import json
import logging
import os
import sys

import boto3

import dateutil

OBJECT_DELETED_SINCE = os.getenv('OBJECT_DELETED_SINCE')
OBJECT_DELETED_TILL = os.getenv('OBJECT_DELETED_TILL')

CLOUDWATCH_NAMESPACE = os.getenv('CLOUDWATCH_NAMESPACE', 's3restore')

AWS_DEFAULT_REGION = os.environ.get('AWS_DEFAULT_REGION', 'us-east-1')
AWS_REGION = os.environ.get('AWS_REGION', AWS_DEFAULT_REGION)

LOG_LEVEL = os.getenv('LOG_LEVEL', logging.INFO)

s3 = boto3.resource('s3', region_name=AWS_REGION)
cloudwatch = boto3.resource('cloudwatch', region_name=AWS_REGION)

object_deleted_since = None
object_deleted_till = None

restored_object_count = {}


def init():
    if len(logging.getLogger().handlers) > 0:
        logging.getLogger().setLevel(LOG_LEVEL)
    else:
        logging.basicConfig(
            format='%(asctime)s %(levelname)s %(message)s',
            level=LOG_LEVEL
        )

    if not OBJECT_DELETED_SINCE:
        logging.error('You need to set "OBJECT_DELETED_SINCE" environment '
                      'variable in the ISO 8601 format '
                      '(i.e. "2023-03-30T10:00:00.000Z").')
        sys.exit(1)

    if not OBJECT_DELETED_TILL:
        logging.error('You need to set "OBJECT_DELETED_TILL" environment '
                      'variable in the ISO 8601 format '
                      '(i.e. "2023-03-31T10:00:00.000Z").')
        sys.exit(1)

    try:
        global object_deleted_since, object_deleted_till
        object_deleted_since = dateutil.parser.parse(OBJECT_DELETED_SINCE)
        object_deleted_till = dateutil.parser.parse(OBJECT_DELETED_TILL)
    except dateutil.parser._parser.ParserError:
        logging.error('Incorrect format specified for "OBJECT_DELETED_SINCE" '
                      'or "OBJECT_DELETED_TILL" environment variable which '
                      'should be in the ISO 8601.')
        sys.exit(1)


def handler(event, context):
    global restored_object_count

    for message in event['Records']:
        logging.info('Processing message ID "%s".', message['messageId'])
        data = json.loads(message['body'])
        for object_key in data['object_keys']:
            restored_object_count[data['bucket_name']] = 0
            process_object(data['bucket_name'], object_key)

    publish_metrics()


def process_object(bucket_name, object_key):
    global object_deleted_since, object_deleted_till
    global restored_object_count

    bucket = s3.Bucket(bucket_name)

    response = s3.meta.client.list_object_versions(
        Bucket=bucket.name, Prefix=object_key, MaxKeys=1)

    if 'DeleteMarkers' in response:
        latest_version = response['DeleteMarkers'][0]
        if latest_version['IsLatest']:
            last_modified = latest_version['LastModified']

            logging.info('Object "s3://%s/%s" was deleted on "%s".',
                         bucket.name, object_key, last_modified)

            if last_modified <= object_deleted_since:
                logging.info('Object "s3://%s/%s" was deleted before the '
                             'deletion time window. Restoration will NOT be '
                             'initialized.', bucket.name, object_key)
                return

            if last_modified >= object_deleted_till:
                logging.info('Object "s3://%s/%s" was deleted after the '
                             'deletion time window. Restoration will NOT be '
                             'initialized.', bucket.name, object_key)
                return

            logging.info('Object "s3://%s/%s" was deleted during the deletion '
                         'time window. Restoration will be initialized.',
                         bucket.name, object_key)

            obj = bucket.Object(object_key)
            obj.Version(latest_version['VersionId']).delete()

            restored_object_count[bucket.name] += 1

            logging.warning('Object "s3://%s/%s" will be restored soon.',
                            bucket.name, object_key)
        else:
            logging.info('Object "s3://%s/%s" was updated after deletion as '
                         'it does not have the latest version of the delete '
                         'marker.', bucket.name, object_key)
    elif 'Versions' in response:
        logging.info('Object "s3://%s/%s" does not have a delete marker, '
                     'nothing to do.', bucket.name, object_key)
    else:
        logging.error('Failed to get any version info for "s3://%s/%s" '
                      'object.', bucket.name, object_key)


def publish_metrics():
    global restored_object_count

    # for bucket_name, value in restored_object_count.items():
    #     cloudwatch.meta.client.put_metric_data(
    #         Namespace=CLOUDWATCH_NAMESPACE,
    #         MetricData=[
    #             {
    #                 'MetricName': 'objects-restored',
    #                 'Dimensions': [
    #                     {'Name': 'bucket_name', 'Value': bucket_name}
    #                 ],
    #                 'Value': value,
    #                 'Unit': 'Count'
    #             }
    #         ])

    restored_object_count = {}


init()