"""Background media parsing runner used by Celery workers."""

import logging
import os
import shutil
import tempfile
from datetime import datetime, timezone
from pathlib import Path
from typing import Any

from sqlalchemy.orm import Session

from minio_client import BUCKET_NAME, download_file, get_minio_client, upload_file
from models import Frame, ProcessingTask, Project
from progress_events import publish_task_progress_event
from services.frame_parser import (
    extract_thumbnail,
    parse_dicom,
    parse_video,
    upload_frames_to_minio,
)
from statuses import (
    PROJECT_STATUS_PENDING,
    PROJECT_STATUS_ERROR,
    PROJECT_STATUS_PARSING,
    PROJECT_STATUS_READY,
    TASK_STATUS_CANCELLED,
    TASK_STATUS_FAILED,
    TASK_STATUS_RUNNING,
    TASK_STATUS_SUCCESS,
)

logger = logging.getLogger(__name__)


class TaskCancelled(RuntimeError):
    """Raised internally when a persisted task has been cancelled."""


def _now() -> datetime:
    return datetime.now(timezone.utc)


def _set_task_state(
    db: Session,
    task: ProcessingTask,
    *,
    status: str | None = None,
    progress: int | None = None,
    message: str | None = None,
    result: dict[str, Any] | None = None,
    error: str | None = None,
    started: bool = False,
    finished: bool = False,
) -> None:
    if status is not None:
        task.status = status
    if progress is not None:
        task.progress = max(0, min(100, progress))
    if message is not None:
        task.message = message
    if result is not None:
        task.result = result
    if error is not None:
        task.error = error
    if started:
        task.started_at = _now()
    if finished:
        task.finished_at = _now()
    db.commit()
    db.refresh(task)
    publish_task_progress_event(task)


def _project_status_after_stop(project: Project) -> str:
    return PROJECT_STATUS_READY if project.frames else PROJECT_STATUS_PENDING


def _positive_int(value: Any, default: int | None = None) -> int | None:
    try:
        parsed = int(value)
    except (TypeError, ValueError):
        return default
    return parsed if parsed > 0 else default


def _positive_float(value: Any, default: float) -> float:
    try:
        parsed = float(value)
    except (TypeError, ValueError):
        return default
    return parsed if parsed > 0 else default


def _frame_sequence_metadata(
    index: int,
    parse_fps: float,
    original_fps: float | None,
) -> dict[str, float | int | None]:
    safe_parse_fps = max(float(parse_fps or 1.0), 1e-6)
    timestamp_ms = index * 1000.0 / safe_parse_fps
    source_frame_number = None
    if original_fps and original_fps > 0:
        source_frame_number = int(round(index * original_fps / safe_parse_fps))
    return {
        "timestamp_ms": timestamp_ms,
        "source_frame_number": source_frame_number,
    }


def _ensure_not_cancelled(db: Session, task: ProcessingTask) -> None:
    db.refresh(task)
    if task.status == TASK_STATUS_CANCELLED:
        raise TaskCancelled("Task was cancelled")


def run_parse_media_task(db: Session, task_id: int) -> dict[str, Any]:
    """Parse one project's media and update task progress in the database."""
    task = db.query(ProcessingTask).filter(ProcessingTask.id == task_id).first()
    if not task:
        raise ValueError(f"Task not found: {task_id}")

    if task.status == TASK_STATUS_CANCELLED:
        return {
            "task_id": task.id,
            "status": TASK_STATUS_CANCELLED,
            "message": task.message or "任务已取消",
        }

    if task.project_id is None:
        _set_task_state(
            db,
            task,
            status=TASK_STATUS_FAILED,
            progress=100,
            message="任务缺少 project_id",
            error="Task has no project_id",
            finished=True,
        )
        raise ValueError("Task has no project_id")

    project = db.query(Project).filter(Project.id == task.project_id).first()
    if not project:
        _set_task_state(
            db,
            task,
            status=TASK_STATUS_FAILED,
            progress=100,
            message="项目不存在",
            error="Project not found",
            finished=True,
        )
        raise ValueError(f"Project not found: {task.project_id}")

    if not project.video_path:
        _set_task_state(
            db,
            task,
            status=TASK_STATUS_FAILED,
            progress=100,
            message="项目没有可解析媒体",
            error="Project has no media uploaded",
            finished=True,
        )
        project.status = PROJECT_STATUS_ERROR
        db.commit()
        raise ValueError("Project has no media uploaded")

    _ensure_not_cancelled(db, task)
    project.status = PROJECT_STATUS_PARSING
    _set_task_state(db, task, status=TASK_STATUS_RUNNING, progress=5, message="后台解析已启动", started=True)

    payload = task.payload or {}
    effective_source = payload.get("source_type") or project.source_type or "video"
    parse_fps = _positive_float(payload.get("parse_fps"), project.parse_fps or 30.0)
    max_frames = _positive_int(payload.get("max_frames"))
    target_width = _positive_int(payload.get("target_width"), 640) or 640
    project.parse_fps = parse_fps
    tmp_dir = tempfile.mkdtemp(prefix=f"seg_parse_{project.id}_")
    output_dir = os.path.join(tmp_dir, "frames")
    os.makedirs(output_dir, exist_ok=True)

    try:
        _ensure_not_cancelled(db, task)
        _set_task_state(db, task, progress=15, message="正在下载媒体文件")
        if effective_source == "dicom":
            dcm_dir = os.path.join(tmp_dir, "dcm")
            os.makedirs(dcm_dir, exist_ok=True)

            client = get_minio_client()
            objects = list(client.list_objects(BUCKET_NAME, prefix=project.video_path, recursive=True))
            for obj in objects:
                _ensure_not_cancelled(db, task)
                if obj.object_name.lower().endswith(".dcm"):
                    data = download_file(obj.object_name)
                    local_dcm = os.path.join(dcm_dir, os.path.basename(obj.object_name))
                    with open(local_dcm, "wb") as f:
                        f.write(data)

