import boto3

from utility import *

# initialize dynamodb instance
db_client = boto3.client(
    "dynamodb",
    aws_access_key_id = aws_access_key_id,
    aws_secret_access_key = aws_secret_access_key,
    region_name = "us-east-1"
    )

'''
dynamodb data operations
'''

# get the list of items from a table in dynamodb
def get_table(table_name:str):
    '''
    get the list of items from table in dynamodb
    
    Args:
        table_name (str): the name of the table in dynamodb
        
    Returns:
        list: a list of items in the table
    '''
    result = db_client.scan(TableName = table_name,AttributesToGet = data_structure[table_name]["fields"])
    return [db_map_to_py_dict(r) for r in result["Items"]]

# add a new item to a table in dynamodb, return error if failed
def post_item(table_name:str,item:dict):
    '''
    add a new item to table in dynamodb, return error if failed
    
    Args:
        table_name (str): the name of the table in dynamodb
        item (dict): the item to be added to the table
        
    Returns:
        dict: the result of the operation'''
    try:
        res = db_client.put_item(
            TableName = table_name,
            Item = py_dict_to_db_map(item)
        )
    except Exception as e:
        return {"Error":e}
    return res

# update an item in a table in dynamodb, return error if failed
def put_item(table_name:str,item:dict):
    '''
    update an item in table in dynamodb, return error if failed
    
    Args:
        table_name (str): the name of the table in dynamodb
        item (dict): the item to be updated to the table
        
    Returns:
        dict: the result of the operation
    '''
    try:
        res = db_client.put_item(
            TableName = table_name,
            Item = py_dict_to_db_map(item)
        )
    except Exception as e:
        return {"Error":e}
    return res

# delete an item in a table in dynamodb, return error if not found.
def delete_item(table_name:str,key:dict):
    '''
    delete an item in table in dynamodb, return error if not found.

    Args:
        table_name (str): the name of the table in dynamodb
        key (dict): the key of the item to be deleted

    Returns:
        dict: the result of the operation
    '''
    try:
        res = db_client.delete_item(
            TableName = table_name,
            Key = py_dict_to_db_map(key)
        )
    except Exception as e:
        return {"Error":e}
    return res

def get_item(table_name:str,key:dict):
    '''
    get an item in table in dynamodb, return error if not found.
    
    Args:
        table_name (str): the name of the table in dynamodb
        key (dict): the key of the item to be deleted
        
    Returns:
        dict: the result of the operation
    '''
    try:
        res = db_client.get_item(
            TableName = table_name,
            Key = py_dict_to_db_map(key)
        )
    except Exception as e:
        return {"Error":e}
    return res

'''
dynamodb structure management
'''
def get_structure(table_name:str):
    '''
    get the structure of a table in dynamodb

    Args:
        table_name (str): the name of the table in dynamodb

    Returns:
        dict: the structure of the table
    '''
    result = db_client.describe_table(TableName = table_name)
    return result["Table"]["AttributeDefinitions"]