"""
项目导出业务服务
"""
import asyncio
import threading
import time
import uuid
import zipfile
from pathlib import Path

from fastapi import HTTPException

from app.services.storage import storage_service


class ProjectExportService:
    """管理项目导出任务及其文件打包流程。"""

    def __init__(self, ttl_seconds: int = 3600):
        self.ttl_seconds = ttl_seconds
        self._tasks: dict[str, dict] = {}
        self._tasks_lock = threading.Lock()

    @staticmethod
    def _build_zip_filename(project_name: str) -> str:
        safe_project_name = project_name.replace("/", "_").replace("\\", "_")
        return f"{safe_project_name}.zip"

    @staticmethod
    def _serialize_task(task: dict) -> dict:
        total_files = task.get("total_files", 0) or 0
        processed_files = task.get("processed_files", 0) or 0
        progress = task.get("progress")
        if progress is None:
            progress = int(processed_files * 100 / total_files) if total_files else 0

        return {
            "task_id": task["task_id"],
            "project_id": task["project_id"],
            "status": task["status"],
            "message": task.get("message", ""),
            "progress": progress,
            "processed_files": processed_files,
            "total_files": total_files,
            "file_count": total_files,
            "zip_filename": task["zip_filename"],
            "error": task.get("error"),
            "created_at": task.get("created_at"),
            "completed_at": task.get("completed_at"),
        }

    def _remove_task(self, task_id: str) -> None:
        with self._tasks_lock:
            task = self._tasks.pop(task_id, None)

        if not task:
            return

        file_path = task.get("file_path")
        if file_path:
            try:
                Path(file_path).unlink(missing_ok=True)
            except Exception:
                pass

    def cleanup_expired_tasks(self) -> None:
        now = time.time()
        expired_task_ids = []

        with self._tasks_lock:
            for task_id, task in self._tasks.items():
                created_at = task.get("created_at", now)
                completed_at = task.get("completed_at")
                if completed_at and now - completed_at > self.ttl_seconds:
                    expired_task_ids.append(task_id)
                elif task.get("status") == "failed" and now - created_at > self.ttl_seconds:
                    expired_task_ids.append(task_id)

        for task_id in expired_task_ids:
            self._remove_task(task_id)

    def _update_task(self, task_id: str, **fields) -> None:
        with self._tasks_lock:
            task = self._tasks.get(task_id)
            if task:
                task.update(fields)

    def get_task_or_404(self, task_id: str) -> dict:
        self.cleanup_expired_tasks()

        with self._tasks_lock:
            task = self._tasks.get(task_id)

        if not task:
            raise HTTPException(status_code=404, detail="导出任务不存在或已过期")

        return task

    def get_owned_task_or_404(self, project_id: int, task_id: str, user_id: int) -> dict:
        task = self.get_task_or_404(task_id)
        if task["project_id"] != project_id or task["user_id"] != user_id:
            raise HTTPException(status_code=404, detail="导出任务不存在")
        return task

    def cleanup_task(self, task_id: str) -> None:
        self._remove_task(task_id)

    def serialize_task(self, task: dict) -> dict:
        return self._serialize_task(task)

    def _run_export_task(self, task_id: str, source_dir: Path) -> None:
        try:
            self._update_task(
                task_id,
                status="scanning",
                progress=0,
                message="正在统计导出文件...",
                processed_files=0,
                total_files=0,
            )

            files = [file_path for file_path in source_dir.rglob("*") if file_path.is_file()]
            total_files = len(files)

            storage_service.temp_root.mkdir(parents=True, exist_ok=True)
            zip_path = storage_service.temp_root / f"{task_id}.zip"

            self._update_task(
                task_id,
                status="zipping",
                progress=0 if total_files else 100,
                message="正在打包项目文件...",
                total_files=total_files,
                file_path=str(zip_path),
            )

            with zipfile.ZipFile(zip_path, "w", zipfile.ZIP_DEFLATED) as zip_file:
                for index, file_path in enumerate(files, start=1):
                    arcname = file_path.relative_to(source_dir)
                    zip_file.write(file_path, arcname)
                    progress = int(index * 100 / total_files) if total_files else 100
                    self._update_task(
                        task_id,
                        processed_files=index,
                        progress=progress,
                    )

            self._update_task(
                task_id,
                status="completed",
                progress=100,
                message="项目导出已完成",
                completed_at=time.time(),
            )
        except Exception as exc:
            self._update_task(
                task_id,
                status="failed",
                message="项目导出失败",
                error=str(exc),
                completed_at=time.time(),
            )
            task = self.get_task_or_404(task_id)
            file_path = task.get("file_path")
            if file_path:
                try:
                    Path(file_path).unlink(missing_ok=True)
                except Exception:
                    pass
                self._update_task(task_id, file_path=None)

    async def start_export(self, project_id: int, user_id: int, project_name: str, source_dir: Path) -> dict:
        if not source_dir.exists() or not source_dir.is_dir():
            raise HTTPException(status_code=404, detail="项目目录不存在")

        self.cleanup_expired_tasks()

        task_id = uuid.uuid4().hex
        task = {
            "task_id": task_id,
            "project_id": project_id,
            "user_id": user_id,
            "status": "pending",
            "message": "导出任务已创建",
            "progress": 0,
            "processed_files": 0,
            "total_files": 0,
            "zip_filename": self._build_zip_filename(project_name),
            "file_path": None,
            "error": None,
            "created_at": time.time(),
            "completed_at": None,
        }

        with self._tasks_lock:
            self._tasks[task_id] = task

        asyncio.create_task(asyncio.to_thread(self._run_export_task, task_id, source_dir))
        return self._serialize_task(task)


project_export_service = ProjectExportService()