# SPDX-License-Identifier: AGPL-3.0-or-later

import pwd
import re

from django import forms
from django.contrib import auth, messages
from django.contrib.auth.forms import SetPasswordForm, UserCreationForm
from django.contrib.auth.hashers import check_password
from django.contrib.auth.models import Group, User
from django.core import validators
from django.core.exceptions import ValidationError
from django.utils.deconstruct import deconstructible
from django.utils.translation import ugettext as _
from django.utils.translation import ugettext_lazy

import plinth.forms
from plinth import actions
from plinth.errors import ActionError
from plinth.modules import first_boot
from plinth.modules.security import set_restricted_access
from plinth.translation import set_language
from plinth.utils import is_user_admin

from . import get_last_admin_user
from .components import UsersAndGroups


class ValidNewUsernameCheckMixin:
    """Mixin to check if a username is valid for created new user."""

    def clean_username(self):
        """Check for username collisions with system users."""
        username = self.cleaned_data['username']
        if self.instance.username != username and \
                not self.is_valid_new_username():
            raise ValidationError(_('Username is taken or is reserved.'),
                                  code='invalid')

        return username

    def is_valid_new_username(self):
        """Check for username collisions with system users."""
        username = self.cleaned_data['username']
        existing_users = (a.pw_name.lower() for a in pwd.getpwall())
        if username.lower() in existing_users:
            return False

        if UsersAndGroups.is_username_reserved(username.lower()):
            return False

        return True


@deconstructible
class UsernameValidator(validators.RegexValidator):
    """Username validator.

    Compared to django builtin ASCIIUsernameValidator, do not allow
    '+' characters and no '-' character at the beginning.

    """
    regex = r'^[\w.@][\w.@-]+\Z'
    message = ugettext_lazy('Enter a valid username.')
    flags = re.ASCII


USERNAME_FIELD = forms.CharField(
    label=ugettext_lazy('Username'), max_length=150,
    validators=[UsernameValidator()],
    help_text=ugettext_lazy('Required. 150 characters or fewer. English '
                            'letters, digits and @/./-/_ only.'))


class PasswordConfirmForm(forms.Form):
    """Password confirmation form."""
    confirm_password = forms.CharField(
        widget=forms.PasswordInput,
        label=ugettext_lazy('Authorization Password'), help_text=ugettext_lazy(
            'Enter your current password to authorize account modifications.'))

    def clean_confirm_password(self):
        """Check that current user's password matches."""
        confirm_password = self.cleaned_data['confirm_password']
        password_matches = check_password(confirm_password,
                                          self.request.user.password)
        if not password_matches:
            raise ValidationError(_('Invalid password.'), code='invalid')

        return confirm_password


class CreateUserForm(ValidNewUsernameCheckMixin,
                     plinth.forms.LanguageSelectionFormMixin,
                     PasswordConfirmForm, UserCreationForm):
    """Custom user create form.

    Include options to add user to groups.
    """
    username = USERNAME_FIELD
    groups = forms.MultipleChoiceField(
        choices=UsersAndGroups.get_group_choices,
        label=ugettext_lazy('Permissions'), required=False,
        widget=forms.CheckboxSelectMultiple, help_text=ugettext_lazy(
            'Select which services should be available to the new '
            'user. The user will be able to log in to services that '
            'support single sign-on through LDAP, if they are in the '
            'appropriate group.<br /><br />Users in the admin group '
            'will be able to log in to all services. They can also '
            'log in to the system through SSH and have '
            'administrative privileges (sudo).'))

    language = plinth.forms.LanguageSelectionFormMixin.language

    class Meta(UserCreationForm.Meta):
        """Metadata to control automatic form building."""
        fields = ('username', 'password1', 'password2', 'groups', 'language',
                  'confirm_password')

    def __init__(self, request, *args, **kwargs):
        """Initialize the form with extra request argument."""
        self.request = request
        super(CreateUserForm, self).__init__(*args, **kwargs)
        self.fields['username'].widget.attrs.update({
            'autofocus': 'autofocus',
            'autocapitalize': 'none',
            'autocomplete': 'username',
        })

    def save(self, commit=True):
        """Save the user model and create LDAP user if required."""
        user = super(CreateUserForm, self).save(commit)

        if commit:
            user.userprofile.language = self.cleaned_data['language']
            user.userprofile.save()
            auth_username = self.request.user.username
            confirm_password = self.cleaned_data['confirm_password']

