from django.core import validators
from django.db import backend, connection, models
from django.contrib.contenttypes.models import ContentType
from django.utils.translation import gettext_lazy as _
import datetime

SESSION_KEY = '_auth_user_id'

class SiteProfileNotAvailable(Exception):
    pass

class Permission(models.Model):
    name = models.CharField(_('name'), maxlength=50)
    content_type = models.ForeignKey(ContentType)
    codename = models.CharField(_('codename'), maxlength=100)
    class Meta:
        verbose_name = _('permission')
        verbose_name_plural = _('permissions')
        unique_together = (('content_type', 'codename'),)
        ordering = ('content_type', 'codename')

    def __str__(self):
        return "%s | %s" % (self.content_type, self.name)

class Group(models.Model):
    name = models.CharField(_('name'), maxlength=80, unique=True)
    permissions = models.ManyToManyField(Permission, verbose_name=_('permissions'), blank=True, filter_interface=models.HORIZONTAL)
    class Meta:
        verbose_name = _('group')
        verbose_name_plural = _('groups')
        ordering = ('name',)
    class Admin:
        search_fields = ('name',)

    def __str__(self):
        return self.name

class UserManager(models.Manager):
    def create_user(self, username, email, password):
        "Creates and saves a User with the given username, e-mail and password."
        now = datetime.datetime.now()
        user = self.model(None, username, '', '', email.strip().lower(), 'placeholder', False, True, False, now, now)
        user.set_password(password)
        user.save()
        return user

    def make_random_password(self, length=10, allowed_chars='abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789'):
        "Generates a random password with the given length and given allowed_chars"
        # Note that default value of allowed_chars does not have "I" or letters
        # that look like it -- just to avoid confusion.
        from random import choice
        return ''.join([choice(allowed_chars) for i in range(length)])

class User(models.Model):
    username = models.CharField(_('username'), maxlength=30, unique=True, validator_list=[validators.isAlphaNumeric])
    first_name = models.CharField(_('first name'), maxlength=30, blank=True)
    last_name = models.CharField(_('last name'), maxlength=30, blank=True)
    email = models.EmailField(_('e-mail address'), blank=True)
    password = models.CharField(_('password'), maxlength=128, help_text=_("Use '[algo]$[salt]$[hexdigest]'"))
    is_staff = models.BooleanField(_('staff status'), help_text=_("Designates whether the user can log into this admin site."))
    is_active = models.BooleanField(_('active'), default=True)
    is_superuser = models.BooleanField(_('superuser status'))
    last_login = models.DateTimeField(_('last login'), default=models.LazyDate())
    date_joined = models.DateTimeField(_('date joined'), default=models.LazyDate())
    groups = models.ManyToManyField(Group, verbose_name=_('groups'), blank=True,
        help_text=_("In addition to the permissions manually assigned, this user will also get all permissions granted to each group he/she is in."))
    user_permissions = models.ManyToManyField(Permission, verbose_name=_('user permissions'), blank=True, filter_interface=models.HORIZONTAL)
    objects = UserManager()
    class Meta:
        verbose_name = _('user')
        verbose_name_plural = _('users')
        ordering = ('username',)
    class Admin:
        fields = (
            (None, {'fields': ('username', 'password')}),
            (_('Personal info'), {'fields': ('first_name', 'last_name', 'email')}),
            (_('Permissions'), {'fields': ('is_staff', 'is_active', 'is_superuser', 'user_permissions')}),
            (_('Important dates'), {'fields': ('last_login', 'date_joined')}),
            (_('Groups'), {'fields': ('groups',)}),
        )
        list_display = ('username', 'email', 'first_name', 'last_name', 'is_staff')
        list_filter = ('is_staff', 'is_superuser')
        search_fields = ('username', 'first_name', 'last_name', 'email')

    def __str__(self):
        return self.username

    def get_absolute_url(self):
        return "/users/%s/" % self.username

    def is_anonymous(self):
        return False

    def get_full_name(self):
        full_name = '%s %s' % (self.first_name, self.last_name)
        return full_name.strip()

    def set_password(self, raw_password):
        import sha, random
        algo = 'sha1'
        salt = sha.new(str(random.random())).hexdigest()[:5]
        hsh = sha.new(salt+raw_password).hexdigest()
        self.password = '%s$%s$%s' % (algo, salt, hsh)

    def check_password(self, raw_password):
        """
        Returns a boolean of whether the raw_password was correct. Handles
        encryption formats behind the scenes.
        """
        # Backwards-compatibility check. Older passwords won't include the
        # algorithm or salt.
        if '$' not in self.password:
            import md5
            is_correct = (self.password == md5.new(raw_password).hexdigest())
            if is_correct:
                # Convert the password to the new, more secure format.
                self.set_password(raw_password)
                self.save()
            return is_correct
        algo, salt, hsh = self.password.split('$')
        if algo == 'md5':
            import md5
            return hsh == md5.new(salt+raw_password).hexdigest()
        elif algo == 'sha1':
            import sha
            return hsh == sha.new(salt+raw_password).hexdigest()
        raise ValueError, "Got unknown password algorithm type in password."

