import json
import os
import subprocess
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Dict, List

import httpx

from backend.settings import Settings


def _project_root() -> Path:
    return Path(__file__).resolve().parents[1]


def _read_version() -> str:
    try:
        return (_project_root() / "VERSION").read_text(encoding="utf-8").strip()
    except OSError:
        return "unknown"


def _status_path(settings: Settings) -> Path:
    return Path(settings.update_status_file)


def _log_path(settings: Settings) -> Path:
    return Path(settings.update_log_file)


def _ensure_parent(path: Path) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)


def _write_status(settings: Settings, status: str, version: str, error: str | None = None) -> None:
    status_path = _status_path(settings)
    _ensure_parent(status_path)
    payload = {
        "device_id": os.uname().nodename,
        "version": version,
        "status": status,
        "error": error or "",
        "timestamp": datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
    }
    status_path.write_text(json.dumps(payload), encoding="utf-8")
    _append_log(settings, payload)


def _append_log(settings: Settings, payload: Dict[str, Any]) -> None:
    log_path = _log_path(settings)
    _ensure_parent(log_path)
    with log_path.open("a", encoding="utf-8") as handle:
        handle.write(json.dumps(payload) + "\n")


def get_status(settings: Settings) -> Dict[str, Any]:
    current_version = _read_version()
    status_path = _status_path(settings)
    if status_path.exists():
        try:
            data = json.loads(status_path.read_text(encoding="utf-8"))
        except json.JSONDecodeError:
            data = {}
    else:
        data = {}

    return {
        "current_version": current_version,
        "last_status": data.get("status", "unknown"),
        "last_error": data.get("error") or None,
        "last_timestamp": data.get("timestamp"),
    }


def _parse_version(value: str) -> List[int]:
    return [int(part) for part in value.split(".")]


def check_update(settings: Settings) -> Dict[str, Any]:
    headers = {}
    if settings.update_token:
        headers["Authorization"] = f"Bearer {settings.update_token}"

    with httpx.Client(timeout=10.0) as client:
        response = client.get(settings.update_url, headers=headers)
        response.raise_for_status()
        manifest = response.json()

    latest_version = manifest.get("version", "")
    artifact_url = manifest.get("artifact_url", "")
    sha256 = manifest.get("sha256", "")
    message = manifest.get("message")

    available = False
    current_version = _read_version()
    try:
        available = _parse_version(latest_version) > _parse_version(current_version)
    except ValueError:
        if latest_version and latest_version != current_version:
            available = True

    return {
        "available": available,
        "latest_version": latest_version,
        "artifact_url": artifact_url,
        "sha256": sha256,
        "message": message,
    }


def _run_async(script_path: Path, settings: Settings) -> None:
    env = os.environ.copy()
    env["SKD_UPDATE_STATUS_FILE"] = settings.update_status_file
    env["SKD_UPDATE_LOG_FILE"] = settings.update_log_file
    subprocess.Popen([str(script_path)], env=env, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)


def start_update(settings: Settings, version: str | None = None) -> None:
    _write_status(settings, "in_progress", version or _read_version())
    script = _project_root() / "scripts" / "update_client.sh"
    _run_async(script, settings)


def start_rollback(settings: Settings) -> None:
    _write_status(settings, "in_progress", _read_version())
    script = _project_root() / "scripts" / "rollback_client.sh"
    _run_async(script, settings)


def get_logs(settings: Settings, limit: int = 200) -> List[Dict[str, Any]]:
    log_path = _log_path(settings)
    if not log_path.exists():
        return []
    lines = log_path.read_text(encoding="utf-8").splitlines()
    entries: List[Dict[str, Any]] = []
    for line in lines[-limit:]:
        try:
            entries.append(json.loads(line))
        except json.JSONDecodeError:
            continue
    return entries