from django.core.exceptions import ObjectDoesNotExist

from django.db import models

from django.utils.html import escape

from django.utils.safestring import mark_safe

from django.utils.text import capfirst

from django.utils.encoding import force_unicode

from django.utils.translation import ungettext, ugettext as _

from django.core.urlresolvers import reverse, NoReverseMatch

def quote(s):

    """

    Ensure that primary key values do not confuse the admin URLs by escaping

    any '/', '_' and ':' characters. Similar to urllib.quote, except that the

    quoting is slightly different so that it doesn't get automatically

    unquoted by the Web browser.

    """

    if not isinstance(s, basestring):

        return s

    res = list(s)

    for i in range(len(res)):

        c = res[i]

        if c in """:/_#?;@&=+$,"<>%\\""":

            res[i] = '_%02X' % ord(c)

    return ''.join(res)

def unquote(s):

    """

    Undo the effects of quote(). Based heavily on urllib.unquote().

    """

    mychr = chr

    myatoi = int

    list = s.split('_')

    res = [list[0]]

    myappend = res.append

    del list[0]

    for item in list:

        if item[1:2]:

            try:

                myappend(mychr(myatoi(item[:2], 16)) + item[2:])

            except ValueError:

                myappend('_' + item)

        else:

            myappend('_' + item)

    return "".join(res)

def flatten_fieldsets(fieldsets):

    """Returns a list of field names from an admin fieldsets structure."""

    field_names = []

    for name, opts in fieldsets:

        for field in opts['fields']:

            # type checking feels dirty, but it seems like the best way here

            if type(field) == tuple:

                field_names.extend(field)

            else:

                field_names.append(field)

    return field_names

def _nest_help(obj, depth, val):

    current = obj

    for i in range(depth):

        current = current[-1]

    current.append(val)

def get_change_view_url(app_label, module_name, pk, admin_site, levels_to_root):

    """

    Returns the url to the admin change view for the given app_label,

    module_name and primary key.

    """

    try:

        return reverse('%sadmin_%s_%s_change' % (admin_site.name, app_label, module_name), None, (pk,))

    except NoReverseMatch:

        return '%s%s/%s/%s/' % ('../'*levels_to_root, app_label, module_name, pk)

def get_deleted_objects(deleted_objects, perms_needed, user, obj, opts, current_depth, admin_site, levels_to_root=4):

    """

    Helper function that recursively populates deleted_objects.

    `levels_to_root` defines the number of directories (../) to reach the

    admin root path. In a change_view this is 4, in a change_list view 2.

    This is for backwards compatibility since the options.delete_selected

    method uses this function also from a change_list view.

    This will not be used if we can reverse the URL.

    """

    nh = _nest_help # Bind to local variable for performance

    if current_depth > 16:

        return # Avoid recursing too deep.

    opts_seen = []

    for related in opts.get_all_related_objects():

        has_admin = related.model in admin_site._registry

        if related.opts in opts_seen:

            continue

        opts_seen.append(related.opts)

        rel_opts_name = related.get_accessor_name()

        if isinstance(related.field.rel, models.OneToOneRel):

            try:

                sub_obj = getattr(obj, rel_opts_name)

            except ObjectDoesNotExist:

                pass

            else:

                if has_admin:

                    p = '%s.%s' % (related.opts.app_label, related.opts.get_delete_permission())

                    if not user.has_perm(p):

                        perms_needed.add(related.opts.verbose_name)

                        # We don't care about populating deleted_objects now.

                        continue

                if not has_admin:

                    # Don't display link to edit, because it either has no

                    # admin or is edited inline.

                    nh(deleted_objects, current_depth,

                        [u'%s: %s' % (capfirst(related.opts.verbose_name), force_unicode(sub_obj)), []])

                else:

                    # Display a link to the admin page.

                    nh(deleted_objects, current_depth, [mark_safe(u'%s: <a href="%s">%s</a>' %

                        (escape(capfirst(related.opts.verbose_name)),

                        get_change_view_url(related.opts.app_label,

                                            related.opts.object_name.lower(),

                                            sub_obj._get_pk_val(),

                                            admin_site,

                                            levels_to_root),

                        escape(sub_obj))), []])

                get_deleted_objects(deleted_objects, perms_needed, user, sub_obj, related.opts, current_depth+2, admin_site)

        else:

            has_related_objs = False

            for sub_obj in getattr(obj, rel_opts_name).all():

                has_related_objs = True

                if not has_admin:

