#!/usr/bin/perl -w

use strict;
use Term::ReadKey;

my (@top, @bottom, @board, $x, $y, $barrier);

my ($hieght) = 20; #hieght of the cave
my ($width) = 70; #width of the cave
my ($slope) = 80; #how often the standard wall hieght increases by 1
my ($count) = 0; #for waiting till $slope iterations for increasing wall hieght
my ($wall_hieght) = 1; 
my ($score) = 0; 
my ($ship_char) = '>';
my ($ship_y) = int(.5 * $hieght); #where the ship is located on the y axis
my ($ship_x) = 6;#where the ship is located on the x axis
my ($wall_char) = ':';
my ($clear) = `clear`; #clear the screen and cache the response

for (1 .. $width) {push @top, $wall_hieght;} #initilize the top wall with the initial wall hieght
for (1 .. $width) {push @bottom, $wall_hieght;}#initilize the bottom wall with the initial wall hieght


#main loop
while (1) {
    generate_board(\@top, \@bottom, \@board, \$hieght); #generate board
    check_input(\$ship_y); #check for input and move ship if necessary

    print $clear; #clear screen
    #go through board looking for 1s (represent wall)
    for $y (0 .. $#board) {
        for $x (0 .. $#{$board[$y]}) {
            if ($board[$y][$x] == 1) {
                #on crash
                if ($y == $ship_y && $x == $ship_x) {
                    crash(\$score);
                } else {
                    print $wall_char;
                }
            } else {
                #if ship here
                if ($y == $ship_y && $x == $ship_x) {
                    print $ship_char;
                } else {
                    print " ";
                }
            }
        }
         print "\n";
    }
    print "Score: " . $score; 

    $barrier = int(rand($hieght-$wall_hieght))/2+int(.4 * $hieght); #odd way to calculate new barriers, made from approximations and altered after running like 9 bizillion times

    shift @top;
    shift @bottom;
    #only add barriers some times
    if (int(rand(5)) == 3) { 
        #add barrier to top
        if (int(rand(2)) == 1) {
            push @top, $wall_hieght + $barrier;
            push @bottom, $wall_hieght;
        } else {
            #add barrier to bottom
            push @top, $wall_hieght;
            push @bottom, $wall_hieght + $barrier;
        }
    } else {
        #no barrier
        push @top, $wall_hieght;
        push @bottom, $wall_hieght;
    }

    $count++;
    $score++;

    #check to make wall hieght greater
    if ($count == $slope and $wall_hieght < (int(.5 * $hieght)-1)) {
        $wall_hieght++;
        $count = 0;
    }
}


sub generate_board {
    my ($top, $bottom, $board, $hieght) = @_;
    my (@tmp_top) = @{$top};
    my (@tmp_bottom) = @{$bottom};
    my ($check) = 0;
    my ($y) = 0;
    @{$board} = ();    

    while ($check < ($#tmp_top+1)) {
        $check = 0;
        for (0 .. $#tmp_top) {
            if ($tmp_top[$_] > 0) {
                $$board[$y][$_] = 1;
                $tmp_top[$_]--;
            } else {
                $$board[$y][$_] = 0;
                $check++;
            }
        }
        $y++;
    }
    
    $check = 0;
    $y = $$hieght-1;

    while ($check < ($#tmp_bottom+1)) {
        $check = 0;
        for (0 .. $#tmp_bottom) {   
            if ($tmp_bottom[$_] > 0) {   
                $$board[$y][$_] = 1;
                $tmp_bottom[$_]--;
            } else {
                $$board[$y][$_] = 0;
                $check++;
            }
        }
        $y--;
    }

    for $y (0 .. ($$hieght-1)) {
        for $x (0 .. ($#tmp_top)) {
            $$board[$y][$x] = 0 unless defined($$board[$y][$x]);
        }
    }
}

sub check_input {
    my ($ship_y) = @_;
    my ($char);    

    ReadMode ('cbreak');
    if (defined ($char = ReadKey(-1)) ) {
        if ($char =~ /[Uu]/) {
            $$ship_y--;
        } elsif ($char =~ /[Jj]/) {
            $$ship_y++;
        }
     }
    ReadMode ('normal');
}

sub crash {
    my ($$score) = @_;
    print "\ncrash\nScore: $$score\n";
    exit();
}