import os
import functools
import hashlib

from wpull.database.sqltable import SQLiteURLTable
from wpull.document.html import HTMLReader
import wpull.processor.rule

from libgrabsite import dupespotter
from libgrabsite.dupes import DupesOnDisk



class NoFsyncSQLTable(SQLiteURLTable):
	@classmethod
	def _apply_pragmas_callback(cls, connection, record):
		super()._apply_pragmas_callback(connection, record)
		connection.execute('PRAGMA synchronous=OFF')


class DupeSpottingProcessingRule(wpull.processor.rule.ProcessingRule):
	def __init__(self, *args, **kwargs):
		self.dupes_db = kwargs.pop('dupes_db', None)
		super().__init__(*args, **kwargs)

	def scrape_document(self, request, response, url_item):
		if response.body.size() < 30*1024*1024:
			dupes_db = self.dupes_db
			body = response.body.content()
			if HTMLReader.is_response(response):
				body = dupespotter.process_body(body, response.request.url)
			digest = hashlib.md5(body).digest()
			if dupes_db is not None:
				dupe_of = dupes_db.get_old_url(digest)
			else:
				dupe_of = None
			if dupe_of is not None:
				# Don't extract links from pages we've already seen
				# to avoid loops that descend a directory endlessly
				print("DUPE {}\n  OF {}".format(response.request.url, dupe_of))
				return
			else:
				if dupes_db is not None:
					dupes_db.set_old_url(digest, response.request.url)

		super().scrape_document(request, response, url_item)


wpull_plugin.factory.class_map['URLTableImplementation'] = NoFsyncSQLTable
if int(os.environ["DUPESPOTTER_ENABLED"]):
	wpull_plugin.factory.class_map['ProcessingRule'] = functools.partial(
		DupeSpottingProcessingRule,
		dupes_db=DupesOnDisk(
			os.path.join(os.environ["GRAB_SITE_WORKING_DIR"], "dupes_db"))
	)