import ipaddress
import re

import pyotp
from argon2 import PasswordHasher
from crispy_forms.bootstrap import PrependedText
from crispy_forms.helper import FormHelper
from crispy_forms.layout import Layout, Submit, HTML, Div
from django import forms
from django.utils.translation import gettext_lazy as _

from gatekeeper.models import GatekeeperUser, GatekeeperGroup, AuthMethod, AuthMethodAllowedDomain, \
    AuthMethodAllowedEmail, GatekeeperIPAddress


class GatekeeperUserForm(forms.ModelForm):
    password = forms.CharField(
        label=_('Password'),
        required=False,
        widget=forms.PasswordInput(render_value=False),
        help_text=_('Minimum 8 characters, with at least one uppercase letter, one lowercase letter, and one number.'),
    )
    password_confirm = forms.CharField(
        label=_('Confirm Password'),
        required=False,
        widget=forms.PasswordInput(render_value=False),
    )
    totp_pin = forms.CharField(
        label=_('TOTP Validation PIN'),
        max_length=6,
        required=False,
        help_text=_('Enter a 6-digit PIN generated by your authenticator app to validate the secret.'),
    )

    class Meta:
        model = GatekeeperUser
        fields = ['username', 'email', 'totp_secret']
        labels = {
            'username': _('Username'),
            'email': _('Email'),
            'totp_secret': _('TOTP Secret'),
        }

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)

        is_edit = bool(self.instance and self.instance.pk)
        self.fields['password'].required = not is_edit
        self.fields['password_confirm'].required = not is_edit

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('username', css_class='col-xl-6'),
                Div('email', css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div('password', css_class='col-xl-6'),
                Div('password_confirm', css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div('totp_secret', css_class='col-xl-6'),
                Div('totp_pin', css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )

    def clean(self):
        cleaned_data = super().clean()
        password = cleaned_data.get('password')
        password_confirm = cleaned_data.get('password_confirm')
        totp_secret = cleaned_data.get('totp_secret')
        is_new = not (self.instance and self.instance.pk)

        if password or is_new:
            if not password:
                self.add_error('password', _('Password is required.'))
            else:
                if len(password) < 8:
                    self.add_error('password', _('Password must be at least 8 characters long.'))
                elif not re.search(r'[a-z]', password):
                    self.add_error('password', _('Password must contain at least one lowercase letter.'))
                elif not re.search(r'[A-Z]', password):
                    self.add_error('password', _('Password must contain at least one uppercase letter.'))
                elif not re.search(r'[0-9]', password):
                    self.add_error('password', _('Password must contain at least one number.'))
                elif password != password_confirm:
                    self.add_error('password_confirm', _('Passwords do not match.'))

        if totp_secret:
            totp_pin = cleaned_data.get('totp_pin')
            if not totp_pin:
                self.add_error('totp_pin', _('Please provide a PIN to validate the TOTP secret.'))
            else:
                try:
                    totp = pyotp.TOTP(totp_secret)
                    if not totp.verify(totp_pin):
                        self.add_error('totp_pin', _('Invalid TOTP PIN.'))
                except Exception:
                    self.add_error('totp_secret', _('Invalid TOTP secret format. Must be a valid Base32 string.'))

        return cleaned_data

    def save(self, commit=True):
        user = super().save(commit=False)
        password = self.cleaned_data.get('password')
        if password:
            ph = PasswordHasher()
            user.password = ph.hash(password)
        if commit:
            user.save()
        return user


class GatekeeperGroupForm(forms.ModelForm):
    class Meta:
        model = GatekeeperGroup
        fields = ['display_name', 'users']
        labels = {
            'display_name': _('Group Name'),
            'users': _('Members'),
        }

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)
        self.fields['display_name'].required = True

