"""Settings — config read/write, hostname, timezone management."""

import asyncio
import platform
import socket
from typing import Optional

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

from backend.auth import get_current_user
from backend.config import load_config, save_config

router = APIRouter(prefix="/api/settings", tags=["settings"])


class ConfigUpdate(BaseModel):
    """Partial config update — only send fields to change."""
    hostname_display: Optional[str] = None
    timezone: Optional[str] = None
    ntp_enabled: Optional[bool] = None
    dock_apps: Optional[list[str]] = None
    panel_services: Optional[list[str]] = None
    gui_apps: Optional[list[dict]] = None
    session_timeout_minutes: Optional[int] = None
    stats_interval_seconds: Optional[int] = None
    update_check_enabled: Optional[bool] = None
    update_check_interval: Optional[int] = None


class HostnameRequest(BaseModel):
    hostname: str


class TimezoneRequest(BaseModel):
    timezone: str


async def _run(cmd: list[str]) -> tuple[int, str, str]:
    import shutil
    if not shutil.which(cmd[0]):
        return 1, "", f"{cmd[0]}: command not found"
    proc = await asyncio.create_subprocess_exec(
        *cmd,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE,
    )
    stdout, stderr = await proc.communicate()
    return proc.returncode, stdout.decode(), stderr.decode()


@router.get("")
async def get_config(_user: str = Depends(get_current_user)):
    return load_config()


@router.put("")
async def update_config(update: ConfigUpdate, _user: str = Depends(get_current_user)):
    cfg = load_config()
    for field, value in update.model_dump(exclude_none=True).items():
        cfg[field] = value
    save_config(cfg)
    return cfg


@router.get("/system")
async def system_info(_user: str = Depends(get_current_user)):
    """System info for the About section."""
    hostname = socket.gethostname()
    uname = platform.uname()

    # OS release info
    os_name = "Linux"
    os_version = ""
    try:
        with open("/etc/os-release") as f:
            for line in f:
                if line.startswith("PRETTY_NAME="):
                    os_name = line.split("=", 1)[1].strip().strip('"')
                elif line.startswith("VERSION="):
                    os_version = line.split("=", 1)[1].strip().strip('"')
    except FileNotFoundError:
        pass

    return {
        "hostname": hostname,
        "os": os_name,
        "os_version": os_version,
        "kernel": uname.release,
        "arch": uname.machine,
        "python": platform.python_version(),
    }


@router.post("/hostname")
async def set_hostname(req: HostnameRequest, _user: str = Depends(get_current_user)):
    rc, _, err = await _run(["hostnamectl", "set-hostname", req.hostname])
    if rc != 0:
        raise HTTPException(500, f"Failed to set hostname: {err}")
    return {"hostname": req.hostname}


@router.get("/timezone")
async def get_timezone(_user: str = Depends(get_current_user)):
    rc, out, _ = await _run(["timedatectl", "show", "--property=Timezone", "--value"])
    return {"timezone": out.strip() if rc == 0 else "unknown"}


@router.post("/timezone")
async def set_timezone(req: TimezoneRequest, _user: str = Depends(get_current_user)):
    rc, _, err = await _run(["timedatectl", "set-timezone", req.timezone])
    if rc != 0:
        raise HTTPException(500, f"Failed to set timezone: {err}")
    return {"timezone": req.timezone}


@router.get("/timezones")
async def list_timezones(_user: str = Depends(get_current_user)):
    rc, out, _ = await _run(["timedatectl", "list-timezones"])
    if rc != 0:
        return []
    return out.strip().splitlines()