            process_input = '{0}\n{1}'.format(self.cleaned_data['password1'],
                                              confirm_password).encode()
            try:
                actions.superuser_run('users', [
                    'create-user',
                    user.get_username(), '--auth-user', auth_username
                ], input=process_input)
            except ActionError as error:
                messages.error(
                    self.request,
                    _('Creating LDAP user failed: {error}'.format(
                        error=error)))

            for group in self.cleaned_data['groups']:
                try:
                    actions.superuser_run('users', [
                        'add-user-to-group',
                        user.get_username(), group, '--auth-user',
                        auth_username
                    ], input=confirm_password.encode())
                except ActionError as error:
                    messages.error(
                        self.request,
                        _('Failed to add new user to {group} group: {error}').
                        format(group=group, error=error))

                group_object, created = Group.objects.get_or_create(name=group)
                group_object.user_set.add(user)

        return user


class UserUpdateForm(ValidNewUsernameCheckMixin, PasswordConfirmForm,
                     plinth.forms.LanguageSelectionFormMixin, forms.ModelForm):
    """When user info is changed, also updates LDAP user."""
    username = USERNAME_FIELD
    ssh_keys = forms.CharField(
        label=ugettext_lazy('Authorized SSH Keys'), required=False,
        widget=forms.Textarea, help_text=ugettext_lazy(
            'Setting an SSH public key will allow this user to '
            'securely log in to the system without using a '
            'password. You may enter multiple keys, one on each '
            'line. Blank lines and lines starting with # will be '
            'ignored.'))

    language = plinth.forms.LanguageSelectionFormMixin.language

    class Meta:
        """Metadata to control automatic form building."""
        fields = ('username', 'groups', 'ssh_keys', 'language', 'is_active',
                  'confirm_password')
        model = User
        widgets = {
            'groups': plinth.forms.CheckboxSelectMultipleWithReadOnly(),
        }

    def __init__(self, request, username, *args, **kwargs):
        """Initialize the form with extra request argument."""
        group_choices = dict(UsersAndGroups.get_group_choices())
        for group in group_choices:
            Group.objects.get_or_create(name=group)

        self.request = request
        self.username = username
        super(UserUpdateForm, self).__init__(*args, **kwargs)
        self.is_last_admin_user = get_last_admin_user() == self.username
        self.fields['username'].widget.attrs.update({
            'autofocus': 'autofocus',
            'autocapitalize': 'none',
            'autocomplete': 'username'
        })

        choices = []

        for c in sorted(self.fields['groups'].choices, key=lambda x: x[1]):
            # Handle case where groups exist in database for
            # applications not installed yet.
            if c[1] in group_choices:
                # Replace group names with descriptions
                if c[1] == 'admin' and self.is_last_admin_user:
                    choices.append((c[0], {
                        'label': group_choices[c[1]],
                        'readonly': True
                    }))
                else:
                    choices.append((c[0], group_choices[c[1]]))

        self.fields['groups'].label = _('Permissions')
        self.fields['groups'].choices = choices

        if not is_user_admin(request):
            self.fields['is_active'].widget = forms.HiddenInput()
            self.fields['groups'].disabled = True

        if self.is_last_admin_user:
            self.fields['is_active'].disabled = True

    def save(self, commit=True):
        """Update LDAP user name and groups after saving user model."""
        user = super(UserUpdateForm, self).save(commit=False)
        # Profile is auto saved with user object
        user.userprofile.language = self.cleaned_data['language']
        auth_username = self.request.user.username
        confirm_password = self.cleaned_data['confirm_password']

        # If user is updating their own profile then only translate the pages
        if self.username == auth_username:
            set_language(self.request, None, user.userprofile.language)

        if commit:
            user.save()
            self.save_m2m()

            output = actions.superuser_run('users',
                                           ['get-user-groups', self.username])
            old_groups = output.strip().split('\n')
            old_groups = [group for group in old_groups if group]

            if self.username != user.get_username():
                try:
                    actions.superuser_run(
                        'users',
                        ['rename-user', self.username,
                         user.get_username()])
                except ActionError:
                    messages.error(self.request,
                                   _('Renaming LDAP user failed.'))

            new_groups = user.groups.values_list('name', flat=True)
            for old_group in old_groups:
                if old_group not in new_groups:
                    try:
                        actions.superuser_run('users', [
                            'remove-user-from-group',
                            user.get_username(), old_group, '--auth-user',
                            auth_username
                        ], input=confirm_password.encode())
                    except ActionError:
                        messages.error(self.request,
                                       _('Failed to remove user from group.'))

