import json
import boto3

VOLUME_ID = 'vol-123412341234'
TARGET_ACCOUNT = "123412341234"

print("START")

def lambda_handler(event, context):
    ec2 = boto3.resource('ec2')
    print("Fetching snapshots for volume " + VOLUME_ID)
    volume = ec2.Volume(id=VOLUME_ID)
    snapshots = volume.snapshots.all()
    snapshot_ids = []
    
    for snapshot in snapshots:
        shared = snapshot.describe_attribute(Attribute='createVolumePermission')
        already_shared = False
        
        for i in range(0, len(shared['CreateVolumePermissions'])):
            if 'UserId' in shared['CreateVolumePermissions'][i] and shared['CreateVolumePermissions'][i]['UserId'] == TARGET_ACCOUNT:
                already_shared = True
                break
        
        if not already_shared:
            print("Sharing " + snapshot.id)
            snapshot_ids.append(snapshot.id)
            snapshot.modify_attribute(
                Attribute='createVolumePermission',
                OperationType='add',
                UserIds=[TARGET_ACCOUNT])
   
    return {
        'statusCode': 200,
        'body': json.dumps(snapshot_ids)
    }