                    # Don't display link to edit, because it either has no

                    # admin or is edited inline.

                    nh(deleted_objects, current_depth,

                        [u'%s: %s' % (capfirst(related.opts.verbose_name), force_unicode(sub_obj)), []])

                else:

                    # Display a link to the admin page.

                    nh(deleted_objects, current_depth, [mark_safe(u'%s: <a href="%s">%s</a>' %

                        (escape(capfirst(related.opts.verbose_name)),

                        get_change_view_url(related.opts.app_label,

                                            related.opts.object_name.lower(),

                                            sub_obj._get_pk_val(),

                                            admin_site,

                                            levels_to_root),

                        escape(sub_obj))), []])

                get_deleted_objects(deleted_objects, perms_needed, user, sub_obj, related.opts, current_depth+2, admin_site)

            # If there were related objects, and the user doesn't have

            # permission to delete them, add the missing perm to perms_needed.

            if has_admin and has_related_objs:

                p = '%s.%s' % (related.opts.app_label, related.opts.get_delete_permission())

                if not user.has_perm(p):

                    perms_needed.add(related.opts.verbose_name)

    for related in opts.get_all_related_many_to_many_objects():

        has_admin = related.model in admin_site._registry

        if related.opts in opts_seen:

            continue

        opts_seen.append(related.opts)

        rel_opts_name = related.get_accessor_name()

        has_related_objs = False

        # related.get_accessor_name() could return None for symmetrical relationships

        if rel_opts_name:

            rel_objs = getattr(obj, rel_opts_name, None)

            if rel_objs:

                has_related_objs = True

        if has_related_objs:

            for sub_obj in rel_objs.all():

                if not has_admin:

                    # Don't display link to edit, because it either has no

                    # admin or is edited inline.

                    nh(deleted_objects, current_depth, [_('One or more %(fieldname)s in %(name)s: %(obj)s') % \

                        {'fieldname': force_unicode(related.field.verbose_name), 'name': force_unicode(related.opts.verbose_name), 'obj': escape(sub_obj)}, []])

                else:

                    # Display a link to the admin page.

                    nh(deleted_objects, current_depth, [

                        mark_safe((_('One or more %(fieldname)s in %(name)s:') % {'fieldname': escape(force_unicode(related.field.verbose_name)), 'name': escape(force_unicode(related.opts.verbose_name))}) + \

                        (u' <a href="%s">%s</a>' % \

                            (get_change_view_url(related.opts.app_label,

                                                 related.opts.object_name.lower(),

                                                 sub_obj._get_pk_val(),

                                                 admin_site,

                                                 levels_to_root),

                            escape(sub_obj)))), []])

        # If there were related objects, and the user doesn't have

        # permission to change them, add the missing perm to perms_needed.

        if has_admin and has_related_objs:

            p = u'%s.%s' % (related.opts.app_label, related.opts.get_change_permission())

            if not user.has_perm(p):

                perms_needed.add(related.opts.verbose_name)

def model_format_dict(obj):

    """

    Return a `dict` with keys 'verbose_name' and 'verbose_name_plural',

    typically for use with string formatting.

    `obj` may be a `Model` instance, `Model` subclass, or `QuerySet` instance.

    """

    if isinstance(obj, (models.Model, models.base.ModelBase)):

        opts = obj._meta

    elif isinstance(obj, models.query.QuerySet):

        opts = obj.model._meta

    else:

        opts = obj

    return {

        'verbose_name': force_unicode(opts.verbose_name),

        'verbose_name_plural': force_unicode(opts.verbose_name_plural)

    }

def model_ngettext(obj, n=None):

    """

    Return the appropriate `verbose_name` or `verbose_name_plural` value for

    `obj` depending on the count `n`.

    `obj` may be a `Model` instance, `Model` subclass, or `QuerySet` instance.

    If `obj` is a `QuerySet` instance, `n` is optional and the length of the

    `QuerySet` is used.

    """

    if isinstance(obj, models.query.QuerySet):

        if n is None:

            n = obj.count()

        obj = obj.model

    d = model_format_dict(obj)

    singular, plural = d["verbose_name"], d["verbose_name_plural"]

    return ungettext(singular, plural, n or 0)