import os
import uuid
import json
import argparse
import base64

import boto3


AUTH_KEY_PARAM_NAME = '/todo-sample-app/auth-key'
TABLES = {
    'app': {
        'prefix': 'todo-app',
        'env_var': 'APP_TABLE_NAME',
        'hash_key': 'username',
        'range_key': 'uid'
    },
    'users': {
        'prefix': 'users-app',
        'env_var': 'USERS_TABLE_NAME',
        'hash_key': 'username',
    }
}


def create_table(table_name_prefix, hash_key, range_key=None):
    table_name = '%s-%s' % (table_name_prefix, str(uuid.uuid4()))
    client = boto3.client('dynamodb')
    key_schema = [
        {
            'AttributeName': hash_key,
            'KeyType': 'HASH',
        }
    ]
    attribute_definitions = [
        {
            'AttributeName': hash_key,
            'AttributeType': 'S',
        }
    ]
    if range_key is not None:
        key_schema.append({'AttributeName': range_key, 'KeyType': 'RANGE'})
        attribute_definitions.append(
            {'AttributeName': range_key, 'AttributeType': 'S'})
    client.create_table(
        TableName=table_name,
        KeySchema=key_schema,
        AttributeDefinitions=attribute_definitions,
        ProvisionedThroughput={
            'ReadCapacityUnits': 5,
            'WriteCapacityUnits': 5,
        }
    )
    waiter = client.get_waiter('table_exists')
    waiter.wait(TableName=table_name, WaiterConfig={'Delay': 1})
    return table_name


def record_as_env_var(key, value, stage):
    with open(os.path.join('.chalice', 'config.json')) as f:
        data = json.load(f)
        data['stages'].setdefault(stage, {}).setdefault(
            'environment_variables', {}
        )[key] = value
    with open(os.path.join('.chalice', 'config.json'), 'w') as f:
        serialized = json.dumps(data, indent=2, separators=(',', ': '))
        f.write(serialized + '\n')


def _already_in_config(env_var, stage):
    with open(os.path.join('.chalice', 'config.json')) as f:
        return env_var in json.load(f)['stages'].get(
            stage, {}).get('environment_variables', {})


def create_auth_key_if_needed(stage):
    ssm = boto3.client('ssm')
    try:
        ssm.get_parameter(Name=AUTH_KEY_PARAM_NAME)
    except ssm.exceptions.ParameterNotFound:
        print(f"Generating auth key.")
        kms = boto3.client('kms')
        random_bytes = kms.generate_random(NumberOfBytes=32)['Plaintext']
        encoded_random_bytes = base64.b64encode(random_bytes).decode()
        ssm.put_parameter(Name=AUTH_KEY_PARAM_NAME, Value=encoded_random_bytes,
                          Type='SecureString')


def create_resources(args):
    for table_config in TABLES.values():
        # We assume if it a value is recorded in the Chalice config
        # file, the table already exists.
        if _already_in_config(table_config['env_var'], args.stage):
            continue
        print(f"Creating table: {table_config['prefix']}")
        table_name = create_table(
            table_config['prefix'], table_config['hash_key'],
            table_config.get('range_key')
        )
        record_as_env_var(table_config['env_var'], table_name, args.stage)
    create_auth_key_if_needed(args.stage)


def cleanup_resources(args):
    ddb = boto3.client('dynamodb')
    ssm = boto3.client('ssm')
    with open(os.path.join('.chalice', 'config.json')) as f:
        config = json.load(f)
        env_vars = config['stages'].get(args.stage, {}).get(
            'environment_variables', {})
        for key in list(env_vars):
            value = env_vars.pop(key)
            if key.endswith('_TABLE_NAME'):
                print(f"Deleting table: {value}")
                ddb.delete_table(TableName=value)
        if not env_vars:
            del config['stages'][args.stage]['environment_variables']
    try:
        print(f"Deleting SSM param: {AUTH_KEY_PARAM_NAME}")
        ssm.delete_parameter(Name=AUTH_KEY_PARAM_NAME)
    except Exception:
        pass

    with open(os.path.join('.chalice', 'config.json'), 'w') as f:
        serialized = json.dumps(config, indent=2, separators=(',', ': '))
        f.write(serialized + '\n')

    print("Resources deleted.  If you haven't already, be "
          "sure to run 'chalice delete' to delete your Chalice application.")


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('-s', '--stage', default='dev')
    parser.add_argument('-c', '--cleanup', action='store_true')
    # app - stores the todo items
    # users - stores the user data.
    args = parser.parse_args()
    if args.cleanup:
        cleanup_resources(args)
    else:
        create_resources(args)


if __name__ == '__main__':
    main()