/*
 *
 * ncursesdemo.c
 *
 * REFERENCES
 * https://tldp.org/HOWTO/pdf/NCURSES-Programming-HOWTO.pdf
 *
 * Hyperlinked man page - very useful
 * https://man.netbsd.org/curses.3
 *
 */

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



int main(int argc, char* argv[ ])
{
  WINDOW* W = 0;                     /* Curses Window handle */
  int rowLimit, colLimit;            /* Num of rows and columns in terminal window */  
  int playerRow, playerCol;          /* Player row-column position */
  int deltaRow, deltaCol;            /* Change in row-column position based on key input */


  /* Initialize ncurses -- you will want to use the following settings */
  W = initscr();     /* Determine terminal type and initialize curses data structures */
  start_color();     /* Enable use of color with ncurses */
  cbreak();          /* Disable line buffering and make char inputs immediately accessible to program */
  noecho();          /* Disable echo printing of chars type by user */
  nodelay(W, true);  /* Make getch( ) a non-blocking call */
  keypad(W, true);   /* Enable keypad and arrow keys */
  curs_set(0);       /* Set cursor to be invisible - 0 */
  getmaxyx(W, rowLimit, colLimit);  /* Query terminal dimensions */

  /* Define color pallete foreground-background color pairs */
  /* PairID#, Foreground Color, Background Color */
  /* Foreground color == Background color ==> solid color block */
  init_pair(1, COLOR_BLACK, COLOR_BLACK);      /* Black text on Black background */
  init_pair(2, COLOR_RED, COLOR_BLACK);        /* Red text on Black background */
  init_pair(3, COLOR_WHITE, COLOR_BLUE);       /* White text on Blue background */
  init_pair(4, COLOR_YELLOW, COLOR_YELLOW);    /* Yellow text on Yellow background */
 
  /* Draw some obstacle */
  attron(COLOR_PAIR(2));                  /* Turn on color attribute #2 */
  wmove(W, rowLimit/2, colLimit/2);       /* Position cursor in middle of terminal window */
  waddch(W, '#');                         /* Draw # symbol */
  attroff(COLOR_PAIR(2));                 /* Turn off color attribute #2 */

  /* Initialize player movement variables */
  playerRow = rowLimit/4;
  playerCol =  colLimit/4;
  deltaCol = 0;
  deltaRow = 0;
 
  /* Player movement loop */
  do
  {
    int kb = wgetch(W);                   /* Grab keypress */

    /* Support player movement via WASD, IJKL, and arrow keys */
    if (kb == 'a' || kb == 'j' || kb == KEY_LEFT)
    {
        /* Move Left */
        deltaCol = -1;
        deltaRow = 0;  
    }
    else if (kb == 'd' || kb == 'l' || kb == KEY_RIGHT)
    {
        /* Move Right */
        deltaCol = 1;
        deltaRow = 0;
    }
    else if (kb == 'w' || kb == 'i' || kb == KEY_UP)
    {
        /* Move Up */
        deltaCol = 0;
        deltaRow = -1;  
    }
    else if (kb == 's' || kb == 'k' || kb == KEY_DOWN)
    {
        /* Move Down */
        deltaCol = 0;
        deltaRow = 1; 
    }
    else if (kb == 'q')
    {
        /* q to exit player movement loop */ 
        break;
    };

    /* Erase player from current position                                    */
    /* An alternate option is to invoke clear()                              */
    /* which erases everything on the screen                                 */
    /* If you comment out this code, the player will leave an onscreen trail */
    /*                                                                       */ 
    /* Algorithm:                                                            */
    /* - Turn on color attribute #1  (solid block of background color)       */
    /* - Position cursor                                                     */
    /* - Draw player symbol                                                  */
    /* - Turn off color attribute #1                                         */
    attron(COLOR_PAIR(1));                  
    wmove(W, playerRow, playerCol);         
    waddch(W, 'P');                         
    attroff(COLOR_PAIR(1));                 

    /* Compute new player position without checking to see if new position is valid */
    playerRow = playerRow + deltaRow;
    playerCol = playerCol + deltaCol;


    /* Redraw player in new position */
    attron(COLOR_PAIR(3));                  /* Turn on color attribute #3 */
    wmove(W, playerRow, playerCol);         /* Position cursor */
    waddch(W, 'P');                         /* Draw player symbol */
    attroff(COLOR_PAIR(3));                 /* Turn off color attribute #3 */

    /* Zero offsets prior to next key press */
    deltaRow = 0;
    deltaCol = 0;

    wrefresh(W);                            /* Refresh ncurses window */

  } while (true);                           /* Repeat until user selects q to quit */

  endwin();                                 /* Terminate ncurses window -- very important */

  return 0;
}