{
    "AWSTemplateFormatVersion": "2010-09-09",
    "Metadata": {

    },
    "Parameters" : {
        "BucketName": {
            "Description": "Name of the S3 bucket you will deploy the CSV file to",
            "Type": "String",
            "ConstraintDescription": "must be a valid bucket name."
        },
        "FileName": {
            "Description": "Name of the S3 file (including suffix)",
            "Type": "String",
            "ConstraintDescription": "Valid S3 file name."
        },
        "DynamoDBTableName": {
            "Description": "Name of the dynamoDB table you will use",
            "Type": "String",
            "ConstraintDescription": "must be a valid dynamoDB name."
        }
    },
    "Resources": {
        "DynamoDBTable":{
            "Type": "AWS::DynamoDB::Table",
            "Properties":{
                "TableName": {"Ref" : "DynamoDBTableName"},
                "BillingMode": "PAY_PER_REQUEST",
                "AttributeDefinitions":[
                    {
                        "AttributeName": "uuid",
                        "AttributeType": "S"
                    }
                ],
                "KeySchema":[
                    {
                        "AttributeName": "uuid",
                        "KeyType": "HASH"
                    }
                ],
                "Tags":[
                    {
                        "Key": "Name",
                        "Value": {"Ref" : "DynamoDBTableName"}
                    }
                ]
            }
        },
        "LambdaRole" : {
          "Type" : "AWS::IAM::Role",
          "Properties" : {
            "AssumeRolePolicyDocument": {
              "Version" : "2012-10-17",
              "Statement" : [
                {
                  "Effect" : "Allow",
                  "Principal" : {
                    "Service" : ["lambda.amazonaws.com","s3.amazonaws.com"]
                  },
                  "Action" : [
                    "sts:AssumeRole"
                  ]
                }
              ]
            },
            "Path" : "/",
            "ManagedPolicyArns":["arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole","arn:aws:iam::aws:policy/AWSLambdaInvocation-DynamoDB","arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess"],
            "Policies": [{
                        "PolicyName": "policyname",
                        "PolicyDocument": {
                                 "Version": "2012-10-17",
                                 "Statement": [{
                                    "Effect": "Allow",
                                         "Resource": "*",
                                           "Action": [
                                                      "dynamodb:PutItem",
                                                              "dynamodb:BatchWriteItem"
                                           ]
                                }]
                        }
                }]
          }
       },
        "CsvToDDBLambdaFunction": {
            "Type": "AWS::Lambda::Function",
            "Properties": {
                "Handler": "index.lambda_handler",
                "Role": {
                    "Fn::GetAtt": [
                        "LambdaRole",
                        "Arn"
                    ]
                },
                "Code": {
                    "ZipFile": {
                        "Fn::Join": [
                            "\n",
                            [
                                "import json",
                                "import boto3",
                                "import os",
                                "import csv",
                                "import codecs",
                                "import sys",
                                "",
                                "s3 = boto3.resource('s3')",
                                "dynamodb = boto3.resource('dynamodb')",
                                "",
                                "bucket = os.environ['bucket']",
                                "key = os.environ['key']",
                                "tableName = os.environ['table']",
                                "",
                                "def lambda_handler(event, context):",
                                "",
                                "",
                                "   #get() does not store in memory",
                                "   try:",
                                "       obj = s3.Object(bucket, key).get()['Body']",
                                "   except Exception as error:",
                                "       print(error)",
                                "       print(\"S3 Object could not be opened. Check environment variable. \")",
                                "   try:",
                                "       table = dynamodb.Table(tableName)",
                                "   except Exception as error:",
                                "       print(error)",
                                "       print(\"Error loading DynamoDB table. Check if table was created correctly and environment variable.\")",
                                "",
                                "   batch_size = 100",
                                "   batch = []",
                                "",
                                "   #DictReader is a generator; not stored in memory",
                                "   for row in csv.DictReader(codecs.getreader('utf-8-sig')(obj)):",
                                "      if len(batch) >= batch_size:",
                                "         write_to_dynamo(batch)",
                                "         batch.clear()",
                                "",
                                "      batch.append(row)",
                                "",
                                "   if batch:",
                                "      write_to_dynamo(batch)",
                                "",
                                "   return {",
                                "      'statusCode': 200,",
                                "      'body': json.dumps('Uploaded to DynamoDB Table')",
                                "   }",
                                "",
                                "",
                                "def write_to_dynamo(rows):",
                                "   try:",
                                "      table = dynamodb.Table(tableName)",
                                "   except Exception as error:",
                                "       print(error)",
                                "      print(\"Error loading DynamoDB table. Check if table was created correctly and environment variable.\")",
                                "",
                                "   try:",
                                "      with table.batch_writer() as batch:",
                                "         for i in range(len(rows)):",
                                "            batch.put_item(",
                                "               Item=rows[i]",
                                "            )",
                                "   except Exception as error:",
                                "       print(error)",
                                "      print(\"Error executing batch_writer\")"
                            ]
                        ]
                    }
                },
                "Runtime": "python3.7",
                "Timeout": 900,
                "MemorySize": 3008,
                "Environment" : {
                    "Variables" : {"bucket" : { "Ref" : "BucketName" }, "key" : { "Ref" : "FileName" },"table" : { "Ref" : "DynamoDBTableName" }}
                }
            }
        },

        "S3Bucket": {
            "DependsOn" : ["CsvToDDBLambdaFunction","BucketPermission"],
            "Type": "AWS::S3::Bucket",
            "Properties": {

                "BucketName": {"Ref" : "BucketName"},
                "AccessControl": "BucketOwnerFullControl",
                "NotificationConfiguration":{
                    "LambdaConfigurations":[
                        {
                            "Event":"s3:ObjectCreated:*",
                            "Function":{
                                "Fn::GetAtt": [
                                    "CsvToDDBLambdaFunction",
                                    "Arn"
                                ]
                            }
                        }
                    ]
                }
            }
        },
        "BucketPermission":{
            "Type": "AWS::Lambda::Permission",
            "Properties":{
                "Action": "lambda:InvokeFunction",
                "FunctionName":{"Ref" : "CsvToDDBLambdaFunction"},
                "Principal": "s3.amazonaws.com",
                "SourceAccount": {"Ref":"AWS::AccountId"}
            }
        }
    },
    "Outputs" : {

    }
}