
from hashlib import md5
import os
from urllib import urlopen, urlencode, quote, unquote

from django.contrib import admin
from django.contrib.auth import REDIRECT_FIELD_NAME
from django.contrib.sites.models import Site
from django.core.files import File
from django.core.files.storage import default_storage
from django.core.urlresolvers import reverse, NoReverseMatch
from django.db.models import Model, get_model

from django.template import (Context, Node, TextNode, Template,
                             TemplateSyntaxError, TOKEN_TEXT, TOKEN_VAR,
                             TOKEN_COMMENT, TOKEN_BLOCK)

from django.template.defaultfilters import escape
from django.template.loader import get_template
from django.utils.html import strip_tags
from django.utils.simplejson import loads
from django.utils.text import capfirst

# Try to import PIL in either of the two ways it can end up installed.
try:
    from PIL import Image, ImageFile, ImageOps
except ImportError:
    import Image
    import ImageFile
    import ImageOps

from mezzanine.conf import settings
from mezzanine.core.fields import RichTextField
from mezzanine.core.forms import get_edit_form
from mezzanine.utils.cache import nevercache_token, cache_installed
from mezzanine.utils.html import decode_entities
from mezzanine.utils.importing import import_dotted_path
from mezzanine.utils.sites import current_site_id, has_site_permission
from mezzanine.utils.urls import admin_url
from mezzanine.utils.views import is_editable
from mezzanine import template


register = template.Library()


if "compressor" in settings.INSTALLED_APPS:
    @register.tag
    def compress(parser, token):
        """
        Shadows django-compressor's compress tag so it can be
        loaded from ``mezzanine_tags``, allowing us to provide
        a dummy version when django-compressor isn't installed.
        """
        from compressor.templatetags.compress import compress
        return compress(parser, token)
else:
    @register.to_end_tag
    def compress(parsed, context, token):
        """
        Dummy tag for fallback when django-compressor isn't installed.
        """
        return parsed


if cache_installed():
    @register.tag
    def nevercache(parser, token):
        """
        Tag for two phased rendering. Converts enclosed template
        code and content into text, which gets rendered separately
        in ``mezzanine.core.middleware.UpdateCacheMiddleware``.
        This is to bypass caching for the enclosed code and content.
        """
        text = []
        end_tag = "endnevercache"
        tag_mapping = {
            TOKEN_TEXT: ("", ""),
            TOKEN_VAR: ("{{", "}}"),
            TOKEN_BLOCK: ("{%", "%}"),
            TOKEN_COMMENT: ("{#", "#}"),
        }
        delimiter = nevercache_token()
        while parser.tokens:
            token = parser.next_token()
            if token.token_type == TOKEN_BLOCK and token.contents == end_tag:
                return TextNode(delimiter + "".join(text) + delimiter)
            start, end = tag_mapping[token.token_type]
            text.append("%s%s%s" % (start, token.contents, end))
        parser.unclosed_block_tag(end_tag)
else:
    @register.to_end_tag
    def nevercache(parsed, context, token):
        """
        Dummy fallback ``nevercache`` for when caching is not
        configured.
        """
        return parsed


@register.inclusion_tag("includes/form_fields.html", takes_context=True)
def fields_for(context, form):
    """
    Renders fields for a form.
    """
    context["form_for_fields"] = form
    return context


@register.filter
def sort_by(items, attr):
    """
    General sort filter - sorts by either attribute or key.
    """
    def key_func(item):
        try:
            return getattr(item, attr)
        except AttributeError:
            try:
                return item[attr]
            except TypeError:
                getattr(item, attr)  # Reraise AttributeError
    return sorted(items, key=key_func)


@register.filter
def is_installed(app_name):
    """
    Returns ``True`` if the given app name is in the
    ``INSTALLED_APPS`` setting.
    """
    from warnings import warn
    warn("The is_installed filter is deprecated. Please use the tag "
         "{% ifinstalled appname %}{% endifinstalled %}")
    return app_name in settings.INSTALLED_APPS


@register.tag
def ifinstalled(parser, token):
    """
    Old-style ``if`` tag that renders contents if the given app is
    installed. The main use case is:

