/* userio.c -- handy user interface functions */

/*****************************************************************************
*	    Change Log
*  Date	    | Change
*-----------+-----------------------------------------------------------------
* 21-May-86 | Created
*****************************************************************************/

#include "cext.h"
#include "stdio.h"
#include "userio.h"


/****************************************************************************
*				askbool
* Inputs:
*	char *prompt: string to prompt for user input
*	int deflt: true or false default
* Returns:
*	boolean: true or false as entered by user
* Effect:
*	prompts user for yes or no input, returns result
****************************************************************************/

int askbool(prompt, deflt)
    char *prompt;
    int deflt;
{
#define undefined -1
    char defchar;	/* the default answer */
    char c;		/* user input */
    int result = -1;	/* the result: -1 = undefined, 0 = false, 1 = true */
    if (deflt) defchar = 'y';
    else defchar = 'n';
    while (result == undefined) {
	fprintf(stderr, "%s? [%c]: ", prompt, defchar);
	c = getchar();
	if (toupper(c) == 'Y') result = true;
	else if (toupper(c) == 'N') result = false;
	else if (c == '\n') result = deflt;
	else fprintf(stderr, "Please type Y or N.\n");
    }
    while (c != '\n') c = getchar();	/* flush the input line */
    return result;
}


/****************************************************************************
*				fileopen
* Inputs:
*	char *deflt: the default file name (e.g. from command line)
*	char *extension: default extension
*	char *mode: read ("r") or write ("w")
*	char *prompt: prompt for user
* Returns:
*	opened file pointer
* Effect: 
*	opens file, prompts for user input if necessary and warns about
*	possible confusion.  If deflt is a null string, the user will
*	be prompted for a name.	 The routine loops until a file is opened.
*	If the mode is "r", a check is made to see if the file exists
*	with and without the extension.	 If both exist a warning is given.
*	For mode "w", a check is made to see if the file will be overwritten.
*	The extension is automatically added if the default or user-typed
*	file has no "."	 At the bottom of the loop body, if no file has
*	been opened, the user is prompted for another file name.
****************************************************************************/

FILE *fileopen(deflt, extension, mode, prompt)
    char *deflt;
    char *extension;	/* default extension */
    char *mode;		/* read "r" or write "w" */
    char *prompt;	/* prompt for user */
{
    char filename[100]; /* trial name */
    char extname[100];	/* trial name with extension added */
    FILE *fp = NULL;	/* file corresponding to filename */
    FILE *fpext;	/* file corresponding to extname */
    char *problem;	/* tells user why he has to try again */

    strcpy(filename, deflt);
    while (fp == NULL) {	/* keep trying until a good file is found */
	while (strlen(filename) == 0) { /* avoid null file names */
	    fprintf(stderr, "%s: ", prompt);
	    gets(filename);
	}
	if (mode[0] == 'r') {
	    strcpy(extname, filename);
	    strcat(extname, ".");
	    strcat(extname, extension);
	    fp = fopen(filename, mode);
	    fpext = fopen(extname, mode);
	    if (fp != NULL && fpext != NULL) {
		fprintf(stderr,
			"warning: both %s and %s exist.	 %s will be used.\n",
			filename, extname, filename);
		fclose(fpext);
	    } else if (fpext != NULL) {
		fp = fpext;
	    }
	    if (fp == NULL) problem = "Couldn't find %s.";
	} else if (mode[0] == 'w') {
	    /* add the extension if there is no '.' in the file name */
	    if (!strchr(filename, '.')) {
		strcat(filename, ".");
		strcat(filename, extension);
	    }
	    fp = fopen(filename, "r");
	    if (fp != NULL) {
		char question[100];
		fclose(fp);
		strcpy(question, "OK to overwrite ");
		strcat(question, filename);
		if (askbool(question, false)) {
		    fp = fopen(filename, mode);
		} else {
		    fp = NULL;
		    problem = "";
		}
	    } else {
		fp = fopen(filename, mode);
		if (fp == NULL) problem = "Couldn't create %s.";
	    }
	}
	if (fp == NULL) {
	    fprintf(stderr, problem, filename);
	    fprintf(stderr, "  Try again.\n%s: ", prompt);
	    gets(filename);
	}
    }
    return fp;
}

/****************************************************************************
*				    readln
* Inputs:
*	FILE * fp: File to read from
* Effect: 
*	Reads and discards characters until a newline is seen
****************************************************************************/

void readln(fp)
FILE *fp;
{
	while (getc(fp) != '\n')
		;
}