<?php

class Monster{
    private $health = 0;

    function __construct($health) {
        if(!is_numeric($health)){
             throw new Exception('Non numeric health');
        }
        $this->health = $health;
    }

    public function __toString() {
        return (string)$this->health;
    }

    public function add($ammount){
        if(!is_numeric($ammount)){
             throw new Exception('Non numeric ammount');
        }
        $this->health += $ammount;
        return $this->health;
    }

    public function subtract($ammount){
        if(!is_numeric($ammount)){
             throw new Exception('Non numeric ammount');
        }
        $this->health -= $ammount;
        if($this->health <= 0){
            $this->health = 0;
        }
        return $this->health;
    }
}

class Encounter{
    private $monsters = array();

    function __construct() {
        $args = func_num_args();
        for($i = 0; $i < $args; $i++){
            $this->create_monster(func_get_arg($i));
        }
    }

    public function __toString() {
        $value = "Monster List\n";
        $number = 0;
        foreach($this->monsters as &$monster){
             $value .= "Monster : $number | health: $monster \n";
             $number ++;
        }
        return (string)$value;
    }

    function create_monster($health){
        try{
            array_push($this->monsters, new Monster($health));
            echo "Monster created!\n";
        }
        catch(Exception $e){
            echo 'Monster could not be created: '.$e->getMessage()." \n";

        }
    }

    function remove_monster($monster_alias){
        if($this->exists($monster_alias)){
            unset($this->monsters[$monster_alias]);
            $this->monsters = array_values($this->monsters);
            echo "Monster $monster_alias removed\n";
        }
        echo $this;
    }

    function add($monster_alias, $ammount){
        if($this->exists($monster_alias)){
            try{
                $health = $this->monsters[$monster_alias]->add($ammount);
                echo "Monster $monster_alias gained $ammount health and now has $health hp\n";
            }
            catch(Exception $e){
                echo 'Health could not be added: '.$e->getMessage()." \n";
            }
        }
    }

    function subtract($monster_alias, $ammount){
        if($this->exists($monster_alias)){
            try{
                $health = $this->monsters[$monster_alias]->subtract($ammount);
                if($health == 0){
                    echo "Monster $monster_alias has died!\n";
                    $this->remove_monster($monster_alias);
                }
                else{
                    echo "Monster $monster_alias lost $ammount health and has $health hp remaining\n";
                }
            }
            catch(Exception $e){
                echo 'Health could not be subtracted: '.$e->getMessage().' \n';
            }
        }
    }

    private function exists($monster_alias){
        if(!is_numeric($monster_alias) || count($this->monsters) <= $monster_alias || $monster_alias < 0){
            echo "Invalid number! Monster \"$monster_alias\" does not exist\n";
            return false;
        }
        return true;
    }
}

class Interpreter{

    private $encounter;

    public function __construct($encounter){
        $this->encounter = $encounter;
        $this->echo_commands();
    }

    function interpret($cmd){
        switch($cmd){
            case 'monster list':
                echo $this->encounter;
                break;
            case 'command list':
                $this->echo_commands();
                break;
            case 'create':
                echo 'health: ';
                $health = trim(fgets(STDIN));
                $this->encounter->create_monster($health);
                break;
            case 'remove':
                echo 'monster number: ';
                $number = trim(fgets(STDIN));
                $this->encounter->remove_monster($number);
                break;
            case 'add':
                echo 'monster number: ';
                $number = trim(fgets(STDIN));
                echo 'ammount to add: ';
                $ammount = trim(fgets(STDIN));
                $this->encounter->add($number, $ammount);
                break;
            case 'sub':
                echo 'monster number: ';
                $number = trim(fgets(STDIN));
                echo 'ammount to subtract: ';
                $ammount = trim(fgets(STDIN));
                $this->encounter->subtract($number, $ammount);
                break;
            case 'exit':
                exit();
                break;
            default:
                "Invalid command!\n";
        }

    }

    function echo_commands(){
        echo "\nmonster list\ncommand list\ncreate\nremove\nadd\nsub\nexit\n";
    }

}

//PROGRAM BEGINS
echo "WELCOME\n";
$encounter = new Encounter(200, 300, 400, 500);
$interpreter = new Interpreter($encounter);

while(true){
    $interpreter->interpret(trim(fgets(STDIN)));
}