"""Expenses claim form."""

from django import forms
from string import ascii_uppercase


class ExpensesClaim(forms.Form):
    """Expenses claim form"""

    name = forms.CharField(label='Nimi', max_length=100)
    iban = forms.CharField(label='IBAN', max_length=100)
    amount = forms.DecimalField(label="Summa", decimal_places=2)

    def clean_iban(self):
        """Validate IBAN."""
        data = self.cleaned_data['iban']
        # Remove spaces.
        data = data.replace(" ", "")
        # Move first 4 symbols to the end of the string.
        data = data[4:] + data[0:4]
        LETTERS = {letter: str(index) for index,
                   letter in enumerate(ascii_uppercase, start=10)}
        data = data.upper()
        # Replace all letters with numbers, so that A=10, B=11, ..., Z=35.
        data = [LETTERS[char] if char in LETTERS else char for char in data]
        data = ''.join(data)
        # If data modulo 97 != 1 the IBAN number is invalid.
        if int(data) % 97 != 1:
            raise forms.ValidationError("Invalid IBAN number!")
        return data