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('display_name', css_class='col-xl-12'),
                css_class='row'
            ),
            Div(
                Div('users', css_class='col-xl-12'),
                css_class='row'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )


class AuthMethodForm(forms.ModelForm):
    totp_pin = forms.CharField(
        label=_('TOTP Validation PIN'),
        max_length=6,
        required=False,
        help_text=_('Enter a 6-digit PIN generated by your authenticator app to validate the secret.')
    )
    session_expiration_value = forms.IntegerField(
        label=_('Session Expiration'),
        min_value=1,
        required=False,
        initial=12,
    )
    session_expiration_unit = forms.ChoiceField(
        label=_('Unit'),
        choices=[('hours', _('Hour(s)')), ('days', _('Day(s)'))],
        required=False,
        initial='hours',
    )

    class Meta:
        model = AuthMethod
        fields = [
            'display_name', 'auth_type', 'totp_secret',
            'oidc_provider', 'oidc_client_id', 'oidc_client_secret'
        ]
        labels = {
            'display_name': _('Name'),
            'auth_type': _('Authentication Type'),
            'totp_secret': _('Global TOTP Secret'),
            'oidc_provider': _('OIDC Provider URL'),
            'oidc_client_id': _('OIDC Client ID'),
            'oidc_client_secret': _('OIDC Client Secret'),
        }

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)

        self.fields['display_name'].required = True
        if self.instance and self.instance.pk:
            self.fields['auth_type'].disabled = True
            exp_min = self.instance.session_expiration_minutes
            if exp_min % 1440 == 0:
                self.initial['session_expiration_value'] = exp_min // 1440
                self.initial['session_expiration_unit'] = 'days'
            else:
                self.initial['session_expiration_value'] = max(1, round(exp_min / 60))
                self.initial['session_expiration_unit'] = 'hours'

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('display_name', css_class='col-xl-6'),
                Div('auth_type', css_class='col-xl-6'),
                css_class='row auth-type-group'
            ),
            Div(
                Div('totp_secret', css_class='col-xl-6'),
                Div('totp_pin', css_class='col-xl-6'),
                css_class='row totp-group'
            ),
            Div(
                Div('oidc_provider', css_class='col-xl-12'),
                css_class='row oidc-group'
            ),
            Div(
                Div('oidc_client_id', css_class='col-xl-6'),
                Div('oidc_client_secret', css_class='col-xl-6'),
                css_class='row oidc-group'
            ),
            Div(
                Div('session_expiration_value', css_class='col-xl-6'),
                Div('session_expiration_unit', css_class='col-xl-6'),
                css_class='row expiration-group'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )

    def clean(self):
        cleaned_data = super().clean()
        auth_type = cleaned_data.get('auth_type')
        totp_secret = cleaned_data.get('totp_secret')
        oidc_provider = cleaned_data.get('oidc_provider')
        oidc_client_id = cleaned_data.get('oidc_client_id')
        oidc_client_secret = cleaned_data.get('oidc_client_secret')

        if auth_type == 'local_password':
            if totp_secret:
                self.add_error('totp_secret', _('TOTP secret must be empty for Local Password authentication.'))
            if cleaned_data.get('totp_pin'):
                self.add_error('totp_pin', _('TOTP validation PIN must be empty for Local Password authentication.'))
            if oidc_provider or oidc_client_id or oidc_client_secret:
                self.add_error(None, _('OIDC fields must be empty for Local Password authentication.'))

            existing_local = AuthMethod.objects.filter(auth_type='local_password')
            if self.instance and self.instance.pk:
                existing_local = existing_local.exclude(pk=self.instance.pk)
            if existing_local.exists():
                self.add_error('auth_type', _('Only one Local Password authentication method can be configured.'))
        elif auth_type == 'totp':
            if oidc_provider or oidc_client_id or oidc_client_secret:
                self.add_error(None, _('OIDC fields must be empty for TOTP authentication.'))
            if not totp_secret:
                self.add_error('totp_secret', _('TOTP secret is required for TOTP authentication.'))
            else:
                totp_pin = cleaned_data.get('totp_pin')
                if not totp_pin:
                    self.add_error('totp_pin', _('Please provide a PIN to validate the TOTP secret.'))
                else:
                    try:
                        totp = pyotp.TOTP(totp_secret)
                        if not totp.verify(totp_pin):
                            self.add_error('totp_pin', _('Invalid TOTP PIN.'))
                    except Exception:
                        self.add_error('totp_secret', _('Invalid TOTP secret format. Must be a valid Base32 string.'))
        elif auth_type == 'oidc':
            self.add_error('auth_type', _('OIDC authentication is temporarily unavailable and will be available soon.'))
            if totp_secret:
                self.add_error('totp_secret', _('TOTP secret must be empty for OIDC authentication.'))
            if cleaned_data.get('totp_pin'):
                self.add_error('totp_pin', _('TOTP validation PIN must be empty for OIDC authentication.'))

