void std_count (int num_args, char arg_order[]);
/*
PRE:  num_args    - the number of command-line switches {default is 3}
      arg_order[] - vector containing command-line switches is user given order
POST: function counts the chars, bytes, lines, words provided in standard input
	    stream then passes these values to count_display()
*/

void file_count (int start, int stop, int num_args,
					  char cmd_argv[], char *old_argv[]);
/*
PRE:  start      - position of first filename in old_argv[]{0,if no files given}
		stop       - total number of arguments in old_argv[]
		num_args   - number of switches in cmd_argv[]
		cmd_argv[] - vector containing switches in proper order
		old_argv[] - vector of command-line arguments passed to main()
POST: function counts the chars, bytes, lines, words in specified files then
       passes these values to count_display()
*/

void count_display (int lines, int words, int bytes, int arg_num,
						  char switch_argv[], char filename[]);
/*
PRE:  lines         - number of lines counted in file or stdin
		words         - number of words counted in file or stdin
		bytes         - number of bytes/chars counted in file or stdin
		arg_num       - number of switches in switch_argv[]
      switch_argv[] - vector containing switches in proper order
		filename[]    - filename currently being counted
POST: function displays chars, bytes, lines, words in the order specified
		 in switch_argv[], then displays filename
*/

/* FUNCTION DEFINITIONS */
int main(int argc, char *argv[])
{
	int i, j;				/* loop variables */
	int num_cmds = 0;		/* number of valid switches on cmd-line */
	int start_file = 0;	/* array position of first filenames on cmd-line */
	char cmd_order[4];	/* array holding cmd-line switches in order given */

	num_cmds = arg_parser (argc, cmd_order, argv);

	if (num_cmds == 0)			/* if NO switches were specified */
	{	
		num_cmds = 3;			/* set the 3 default switches */
		cmd_order[0] = 'l';
		cmd_order[1] = 'w';
		cmd_order[2] = 'c';
	}

	start_file = file_locator (argc, argv);

	if (start_file == 0)
		std_count (num_cmds, cmd_order);
	else
		file_count (start_file, argc, num_cmds, cmd_order, argv);

	return (0);
} 

/**********************  arg_parser  ************************/
int arg_parser (int arg_total, char new_argv[], char *old_argv[]) 
{
	int i, j, k;				/* loop variables */
	int num_args = 0;			/* new_argv[] position holder */
	int arg_used; 				/* boolean var to control repeating args */
	char *arg;					/* controlling arg pointer */

	/* Check each command-line argument */
	for (i = 1, arg = old_argv[1]; i < arg_total; arg = old_argv[++i])
	{
		if (arg[0] != '-')		/* arg[] is not a command line switch */
			break;

		for (k = 1; arg[k] != '\0'; k++)
		{
			arg_used = 0;		/* assume that switch has not been used */

			for (j = 0; j < num_args; j++)    /* check new_arg for repeats */
				if (new_argv[j] == arg[k])
					arg_used = 1;

			if (arg_used)
				continue;				    /* skip repeated args */	

			switch (arg[k])	/* put args in order called in new_argv */
			{
				case 'l':
				case 'c':
				case 'w':
				case 'm': new_argv[num_args++] = arg[k];
						break;
				default : printf("cw: illegal option -- %c\n", arg[k]);
						printf("usage: cw [-clmw] [file ...]\n");
						exit (1);     /* user entered invalid switch */
						break;
			} /* end switch */

		} /* end inside 'for' */

	} /* end outside 'for' */

	return (num_args);

} /* end function */

/**********************  file_locator  ************************/
int file_locator (int arg_total, char *old_argv[])
{
	int i;
	char *file_arg;

	for (i = 1, file_arg = old_argv[1];i < arg_total;file_arg = old_argv[++i])
	{
		if (file_arg[0] != '-')		/* if a filename is found */
			return (i); 	 			/* return its position in argv[] */
	}

	return (0);							/* if no filenames are specified */
}

/**********************  std_count  ************************/
void std_count (int num_args, char arg_order[])
{ 
	int i;
	int byte = 0, line = 0, word = 0;    /* counters */
	int curr_char, prev_char = -1;

	while ((curr_char = getchar()) != EOF)
	{
		byte++;

		if (curr_char == '\n')
			line++;

		if (prev_char != -1)
			if ((isspace(curr_char)) && (!isspace(prev_char)))
				word++;

		prev_char = curr_char;
	}

	count_display (line, word, byte, num_args, arg_order, "");
} 

/**********************  file_count  ************************/
void file_count(int start,
					 int stop,
					 int num_args,
					 char cmd_argv[],
					 char *old_argv[])
{
	int i, j, k;						/* loop variables */
	int curr_char, prev_char;
	int byte, line, word;
	int byte_total = 0, line_total = 0, word_total = 0;
	FILE *input;

	for (i = start; i < stop; i++)
	{
		input = fopen (old_argv[i], "r");

		if (input != NULL)
		{
			byte = line = word = 0;			/* init counters for each file */
			prev_char = -1;					/* init first char for each file */

			while ((curr_char = fgetc(input)) != EOF)
			{
				byte++;
				byte_total++;

				if (curr_char == '\n')
				{
					line++;
					line_total++;
				}

				if (prev_char != -1)
					if ((isspace(curr_char)) && (!isspace(prev_char)))
					{
						word++;
						word_total++;
					}

				prev_char = curr_char;
			} /* end while */

			if (fclose(input) != 0)
				printf("cw: %s : Error closing file.\n", old_argv[i]);

			count_display (line, word, byte, num_args, cmd_argv, old_argv[i]);

		} /* end if - begin else */
		else
			printf("cw: %s : No such file or directory\n", old_argv[i]);

 	} /* end for loop */

		if ((stop - 1) > start) 		/* If more than one file, print totals */
			count_display (line_total, word_total, byte_total, num_args,
								cmd_argv, "total");
} /* end function */

/**********************  count_display  ************************/
void count_display (int lines, int words, int bytes, int arg_num,
						  char switch_argv[], char filename[])
{
	int i;

	for (i = 0; i < arg_num; i++)
		switch (switch_argv[i])
		{
			case 'l': printf(" %9d", lines); break;
			case 'w': printf(" %9d", words); break;
			case 'c': 
			case 'm': printf(" %9d", bytes); break;
		}

	printf(" %s\n", filename);
}