"""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)
    email = forms.EmailField(label='Sähköposti', max_length=100)
    amount = forms.DecimalField(label='Yhteensä', decimal_places=2)

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