    def get_group_permissions(self):
        "Returns a list of permission strings that this user has through his/her groups."
        if not hasattr(self, '_group_perm_cache'):
            import sets
            cursor = connection.cursor()
            # The SQL below works out to the following, after DB quoting:
            # cursor.execute("""
            #     SELECT ct."app_label", p."codename"
            #     FROM "auth_permission" p, "auth_group_permissions" gp, "auth_user_groups" ug, "django_content_type" ct
            #     WHERE p."id" = gp."permission_id"
            #         AND gp."group_id" = ug."group_id"
            #         AND ct."id" = p."content_type_id"
            #         AND ug."user_id" = %s, [self.id])
            sql = """
                SELECT ct.%s, p.%s
                FROM %s p, %s gp, %s ug, %s ct
                WHERE p.%s = gp.%s
                    AND gp.%s = ug.%s
                    AND ct.%s = p.%s
                    AND ug.%s = %%s""" % (
                backend.quote_name('app_label'), backend.quote_name('codename'),
                backend.quote_name('auth_permission'), backend.quote_name('auth_group_permissions'),
                backend.quote_name('auth_user_groups'), backend.quote_name('django_content_type'),
                backend.quote_name('id'), backend.quote_name('permission_id'),
                backend.quote_name('group_id'), backend.quote_name('group_id'),
                backend.quote_name('id'), backend.quote_name('content_type_id'),
                backend.quote_name('user_id'),)
            cursor.execute(sql, [self.id])
            self._group_perm_cache = sets.Set(["%s.%s" % (row[0], row[1]) for row in cursor.fetchall()])
        return self._group_perm_cache

    def get_all_permissions(self):
        if not hasattr(self, '_perm_cache'):
            import sets
            self._perm_cache = sets.Set(["%s.%s" % (p.content_type.app_label, p.codename) for p in self.user_permissions.all()])
            self._perm_cache.update(self.get_group_permissions())
        return self._perm_cache

    def has_perm(self, perm):
        "Returns True if the user has the specified permission."
        if not self.is_active:
            return False
        if self.is_superuser:
            return True
        return perm in self.get_all_permissions()

    def has_perms(self, perm_list):
        "Returns True if the user has each of the specified permissions."
        for perm in perm_list:
            if not self.has_perm(perm):
                return False
        return True

    def has_module_perms(self, app_label):
        "Returns True if the user has any permissions in the given app label."
        if self.is_superuser:
            return True
        return bool(len([p for p in self.get_all_permissions() if p[:p.index('.')] == app_label]))

    def get_and_delete_messages(self):
        messages = []
        for m in self.message_set.all():
            messages.append(m.message)
            m.delete()
        return messages

    def email_user(self, subject, message, from_email=None):
        "Sends an e-mail to this User."
        from django.core.mail import send_mail
        send_mail(subject, message, from_email, [self.email])

    def get_profile(self):
        """
        Returns site-specific profile for this user. Raises
        SiteProfileNotAvailable if this site does not allow profiles.
        """
        if not hasattr(self, '_profile_cache'):
            from django.conf import settings
            if not settings.AUTH_PROFILE_MODULE:
                raise SiteProfileNotAvailable
            try:
                app_label, model_name = settings.AUTH_PROFILE_MODULE.split('.')
                model = models.get_model(app_label, model_name)
                self._profile_cache = model._default_manager.get(user__id__exact=self.id)
            except ImportError, ImproperlyConfigured:
                raise SiteProfileNotAvailable
        return self._profile_cache

class Message(models.Model):
    user = models.ForeignKey(User)
    message = models.TextField(_('message'))

    def __str__(self):
        return self.message

class AnonymousUser(object):
    id = None
    username = ''

    def __init__(self):
        pass

    def __str__(self):
        return 'AnonymousUser'

    def save(self):
        raise NotImplementedError

    def delete(self):
        raise NotImplementedError

    def set_password(self, raw_password):
        raise NotImplementedError

    def check_password(self, raw_password):
        raise NotImplementedError

    def _get_groups(self):
        raise NotImplementedError
    groups = property(_get_groups)

    def _get_user_permissions(self):
        raise NotImplementedError
    user_permissions = property(_get_user_permissions)

    def has_perm(self, perm):
        return False

    def has_module_perms(self, module):
        return False

    def get_and_delete_messages(self):
        return []

    def is_anonymous(self):
        return True