from __future__ import annotations

import argparse
import json
import os
from pathlib import Path
import shutil
import signal
import subprocess
import sys
import time
import urllib.request


INSTALL_ROOT = Path(__file__).resolve().parent
DATA_DIR = INSTALL_ROOT / "data"
LOG_DIR = INSTALL_ROOT / "logs"
UPDATES_DIR = INSTALL_ROOT / "updates"
LOCK_FILE = DATA_DIR / "supervisor.lock"
STATE_FILE = DATA_DIR / "supervisor_state.json"
REQUEST_FILE = UPDATES_DIR / "supervisor_request.json"
WORKER_LOG = LOG_DIR / "worker-supervisor.log"
SUPERVISOR_LOG = LOG_DIR / "supervisor.log"
DASHBOARD_URL = "http://127.0.0.1:8788"
WORKER_MODULE = "erp_local_agent.main"
RESTART_DELAY_SECONDS = 3
HEALTH_TIMEOUT_SECONDS = 60


def _create_no_window() -> int:
    return getattr(subprocess, "CREATE_NO_WINDOW", 0)


def _log(message: str) -> None:
    LOG_DIR.mkdir(parents=True, exist_ok=True)
    line = f"{time.strftime('%Y-%m-%d %H:%M:%S')} {message}\n"
    try:
        with SUPERVISOR_LOG.open("a", encoding="utf-8") as handle:
            handle.write(line)
    except Exception:
        pass


def _pid_alive(pid: int) -> bool:
    if pid <= 0:
        return False
    try:
        os.kill(pid, 0)
        return True
    except OSError:
        return False


def _write_json_atomic(path: Path, payload: dict) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(json.dumps(payload, indent=2, sort_keys=True), encoding="utf-8")
    tmp.replace(path)


def _state(status: str, message: str, **extra) -> None:
    payload = {
        "status": status,
        "message": message,
        "supervisor_pid": os.getpid(),
        "updated_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
    }
    payload.update(extra)
    _write_json_atomic(STATE_FILE, payload)
    _log(f"{status}: {message}")


def _dashboard_ready(timeout: float = 1.5) -> bool:
    try:
        with urllib.request.urlopen(DASHBOARD_URL + "/api/status", timeout=timeout) as response:
            return int(getattr(response, "status", 200)) < 500
    except Exception:
        return False


def _python(console: bool = True) -> Path:
    name = "python.exe" if console else "pythonw.exe"
    candidate = INSTALL_ROOT / ".venv" / "Scripts" / name
    if candidate.exists():
        return candidate
    fallback = INSTALL_ROOT / ".venv" / "Scripts" / "python.exe"
    if fallback.exists():
        return fallback
    raise RuntimeError(f"ERP Local Agent Python environment not found under {INSTALL_ROOT / '.venv'}")


def _terminate_process_tree(process: subprocess.Popen | None) -> None:
    if process is None:
        return
    if process.poll() is not None:
        return
    try:
        subprocess.run(
            ["taskkill", "/PID", str(process.pid), "/T", "/F"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            creationflags=_create_no_window(),
            check=False,
        )
    except Exception:
        try:
            process.terminate()
        except Exception:
            pass
    try:
        process.wait(timeout=15)
    except Exception:
        pass


def _kill_unmanaged_workers() -> None:
    script = (
        "$root='" + str(INSTALL_ROOT).replace("'", "''") + "';"
        "Get-CimInstance Win32_Process -ErrorAction SilentlyContinue | "
        "Where-Object { $_.CommandLine -and $_.CommandLine -match 'erp_local_agent\\.main' "
        "-and $_.CommandLine -like ('*'+$root+'*') } | "
        "ForEach-Object { Stop-Process -Id $_.ProcessId -Force -ErrorAction SilentlyContinue }"
    )
    subprocess.run(
        ["powershell.exe", "-NoProfile", "-ExecutionPolicy", "Bypass", "-Command", script],
        cwd=str(INSTALL_ROOT),
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
        creationflags=_create_no_window(),
        check=False,
    )


class Supervisor:
    def __init__(self):
        self.worker: subprocess.Popen | None = None
        self.running = True

    def acquire_lock(self) -> bool:
        DATA_DIR.mkdir(parents=True, exist_ok=True)
        if LOCK_FILE.exists():
            try:
                existing = int(LOCK_FILE.read_text(encoding="utf-8").strip() or "0")
            except Exception:
                existing = 0
            if existing and existing != os.getpid() and _pid_alive(existing):
                return False
        LOCK_FILE.write_text(str(os.getpid()), encoding="utf-8")
        return True

