'''
warcprox/playback.py - rudimentary support for playback of urls archived by
warcprox (not much used or maintained)

Copyright (C) 2013-2017 Internet Archive

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA.
'''

from __future__ import absolute_import

try:
    import http.server as http_server
except ImportError:
    import BaseHTTPServer as http_server

try:
    import socketserver
except ImportError:
    import SocketServer as socketserver

import logging
import os
from hanzo import warctools
import json
import traceback
import re
from warcprox.mitmproxy import MitmProxyHandler
import warcprox
import sqlite3
import threading

class PlaybackProxyHandler(MitmProxyHandler):
    logger = logging.getLogger("warcprox.playback.PlaybackProxyHandler")

    # @Override
    def _connect_to_remote_server(self):
        # don't connect to any remote server!
        pass

    # @Override
    def _proxy_request(self):
        date, location = self.server.playback_index_db.lookup_latest(self.url)
        self.logger.debug('lookup_latest returned {}:{}'.format(date, location))

        status = None
        if location is not None:
            try:
                status, sz = self._send_response_from_warc(location['f'], location['o'])
            except:
                status = 500
                self.logger.error('PlaybackProxyHandler problem playing back {}'.format(self.url), exc_info=1)
                payload = '500 Warcprox Error\n\n{}\n'.format(traceback.format_exc()).encode('utf-8')
                headers = (b'HTTP/1.1 500 Internal Server Error\r\n'
                        +  b'Content-Type: text/plain;charset=utf-8\r\n'
                        +  b'Content-Length: ' + str(len(payload)).encode('utf-8') + b'\r\n'
                        +  b'\r\n')
                self.connection.sendall(headers)
                self.connection.sendall(payload)
                sz = len(headers) + len(payload)
        else:
            status = 404
            payload = b'404 Not in Archive\n'
            headers = (b'HTTP/1.1 404 Not Found\r\n'
                    +  b'Content-Type: text/plain;charset=utf-8\r\n'
                    +  b'Content-Length: ' + str(len(payload)).encode('ascii') + b'\r\n'
                    +  b'\r\n')
            self.connection.sendall(headers)
            self.connection.sendall(payload)
            sz = len(headers) + len(payload)

        self.log_message('%r %s %s %s',
                         self.requestline, str(status), str(sz),
                         repr(location) if location else '-')


    def _open_warc_at_offset(self, warcfilename, offset):
        self.logger.debug('opening {} at offset {}'.format(warcfilename, offset))

        warcpath = None
        for p in (os.path.sep.join([self.server.warcs_dir, warcfilename]),
                os.path.sep.join([self.server.warcs_dir, '{}.open'.format(warcfilename)])):
            if os.path.exists(p):
                warcpath = p

        if warcpath is None:
            raise Exception('{} not found'.format(warcfilename))

        return warctools.warc.WarcRecord.open_archive(filename=warcpath, mode='rb', offset=offset)

    def _send_response(self, headers, payload_fh):
        status = '-'
        m = re.match(br'^HTTP/\d\.\d (\d{3})', headers)
        if m is not None:
            status = m.group(1)

        self.connection.sendall(headers)
        sz = len(headers)

        while True:
            buf = payload_fh.read(8192)
            if buf == b'': break
            self.connection.sendall(buf)
            sz += len(buf)

        return status, sz


    def _send_headers_and_refd_payload(
            self, headers, refers_to_target_uri, refers_to_date, payload_digest):
        """Parameters:

        """
        location = self.server.playback_index_db.lookup_exact(
                refers_to_target_uri, refers_to_date, payload_digest)
        self.logger.debug('loading http payload from {}'.format(location))

        fh = self._open_warc_at_offset(location['f'], location['o'])
        try:
            for (offset, record, errors) in fh.read_records(limit=1, offsets=True):
                pass

            if errors:
                raise Exception('warc errors at {}:{} -- {}'.format(location['f'], offset, errors))

            warc_type = record.get_header(warctools.WarcRecord.TYPE)
            if warc_type != warctools.WarcRecord.RESPONSE:
                raise Exception('invalid attempt to retrieve http payload of "{}" record'.format(warc_type))

            # find end of headers
            while True:
                line = record.content_file.readline()
                if line == b'' or re.match(br'^\r?\n$', line):
                    break

            return self._send_response(headers, record.content_file)

        finally:
            fh.close()


    def _send_response_from_warc(self, warcfilename, offset):
        fh = self._open_warc_at_offset(warcfilename, offset)
        try:
            for (offset, record, errors) in fh.read_records(limit=1, offsets=True):
                pass

            if errors:
                raise Exception('warc errors at {}:{} -- {}'.format(warcfilename, offset, errors))

            warc_type = record.get_header(warctools.WarcRecord.TYPE)

            if warc_type == warctools.WarcRecord.RESPONSE:
                headers_buf = bytearray()
                while True:
                    line = record.content_file.readline()
                    headers_buf.extend(line)
                    if line == b'' or re.match(b'^\r?\n$', line):
                        break

                return self._send_response(headers_buf, record.content_file)

            elif warc_type == warctools.WarcRecord.REVISIT:
                # response consists of http headers from revisit record and
                # payload from the referenced record
                warc_profile = record.get_header(warctools.WarcRecord.PROFILE)
                if warc_profile != warctools.WarcRecord.PROFILE_IDENTICAL_PAYLOAD_DIGEST:
                    raise Exception('unknown revisit record profile {}'.format(warc_profile))

