import argparse
import functools
import hashlib

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

import dupespotter
from dupes import DupesInMemory, DupesOnDisk



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


class DupSpottingProcessingRule(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)


arg_parser = argparse.ArgumentParser()
arg_parser.add_argument(
    '--dupes-db',
    metavar='DIR',
    default=':memory:',
    help='save dupes db into DIR instead of memory',
)
args = arg_parser.parse_args(wpull_plugin.plugin_args.split())

if args.dupes_db == ':memory:':
    dupes_db = DupesInMemory()
else:
    dupes_db = DupesOnDisk(args.dupes_db)

wpull_plugin.factory.class_map['URLTableImplementation'] = NoFsyncSQLTable
wpull_plugin.factory.class_map['ProcessingRule'] = functools.partial(
    DupSpottingProcessingRule, dupes_db=dupes_db
)