        if auth_type in ('local_password', 'oidc'):
            value = cleaned_data.get('session_expiration_value') or 12
            unit = cleaned_data.get('session_expiration_unit') or 'hours'
            if unit == 'days':
                cleaned_data['_session_expiration_minutes'] = value * 1440
            else:
                cleaned_data['_session_expiration_minutes'] = value * 60

        return cleaned_data

    def save(self, commit=True):
        instance = super().save(commit=False)
        if instance.auth_type in ('local_password', 'oidc'):
            instance.session_expiration_minutes = self.cleaned_data.get('_session_expiration_minutes', 720)
        if commit:
            instance.save()
        return instance

class GatekeeperIPAddressForm(forms.ModelForm):
    class Meta:
        model = GatekeeperIPAddress
        fields = ['auth_method', 'address', 'prefix_length', 'action', 'description']
        labels = {
            'auth_method': _('Authentication Method'),
            'address': _('IP Address'),
            'prefix_length': _('Prefix Length'),
            'action': _('Action'),
            'description': _('Description'),
        }

    def clean(self):
        cleaned_data = super().clean()
        address = cleaned_data.get('address')
        prefix_length = cleaned_data.get('prefix_length')
        if address and prefix_length is not None:
            try:
                ip = ipaddress.ip_address(address)
                max_prefix = 32 if ip.version == 4 else 128
                if prefix_length > max_prefix:
                    self.add_error(
                        'prefix_length',
                        _('Prefix length for IPv%(version)d must be between 0 and %(max)d.') % {
                            'version': ip.version, 'max': max_prefix,
                        },
                    )
            except ValueError:
                pass  # address field validation handles invalid IPs
        return cleaned_data

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('auth_method', css_class='col-xl-12'),
                css_class='row'
            ),
            Div(
                Div('address', css_class='col-xl-6'),
                Div(PrependedText('prefix_length', '/'), css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div('action', css_class='col-xl-4'),
                Div('description', css_class='col-xl-8'),
                css_class='row'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )

class AuthMethodAllowedDomainForm(forms.ModelForm):
    class Meta:
        model = AuthMethodAllowedDomain
        fields = ['auth_method', 'domain']
        labels = {
            'auth_method': _('Authentication Method'),
            'domain': _('Domain'),
        }

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('auth_method', css_class='col-xl-6'),
                Div(PrependedText('domain', '@'), css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )


class AuthMethodAllowedEmailForm(forms.ModelForm):
    class Meta:
        model = AuthMethodAllowedEmail
        fields = ['auth_method', 'email']
        labels = {
            'auth_method': _('Authentication Method'),
            'email': _('Email'),
        }

    def __init__(self, *args, **kwargs):
        cancel_url = kwargs.pop('cancel_url', '#')
        super().__init__(*args, **kwargs)

        self.helper = FormHelper()
        self.helper.layout = Layout(
            Div(
                Div('auth_method', css_class='col-xl-6'),
                Div('email', css_class='col-xl-6'),
                css_class='row'
            ),
            Div(
                Div(
                    Submit('submit', _('Save'), css_class='btn btn-primary'),
                    HTML(f'<a href="{cancel_url}" class="btn btn-secondary">{_("Cancel")}</a>'),
                    css_class='col-xl-12'
                ),
                css_class='row'
            )
        )