import getpass
import hashlib
import json
import os
from datetime import datetime

DATA_FILE = "invoice_data.json"
INVOICE_FOLDER = "invoices"


def hash_password(password: str) -> str:
    return hashlib.sha256(password.encode("utf-8")).hexdigest()


def prompt_non_empty(prompt: str) -> str:
    while True:
        value = input(prompt).strip()
        if value:
            return value
        print("Pole nie moze byc puste.")


def prompt_positive_float(prompt: str) -> float:
    while True:
        raw_value = input(prompt).replace(",", ".").strip()
        try:
            value = float(raw_value)
        except ValueError:
            print("Wprowadz liczbe.")
            continue
        if value <= 0:
            print("Wartosc musi byc wieksza od zera.")
            continue
        return value


def load_data():
    if not os.path.exists(DATA_FILE):
        return None
    with open(DATA_FILE, "r", encoding="utf-8") as handle:
        return json.load(handle)


def save_data(data) -> None:
    with open(DATA_FILE, "w", encoding="utf-8") as handle:
        json.dump(data, handle, indent=2, ensure_ascii=False)


def run_setup():
    print("=== Konfiguracja konta przedsiebiorcy ===")
    business = {
        "company_name": prompt_non_empty("Nazwa firmy: "),
        "owner_name": prompt_non_empty("Imie i nazwisko wlasciciela: "),
        "address": prompt_non_empty("Adres: "),
        "tax_id": prompt_non_empty("NIP: "),
        "bank_account": prompt_non_empty("Numer konta bankowego: "),
    }

    print("\nUstaw haslo do logowania.")
    while True:
        password = getpass.getpass("Haslo: ")
        confirm = getpass.getpass("Powtorz haslo: ")
        if not password:
            print("Haslo nie moze byc puste.")
            continue
        if password != confirm:
            print("Hasla nie sa identyczne. Sprobuj ponownie.")
            continue
        break

    data = {
        "business": business,
        "password_hash": hash_password(password),
        "invoices": [],
    }
    save_data(data)
    print("\nDane zapisane. Uruchom aplikacje ponownie, aby zalogowac sie i wystawiac faktury.")


def authenticate(data) -> bool:
    for attempt in range(3):
        password = getpass.getpass("Haslo: ")
        if hash_password(password) == data["password_hash"]:
            return True
        print("Nieprawidlowe haslo.")
    return False


def prompt_client_details():
    answer = input("Dodac dane klienta? (T/N): ").strip().lower()
    if answer not in ("t", "tak"):
        return {}
    print("\n=== Dane klienta ===")
    client = {
        "name": prompt_non_empty("Nazwa / Imie i nazwisko: "),
        "address": prompt_non_empty("Adres: "),
        "tax_id": input("NIP (opcjonalnie): ").strip(),
    }
    return client


def format_invoice_text(invoice_id: str, business: dict, invoice: dict) -> str:
    lines = [
        f"Faktura: {invoice_id}",
        f"Data wystawienia: {invoice['issued_at']}",
        "",
        "=== Sprzedawca ===",
        f"Nazwa: {business['company_name']}",
        f"Wlasciciel: {business['owner_name']}",
        f"Adres: {business['address']}",
        f"NIP: {business['tax_id']}",
        f"Konto bankowe: {business['bank_account']}",
        "",
        "=== Nabywca ===",
    ]

    client = invoice.get("client", {})
    if client:
        lines.extend(
            [
                f"Nazwa: {client.get('name', '')}",
                f"Adres: {client.get('address', '')}",
                f"NIP: {client.get('tax_id', '') or '---'}",
            ]
        )
    else:
        lines.append("Brak danych klienta (pole opcjonalne).")

    lines.extend(
        [
            "",
            "=== Pozycja ===",
            f"Opis: {invoice['item_description']}",
            f"Ilosc: {invoice['quantity']}",
            f"Cena jednostkowa: {invoice['unit_price']:.2f} PLN",
            f"Wartosc netto: {invoice['net_total']:.2f} PLN",
        ]
    )
    return "\n".join(lines)


def create_invoice(data):
    print("\n=== Wystaw fakture ===")
    description = prompt_non_empty("Opis uslugi / towaru: ")
    quantity = prompt_positive_float("Ilosc: ")
    unit_price = prompt_positive_float("Cena jednostkowa (PLN): ")
    client = prompt_client_details()

    issued_at = datetime.now().strftime("%Y-%m-%d %H:%M")
    invoice_id = datetime.now().strftime("FV-%Y%m%d-%H%M%S")
    net_total = quantity * unit_price

    invoice = {
        "invoice_id": invoice_id,
        "issued_at": issued_at,
        "item_description": description,
        "quantity": quantity,
        "unit_price": unit_price,
        "net_total": net_total,
        "client": client,
    }

    os.makedirs(INVOICE_FOLDER, exist_ok=True)
    invoice_path = os.path.join(INVOICE_FOLDER, f"{invoice_id}.txt")
    with open(invoice_path, "w", encoding="utf-8") as handle:
        handle.write(format_invoice_text(invoice_id, data["business"], invoice))

    data["invoices"].append(invoice)
    save_data(data)

    print(f"\nFaktura zapisana do {invoice_path}")
    print(f"Suma do zaplaty: {net_total:.2f} PLN")


def main():
    data = load_data()
    if data is None:
        run_setup()
        return

    print("=== Logowanie ===")
    if not authenticate(data):
        print("Zbyt wiele nieudanych prob logowania. Zakonczono.")
        return

    create_invoice(data)


if __name__ == "__main__":
    main()