from django import template
from django.conf import settings
register = template.Library()

"""
Usage:

{% setting DEBUG %}
or
{% setting DATABASES.default.NAME %} # Get the name of the database
or
{% setting INSTALLED_APPS.2 %}  #get the third installed app.
or
{% setting DEBUG %}
"""

@register.tag
def setting ( parser, token ):
    try:
        tag_name, option = token.split_contents()
    except ValueError:
        raise template.TemplateSyntaxError, "%r tag requires a single argument" % token.contents[0]
    return SettingNode( option )

class SettingNode ( template.Node ):
    def __init__ ( self, option ):
        self.option = option

    def render ( self, context ):
        # if FAILURE then FAIL silently
        try:
            setting = settings
            # Enables param to tag to be for example "DATABASES.default.ENGINE"
            for name in self.option.split('.'):
                # if is an int. get from the setting by index.
                if name.isdigit():
                    setting = setting[int(name)]
                else:
                    if type(setting) == dict:
                        setting = setting.get(name)
                    else:
                        setting = setting.__getattr__(name)
            
            return str(setting)
        except:
            return ""