import os
import boto3
import mimetypes
import json
import requests
import subprocess
import tempfile
import pathlib
import shutil

s3 = boto3.resource('s3')
defaultContentType = 'application/octet-stream'

def resource_handler(event, context):
  print(event)
  try:
    target_bucket = event['ResourceProperties']['TargetBucket']
    lambda_src = os.getcwd()
    acl = event['ResourceProperties']['Acl']
    cacheControl = 'max-age=' + \
        event['ResourceProperties']['CacheControlMaxAge']
    print(event['RequestType'])
    if event['RequestType'] == 'Create' or event['RequestType'] == 'Update':
      
      if 'Substitutions' in event['ResourceProperties'].keys():
        temp_dir = os.path.join(tempfile.mkdtemp(), context.aws_request_id)
        apply_substitutions(event['ResourceProperties']['Substitutions'], temp_dir)
        lambda_src = temp_dir

      print('uploading')
      upload(lambda_src, target_bucket, acl, cacheControl)
    elif event['RequestType'] == 'Delete':
      delete(lambda_src, target_bucket, s3)
    else:
      print('ignoring')

    if not lambda_src == os.getcwd():
      print('removing temporary', lambda_src)
      shutil.rmtree(lambda_src)
    send_result(event)

  except Exception as err:
    send_error(event, err)
  return event


def upload(lambda_src, target_bucket, acl, cacheControl):
  for folder, subs, files in os.walk(lambda_src):
    for filename in files:
        source_file_path = os.path.join(folder, filename)
        destination_s3_key = os.path.relpath(source_file_path, lambda_src)
        contentType, encoding = mimetypes.guess_type(source_file_path)
        upload_file(source_file_path, target_bucket,
                    destination_s3_key, s3, acl, cacheControl, contentType)


def upload_file(source, bucket, key, s3lib, acl, cacheControl, contentType):
    print('uploading from {} {} {}'.format(source, bucket, key))
    contentType = contentType or defaultContentType
    s3lib.Object(bucket, key).put(ACL=acl, Body=open(source, 'rb'),
                                  CacheControl=cacheControl, ContentType=contentType)

def delete(lambda_src, target_bucket, s3lib):
  for folder, subs, files in os.walk(lambda_src):
    for filename in files:
        source_file_path = os.path.join(folder, filename)
        destination_s3_key = os.path.relpath(source_file_path, lambda_src)
        print('deleting file {} from {}'.format(destination_s3_key, target_bucket))
        s3lib.Object(target_bucket, destination_s3_key).delete()

def send_result(event):
  response_body = json.dumps({
    'Status': 'SUCCESS',
    'PhysicalResourceId': get_physical_resource_id(event),
    'StackId': event['StackId'],
    'RequestId': event['RequestId'],
    'LogicalResourceId': event['LogicalResourceId']
  })
  print(response_body)
  requests.put(event['ResponseURL'], data=response_body)


def send_error(event, error):
  response_body = json.dumps({
    'Status': 'FAILED',
    'Reason': str(error),
    'PhysicalResourceId': get_physical_resource_id(event),
    'StackId': event['StackId'],
    'RequestId': event['RequestId'],
    'LogicalResourceId': event['LogicalResourceId']
  })
  print(response_body)
  requests.put(event['ResponseURL'], data=response_body)

def get_physical_resource_id(event):
  if 'PhysicalResourceId' in event.keys():
    return event['PhysicalResourceId']
  else:
    return event['RequestId']

def apply_substitutions(substitutions, temp_dir):
  if not 'Values' in substitutions.keys():
    raise ValueError('Substitutions must contain Values')

  if not isinstance(substitutions['Values'], dict):
    raise ValueError('Substitutions.Values must be an Object')

  if len(substitutions['Values']) < 1:
    raise ValueError('Substitutions.Values must not be empty')

  if not 'FilePattern' in substitutions.keys():
    raise ValueError('Substitutions must contain FilePattern')

  if not isinstance(substitutions['FilePattern'], str):
    raise ValueError('Substitutions.FilePattern must be a String')

  if len(substitutions['FilePattern']) < 1:
    raise ValueError('Substitutions.FilePattern must not be empty')

  values = substitutions['Values']
  file_pattern = substitutions['FilePattern']

  subprocess.run(['cp', '-r', os.getcwd(), temp_dir])

  for full_path in pathlib.Path(temp_dir).glob(file_pattern):
    replace_with_command = lambda key: 's/\\${%s}/%s/g'% (sed_escape(key), sed_escape(values[key]))
    replacements = list(map(replace_with_command, values.keys()))
    sed_script = ';'.join(replacements)
    subprocess.run(['sed', sed_script, '-i', str(full_path)], cwd=tempfile.gettempdir(), check=True)

def sed_escape(text):
 return text.replace('/', '\\/')