from __future__ import absolute_import, unicode_literals

from collections import OrderedDict
from os.path import join, normpath

from django.conf import settings
from django.contrib.staticfiles import finders, storage
from django.contrib.staticfiles.templatetags import staticfiles
from django.core.files.storage import get_storage_class
from django.utils.encoding import python_2_unicode_compatible
from django.utils.functional import LazyObject
from django.utils.translation import ugettext_lazy as _, ungettext

from debug_toolbar import panels
from debug_toolbar.utils import ThreadCollector

try:
    import threading
except ImportError:
    threading = None


@python_2_unicode_compatible
class StaticFile(object):
    """
    Representing the different properties of a static file.
    """
    def __init__(self, path):
        self.path = path

    def __str__(self):
        return self.path

    def real_path(self):
        return finders.find(self.path)

    def url(self):
        return storage.staticfiles_storage.url(self.path)


class FileCollector(ThreadCollector):

    def collect(self, path, thread=None):
        # handle the case of {% static "admin/" %}
        if path.endswith('/'):
            return
        super(FileCollector, self).collect(StaticFile(path), thread)


collector = FileCollector()


class DebugConfiguredStorage(LazyObject):
    """
    A staticfiles storage class to be used for collecting which paths
    are resolved by using the {% static %} template tag (which uses the
    `url` method).
    """
    def _setup(self):

        configured_storage_cls = get_storage_class(settings.STATICFILES_STORAGE)

        class DebugStaticFilesStorage(configured_storage_cls):

            def __init__(self, collector, *args, **kwargs):
                super(DebugStaticFilesStorage, self).__init__(*args, **kwargs)
                self.collector = collector

            def url(self, path):
                self.collector.collect(path)
                return super(DebugStaticFilesStorage, self).url(path)

        self._wrapped = DebugStaticFilesStorage(collector)


_original_storage = storage.staticfiles_storage


class StaticFilesPanel(panels.Panel):
    """
    A panel to display the found staticfiles.
    """
    name = 'Static files'
    template = 'debug_toolbar/panels/staticfiles.html'

    @property
    def title(self):
        return (_("Static files (%(num_found)s found, %(num_used)s used)") %
                {'num_found': self.num_found, 'num_used': self.num_used})

    def __init__(self, *args, **kwargs):
        super(StaticFilesPanel, self).__init__(*args, **kwargs)
        self.num_found = 0
        self._paths = {}

    def enable_instrumentation(self):
        storage.staticfiles_storage = staticfiles.staticfiles_storage = DebugConfiguredStorage()

    def disable_instrumentation(self):
        storage.staticfiles_storage = staticfiles.staticfiles_storage = _original_storage

    @property
    def num_used(self):
        return len(self._paths[threading.currentThread()])

    nav_title = _('Static files')

    @property
    def nav_subtitle(self):
        num_used = self.num_used
        return ungettext("%(num_used)s file used",
                         "%(num_used)s files used",
                         num_used) % {'num_used': num_used}

    def process_request(self, request):
        collector.clear_collection()

    def generate_stats(self, request, response):
        used_paths = collector.get_collection()
        self._paths[threading.currentThread()] = used_paths

        self.record_stats({
            'num_found': self.num_found,
            'num_used': self.num_used,
            'staticfiles': used_paths,
            'staticfiles_apps': self.get_staticfiles_apps(),
            'staticfiles_dirs': self.get_staticfiles_dirs(),
            'staticfiles_finders': self.get_staticfiles_finders(),
        })

    def get_staticfiles_finders(self):
        """
        Returns a sorted mapping between the finder path and the list
        of relative and file system paths which that finder was able
        to find.
        """
        finders_mapping = OrderedDict()
        for finder in finders.get_finders():
            for path, finder_storage in finder.list([]):
                if getattr(finder_storage, 'prefix', None):
                    prefixed_path = join(finder_storage.prefix, path)
                else:
                    prefixed_path = path
                finder_cls = finder.__class__
                finder_path = '.'.join([finder_cls.__module__,
                                        finder_cls.__name__])
                real_path = finder_storage.path(path)
                payload = (prefixed_path, real_path)
                finders_mapping.setdefault(finder_path, []).append(payload)
                self.num_found += 1
        return finders_mapping

    def get_staticfiles_dirs(self):
        """
        Returns a list of paths to inspect for additional static files
        """
        dirs = []
        for finder in finders.get_finders():
            if isinstance(finder, finders.FileSystemFinder):
                dirs.extend(finder.locations)
        return [(prefix, normpath(dir)) for prefix, dir in dirs]

    def get_staticfiles_apps(self):
        """
        Returns a list of app paths that have a static directory
        """
        apps = []
        for finder in finders.get_finders():
            if isinstance(finder, finders.AppDirectoriesFinder):
                for app in finder.apps:
                    if app not in apps:
                        apps.append(app)
        return apps