    {% ifinstalled app_name %}
    {% include "app_name/template.html" %}
    {% endifinstalled %}

    so we need to manually pull out all tokens if the app isn't
    installed, since if we used a normal ``if`` tag with a False arg,
    the include tag will still try and find the template to include.
    """
    try:
        tag, app = token.split_contents()
    except ValueError:
        raise TemplateSyntaxError("ifinstalled should be in the form: "
                                  "{% ifinstalled app_name %}"
                                  "{% endifinstalled %}")

    end_tag = "end" + tag
    if app.strip("\"'") not in settings.INSTALLED_APPS:
        while True:
            token = parser.tokens.pop(0)
            if token.token_type == TOKEN_BLOCK and token.contents == end_tag:
                parser.tokens.insert(0, token)
                break
    nodelist = parser.parse((end_tag,))
    parser.delete_first_token()

    class IfInstalledNode(Node):
        def render(self, context):
            return nodelist.render(context)

    return IfInstalledNode()


@register.render_tag
def set_short_url_for(context, token):
    """
    Sets the ``short_url`` attribute of the given model using the bit.ly
    credentials if they have been specified and saves it.
    """
    obj = context[token.split_contents()[1]]
    request = context["request"]
    if getattr(obj, "short_url") is None:
        obj.short_url = request.build_absolute_uri(request.path)
        if context["settings"].BITLY_ACCESS_TOKEN:
            url = "https://api-ssl.bit.ly/v3/shorten?%s" % urlencode({
                "access_token": context["settings"].BITLY_ACCESS_TOKEN,
                "uri": obj.short_url,
            })
            response = loads(urlopen(url).read())
            if response["status_code"] == 200:
                obj.short_url = response["data"]["url"]
                obj.save()
    return ""


@register.simple_tag
def gravatar_url(email, size=32):
    """
    Return the full URL for a Gravatar given an email hash.
    """
    bits = (md5(email.lower()).hexdigest(), size)
    return "http://www.gravatar.com/avatar/%s?s=%s&d=identicon&r=PG" % bits


@register.to_end_tag
def metablock(parsed):
    """
    Remove HTML tags, entities and superfluous characters from meta blocks.
    """
    parsed = " ".join(parsed.replace("\n", "").split()).replace(" ,", ",")
    return escape(strip_tags(decode_entities(parsed)))


@register.inclusion_tag("includes/pagination.html", takes_context=True)
def pagination_for(context, current_page, page_var="page", exclude_vars=""):
    """
    Include the pagination template and data for persisting querystring
    in pagination links. Can also contain a comma separated string of
    var names in the current querystring to exclude from the pagination
    links, via the ``exclude_vars`` arg.
    """
    querystring = context["request"].GET.copy()
    exclude_vars = [v for v in exclude_vars.split(",") if v] + [page_var]
    for exclude_var in exclude_vars:
        if exclude_var in querystring:
            del querystring[exclude_var]
    querystring = querystring.urlencode()
    return {
        "current_page": current_page,
        "querystring": querystring,
        "page_var": page_var,
    }


@register.inclusion_tag("includes/search_form.html", takes_context=True)
def search_form(context, search_model_names=None):
    """
    Includes the search form with a list of models to use as choices for
    filtering the search by. Models should be a string with models in the
    format ``app_label.model_name`` separated by spaces. The string ``all``
    can also be used, in which case the models defined by the
    ``SEARCH_MODEL_CHOICES`` setting will be used.
    """
    if not search_model_names:
        search_model_names = []
    elif search_model_names == "all":
        search_model_names = list(settings.SEARCH_MODEL_CHOICES)
    else:
        search_model_names = search_model_names.split(" ")
    search_model_choices = []
    for model_name in search_model_names:
        model = get_model(*model_name.split(".", 1))
        if model:  # Might not be installed.
            verbose_name = model._meta.verbose_name_plural.capitalize()
            search_model_choices.append((verbose_name, model_name))
    context["search_model_choices"] = sorted(search_model_choices)
    return context


@register.simple_tag
def thumbnail(image_url, width, height, quality=95):
    """
    Given the URL to an image, resizes the image using the given width and
    height on the first time it is requested, and returns the URL to the new
    resized image. if width or height are zero then original ratio is
    maintained.
    """
    if not image_url:
        return ""

    image_url = unquote(unicode(image_url))
    if image_url.startswith(settings.MEDIA_URL):
        image_url = image_url.replace(settings.MEDIA_URL, "", 1)
    image_dir, image_name = os.path.split(image_url)
    image_prefix, image_ext = os.path.splitext(image_name)
    filetype = {".png": "PNG", ".gif": "GIF"}.get(image_ext, "JPEG")
    thumb_name = "%s-%sx%s%s" % (image_prefix, width, height, image_ext)
    thumb_dir = os.path.join(settings.MEDIA_ROOT, image_dir,
                             settings.THUMBNAILS_DIR_NAME)
    if not os.path.exists(thumb_dir):
        os.makedirs(thumb_dir)
    thumb_path = os.path.join(thumb_dir, thumb_name)
    thumb_url = "%s/%s" % (settings.THUMBNAILS_DIR_NAME,
                           quote(thumb_name.encode("utf-8")))
    image_url_path = os.path.dirname(image_url)
    if image_url_path:
        thumb_url = "%s/%s" % (image_url_path, thumb_url)

