"""
The main DebugToolbar class that loads and renders the Toolbar.
"""

from __future__ import unicode_literals

from django.conf import settings
from django.template.loader import render_to_string
from django.utils.datastructures import SortedDict
from django.utils.importlib import import_module

from debug_toolbar.utils.settings import CONFIG


class DebugToolbar(object):

    def __init__(self, request):
        self.request = request
        self._panels = SortedDict()
        base_url = self.request.META.get('SCRIPT_NAME', '')
        self.config = {
            'MEDIA_URL': '%s/__debug__/m/' % base_url,
        }
        self.config.update(CONFIG)
        self.template_context = {
            'BASE_URL': base_url,  # for backwards compatibility
            'DEBUG_TOOLBAR_MEDIA_URL': self.config['MEDIA_URL'],
            'STATIC_URL': settings.STATIC_URL,
            'TOOLBAR_ROOT_TAG_ATTRS': self.config['ROOT_TAG_ATTRS'],
        }

        self.load_panels()
        self.stats = {}

    def _get_panels(self):
        return list(self._panels.values())
    panels = property(_get_panels)

    def get_panel(self, cls):
        return self._panels[cls]

    def load_panels(self):
        """
        Populate debug panels
        """
        global panel_classes
        for panel_class in panel_classes:
            panel_instance = panel_class(self, context=self.template_context)
            self._panels[panel_class] = panel_instance

    def render_toolbar(self):
        """
        Renders the overall Toolbar with panels inside.
        """
        context = self.template_context.copy()
        context.update({
            'panels': self.panels,
            'toolbar_id': save_toolbar(self),
        })
        return render_to_string('debug_toolbar/base.html', context)


panel_classes = []


def load_panel_classes():
    from django.conf import settings
    from django.core.exceptions import ImproperlyConfigured

    # Check if settings has a DEBUG_TOOLBAR_PANELS, otherwise use default
    panels = getattr(settings, 'DEBUG_TOOLBAR_PANELS', (
        'debug_toolbar.panels.version.VersionDebugPanel',
        'debug_toolbar.panels.timer.TimerDebugPanel',
        'debug_toolbar.panels.settings_vars.SettingsVarsDebugPanel',
        'debug_toolbar.panels.headers.HeaderDebugPanel',
        'debug_toolbar.panels.request_vars.RequestVarsDebugPanel',
        'debug_toolbar.panels.sql.SQLDebugPanel',
        'debug_toolbar.panels.template.TemplateDebugPanel',
        'debug_toolbar.panels.cache.CacheDebugPanel',
        'debug_toolbar.panels.signals.SignalDebugPanel',
        'debug_toolbar.panels.logger.LoggingPanel',
    ))
    for panel_path in panels:
        try:
            dot = panel_path.rindex('.')
        except ValueError:
            raise ImproperlyConfigured(
                "%s isn't a debug panel module" % panel_path)
        panel_module, panel_classname = panel_path[:dot], panel_path[dot + 1:]
        try:
            mod = import_module(panel_module)
        except ImportError as e:
            raise ImproperlyConfigured(
                'Error importing debug panel %s: "%s"' %
                (panel_module, e))
        try:
            panel_class = getattr(mod, panel_classname)
        except AttributeError:
            raise ImproperlyConfigured(
                'Toolbar Panel module "%s" does not define a "%s" class' %
                (panel_module, panel_classname))
        panel_classes.append(panel_class)


toolbar_counter = 0
toolbar_maxsize = 10            # keep data for the last 10 requests
toolbar_results = SortedDict()


def save_toolbar(toolbar):
    global toolbar_counter, toolbar_results
    toolbar_counter += 1
    toolbar_results[toolbar_counter] = toolbar
    for _ in range(len(toolbar_results) - toolbar_maxsize):
        # When we drop support for Python 2.6 and switch to
        # collections.OrderedDict, use popitem(last=False).
        del toolbar_results[toolbar_results.keyOrder[0]]
    return toolbar_counter


def get_saved_toolbar(toolbar_id):
    return toolbar_results.get(toolbar_id)