<?php
$input = file('input.txt');

$units = array();
$attack_units = array();

$current_type = '';

foreach ($input as $line) {
    $line = trim($line);

    if ($line !== '') {

        if ($line === 'Immune System:') {
            $current_type = 'immune';
        } elseif ($line === 'Infection:') {
            $current_type = 'infection';
        } else {
            preg_match_all('/(\d+)\sunits.*?(\d+).*?does\s(\d+)\s(.*?)\s.*?initiative\s(\d+)/', $line, $match);
            preg_match_all('/(immune|weak)\sto\s(.*?)[;|\)]/', $line, $match2);


            $data = array('units' => (int)$match[1][0], 'hit_points' => (int)$match[2][0], 'damage' => (int)$match[3][0], 'damage_type' => trim($match[4][0]), 'initiative' => (int)$match[5][0]);


            $immune = array();
            $weak = array();

            for ($i = 0; $i < count($match2[0]); $i++) {
                if ($match2[1][$i] === 'immune') {
                    $immune = explode(', ', $match2[2][$i]);
                } elseif ($match2[1][$i] === 'weak') {
                    $weak = explode(', ', $match2[2][$i]);
                }
            }

            $units[] = new Unit($current_type, $data, $immune, $weak);
        }
    }
}

$backup_units = $units;
$reindeer = false;
$boost = 0;

while (!$reindeer) {

    $units = $backup_units;

    foreach ($units as $key => $unit) {
        $unit->reset();
        if ($unit->unit_type === 'immune') {
            $units[$key]->damage += $boost;
        }
    }
    $both = true;

    while ($both) {

        $attack_units = array();

        usort($units, 'sort_units');

        foreach ($units as $key => $unit) {
            $best_match = null;

            foreach ($units as $key2 => $unit2) {
                if ($unit2->would_deal_damage($unit) !== false) {
                    if (($best_match === null || ($unit2->would_deal_damage($unit) > $best_match->would_deal_damage($unit))) && !in_array($unit2, $attack_units)) {
                        $best_match = $unit2;
                    }
                }
            }
            if ($best_match !== null) {
                $unit->set_attack($best_match);
                $attack_units[] = $best_match;
            }
        }

        usort($units, 'sort_on_initiative');

        $damage = false;
        foreach ($units as $key => $unit) {
            if ($unit->attack()) {
                $damage = true;
            }

        }

        $im = false;
        $in = false;
        foreach ($units as $key => $unit) {
            if ($unit->get_effective_power() <= 0) {
                unset($units[$key]);
            } else {
                if ($unit->unit_type === 'immune') {
                    $im = true;
                } elseif ($unit->unit_type === 'infection') {
                    $in = true;
                }
            }
        }

        $both = $im && $in;

        if ($damage === false) {
            $both = false;
        }

        if ($in === false && $im === true) {
            $reindeer = true;
            $count2 = 0;
            foreach ($units as $unit) {
                $count2 += $unit->units;
            }
            break;
        }
    }

    if ($boost === 0) {
        $count = 0;
        foreach ($units as $unit) {
            $count += $unit->units;
        }

        printf('Part 1: %d', $count);
        echo PHP_EOL;
    }

    $boost++;
}

printf('Part 2: %d', $count2);
echo PHP_EOL;


function sort_units(Unit $a, Unit $b)
{
    if ($a->get_effective_power() === $b->get_effective_power()) {
        return $a->initiative > $b->initiative ? -1 : 1;
    } elseif ($a->get_effective_power() > $b->get_effective_power()) {
        return -1;
    }
    return 1;
}

function sort_on_initiative(Unit $a, Unit $b)
{
    return $a->initiative > $b->initiative ? -1 : 1;
}

class Unit
{

    public $unit_type = '';
    public $units = 0;
    public $hit_points = 0;
    public $damage = 0;
    public $damage_type = '';
    public $initiative = 0;
    public $weakness = array();
    public $immune = array();

    public $attack_unit = null;

    public $org_data = null;

    public function __construct($type, $data, $immune, $weak)
    {
        $this->org_data = $data;

        $this->unit_type = $type;
        $this->units = $data['units'];
        $this->hit_points = $data['hit_points'];
        $this->damage = $data['damage'];
        $this->damage_type = $data['damage_type'];
        $this->initiative = $data['initiative'];

        $this->weakness = $weak;
        $this->immune = $immune;
    }

    public function reset()
    {
        $data = $this->org_data;
        $this->units = $data['units'];
        $this->hit_points = $data['hit_points'];
        $this->damage = $data['damage'];
        $this->damage_type = $data['damage_type'];
        $this->initiative = $data['initiative'];
    }

    public function would_deal_damage(Unit $unit)
    {
        if ($unit->unit_type === $this->unit_type || $this === $unit) {
            return false;
        }

        $power = $unit->get_effective_power();

        if (in_array($unit->damage_type, $this->immune)) {
            return false;
        } elseif (in_array($unit->damage_type, $this->weakness)) {
            $power *= 2;
        }

        return $power;
    }

    public function get_effective_power()
    {
        if ($this->units <= 0) {
            return 0;
        }
        return $this->units * $this->damage;
    }

    public function deal_damage(Unit $unit)
    {
        $power = $this->would_deal_damage($unit);
        $lost_units = floor($power / $this->hit_points);
        if ($lost_units <= 0) {
            return false;
        }
        $this->units -= $lost_units;

        return true;
    }

    public function set_attack(Unit $unit)
    {
        $this->attack_unit = $unit;
    }

    public function attack()
    {
        if ($this->attack_unit !== null) {
            $att = $this->attack_unit->deal_damage($this);
            $this->attack_unit = null;
            return $att;
        }
        return false;

    }
}