    try:
        thumb_exists = os.path.exists(thumb_path)
    except UnicodeEncodeError:
        # The image that was saved to a filesystem with utf-8 support,
        # but somehow the locale has changed and the filesystem does not
        # support utf-8.
        from mezzanine.core.exceptions import FileSystemEncodingChanged
        raise FileSystemEncodingChanged()
    if thumb_exists:
        # Thumbnail exists, don't generate it.
        return thumb_url
    elif not default_storage.exists(image_url):
        # Requested image does not exist, just return its URL.
        return image_url

    f = default_storage.open(image_url)
    try:
        image = Image.open(f)
    except:
        # Invalid image format
        return image_url

    image_info = image.info
    width = int(width)
    height = int(height)

    # If already right size, don't do anything.
    if width == image.size[0] and height == image.size[1]:
        return image_url
    # Set dimensions.
    if width == 0:
        width = image.size[0] * height / image.size[1]
    elif height == 0:
        height = image.size[1] * width / image.size[0]
    if image.mode not in ("P", "L", "RGBA"):
        image = image.convert("RGBA")
    # Required for progressive jpgs.
    ImageFile.MAXBLOCK = image.size[0] * image.size[1]
    try:
        image = ImageOps.fit(image, (width, height), Image.ANTIALIAS)
        image = image.save(thumb_path, filetype, quality=quality, **image_info)
        # Push a remote copy of the thumbnail if MEDIA_URL is
        # absolute.
        if "://" in settings.MEDIA_URL:
            with open(thumb_path, "r") as f:
                default_storage.save(thumb_url, File(f))
    except Exception:
        # If an error occurred, a corrupted image may have been saved,
        # so remove it, otherwise the check for it existing will just
        # return the corrupted image next time it's requested.
        try:
            os.remove(thumb_path)
        except Exception:
            pass
        return image_url
    return thumb_url


@register.inclusion_tag("includes/editable_loader.html", takes_context=True)
def editable_loader(context):
    """
    Set up the required JS/CSS for the in-line editing toolbar and controls.
    """
    user = context["request"].user
    context["has_site_permission"] = has_site_permission(user)
    if settings.INLINE_EDITING_ENABLED and context["has_site_permission"]:
        t = get_template("includes/editable_toolbar.html")
        context["REDIRECT_FIELD_NAME"] = REDIRECT_FIELD_NAME
        context["toolbar"] = t.render(Context(context))
        context["richtext_media"] = RichTextField().formfield().widget.media
    return context


@register.filter
def richtext_filter(content):
    """
    This template filter takes a string value and passes it through the
    function specified by the RICHTEXT_FILTER setting.
    """
    if settings.RICHTEXT_FILTER:
        func = import_dotted_path(settings.RICHTEXT_FILTER)
    else:
        func = lambda s: s
    return func(content)


@register.to_end_tag
def editable(parsed, context, token):
    """
    Add the required HTML to the parsed content for in-line editing, such as
    the icon and edit form if the object is deemed to be editable - either it
    has an ``editable`` method which returns ``True``, or the logged in user
    has change permissions for the model.
    """
    def parse_field(field):
        field = field.split(".")
        obj = context.get(field.pop(0), None)
        attr = field.pop()
        while field:
            obj = getattr(obj, field.pop(0))
        return obj, attr

    fields = [parse_field(f) for f in token.split_contents()[1:]]
    if fields:
        fields = [f for f in fields if len(f) == 2 and f[0] is fields[0][0]]
    if not parsed.strip():
        try:
            parsed = "".join([unicode(getattr(*field)) for field in fields])
        except AttributeError:
            pass

    if settings.INLINE_EDITING_ENABLED and fields and "request" in context:
        obj = fields[0][0]
        if isinstance(obj, Model) and is_editable(obj, context["request"]):
            field_names = ",".join([f[1] for f in fields])
            context["form"] = get_edit_form(obj, field_names)
            context["original"] = parsed
            t = get_template("includes/editable_form.html")
            return t.render(Context(context))
    return parsed


