"""A simple helper for managing downloaded files.

A organizer is bound to a single directory.
"""

import filecmp
import logging
import shutil
from pathlib import Path, PurePath
from typing import List, Set

from .location import Location
from .logging import PrettyLogger
from .utils import prompt_yes_no

LOGGER = logging.getLogger(__name__)
PRETTY = PrettyLogger(LOGGER)


class FileAcceptException(Exception):
    """An exception while accepting a file."""


class Organizer(Location):
    """A helper for managing downloaded files."""

    new_files = []
    modified_files = []

    def __init__(self, path: Path):
        """Create a new organizer for a given path."""
        super().__init__(path)
        self._known_files: Set[Path] = set()

        # Keep the root dir
        self._known_files.add(path.resolve())

    def accept_file(self, src: Path, dst: PurePath) -> None:
        """Move a file to this organizer and mark it."""
        src_absolute = src.resolve()
        dst_absolute = self.resolve(dst)

        if not src_absolute.exists():
            raise FileAcceptException("Source file does not exist")

        if not src_absolute.is_file():
            raise FileAcceptException("Source is a directory")

        LOGGER.debug("Copying %s to %s", src_absolute, dst_absolute)

        if self._is_marked(dst):
            PRETTY.warning(f"File {str(dst_absolute)!r} was already written!")
            if not prompt_yes_no(f"Overwrite file?", default=False):
                PRETTY.ignored_file(dst_absolute, "file was written previously")
                return

        # Destination file is directory
        if dst_absolute.exists() and dst_absolute.is_dir():
            if prompt_yes_no(f"Overwrite folder {dst_absolute} with file?", default=False):
                shutil.rmtree(dst_absolute)
            else:
                PRETTY.warning(f"Could not add file {str(dst_absolute)!r}")
                return

        # Destination file exists
        if dst_absolute.exists() and dst_absolute.is_file():
            if filecmp.cmp(str(src_absolute), str(dst_absolute), shallow=False):
                # Bail out, nothing more to do
                PRETTY.ignored_file(dst_absolute, "same file contents")
                self.mark(dst)
                # Touch it to update the timestamp
                dst_absolute.touch()
                return

            self.modified_files.append(dst_absolute)
            PRETTY.modified_file(dst_absolute)
        else:
            self.new_files.append(dst_absolute)
            PRETTY.new_file(dst_absolute)

        # Create parent dir if needed
        dst_parent_dir: Path = dst_absolute.parent
        dst_parent_dir.mkdir(exist_ok=True, parents=True)

        # Move file
        shutil.move(str(src_absolute), str(dst_absolute))

        self.mark(dst)

    def mark(self, path: PurePath) -> None:
        """Mark a file as used so it will not get cleaned up."""
        absolute_path = self.resolve(path)
        self._known_files.add(absolute_path)
        LOGGER.debug("Tracked %s", absolute_path)

    def _is_marked(self, path: PurePath) -> bool:
        """
        Checks whether a file is marked.
        """
        absolute_path = self.resolve(path)
        return absolute_path in self._known_files

    def cleanup(self) -> None:
        """Remove all untracked files in the organizer's dir."""
        LOGGER.debug("Deleting all untracked files...")

        self._cleanup(self.path)

    def _cleanup(self, start_dir: Path) -> None:
        paths: List[Path] = list(start_dir.iterdir())

        # Recursively clean paths
        for path in paths:
            if path.is_dir():
                self._cleanup(path)
            else:
                if path.resolve() not in self._known_files:
                    self._delete_file_if_confirmed(path)

        # Delete dir if it was empty and untracked
        dir_empty = len(list(start_dir.iterdir())) == 0
        if start_dir.resolve() not in self._known_files and dir_empty:
            start_dir.rmdir()

    @staticmethod
    def _delete_file_if_confirmed(path: Path) -> None:
        prompt = f"Do you want to delete {path}"

        if prompt_yes_no(prompt, False):
            path.unlink()