import os
import shutil
from collections.abc import Generator
from pathlib import Path

from flask import current_app

from configs import dify_config
from extensions.storage.base_storage import BaseStorage


class LocalFsStorage(BaseStorage):
    """Implementation for local filesystem storage."""

    def __init__(self):
        super().__init__()
        folder = dify_config.STORAGE_LOCAL_PATH
        if not os.path.isabs(folder):
            folder = os.path.join(current_app.root_path, folder)
        self.folder = folder

    def save(self, filename, data):
        if not self.folder or self.folder.endswith("/"):
            filename = self.folder + filename
        else:
            filename = self.folder + "/" + filename

        folder = os.path.dirname(filename)
        os.makedirs(folder, exist_ok=True)

        Path(os.path.join(os.getcwd(), filename)).write_bytes(data)

    def load_once(self, filename: str) -> bytes:
        if not self.folder or self.folder.endswith("/"):
            filename = self.folder + filename
        else:
            filename = self.folder + "/" + filename

        if not os.path.exists(filename):
            raise FileNotFoundError("File not found")

        data = Path(filename).read_bytes()
        return data

    def load_stream(self, filename: str) -> Generator:
        def generate(filename: str = filename) -> Generator:
            if not self.folder or self.folder.endswith("/"):
                filename = self.folder + filename
            else:
                filename = self.folder + "/" + filename

            if not os.path.exists(filename):
                raise FileNotFoundError("File not found")

            with open(filename, "rb") as f:
                while chunk := f.read(4096):  # Read in chunks of 4KB
                    yield chunk

        return generate()

    def download(self, filename, target_filepath):
        if not self.folder or self.folder.endswith("/"):
            filename = self.folder + filename
        else:
            filename = self.folder + "/" + filename

        if not os.path.exists(filename):
            raise FileNotFoundError("File not found")

        shutil.copyfile(filename, target_filepath)

    def exists(self, filename):
        if not self.folder or self.folder.endswith("/"):
            filename = self.folder + filename
        else:
            filename = self.folder + "/" + filename

        return os.path.exists(filename)

    def delete(self, filename):
        if not self.folder or self.folder.endswith("/"):
            filename = self.folder + filename
        else:
            filename = self.folder + "/" + filename
        if os.path.exists(filename):
            os.remove(filename)