            for new_group in new_groups:
                if new_group not in old_groups:
                    try:
                        actions.superuser_run('users', [
                            'add-user-to-group',
                            user.get_username(), new_group, '--auth-user',
                            auth_username
                        ], input=confirm_password.encode())
                    except ActionError:
                        messages.error(self.request,
                                       _('Failed to add user to group.'))

            try:
                actions.superuser_run('ssh', [
                    'set-keys',
                    '--username',
                    user.get_username(),
                    '--keys',
                    self.cleaned_data['ssh_keys'].strip(),
                    '--auth-user',
                    auth_username,
                ], input=confirm_password.encode())
            except ActionError:
                messages.error(self.request, _('Unable to set SSH keys.'))

            is_active = self.cleaned_data['is_active']
            if self.initial['is_active'] != is_active:
                if is_active:
                    status = 'active'
                else:
                    status = 'inactive'
                try:
                    actions.superuser_run('users', [
                        'set-user-status',
                        user.get_username(),
                        status,
                        '--auth-user',
                        auth_username,
                    ], input=confirm_password.encode())
                except ActionError:
                    messages.error(self.request,
                                   _('Failed to change user status.'))

        return user

    def validate_last_admin_user(self, groups):
        group_names = [group.name for group in groups]
        if 'admin' not in group_names:
            raise ValidationError(
                _('Cannot delete the only administrator in the system.'))

    def clean(self):
        """Override clean to add form validation logic."""
        cleaned_data = super().clean()
        if self.is_last_admin_user:
            self.validate_last_admin_user(cleaned_data.get("groups"))
        return cleaned_data


class UserChangePasswordForm(PasswordConfirmForm, SetPasswordForm):
    """Custom form that also updates password for LDAP users."""

    def __init__(self, request, *args, **kwargs):
        """Initialize the form with extra request argument."""
        self.request = request
        super(UserChangePasswordForm, self).__init__(*args, **kwargs)
        self.fields['new_password1'].widget.attrs.update(
            {'autofocus': 'autofocus'})

    def save(self, commit=True):
        """Save the user model and change LDAP password as well."""
        user = super(UserChangePasswordForm, self).save(commit)
        auth_username = self.request.user.username
        if commit:
            process_input = '{0}\n{1}'.format(
                self.cleaned_data['new_password1'],
                self.cleaned_data['confirm_password']).encode()
            try:
                actions.superuser_run('users', [
                    'set-user-password',
                    user.get_username(), '--auth-user', auth_username
                ], input=process_input)
            except ActionError:
                messages.error(self.request,
                               _('Changing LDAP user password failed.'))

        return user


class FirstBootForm(ValidNewUsernameCheckMixin, auth.forms.UserCreationForm):
    """User module first boot step: create a new admin user."""
    username = USERNAME_FIELD

    def __init__(self, *args, **kwargs):
        self.request = kwargs.pop('request')
        super().__init__(*args, **kwargs)
        self.fields['username'].widget.attrs.update({'autofocus': 'autofocus'})

    def save(self, commit=True):
        """Create and log the user in."""
        user = super().save(commit=commit)
        if commit:
            first_boot.mark_step_done('users_firstboot')

            try:
                actions.superuser_run(
                    'users',
                    ['create-user',
                     user.get_username(), '--auth-user', ''],
                    input=self.cleaned_data['password1'].encode())
            except ActionError as error:
                messages.error(
                    self.request,
                    _('Creating LDAP user failed: {error}'.format(
                        error=error)))

            try:
                actions.superuser_run(
                    'users',
                    ['add-user-to-group',
                     user.get_username(), 'admin'])
            except ActionError as error:
                messages.error(
                    self.request,
                    _('Failed to add new user to admin group: {error}'.format(
                        error=error)))

            # Create initial Django groups
            for group_choice in UsersAndGroups.get_group_choices():
                auth.models.Group.objects.get_or_create(name=group_choice[0])

            admin_group = auth.models.Group.objects.get(name='admin')
            admin_group.user_set.add(user)

            self.login_user(self.cleaned_data['username'],
                            self.cleaned_data['password1'])

            # Restrict console login to users in admin or sudo group
            try:
                set_restricted_access(True)
            except Exception as error:
                messages.error(
                    self.request,
                    _('Failed to restrict console access: {error}'.format(
                        error=error)))

        return user

    def login_user(self, username, password):
        """Try to login the user with the credentials provided"""
        try:
            user = auth.authenticate(username=username, password=password)
            auth.login(self.request, user)
        except Exception:
            pass
        else:
            message = _('User account created, you are now logged in')
            messages.success(self.request, message)
