Hari 29: Mini Proyek — Sistem Inventaris

Studi Kasus: Sistem Inventaris Sederhana

Kita akan membuat sistem inventaris menggunakan prinsip OOP yang telah dipelajari.

interface Storable {
    public function getStok(): int;
    public function tambahStok(int $jumlah): void;
    public function kurangiStok(int $jumlah): void;
}

class Produk implements Storable {
    private array $riwayat = [];

    public function __construct(
        public readonly string $kode,
        public readonly string $nama,
        public float $harga,
        private int $stok,
    ) {}

    public function getStok(): int { return $this->stok; }

    public function tambahStok(int $jumlah): void {
        if ($jumlah <= 0) throw new \InvalidArgumentException("Jumlah harus positif");
        $this->stok += $jumlah;
        $this->riwayat[] = "+$jumlah (stok: {$this->stok})";
    }

    public function kurangiStok(int $jumlah): void {
        if ($jumlah > $this->stok) throw new \UnderflowException("Stok tidak cukup");
        $this->stok -= $jumlah;
        $this->riwayat[] = "-$jumlah (stok: {$this->stok})";
    }

    public function nilaiInventaris(): float {
        return $this->harga * $this->stok;
    }
}

class Inventaris {
    private array $produk = [];

    public function tambahProduk(Produk $p): void {
        $this->produk[$p->kode] = $p;
    }

    public function cari(string $kode): ?Produk {
        return $this->produk[$kode] ?? null;
    }

    public function totalNilai(): float {
        return array_sum(array_map(fn($p) => $p->nilaiInventaris(), $this->produk));
    }

    public function laporan(): void {
        foreach ($this->produk as $p) {
            printf("%-10s %-15s Stok:%-5d Rp%s\n",
                $p->kode, $p->nama, $p->getStok(),
                number_format($p->nilaiInventaris(), 0, ",", ".")
            );
        }
        echo "Total Nilai: Rp " . number_format($this->totalNilai(), 0, ",", ".") . "\n";
    }
}

$inv = new Inventaris();
$inv->tambahProduk(new Produk("P001", "Laptop",   8500000, 10));
$inv->tambahProduk(new Produk("P002", "Mouse",    150000,  50));
$inv->tambahProduk(new Produk("P003", "Keyboard", 350000,  30));

$inv->cari("P001")->tambahStok(5);
$inv->cari("P002")->kurangiStok(10);

$inv->laporan();