            _ensure_not_cancelled(db, task)
            _set_task_state(db, task, progress=35, message="正在解析 DICOM 序列")
            frame_files = parse_dicom(dcm_dir, output_dir, max_frames=max_frames)
        else:
            _ensure_not_cancelled(db, task)
            media_bytes = download_file(project.video_path)
            local_path = os.path.join(tmp_dir, Path(project.video_path).name)
            with open(local_path, "wb") as f:
                f.write(media_bytes)

            _ensure_not_cancelled(db, task)
            _set_task_state(db, task, progress=35, message="正在使用 FFmpeg/OpenCV 拆帧")
            frame_files, original_fps = parse_video(
                local_path,
                output_dir,
                fps=int(parse_fps),
                max_frames=max_frames,
                target_width=target_width,
            )
            project.original_fps = original_fps

            thumbnail_path = os.path.join(tmp_dir, "thumbnail.jpg")
            try:
                extract_thumbnail(local_path, thumbnail_path)
                with open(thumbnail_path, "rb") as f:
                    thumb_data = f.read()
                thumb_object = f"projects/{project.id}/thumbnail.jpg"
                upload_file(thumb_object, thumb_data, content_type="image/jpeg", length=len(thumb_data))
                project.thumbnail_url = thumb_object
            except Exception as exc:  # noqa: BLE001
                logger.warning("Thumbnail extraction failed: %s", exc)

        _ensure_not_cancelled(db, task)
        _set_task_state(db, task, progress=70, message="正在上传帧到对象存储")
        object_names = upload_frames_to_minio(frame_files, project.id)

        _ensure_not_cancelled(db, task)
        _set_task_state(db, task, progress=85, message="正在写入帧索引")
        frames_out = []
        for idx, obj_name in enumerate(object_names):
            _ensure_not_cancelled(db, task)
            local_frame = frame_files[idx]
            try:
                import cv2

                img = cv2.imread(local_frame)
                h, w = img.shape[:2] if img is not None else (None, None)
            except Exception:  # noqa: BLE001
                h, w = None, None

            sequence_meta = _frame_sequence_metadata(idx, parse_fps, project.original_fps)
            frame = Frame(
                project_id=project.id,
                frame_index=idx,
                image_url=obj_name,
                width=w,
                height=h,
                timestamp_ms=sequence_meta["timestamp_ms"],
                source_frame_number=sequence_meta["source_frame_number"],
            )
            db.add(frame)
            frames_out.append(frame)

        project.status = PROJECT_STATUS_READY
        db.commit()

        result = {
            "project_id": project.id,
            "frames_extracted": len(frames_out),
            "status": PROJECT_STATUS_READY,
            "message": "Frame extraction completed successfully.",
            "frame_sequence": {
                "original_fps": project.original_fps,
                "parse_fps": parse_fps,
                "frame_count": len(frames_out),
                "duration_ms": (len(frames_out) - 1) * 1000.0 / parse_fps if frames_out else 0,
                "target_width": target_width,
                "frame_width": frames_out[0].width if frames_out else None,
                "frame_height": frames_out[0].height if frames_out else None,
                "max_frames": max_frames,
                "object_prefix": f"projects/{project.id}/frames",
            },
        }
        _set_task_state(
            db,
            task,
            status=TASK_STATUS_SUCCESS,
            progress=100,
            message="解析完成",
            result=result,
            finished=True,
        )
        logger.info("Parsed %d frames for project_id=%s", len(frames_out), project.id)
        return result
    except TaskCancelled:
        project.status = _project_status_after_stop(project)
        task.status = TASK_STATUS_CANCELLED
        task.progress = 100
        task.message = task.message or "任务已取消"
        task.error = task.error or "Cancelled by user"
        task.finished_at = task.finished_at or _now()
        db.commit()
        db.refresh(task)
        publish_task_progress_event(task)
        logger.info("Parse task cancelled: task_id=%s project_id=%s", task.id, project.id)
        return {
            "task_id": task.id,
            "project_id": project.id,
            "status": TASK_STATUS_CANCELLED,
            "message": task.message,
        }
    except Exception as exc:  # noqa: BLE001
        project.status = PROJECT_STATUS_ERROR
        _set_task_state(
            db,
            task,
            status=TASK_STATUS_FAILED,
            progress=100,
            message="解析失败",
            error=str(exc),
            finished=True,
        )
        logger.error("Frame extraction failed: %s", exc)
        raise
    finally:
        shutil.rmtree(tmp_dir, ignore_errors=True)