@register.simple_tag
def try_url(url_name):
    """
    Mimics Django's ``url`` template tag but fails silently. Used for url
    names in admin templates as these won't resolve when admin tests are
    running.
    """
    from warnings import warn
    warn("try_url is deprecated, use the url tag with the 'as' arg instead.")
    try:
        url = reverse(url_name)
    except NoReverseMatch:
        return ""
    return url


def admin_app_list(request):
    """
    Adopted from ``django.contrib.admin.sites.AdminSite.index``. Returns a
    list of lists of models grouped and ordered according to
    ``mezzanine.conf.ADMIN_MENU_ORDER``. Called from the
    ``admin_dropdown_menu`` template tag as well as the ``app_list``
    dashboard widget.
    """
    app_dict = {}

    # Model or view --> (group index, group title, item index, item title).
    menu_order = {}
    for (group_index, group) in enumerate(settings.ADMIN_MENU_ORDER):
        group_title, items = group
        group_title = group_title.title()
        for (item_index, item) in enumerate(items):
            if isinstance(item, (tuple, list)):
                item_title, item = item
            else:
                item_title = None
            menu_order[item] = (group_index, group_title,
                                item_index, item_title)

    # Add all registered models, using group and title from menu order.
    for (model, model_admin) in admin.site._registry.items():
        opts = model._meta
        in_menu = not hasattr(model_admin, "in_menu") or model_admin.in_menu()
        if in_menu and request.user.has_module_perms(opts.app_label):
            perms = model_admin.get_model_perms(request)
            admin_url_name = ""
            if perms["change"]:
                admin_url_name = "changelist"
                change_url = admin_url(model, admin_url_name)
            else:
                change_url = None
            if perms["add"]:
                admin_url_name = "add"
                add_url = admin_url(model, admin_url_name)
            else:
                add_url = None
            if admin_url_name:
                model_label = "%s.%s" % (opts.app_label, opts.object_name)
                try:
                    app_index, app_title, model_index, model_title = \
                        menu_order[model_label]
                except KeyError:
                    app_index = None
                    app_title = opts.app_label.title()
                    model_index = None
                    model_title = None
                else:
                    del menu_order[model_label]

                if not model_title:
                    model_title = capfirst(model._meta.verbose_name_plural)

                if app_title not in app_dict:
                    app_dict[app_title] = {
                        "index": app_index,
                        "name": app_title,
                        "models": [],
                    }
                app_dict[app_title]["models"].append({
                    "index": model_index,
                    "perms": model_admin.get_model_perms(request),
                    "name": model_title,
                    "admin_url": change_url,
                    "add_url": add_url
                })

    # Menu may also contain view or url pattern names given as (title, name).
    for (item_url, item) in menu_order.iteritems():
        app_index, app_title, item_index, item_title = item
        try:
            item_url = reverse(item_url)
        except NoReverseMatch:
            continue
        if app_title not in app_dict:
            app_dict[app_title] = {
                "index": app_index,
                "name": app_title,
                "models": [],
            }
        app_dict[app_title]["models"].append({
            "index": item_index,
            "perms": {"custom": True},
            "name": item_title,
            "admin_url": item_url,
        })

    app_list = app_dict.values()
    sort = lambda x: x["name"] if x["index"] is None else x["index"]
    for app in app_list:
        app["models"].sort(key=sort)
    app_list.sort(key=sort)
    return app_list


@register.inclusion_tag("admin/includes/dropdown_menu.html",
                        takes_context=True)
def admin_dropdown_menu(context):
    """
    Renders the app list for the admin dropdown menu navigation.
    """
    context["dropdown_menu_app_list"] = admin_app_list(context["request"])
    user = context["request"].user
    if user.is_superuser:
        sites = Site.objects.all()
    else:
        sites = user.sitepermissions.get().sites.all()
    context["dropdown_menu_sites"] = list(sites)
    context["dropdown_menu_selected_site_id"] = current_site_id()
    return context


@register.inclusion_tag("admin/includes/app_list.html", takes_context=True)
def app_list(context):
    """
    Renders the app list for the admin dashboard widget.
    """
    context["dashboard_app_list"] = admin_app_list(context["request"])
    return context


@register.inclusion_tag("admin/includes/recent_actions.html",
                        takes_context=True)
def recent_actions(context):
    """
    Renders the recent actions list for the admin dashboard widget.
    """
    return context


@register.render_tag
def dashboard_column(context, token):
    """
    Takes an index for retrieving the sequence of template tags from
    ``mezzanine.conf.DASHBOARD_TAGS`` to render into the admin dashboard.
    """
    column_index = int(token.split_contents()[1])
    output = []
    for tag in settings.DASHBOARD_TAGS[column_index]:
        t = Template("{%% load %s %%}{%% %s %%}" % tuple(tag.split(".")))
        output.append(t.render(Context(context)))
    return "".join(output)
