"""Lambda copy-recovery-point function module."""
import json
import os

import boto3
from lambdacommon.common_config import logger
from environs import env
from src.event_source_mapping import set_lambda_event_source_mapping


REFRESH_TABLE_ARN = os.environ.get('REFRESH_TABLE_ARN')
REFRESH_TABLE_NAME = os.environ.get('REFRESH_TABLE_NAME')
REFRESH_TABLE_STREAM_ENABLED = env.bool('REFRESH_TABLE_STREAM_ENABLED', default=False)
REFRESH_TABLE_STREAM_VIEW_TYPE = os.environ.get('REFRESH_TABLE_STREAM_VIEW_TYPE')

REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_ARN = env.str('REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_ARN', default=None)
REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_BATCH_SIZE = env.int(
    'REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_BATCH_SIZE', default=100)
REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_PARALLELIZATION_FACTOR = env.int(
    'REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_PARALLELIZATION_FACTOR', default=1)
REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_STARTING_POSITION = env.str(
    'REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_STARTING_POSITION', default='LATEST')

REFRESH_TABLE_GLOBAL_REPLICAS_ENABLED = env.bool('REFRESH_TABLE_GLOBAL_REPLICAS_ENABLED', default=False)
REFRESH_TABLE_GLOBAL_REPLICAS_REGION = os.environ.get('REFRESH_TABLE_GLOBAL_REPLICAS_REGION')
REFRESH_TABLE_GLOBAL_REPLICAS_KMS_KEY = os.environ.get('REFRESH_TABLE_GLOBAL_REPLICAS_KMS_KEY')
AWS_REGION = 'us-east-1'
TTL_ENABLED = env.bool('TTL_ENABLED', default=False)
TTL_ATTRIBUTE = os.environ.get('TTL_ATTRIBUTE', 'expires_at')
APPLY_TAGS = os.environ.get('APPLY_TAGS', None)

dynamodb = boto3.client('dynamodb',
                        region_name=AWS_REGION)

lambda_client = boto3.client('lambda', region_name=AWS_REGION)


def handler(event, context):
    """Lambda entry point."""
    try:
        if REFRESH_TABLE_STREAM_ENABLED or REFRESH_TABLE_GLOBAL_REPLICAS_ENABLED:
            logger.info(f'Starting table update for {REFRESH_TABLE_NAME}')
            update_table(REFRESH_TABLE_NAME)
        return {'status': 'OK'}
    except Exception as e:
        logger.exception(str(e))
        raise e


def update_table(table_name):
    """Update DynamoDB Table."""
    if REFRESH_TABLE_GLOBAL_REPLICAS_ENABLED:
        try:
            dynamodb.update_table(
                TableName=table_name,
                ReplicaUpdates=replica_update_spec(),
            )
            logger.info('Global table update complete')
        except Exception as e:
            logger.exception(e)
            raise e

    if REFRESH_TABLE_STREAM_ENABLED:
        try:
            dynamodb.update_table(TableName=table_name, StreamSpecification=stream_update_spec())
            logger.info('Stream update complete')
        except Exception as e:
            logger.exception(e)
            raise e
        if REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_ARN:
            event_source_mapping_configs = {
                'BatchSize': REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_BATCH_SIZE,
                'ParallelizationFactor': REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_PARALLELIZATION_FACTOR,
                'StartingPosition': REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_STARTING_POSITION,
            }
            set_lambda_event_source_mapping(
                dynamodb_client=dynamodb,
                dynamodb_table=table_name,
                lambda_client=lambda_client,
                target_lambda_arn=REFRESH_TABLE_STREAM_CONSUMER_LAMBDA_ARN,
                **event_source_mapping_configs,
            )

    if TTL_ENABLED:
        try:
            dynamodb.update_time_to_live(
                TableName=table_name,
                TimeToLiveSpecification={
                    'AttributeName': TTL_ATTRIBUTE,
                    'Enabled': TTL_ENABLED
                }
            )
            logger.info('TTL update complete')
        except Exception as e:
            logger.exception(e)
            raise e

    if APPLY_TAGS:
        try:
            # transform string into tag format
            transformed_tags = json.loads(APPLY_TAGS)
            dynamodb.tag_resource(ResourceArn=REFRESH_TABLE_ARN, Tags=transformed_tags)
        except Exception as e:
            logger.exception(e)
            raise e


def replica_update_spec():
    """Replica Update spec."""
    return [
        {
            'Create': {
                'RegionName': REFRESH_TABLE_GLOBAL_REPLICAS_REGION,
                'KMSMasterKeyId': REFRESH_TABLE_GLOBAL_REPLICAS_KMS_KEY,
            }
        }
    ]


def stream_update_spec():
    """Stream Update spec."""
    return {'StreamEnabled': REFRESH_TABLE_STREAM_ENABLED, 'StreamViewType': REFRESH_TABLE_STREAM_VIEW_TYPE}