import boto3
from botocore.exceptions import ClientError
from datetime import datetime, timedelta
import csv
import sys


def get_bucket_size(bucket_name: str, storage_type: str) -> float:
    client = boto3.client('cloudwatch')
    end_time = datetime.now()
    start_time = end_time - timedelta(days=30)
    response = client.get_metric_statistics(
        Namespace='AWS/S3',
        MetricName='BucketSizeBytes',
        Dimensions=[
            {
                'Name': 'StorageType',
                'Value': storage_type
            },
            {
                'Name': 'BucketName',
                'Value': bucket_name
            }
        ],
        StartTime=start_time,
        EndTime=end_time,
        Period=86400 * 30,
        Statistics=[
            'Average',
        ],
        Unit='Bytes'
    )
    stat = 0
    for datapoint in response['Datapoints']:
        stat = datapoint['Average']
    return bytes_to_gib(stat)


def bytes_to_gib(number: int) -> float:
    return number / 1024 / 1024 / 1024


def get_s3_buckets() -> list:
    client = boto3.client('s3')
    buckets_response = client.list_buckets()
    s3_buckets = []
    for s3_bucket in buckets_response['Buckets']:
        # get bucket size
        bucket_size = get_bucket_size(s3_bucket['Name'], 'StandardStorage')
        # get expiration
        try:
            lifecycle_response = client.get_bucket_lifecycle_configuration(Bucket=s3_bucket['Name'])
            expiration_days = 'No'
            for rule in lifecycle_response['Rules']:
                if 'Expiration' in rule:
                    if 'Days' in rule['Expiration']:
                        expiration_days = rule['Expiration']['Days']
        except ClientError:
            expiration_days = 'No'
        # get bucket tags
        try:
            tagging_response = client.get_bucket_tagging(Bucket=s3_bucket['Name'])
            tag = "".join([tag['Value'] for tag in tagging_response['TagSet'] if tag['Key'] == 'plat_env_project_service'])
        except ClientError:
            tag = ""
        s3_buckets.append((s3_bucket['Name'], bucket_size, tag, expiration_days))
    return s3_buckets


def main(argv):
    with open('s3-buckets.csv', mode='w') as s3_bucket_file:
        s3_buckets_writer = csv.writer(s3_bucket_file, delimiter=',',
                                       quotechar='"',
                                       quoting=csv.QUOTE_MINIMAL)
        s3_buckets_writer.writerow(
            (
                'BUCKET_NAME',
                'BUCKET_SIZE(AVG/MONTH)',
                'TAG_VAL',
                'EXPIRATION_DAYS'
            )
        )
        s3_buckets_writer.writerows(get_s3_buckets())


if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))