import pandas as pd
import os
from typing import Protocol
import boto3
from io import BytesIO, StringIO
from core.CloudClient import BotoClient


def read_parquet_from_s3(client, bucket_name, file_key):
    """
    Read a CSV file from S3 using boto3 and pandas.

    :param bucket_name: Name of the S3 bucket.
    :param file_key: Key of the file (including directory path within the bucket).
    :param aws_access_key_id: AWS Access Key ID
    :param aws_secret_access_key: AWS Secret Access Key
    :return: DataFrame containing the CSV data.
    """

    # Get the object
    s3_object = client.get_object(Bucket=bucket_name, Key=file_key)

    # Read the CSV body into a DataFrame
    csv_body = s3_object["Body"].read()
    df = pd.read_parquet(BytesIO(csv_body))

    return df


def read_csv_from_s3(client, bucket_name, file_key, index_col):
    """
    Read a CSV file from S3 using boto3 and pandas.

    :param bucket_name: Name of the S3 bucket.
    :param file_key: Key of the file (including directory path within the bucket).
    :param aws_access_key_id: AWS Access Key ID
    :param aws_secret_access_key: AWS Secret Access Key
    :return: DataFrame containing the CSV data.
    """

    # Get the object
    s3_object = client.get_object(Bucket=bucket_name, Key=file_key)

    # Read the CSV body into a DataFrame
    csv_body = s3_object["Body"].read().decode("utf-8")
    df = pd.read_csv(StringIO(csv_body), index_col=index_col)

    return df


class DataLoader(Protocol):
    """
    Interface for all DataLoader classes
    """

    @staticmethod
    def load(
        client: BotoClient, filepath: str, index_col: str | None = None
    ) -> pd.DataFrame | None:
        """
        Loading data from the relevant source
        """


class LocalDataLoader:
    """
    Implements the DataLoader Protocol for local files
    """

    @staticmethod
    def load(
        client: BotoClient, filepath: str, index_col: str | None = None
    ) -> pd.DataFrame:

        if not os.path.exists(filepath):
            raise FileNotFoundError(f"File not found: {filepath}")

        if filepath.endswith(".parquet"):
            df = pd.read_parquet(filepath)
            if index_col is not None:
                df = df.set_index(index_col)
        elif filepath.endswith(".csv"):
            df = pd.read_csv(filepath, index_col=index_col)
        else:
            raise ValueError(f"File format not supported for file: {filepath}")

        return df


class S3DataLoader:
    """
    Implements the DataLoader Protocol for s3 files, hosting locally in a mocked service
    """

    @staticmethod
    def load(
        client: BotoClient, filepath: str, index_col: str | None = None
    ) -> pd.DataFrame:

        if not filepath.startswith("s3://"):
            filepath = "s3://" + filepath

        filepath_split = filepath.split("s3://")[-1].split("/", 1)
        bucket = filepath_split[0]
        key = filepath_split[1]

        if filepath.endswith(".parquet"):
            df = read_parquet_from_s3(
                client=client.client, bucket_name=bucket, file_key=key
            )
            if index_col is not None:
                df = df.set_index(index_col)
        elif filepath.endswith(".csv"):
            df = read_csv_from_s3(
                client=client.client,
                bucket_name=bucket,
                file_key=key,
                index_col=index_col,
            )
        else:
            raise ValueError(f"File format not supported for file: {filepath}")

        return df


def dataloader_factory(runtime_environment: str | None = None) -> DataLoader:
    """
    Use factory pattern to determine which loading method we use
    """

    if runtime_environment is None:
        runtime_environment = "local"

    dataloader_types = {
        "local": LocalDataLoader(),
        "local-mock": S3DataLoader(),
        "dev": S3DataLoader(),
        "staging": S3DataLoader(),
        "prod": S3DataLoader(),
    }

    if runtime_environment not in dataloader_types:
        raise ValueError("Incorrect runtime environment specified")

    return dataloader_types[runtime_environment]