# This was taken from https://github.com/ldiqual/django-linestripper/

from django.conf import settings
from django.template.loaders import app_directories

import re

# To be set in settings.py
STRIPPER_TAG = getattr(settings, 'STRIPPER_TAG', '__STRIPPER_TAG__')
STRIPPER_CLEAR_LINE = getattr(settings, 'STRIPPER_CLEAR_LINE', False)
STRIPPER_ENABLED =  getattr(settings, 'STRIPPER_ENABLED', True)
STRIPPER_ALLOWED_CONTENT_TYPES = getattr(settings, 'STRIPPER_ALLOWED_CONTENT_TYPES', (
	'text',
	'xml'
))

# Finders
FIND_BLANK_LINE = r'\n(\s*)\n'
FIND_START_BLANK_LINE = r'^(\s*)\n'
FIND_TAG = STRIPPER_TAG

# Replacers
REPLACE_WITH_TAG = '\n'+ STRIPPER_TAG +'\n' if STRIPPER_CLEAR_LINE else r'\n\1'+ STRIPPER_TAG +'\n'
REPLACE_START_WITH_TAG = STRIPPER_TAG +'\n' if STRIPPER_CLEAR_LINE else r'\n\1'+ STRIPPER_TAG +'\n'

# Deleters
DELETE_BLANK_LINE = '\n'
DELETE_START_BLANK_LINE = ''
DELETE_TAG = ''

'''
This is called AFTER the template generation.
It suppresses blank lines and deletes STRIPPER_TAG
'''
class StripperMiddleware(object):
	def process_response(self, request, response):
		if not STRIPPER_ENABLED:
			return response

		# Checks if the content type is allowed
		allowed = False
		for type in STRIPPER_ALLOWED_CONTENT_TYPES:
			if type in response['Content-Type']:
				allowed = True
				break

		# If the content type is not allowed, untag and return
		if not allowed:
			response.content = response.content.replace(STRIPPER_TAG, DELETE_TAG)
			return response

		# Suppress a blank line at the beginning of the document
		response.content = re.sub(FIND_START_BLANK_LINE, DELETE_START_BLANK_LINE, response.content)
		# Suppress blank lines
		response.content = re.sub(FIND_BLANK_LINE, DELETE_BLANK_LINE, response.content)
		# Delete STRIPPER_TAG
		# response.content = re.sub(FIND_TAG, DELETE_TAG, response.content)
		response.content = response.content.replace(STRIPPER_TAG, DELETE_TAG)
		return response

'''
This is called BEFORE the template generation.
It adds STRIPPER_TAG to blank lines so they aren't removed in the middleware
'''
class Loader(app_directories.Loader):
    is_usable = True

    def process_content(self, content):
    	if not STRIPPER_ENABLED:
			return content

        content = re.sub(FIND_BLANK_LINE, REPLACE_WITH_TAG, content)
        content = re.sub(FIND_START_BLANK_LINE, REPLACE_WITH_TAG, content)
        return content

    def load_template(self, template_name, template_dirs=None):
        source, origin = self.load_template_source(template_name, template_dirs)
        if not STRIPPER_ENABLED:
			return source, origin
        return self.process_content(source), origin