/*
 * Library of some useful-seeming functions for ncurses programs.
 *
 * Called functions are mostly from ncurses library.  "man 3x foobar" 
 * to find out what foobar() does.
 *
 * (Arguably this should be split into .h and .c files, but doing it
 * this way makes the Makefile simpler.)
 */
#include <ncurses.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>

/*
 * declarations for all functions first, so they can appear in any
 * order below.
 */
void ncurses_start(void);
void ncurses_end(void);
void any_key_to_exit(WINDOW *win);
void add_to_row(WINDOW *win, int N);
void add_to_col(WINDOW *win, int N);
void centerline(WINDOW *win, char *line);
void show_with_attrib(WINDOW *win, int attr, char *msg);
char *allocate_and_format(const char *fmt, ...);

/* 
 * startup for programs using ncurses 
 */
void ncurses_start(void) {
    initscr(); 
    cbreak(); 
    noecho(); 
    curs_set(0); /* set cursor to be invisible */
    keypad(stdscr, TRUE); /* enable keypad */
}

/* 
 * cleanup-at-end for programs using ncurses 
 */
void ncurses_end(void) {
    clear();
    refresh();
    endwin();
}

/* 
 * issue "press any key" prompt and wait for input 
 */
void any_key_to_exit(WINDOW *win) {
    centerline(win, "Press any key to exit");
    wrefresh(win);
    getch();
}

/* 
 * move cursor N rows (up or down) 
 */
void add_to_row(WINDOW *win, int N) {
    int row, col;
    getyx(win, row, col);
    wmove(win, row+N, col);
}

/* 
 * move cursor N cols (left or right) 
 */
void add_to_col(WINDOW *win, int N) {
    int row, col;
    getyx(win, row, col);
    wmove(win, row, col+N);
}

/* 
 * display line of text centered in current row 
 */
void centerline(WINDOW *win, char *line) {
    int row, col;
    getyx(win, row, col);
    wmove(win, row, (COLS-strlen(line))/2);
    wprintw(win, "%s", line);
}

/* 
 * display line of text centered in current row, with attributes 
 * (shows the attributes "unpacked" into two 16-bit fields)
 */
void show_with_attrib(WINDOW *win, int attr, char *msg) {
    wattron(win, attr);
    char *line = allocate_and_format("%s (%04x %04x)", msg, 
            (attr >> 16) & 0xffff, attr & 0xffff);
    if (line != NULL) {
        centerline(win, line);
        free(line);
    }
    wattroff(win, attr);
}

/* 
 * create string for formatted text:
 * parameters are similar to those for printf (format string and list of
 *   of expressions)
 * gets just enough space for formatted text using malloc
 * returns pointer to malloc'd line containing the result of "printing"
 *   to a string
 * (caller must free line)
 */
char *allocate_and_format(const char *fmt, ...) {
    va_list args;
    va_start(args,fmt);
    int sz = vsnprintf(NULL, 0, fmt, args) + 1;
    va_end(args);
    char *line = malloc(sz);
    if (line != NULL) {
        va_start(args,fmt);
        vsnprintf(line, sz, fmt, args);
        va_end(args);
    }
    return line;
}