#include <stdlib.h>
#include <cab202_graphics.h>

//  (a) Insert the function signature for a function called fill_rect
//      which returns no value, but which has the following parameters:
//      left - an integer that specifies the horizontal location of
//          the left hand side of the rectangle.
//      top - an integer that specifies the vertical location of
//          the upper edge of the rectangle.
//      right - an integer that specifies the horizontal location of
//          the right hand side of the rectangle.
//      bottom - an integer that specifies the vertical location of
//          the lower edge of the rectangle.
//      ch = a character value that will be used to draw the
//          display the rectangle.
void fill_rect(int left, int top, int right, int bottom, char ch) {

    //  (b) Test to see if either the width or height of the rectangle is less
    //      than 1. If so, the function should stop immediately and draw nothing.
	if (( right-left ) >= 0 && ( bottom-top ) >= 0 ) {

		//  (c) Set up an integer variable called y_ctr which will be used to
		//      iterate from the top of the rectangle to the bottom of the rectangle.
		int y_ctr = top;

		//  (d) Enter a loop that will use y_ctr to iterate over each row of the
		//      rectangle.
		while ( y_ctr <= bottom ) {

			//  (e) Draw a horizontal line from the left edge of the rectangle to
			//      the right edge of the rectangle, in the row defined by y_ctr.
				draw_line( left, y_ctr, right, y_ctr, ch );

			//  (f) Increment y_ctr.
				y_ctr += 1;

			}//  (g) End the loop.
		}
	}//  (h) End the function.

void hrule( void );
void vrule( void );

int main( void ) {
    setup_screen();

    // draw a box.
    int left = 2 + rand() % ( screen_width() - 2 ) / 2;
    int top = 2 + rand() % ( screen_height() - 2 ) / 2;
    int right = left + 1 + rand() % ( screen_width() - left - 1 );
    int bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    int ch = '@';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = '&';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box with zero width.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left - 1;
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = '*';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = '#';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box with negative width.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left - 2;
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = '!';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = '+';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box with zero height.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top - 1;
    ch = 'a';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = 'b';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box with negative right.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top - 2;
    ch = 'c';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    // draw a box.
    left = 2 + rand() % ( screen_width() - 2 ) / 2;
    top = 2 + rand() % ( screen_height() - 2 ) / 2;
    right = left + 1 + rand() % ( screen_width() - left - 1 );
    bottom = top + 1 + rand() % ( screen_height() - top - 1 );
    ch = 'd';
    clear_screen();
    hrule();
    vrule();
    draw_formatted( 5, 1,
        "left: %4d, upper: %4d, right: %4d, lower: %4d - Press key to continue...",
        left, top, right, bottom
        );
    fill_rect( left, top, right, bottom, ch );
    show_screen();
    wait_char();

    cleanup_screen();
    return 0;
}

void hrule( void ) {
    for ( int x = 0; x < screen_width(); x++ ) {
        draw_char( x, 0, '0' + ( x % 10 ) );
    }
}

void vrule( void ) {
    for ( int y = 0; y < screen_height(); y++ ) {
        draw_char( 0, y, '0' + ( y % 10 ) );
    }
}