<?php

function print_clay($clay)
{
    global $ymin, $ymax;

    $water = 0;
    $drain = 0;

    foreach ($clay as $key=>$line)
    {

        printf('%4d : ', $key);
        echo implode('', $line);
        echo PHP_EOL;

        if($key >= $ymin && $key < $ymax) {
            $values = array_count_values($line);
            if (isset($values['~'])) {
                $water += $values['~'];
            }
            if (isset($values['|'])) {
                $drain += $values['|'];
            }
        }
    }

    echo PHP_EOL;
    printf('Part 1: %d', $water + $drain);
    echo PHP_EOL;
    printf('Part 2: %d', $water);
    echo PHP_EOL;
}

function fillable($y, $x)
{
    global $clay, $xmin, $xmax, $ymax;

    if($x<$xmin-1 || $x >$xmax+1 || $y < 0 || $y > $ymax)
        return false;

    return (($c = $clay[$y][$x]) === ' ' || $c === '|' || $c === '+');

}

function fill($y, $x) {
    global $clay, $xmin, $xmax;


    if(!fillable($y, $x)) {
        return;
    }

    if(fillable($y+1, $x)) {
        if($clay[$y][$x] === ' ') {
            $clay[$y][$x] = '|';
            fill($y+1, $x);

            if($clay[$y+1][$x] === '~') {
                fill($y, $x);
            }
        }
    } else {
        $lx = $x;
        while(fillable($y, $lx) && !fillable($y+1, $lx)) {
            $clay[$y][$lx] = '|';
            $lx--;
        }

        $rx = $x;
        while(fillable($y, $rx) && !fillable($y+1, $rx)) {
            $clay[$y][$rx] = '|';
            $rx++;
        }

        if(fillable($y+1, $lx) || fillable($y+1, $rx)) {
            fill($y, $lx);
            fill($y, $rx);
        } elseif($lx > $xmin-1 && $lx < $xmax+1 && $clay[$y][$lx] === '#' && $clay[$y][$rx] === '#') {
            for($fx = $lx+1;$fx<$rx;$fx++) {
                $clay[$y][$fx] = '~';
            }
        }
    }

}

$input = file('input.txt');

$clay = array();

$ymin = $xmin = PHP_INT_MAX;
$ymax = $xmax = PHP_INT_MIN;

foreach ($input as $line)
{
    preg_match_all('/(x|y)=([\d\.]+)/', $line, $match);

    $xv = array();
    $yv = array();

    $m0 = array_map('intval',explode('..',$match[2][0]));
    $m1 = array_map('intval',explode('..',$match[2][1]));

    if($match[1][0] === 'x')
    {
        $xv = $m0;
        $yv = $m1;
    } else {
        $xv = $m1;
        $yv = $m0;
    }

    if(count($xv) === 1)
    {
        $xv[1] = $xv[0];
    }
    if(count($yv) === 1)
    {
        $yv[1] = $yv[0];
    }

    for($y = $yv[0]; $y <= $yv[1] ; $y++)
    {
        $ymin = min($ymin, $y);
        $ymax = max($ymax, $y);

        if(!isset($clay[$y]))
        {
            $clay[$y] = array();
        }
        for($x = $xv[0]; $x <= $xv[1] ; $x++)
        {
            $xmin = min($xmin, $x);
            $xmax = max($xmax, $x);

            $clay[$y][$x] = '#';
        }
    }
}


for($y = 0; $y <= $ymax ; $y++)
{

    $sand = array_fill($xmin-1, $xmax-$xmin+3, ' ');
    if(isset($clay[$y])) {
        $clay[$y] = $clay[$y] + $sand;
        ksort($clay[$y]);
    } else {
        $clay[$y] = $sand;
    }

}
$clay[++$ymax] = $sand;
ksort($clay);


fill(0, 500);
unset($clay[$ymax]);
$clay[0][500] = '+';

print_clay($clay);