import sys
import pymysql
import boto3
import botocore
import json
import os
import random
import time
import requests
from botocore.exceptions import ClientError

# rds settings
rds_host = os.environ['RDS_HOST']
name = os.environ['RDS_USERNAME']
db_name = os.environ['RDS_DB_NAME']
secret_name = os.environ['SECRET_NAME']

SUCCESS = "SUCCESS"
FAILED = "FAILED"

my_session = boto3.session.Session()
region_name = my_session.region_name
conn = None

# Get the service resource.
lambdaClient = boto3.client('lambda')
dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table(os.environ['DDB_TABLE_NAME'])


def openConnection():
    global conn
    password = "None"
    # Create a Secrets Manager client
    session = boto3.session.Session()
    client = session.client(
        service_name='secretsmanager',
        region_name=region_name
    )
    
    # In this sample we only handle the specific exceptions for the 'GetSecretValue' API.
    # See https://docs.aws.amazon.com/secretsmanager/latest/apireference/API_GetSecretValue.html
    # We rethrow the exception by default.
    
    try:
        get_secret_value_response = client.get_secret_value(
            SecretId=secret_name
        )
        print(get_secret_value_response)
    except ClientError as e:
        print(e)
        if e.response['Error']['Code'] == 'DecryptionFailureException':
            # Secrets Manager can't decrypt the protected secret text using the provided KMS key.
            # Deal with the exception here, and/or rethrow at your discretion.
            raise e
        elif e.response['Error']['Code'] == 'InternalServiceErrorException':
            # An error occurred on the server side.
            # Deal with the exception here, and/or rethrow at your discretion.
            raise e
        elif e.response['Error']['Code'] == 'InvalidParameterException':
            # You provided an invalid value for a parameter.
            # Deal with the exception here, and/or rethrow at your discretion.
            raise e
        elif e.response['Error']['Code'] == 'InvalidRequestException':
            # You provided a parameter value that is not valid for the current state of the resource.
            # Deal with the exception here, and/or rethrow at your discretion.
            raise e
        elif e.response['Error']['Code'] == 'ResourceNotFoundException':
            # We can't find the resource that you asked for.
            # Deal with the exception here, and/or rethrow at your discretion.
            raise e
    else:
        # Decrypts secret using the associated KMS CMK.
        # Depending on whether the secret is a string or binary, one of these fields will be populated.
        if 'SecretString' in get_secret_value_response:
            secret = get_secret_value_response['SecretString']
            j = json.loads(secret)
            password = j['password']
        else:
            decoded_binary_secret = base64.b64decode(get_secret_value_response['SecretBinary'])
            print("password binary:" + decoded_binary_secret)
            password = decoded_binary_secret.password    
        
    try:
        #print("Opening Connection")
        if(conn is None):
            conn = pymysql.connect(
                host=rds_host, user=name, password=password, database=db_name, connect_timeout=5)
        elif (not conn.open):
            # print(conn.open)
            conn = pymysql.connect(
                host=rds_host, user=name, password=password, database=db_name, connect_timeout=5)

    except Exception as e:
        print (e)
        print("ERROR: Unexpected error: Could not connect to MySql instance.")
        raise e


# CloudFormation uses a pre-signed S3 URL to receive the response back from the custom resources managed by it. This is a simple function
# which shall be used to send the response back to CFN custom resource by performing PUT request to the pre-signed S3 URL.
def sendResponse(event, context, responseStatus, responseData, physicalResourceId):
    responseUrl = event['ResponseURL']

    # print responseUrl

    responseBody = {}
    responseBody['Status'] = responseStatus
    responseBody['Reason'] = 'See the details in CloudWatch Log Stream: ' + \
        context.log_stream_name
    responseBody['PhysicalResourceId'] = context.log_stream_name
    responseBody['StackId'] = event['StackId']
    responseBody['RequestId'] = event['RequestId']
    responseBody['LogicalResourceId'] = event['LogicalResourceId']
    responseBody['Data'] = responseData

    json_responseBody = json.dumps(responseBody)

    print ("Response body:\n" , json_responseBody)

    headers = {
        'content-type': '',
        'content-length': str(len(json_responseBody))
    }

    try:
        response = requests.put(responseUrl,
                                data=json_responseBody,
                                headers=headers)
        print ("Status code: " , response.reason)
    except Exception as e:
        print ("send(..) failed executing requests.put(..): " , str(e))


def lambda_handler(event, context):

    # For Delete requests, immediately send a SUCCESS response.
    print (event)

    json_requestBody = json.dumps(event)

    print ("Request body:\n", json_requestBody)

    responseData = {}
    responseStatus = SUCCESS
    if event['RequestType'] == 'Delete':
        sendResponse(event, context, responseStatus, responseData, None)
        return True

    try:
        
        # insert test data in RDS instance
        openConnection()

        with conn.cursor() as cur:
             # create table
            cur.execute(
                "Create Table  if not exists Employees (EmployeeID int AUTO_INCREMENT Primary Key, FirstName varchar(50), LastName varchar(50))")

            # insert sample data
            cur.execute(
                "Insert into Employees (EmployeeID, FirstName, LastName) Values (null, \"John\", \"Smith\")")
            cur.execute(
                "Insert into Employees (EmployeeID, FirstName, LastName) Values (null, \"Jane\", \"Doe\")")
            cur.execute(
                "Insert into Employees (EmployeeID, FirstName, LastName) Values (null, \"Bob\", \"Rogers\")")
            conn.commit()

            print ('Created table Employees and inserted 3 rows.')

        # insert a row into DynamoDB
        table.put_item(
            Item={
                'RDBMSName': 'Prod_MySQL',
                'MaxConnections': 50,
                'RemainingConnections': 50
            },
            ConditionExpression='attribute_not_exists(RDBMSName)'
        )
        print ('Insert one item in ' + os.environ['DDB_TABLE_NAME'])
    except Exception as e:
        # Error while opening connection or processing
        print(e)
        responseStatus = FAILED
    finally:
        #print("Closing Connection")
        if(conn is not None and conn.open):
            conn.close()
        # send response back to CFN
        sendResponse(event, context, responseStatus, responseData, None)
    return True