from __future__ import annotations

import threading
from pathlib import Path

from backend.app.db.task_repository import TaskRepository
from backend.app.fs.filesystem_adapter import FilesystemAdapter


class TaskRunner:
    def __init__(self, repository: TaskRepository, filesystem: FilesystemAdapter):
        self._repository = repository
        self._filesystem = filesystem

    def enqueue_copy_file(self, task_id: str, source: str, destination: str, total_bytes: int) -> None:
        thread = threading.Thread(
            target=self._run_copy_file,
            args=(task_id, source, destination, total_bytes),
            daemon=True,
        )
        thread.start()

    def enqueue_move_file(
        self,
        task_id: str,
        source: str,
        destination: str,
        total_bytes: int,
        same_root: bool,
    ) -> None:
        thread = threading.Thread(
            target=self._run_move_file,
            args=(task_id, source, destination, total_bytes, same_root),
            daemon=True,
        )
        thread.start()

    def enqueue_move_directory(self, task_id: str, source: str, destination: str) -> None:
        thread = threading.Thread(
            target=self._run_move_directory,
            args=(task_id, source, destination),
            daemon=True,
        )
        thread.start()

    def enqueue_move_batch(self, task_id: str, items: list[dict[str, str]]) -> None:
        thread = threading.Thread(
            target=self._run_move_batch,
            args=(task_id, items),
            daemon=True,
        )
        thread.start()

    def _run_copy_file(self, task_id: str, source: str, destination: str, total_bytes: int) -> None:
        self._repository.mark_running(
            task_id=task_id,
            done_bytes=0,
            total_bytes=total_bytes,
            current_item=source,
        )

        progress = {"done": 0}

        def on_progress(done_bytes: int) -> None:
            progress["done"] = done_bytes
            self._repository.update_progress(
                task_id=task_id,
                done_bytes=done_bytes,
                total_bytes=total_bytes,
                current_item=source,
            )

        try:
            self._filesystem.copy_file(source=source, destination=destination, on_progress=on_progress)
            self._repository.mark_completed(
                task_id=task_id,
                done_bytes=total_bytes,
                total_bytes=total_bytes,
            )
        except OSError as exc:
            self._repository.mark_failed(
                task_id=task_id,
                error_code="io_error",
                error_message=str(exc),
                failed_item=source,
                done_bytes=progress["done"],
                total_bytes=total_bytes,
            )

    def _run_move_file(
        self,
        task_id: str,
        source: str,
        destination: str,
        total_bytes: int,
        same_root: bool,
    ) -> None:
        self._repository.mark_running(
            task_id=task_id,
            done_bytes=0,
            total_bytes=total_bytes,
            current_item=source,
        )

        progress = {"done": 0}

        try:
            if same_root:
                self._filesystem.move_file(source=source, destination=destination)
                self._repository.mark_completed(
                    task_id=task_id,
                    done_bytes=total_bytes,
                    total_bytes=total_bytes,
                )
                return

            def on_progress(done_bytes: int) -> None:
                progress["done"] = done_bytes
                self._repository.update_progress(
                    task_id=task_id,
                    done_bytes=done_bytes,
                    total_bytes=total_bytes,
                    current_item=source,
                )

            self._filesystem.copy_file(source=source, destination=destination, on_progress=on_progress)
            self._filesystem.delete_file(Path(source))
            self._repository.mark_completed(
                task_id=task_id,
                done_bytes=total_bytes,
                total_bytes=total_bytes,
            )
        except OSError as exc:
            self._repository.mark_failed(
                task_id=task_id,
                error_code="io_error",
                error_message=str(exc),
                failed_item=source,
                done_bytes=progress["done"],
                total_bytes=total_bytes,
            )

    def _run_move_directory(self, task_id: str, source: str, destination: str) -> None:
        self._repository.mark_running(
            task_id=task_id,
            done_items=0,
            total_items=1,
            current_item=source,
        )

        try:
            self._filesystem.move_directory(source=source, destination=destination)
            self._repository.mark_completed(
                task_id=task_id,
                done_items=1,
                total_items=1,
            )
        except OSError as exc:
            self._repository.mark_failed(
                task_id=task_id,
                error_code="io_error",
                error_message=str(exc),
                failed_item=source,
                done_items=0,
                total_items=1,
            )

    def _run_move_batch(self, task_id: str, items: list[dict[str, str]]) -> None:
        total_items = len(items)
        current_item = items[0]["source"] if items else None
        self._repository.mark_running(
            task_id=task_id,
            done_items=0,
            total_items=total_items,
            current_item=current_item,
        )

        completed_items = 0
        for index, item in enumerate(items):
            source = item["source"]
            destination = item["destination"]
            try:
                if item["kind"] == "directory":
                    self._filesystem.move_directory(source=source, destination=destination)
                else:
                    self._filesystem.move_file(source=source, destination=destination)
                completed_items = index + 1
                next_item = items[index + 1]["source"] if index + 1 < total_items else source
                self._repository.update_progress(
                    task_id=task_id,
                    done_items=completed_items,
                    total_items=total_items,
                    current_item=next_item,
                )
            except OSError as exc:
                self._repository.mark_failed(
                    task_id=task_id,
                    error_code="io_error",
                    error_message=str(exc),
                    failed_item=source,
                    done_bytes=None,
                    total_bytes=None,
                    done_items=completed_items,
                    total_items=total_items,
                )
                return

        self._repository.mark_completed(
            task_id=task_id,
            done_items=total_items,
            total_items=total_items,
        )