#!/usr/bin/env python3
r"""
Documentation

License: This program is released under the MIT License
"""

# Imports
import boto3
from openpyxl import load_workbook
import datetime


def getBucketSize(bucket: str) -> int:
    """
    Get size of a s3 bucket through cloudwatch metric

    :param bucket:
    :return: Bucket size in MiB
    """
    s3 = boto3.client('s3')
    region = s3.get_bucket_location(Bucket=bucket)['LocationConstraint']
    if region is None:
        region='us-east-1'
    cloudwatch_client = boto3.client('cloudwatch', region_name=region)
    response = cloudwatch_client.get_metric_statistics(Namespace='AWS/S3',
                                                       MetricName='BucketSizeBytes',
                                                       Dimensions=[
                                                           {
                                                               'Name': 'BucketName',
                                                               'Value': bucket
                                                           },
                                                           {
                                                               'Name': 'StorageType',
                                                               'Value': 'StandardStorage'
                                                           }
                                                       ],
                                                       StartTime=datetime.datetime.now() - datetime.timedelta(
                                                           days=7),
                                                       EndTime=datetime.datetime.now(),
                                                       Period=86400,
                                                       Statistics=['Average']
                                                       )
    if len(response['Datapoints']) == 0:
        return 0
    else:
        return int(response['Datapoints'][0]['Average']/1024/1024/1024)

# Main function
def main() -> None:
    # Open spreadsheet and add a sheet
    wb = load_workbook('aws-inventory.xlsx')
    ws = wb.create_sheet("S3")

    s3_client = boto3.client('s3')

    # Get the list of all buckets
    response = s3_client.list_buckets()

    # Print the names of the buckets
    ws.append(['Buckets', 'SizeGiB'])
    for bucket in response['Buckets']:
        ws.append([bucket["Name"], getBucketSize(bucket["Name"])])

    wb.save('aws-inventory.xlsx')


# Call main function
if __name__ == '__main__':
    main()