from __future__ import annotations

import os
import subprocess
import sys

from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel

from app.core.config import ROOT_DIR
from app.core.security import get_current_user
from app.models.user import User
from app.services.system_control import (
    build_task_id,
    clear_active_task_id,
    get_active_task_id,
    get_allowed_command,
    get_runner_script_path,
    is_task_stale,
    get_task_logs,
    require_super_admin,
    serialize_task,
    set_active_task_id,
    upsert_task_state,
)

router = APIRouter()


class RestartTaskCreate(BaseModel):
    action: str


class RestartTaskResponse(BaseModel):
    task_id: str
    action: str
    status: str
    stage: str
    message: str
    created_at: str
    updated_at: str
    requested_by: dict[str, object] | None = None


class RestartTaskLogsResponse(BaseModel):
    task_id: str
    lines: list[str]


def ensure_super_admin(current_user: User) -> None:
    if not require_super_admin(current_user.role):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only super_admin can restart services",
        )


@router.post("/restart-tasks", response_model=RestartTaskResponse)
async def create_restart_task(
    payload: RestartTaskCreate,
    current_user: User = Depends(get_current_user),
):
    ensure_super_admin(current_user)

    command = get_allowed_command(payload.action)
    if command is None:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Unsupported system action",
        )

    active_task_id = get_active_task_id()
    if active_task_id:
        active_task = serialize_task(active_task_id)
        if active_task and is_task_stale(active_task):
            upsert_task_state(
                active_task_id,
                status="failed",
                stage="failed",
                message="Previous restart task became stale and was released",
            )
            clear_active_task_id(active_task_id)
        elif active_task and active_task.get("status") in {"queued", "running"}:
            raise HTTPException(
                status_code=status.HTTP_409_CONFLICT,
                detail="Another restart task is already in progress",
            )

    task_id = build_task_id()
    requested_by = {"id": current_user.id, "username": current_user.username}
    task_state = upsert_task_state(
        task_id,
        action=payload.action,
        status="queued",
        stage="accepted",
        message="Restart task accepted",
        requested_by=requested_by,
    )
    set_active_task_id(task_id)

    env = os.environ.copy()
    backend_path = str(ROOT_DIR / "backend")
    existing_pythonpath = env.get("PYTHONPATH", "")
    env["PYTHONPATH"] = (
        f"{backend_path}{os.pathsep}{existing_pythonpath}"
        if existing_pythonpath
        else backend_path
    )

    try:
        subprocess.Popen(
            [
                sys.executable,
                str(get_runner_script_path()),
                "--task-id",
                task_id,
                "--action",
                payload.action,
            ],
            cwd=str(ROOT_DIR),
            env=env,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            start_new_session=True,
        )
    except OSError as exc:
        task_state = upsert_task_state(
            task_id,
            action=payload.action,
            status="failed",
            stage="failed",
            message=f"Unable to start restart runner: {exc}",
            requested_by=requested_by,
        )
        clear_active_task_id(task_id)
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=task_state["message"],
        ) from exc

    return task_state


@router.get("/restart-tasks/{task_id}", response_model=RestartTaskResponse)
async def get_restart_task(
    task_id: str,
    current_user: User = Depends(get_current_user),
):
    ensure_super_admin(current_user)

    task = serialize_task(task_id)
    if task is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Restart task not found")
    return task


@router.get("/restart-tasks/{task_id}/logs", response_model=RestartTaskLogsResponse)
async def get_restart_task_logs(
    task_id: str,
    current_user: User = Depends(get_current_user),
):
    ensure_super_admin(current_user)

    task = serialize_task(task_id)
    if task is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Restart task not found")
    return {"task_id": task_id, "lines": get_task_logs(task_id)}