import collections
import datetime
import time
import sys


today = datetime.date.today()
today_string = today.strftime('%Y/%m/%d')
delete_after_days = 2  # Delete snapshots after this many days

# Except after Monday (at Tuesday ~1am), since Friday is only 2 'working' days away:
if datetime.date.today().weekday() == 1:
    delete_after_days = delete_after_days + 2

deletion_date = today - datetime.timedelta(days=delete_after_days)
deletion_date_string = deletion_date.strftime('%Y/%m/%d')


ec2 = boto3.client('ec2')
regions = ec2.describe_regions().get('Regions',[] )
all_regions = [region['RegionName'] for region in regions]

def lambda_handler(event, context):
    snapshot_counter = 0
    snap_size_counter = 0
    deletion_counter = 0
    deleted_size_counter = 0

  for region_name in all_regions:
      print('Instances in EC2 Region {0}:'.format(region_name))
      ec2 = boto3.resource('ec2', region_name=region_name)

      # We only want to look through instances with the following tag key value pair: auto_snapshot : true
      instances = ec2.instances.filter(
          Filters=[
              {'Name': 'tag:auto_snapshot', 'Values': ['true']}
                  ]
              )

      volume_ids = []
      for i in instances.all():

          for tag in i.tags:  # Get the name of the instance
              if tag['Key'] == 'Name':
                  name = tag['Value']

          print('Found tagged instance \'{1}\', id: {0}, state: {2}'.format(i.id, name, i.state['Name']))

          vols = i.volumes.all()  # Iterate through each instance's volumes
          for v in vols:
              print('{0} is attached to volume {1}, proceeding to snapshot'.format(name, v.id))
              volume_ids.extend(v.id)
              snapshot = v.create_snapshot(
                  Description = 'AutoSnapshot of {0}, on volume {1} - Created {2}'.format(name, v.id, today_string),
                  )
              snapshot.create_tags(  # Add the following tags to the new snapshot
                  Tags = [
                      {
                          'Key': 'auto_snap',
                          'Value': 'true'
                      },
                      {
                          'Key': 'volume',
                          'Value': v.id
                      },
                      {
                          'Key': 'CreatedOn',
                          'Value': today_string
                      },
                       {
                          'Key': 'Name',
                          'Value': '{} autosnap'.format(name)
                      }
                  ]
              )
              print('Snapshot completed')
              snapshot_counter += 1
              snap_size_counter += snapshot.volume_size

              # Now iterate through snapshots which were made by autsnap
              snapshots = ec2.snapshots.filter(
                  Filters=[
                      {'Name': 'tag:auto_snap', 'Values': ['true']
                      }
                  ]
              )


              print('Checking for out of date snapshots for instance {0}...'.format(name))
              for snap in snapshots:
                  can_delete = False
                  for tag in snap.tags: # Use these if statements to get each snapshot's
                                        # cleated on date, name and auto_snap tag
                      if tag['Key'] == 'CreatedOn':
                          created_on_string = tag['Value']
                      if tag['Key'] == 'auto_snap':
                          if tag['Value'] == 'true':
                              can_delete = True
                      if tag['Key'] == 'Name':
                          name = tag['Value']
                  created_on = datetime.datetime.strptime(created_on_string, '%Y/%m/%d').date()

                  if created_on <= deletion_date and can_delete == True:
                      print('Snapshot id {0}, ({1}) from {2} is {3} or more days old... deleting'.format(snap.id, name, created_on_string, delete_after_days))
                      deleted_size_counter += snap.volume_size
                      snap.delete()
                      deletion_counter += 1

  print('   Made {0} snapshots totalling {1} GB\
        Deleted {2} snapshots totalling {3} GB'.format(snapshot_counter, snap_size_counter, deletion_counter, deleted_size_counter))
  return