                refers_to_target_uri = record.get_header(
                        warctools.WarcRecord.REFERS_TO_TARGET_URI).decode(
                                'latin1')
                refers_to_date = record.get_header(
                        warctools.WarcRecord.REFERS_TO_DATE).decode('latin1')
                payload_digest = record.get_header(
                        warctools.WarcRecord.PAYLOAD_DIGEST).decode('latin1')
                self.logger.debug(
                        'revisit record references %s:%s capture of %s',
                        refers_to_date, payload_digest, refers_to_target_uri)
                return self._send_headers_and_refd_payload(
                        record.content[1], refers_to_target_uri, refers_to_date,
                        payload_digest)

            else:
                # send it back raw, whatever it is
                headers_buf = bytearray()
                headers_buf.extend(b'HTTP/1.0 200 OK\r\n')
                headers_buf.extend(b'content-length: ' + record.get_header(b'content-length') + b'\r\n')
                headers_buf.extend(b'content-type: ' + record.get_header(b'content-type') + b'\r\n')
                headers_buf.extend(b'\r\n')
                return self._send_response(headers_buf, record.content_file)

        finally:
            fh.close()

        raise Exception('should not reach this point')


class PlaybackProxy(socketserver.ThreadingMixIn, http_server.HTTPServer):
    logger = logging.getLogger("warcprox.playback.PlaybackProxy")

    def __init__(self, ca=None, playback_index_db=None, options=warcprox.Options()):
        server_address = (options.address or 'localhost', options.playback_port if options.playback_port is not None else 8001)
        http_server.HTTPServer.__init__(self, server_address, PlaybackProxyHandler, bind_and_activate=True)
        self.ca = ca
        self.playback_index_db = playback_index_db
        self.warcs_dir = options.directory
        self.options = options

    def server_activate(self):
        http_server.HTTPServer.server_activate(self)
        self.logger.info('PlaybackProxy listening on {0}:{1}'.format(self.server_address[0], self.server_address[1]))

    def server_close(self):
        self.logger.info('PlaybackProxy shutting down')
        http_server.HTTPServer.server_close(self)


class PlaybackIndexDb(object):
    logger = logging.getLogger("warcprox.playback.PlaybackIndexDb")

    def __init__(self, file='./warcprox.sqlite', options=warcprox.Options()):
        self.file = file
        self._lock = threading.RLock()

        if os.path.exists(self.file):
            self.logger.info(
                    'opening existing playback index database %s', self.file)
        else:
            self.logger.info(
                    'creating new playback index database %s', self.file)

        conn = sqlite3.connect(self.file)
        conn.execute(
                'create table if not exists playback ('
                '  url varchar(4000) primary key,'
                '  value varchar(4000)'
                ');')
        conn.commit()
        conn.close()

    def close(self):
        pass

    def sync(self):
        pass

    def notify(self, recorded_url, records):
        if records:
            self.save(records[0].warc_filename, records, records[0].offset)

    def save(self, warcfile, recordset, offset):
        response_record = recordset[0]
        # XXX canonicalize url?
        url = response_record.get_header(warctools.WarcRecord.URL).decode('latin1')
        date_str = response_record.get_header(warctools.WarcRecord.DATE).decode('latin1')
        payload_digest_str = response_record.get_header(warctools.WarcRecord.PAYLOAD_DIGEST).decode('latin1')

        # there could be two visits of same url in the same second, and WARC-Date is
        # prescribed as YYYY-MM-DDThh:mm:ssZ, so we have to handle it :-\

        # url:{date1:[record1={'f':warcfile,'o':response_offset,'q':request_offset,'d':payload_digest},record2,...],date2:[{...}],...}

        with self._lock:
            conn = sqlite3.connect(self.file)
            cursor = conn.execute(
                    'select value from playback where url = ?', (url,))
            result_tuple = cursor.fetchone()
            if result_tuple:
                py_value = json.loads(result_tuple[0])
            else:
                py_value = {}

            if date_str in py_value:
                py_value[date_str].append(
                        {'f': warcfile, 'o': offset, 'd': payload_digest_str})
            else:
                py_value[date_str] = [
                        {'f': warcfile, 'o': offset, 'd': payload_digest_str}]

            json_value = json.dumps(py_value, separators=(',',':'))

            conn.execute(
                    'insert or replace into playback (url, value) '
                    'values (?, ?)', (url, json_value))
            conn.commit()
            conn.close()

        self.logger.debug('playback index saved: {}:{}'.format(url, json_value))

    def lookup_latest(self, url):
        conn = sqlite3.connect(self.file)
        cursor = conn.execute(
                'select value from playback where url = ?', (url,))
        result_tuple = cursor.fetchone()
        conn.close()

        if not result_tuple:
            return None, None

        json_value = result_tuple[0]
        self.logger.debug('%r:%r', url, json_value)
        py_value = json.loads(json_value)

        latest_date = max(py_value)
        result = py_value[latest_date][0]
        result['d'] = result['d'].encode('ascii')
        return latest_date, result

    # in python3 params are bytes
    def lookup_exact(self, url, warc_date, payload_digest):
        conn = sqlite3.connect(self.file)
        cursor = conn.execute(
                'select value from playback where url = ?', (url,))
        result_tuple = cursor.fetchone()
        conn.close()

        if not result_tuple:
            return None

        json_value = result_tuple[0]
        self.logger.debug('%r:%r', url, json_value)
        py_value = json.loads(json_value)

        if warc_date in py_value:
            for record in py_value[warc_date]:
                if record['d'] == payload_digest:
                    self.logger.debug(
                            "found exact match for (%r,%r,%r)",
                            warc_date, payload_digest, url)
                    record['d'] = record['d']
                    return record
        else:
            self.logger.info(
                    "match not found for (%r,%r,%r)", warc_date, payload_digest, url)
            return None