from __future__ import annotations

import json
import secrets
from datetime import UTC, datetime, timedelta
from pathlib import Path
from typing import Any

from app.core.config import ROOT_DIR
from app.core.security import redis_client

SYSTEM_TASK_TTL_SECONDS = 24 * 60 * 60
SYSTEM_TASK_LOG_LIMIT = 100
SYSTEM_TASK_ACTIVE_KEY = "system:restart_task:active"
SYSTEM_TASK_STALE_SECONDS = 5 * 60

ALLOWED_ACTIONS: dict[str, dict[str, Any]] = {
    "restart-backend": {
        "command": ["./planet.sh", "restart", "-b"],
        "recovery_mode": "backend",
    },
    "restart-frontend": {
        "command": ["./planet.sh", "restart", "-f"],
        "recovery_mode": "frontend",
    },
    "restart-ai-provider": {
        "command": ["./planet.sh", "restart", "-a"],
        "recovery_mode": "ai-provider",
    },
    "restart-database": {
        "command": ["./planet.sh", "restart", "-d"],
        "recovery_mode": "database",
    },
    "restart-system": {
        "command": ["./planet.sh", "restart"],
        "recovery_mode": "system",
    },
}


def utc_now_iso() -> str:
    return datetime.now(UTC).isoformat()


def normalize_user_role(role: Any) -> str:
    return role.value if hasattr(role, "value") else str(role)


def require_super_admin(user_role: Any) -> bool:
    return normalize_user_role(user_role) == "super_admin"


def build_task_id(prefix: str = "restart") -> str:
    timestamp = datetime.now(UTC).strftime("%Y%m%d_%H%M%S")
    return f"{prefix}_{timestamp}_{secrets.token_hex(3)}"


def get_task_key(task_id: str) -> str:
    return f"system:restart_task:{task_id}"


def get_task_logs_key(task_id: str) -> str:
    return f"{get_task_key(task_id)}:logs"


def get_allowed_command(action: str) -> list[str] | None:
    config = ALLOWED_ACTIONS.get(action)
    if config is None:
        return None
    return list(config["command"])


def get_action_recovery_mode(action: str) -> str | None:
    config = ALLOWED_ACTIONS.get(action)
    if config is None:
        return None
    return str(config["recovery_mode"])


def serialize_task(task_id: str) -> dict[str, Any] | None:
    payload = redis_client.hgetall(get_task_key(task_id))
    if not payload:
        return None

    if payload.get("requested_by"):
        try:
            payload["requested_by"] = json.loads(payload["requested_by"])
        except json.JSONDecodeError:
            payload["requested_by"] = {"username": payload["requested_by"]}

    return payload


def append_task_log(task_id: str, line: str) -> None:
    logs_key = get_task_logs_key(task_id)
    redis_client.rpush(logs_key, line)
    redis_client.ltrim(logs_key, -SYSTEM_TASK_LOG_LIMIT, -1)
    redis_client.expire(logs_key, SYSTEM_TASK_TTL_SECONDS)


def upsert_task_state(
    task_id: str,
    *,
    action: str | None = None,
    status: str,
    stage: str,
    message: str,
    requested_by: dict[str, Any] | None = None,
) -> dict[str, Any]:
    existing = serialize_task(task_id) or {}
    now = utc_now_iso()

    payload: dict[str, Any] = {
        "task_id": task_id,
        "action": action or existing.get("action") or "",
        "status": status,
        "stage": stage,
        "message": message,
        "created_at": existing.get("created_at") or now,
        "updated_at": now,
    }

    if requested_by is not None:
        payload["requested_by"] = requested_by
    elif existing.get("requested_by") is not None:
        payload["requested_by"] = existing["requested_by"]

    redis_payload = {
        key: json.dumps(value, ensure_ascii=False) if key == "requested_by" else str(value)
        for key, value in payload.items()
        if value is not None
    }
    task_key = get_task_key(task_id)
    redis_client.hset(task_key, mapping=redis_payload)
    redis_client.expire(task_key, SYSTEM_TASK_TTL_SECONDS)
    return payload


def get_task_logs(task_id: str) -> list[str]:
    return [str(item) for item in redis_client.lrange(get_task_logs_key(task_id), 0, -1)]


def get_active_task_id() -> str | None:
    value = redis_client.get(SYSTEM_TASK_ACTIVE_KEY)
    return str(value) if value else None


def set_active_task_id(task_id: str) -> None:
    redis_client.set(SYSTEM_TASK_ACTIVE_KEY, task_id, ex=SYSTEM_TASK_TTL_SECONDS)


def clear_active_task_id(task_id: str) -> None:
    current = get_active_task_id()
    if current == task_id:
        redis_client.delete(SYSTEM_TASK_ACTIVE_KEY)


def parse_task_timestamp(value: str | None) -> datetime | None:
    if not value:
        return None
    try:
        return datetime.fromisoformat(value)
    except ValueError:
        return None


def is_task_stale(task: dict[str, Any], *, max_age_seconds: int = SYSTEM_TASK_STALE_SECONDS) -> bool:
    if task.get("status") not in {"queued", "running"}:
        return False

    updated_at = parse_task_timestamp(str(task.get("updated_at") or ""))
    if updated_at is None:
        return False

    if updated_at.tzinfo is None:
        updated_at = updated_at.replace(tzinfo=UTC)

    return datetime.now(UTC) - updated_at > timedelta(seconds=max_age_seconds)


def get_runner_script_path() -> Path:
    return ROOT_DIR / "backend" / "scripts" / "system_restart_runner.py"