import boto3
from datetime import datetime, timedelta
import sys
import csv


def get_clusters() -> list:
    client = boto3.client('rds')
    paginator = client.get_paginator('describe_db_clusters')
    page_iterator = paginator.paginate()

    clusters = []
    for page in page_iterator:
        for cluster in page['DBClusters']:
            clusters.append(
                (
                    cluster['DBClusterIdentifier'],
                    'Cluster',
                    cluster['AllocatedStorage'],
                    "".join([tag['Value'] for tag in cluster['TagList'] if tag['Key'] == 'plat_env_project_service']),
                    cluster['BackupRetentionPeriod']
                )
            )
        return clusters


def get_instances() -> list:
    client = boto3.client('rds')
    paginator = client.get_paginator('describe_db_instances')
    page_iterator = paginator.paginate()

    instances = []
    for page in page_iterator:
        for cluster in page['DBInstances']:
            instance_type = 'Instance' if 'DBClusterIdentifier' not in cluster else 'Cluster'
            storage_size = cluster['AllocatedStorage'] if cluster['StorageType'] != 'aurora' else get_billed_storage(cluster['DBClusterIdentifier'], cluster['Engine'])
            instances.append(
                (
                    cluster['DBInstanceIdentifier'],
                    instance_type,
                    storage_size,
                    "".join([tag['Value'] for tag in cluster['TagList'] if tag['Key'] == 'plat_env_project_service']),
                    cluster['BackupRetentionPeriod']
                )
            )
        return instances


def get_billed_storage(db_cluster_identifier: str, engine: str) -> float:
    client = boto3.client('cloudwatch')
    end_time = datetime.now()
    start_time = end_time - timedelta(days=30)
    namespace = 'AWS/RDS' if engine != 'docdb' else 'AWS/DocDB'
    response = client.get_metric_statistics(
        Namespace=namespace,
        MetricName='VolumeBytesUsed',
        Dimensions=[
            {
                'Name': 'DBClusterIdentifier',
                'Value': db_cluster_identifier
            },
        ],
        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_docdb_snapshots() -> list:
    client = boto3.client('docdb')
    db_cluster_paginator = client.get_paginator('describe_db_cluster_snapshots')
    db_cluster_page_iterator = db_cluster_paginator.paginate()

    snapshots = []
    for page in db_cluster_page_iterator:
        for db_cluster_snapshot in page['DBClusterSnapshots']:
            result = client.describe_db_cluster_snapshot_attributes(
                DBClusterSnapshotIdentifier=db_cluster_snapshot['DBClusterSnapshotIdentifier']
            )
            snapshots.append(
                (
                    db_cluster_snapshot['DBClusterSnapshotIdentifier'],
                    db_cluster_snapshot['DBClusterIdentifier'],
                    0,
                    "".join([tag['Value'] for tag in db_cluster_snapshot['TagList'] if tag['Key'] == 'plat_env_project_service'])
                )
            )
    return snapshots


def get_rds_snapshots():
    client = boto3.client('rds')
    db_cluster_paginator = client.get_paginator('describe_db_cluster_snapshots')
    db_cluster_page_iterator = db_cluster_paginator.paginate()

    db_paginator = client.get_paginator('describe_db_snapshots')
    db_page_iterator = db_paginator.paginate()

    snapshots = []
    for page in db_cluster_page_iterator:
        for db_cluster_snapshot in page['DBClusterSnapshots']:
            snapshots.append(
                (
                    db_cluster_snapshot['DBClusterSnapshotIdentifier'],
                    db_cluster_snapshot['DBClusterIdentifier'],
                    db_cluster_snapshot['AllocatedStorage'],
                    "".join([tag['Value'] for tag in db_cluster_snapshot['TagList'] if tag['Key'] == 'plat_env_project_service'])
                )
            )

    for page in db_page_iterator:
        for db_snapshot in page['DBSnapshots']:
            snapshots.append(
                (
                    db_snapshot['DBSnapshotIdentifier'],
                    db_snapshot['DBInstanceIdentifier'],
                    db_snapshot['AllocatedStorage'],
                    "".join([tag['Value'] for tag in db_snapshot['TagList'] if tag['Key'] == 'plat_env_project_service'])
                )
            )
    return snapshots


def main(argv):
    with open('rds-instances.csv', mode='w') as rds_instances_file:
        rds_instances_writer = csv.writer(rds_instances_file, delimiter=',',
                                          quotechar='"',
                                          quoting=csv.QUOTE_MINIMAL)
        rds_instances_writer.writerow(
            (
                'DB_INSTANCE',
                'TYPE',
                'CLUSTER_STORAGE_SIZE(AVG/MONTH)',
                'TAG_VAL',
                'BCKP_RETENTION_PERIOD'
            )
        )
        rds_instances_writer.writerows(get_instances())

    with open('rds-snapshots.csv', mode='w') as rds_snapshots_file:
        rds_snapshot_writer = csv.writer(rds_snapshots_file, delimiter=',',
                                         quotechar='"',
                                         quoting=csv.QUOTE_MINIMAL)
        rds_snapshot_writer.writerow(
            (
                'DB_SNAPSHOT',
                'DB_NAME',
                'BCKP_STORAGE_SIZE(AVG/MONTH)',
                'TAG_VAL'
            )
        )
        rds_snapshot_writer.writerows(get_rds_snapshots())


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