    def release_lock(self) -> None:
        try:
            if LOCK_FILE.exists() and LOCK_FILE.read_text(encoding="utf-8").strip() == str(os.getpid()):
                LOCK_FILE.unlink()
        except Exception:
            pass

    def start_worker(self) -> None:
        if self.worker is not None and self.worker.poll() is None:
            return
        _kill_unmanaged_workers()
        LOG_DIR.mkdir(parents=True, exist_ok=True)
        py = _python(console=True)
        handle = WORKER_LOG.open("a", encoding="utf-8")
        handle.write(f"\n--- worker start {time.strftime('%Y-%m-%d %H:%M:%S')} ---\n")
        handle.flush()
        self.worker = subprocess.Popen(
            [str(py), "-m", WORKER_MODULE],
            cwd=str(INSTALL_ROOT),
            stdout=handle,
            stderr=handle,
            creationflags=_create_no_window(),
        )
        _state("running", "ERP Local Agent worker started.", worker_pid=self.worker.pid)

    def stop_worker(self) -> None:
        _state("stopping", "Stopping ERP Local Agent worker.")
        _terminate_process_tree(self.worker)
        self.worker = None
        _kill_unmanaged_workers()

    @staticmethod
    def _read_request() -> dict | None:
        if not REQUEST_FILE.exists():
            return None
        try:
            payload = json.loads(REQUEST_FILE.read_text(encoding="utf-8"))
            return payload if isinstance(payload, dict) else None
        except Exception as exc:
            _state("error", f"Invalid supervisor update request: {exc}")
            try:
                REQUEST_FILE.unlink()
            except Exception:
                pass
            return None

    @staticmethod
    def _clear_request() -> None:
        try:
            REQUEST_FILE.unlink()
        except FileNotFoundError:
            pass

    @staticmethod
    def _validate_staged(staged: Path) -> None:
        if not staged.exists() or not staged.is_dir():
            raise RuntimeError(f"Staged update directory not found: {staged}")
        if not (staged / "erp_local_agent" / "__init__.py").is_file():
            raise RuntimeError("Staged update does not contain erp_local_agent/__init__.py.")
        if not (staged / "requirements.txt").is_file():
            raise RuntimeError("Staged update does not contain requirements.txt.")

    @staticmethod
    def _backup_runtime(version: str) -> Path:
        backup = UPDATES_DIR / f"supervisor_backup_{time.strftime('%Y%m%d_%H%M%S')}_{version}"
        backup.mkdir(parents=True, exist_ok=True)
        agent = INSTALL_ROOT / "erp_local_agent"
        if agent.exists():
            shutil.copytree(agent, backup / "erp_local_agent")
        for name in (
            "requirements.txt",
            "README_ERP_LOCAL_AGENT.txt",
            "run_agent.bat",
            "run_once.bat",
            "check_config.py",
            "check_config.bat",
            "open_dashboard.bat",
            "install_task_scheduler.bat",
            "start_task_scheduler.bat",
            "stop_task_scheduler.bat",
            "status_task_scheduler.bat",
            "uninstall_task_scheduler.bat",
        ):
            src = INSTALL_ROOT / name
            if src.exists():
                shutil.copy2(src, backup / name)
        return backup

    @staticmethod
    def _replace_worker_runtime(staged: Path) -> None:
        target = INSTALL_ROOT / "erp_local_agent"
        new_target = INSTALL_ROOT / "erp_local_agent.__new__"
        old_target = INSTALL_ROOT / "erp_local_agent.__old__"

        shutil.rmtree(new_target, ignore_errors=True)
        shutil.rmtree(old_target, ignore_errors=True)
        shutil.copytree(staged / "erp_local_agent", new_target)

        if target.exists():
            target.rename(old_target)
        try:
            new_target.rename(target)
        except Exception:
            if old_target.exists() and not target.exists():
                old_target.rename(target)
            raise
        shutil.rmtree(old_target, ignore_errors=True)

        # Root helper files are safe to refresh while the stable supervisor is running.
        # Supervisor/dashboard launchers themselves are intentionally excluded here;
        # they are updated only by the explicit direct installer.
        for name in (
            "requirements.txt",
            "README_ERP_LOCAL_AGENT.txt",
            "run_agent.bat",
            "run_once.bat",
            "check_config.py",
            "check_config.bat",
            "open_dashboard.bat",
            "install_task_scheduler.bat",
            "start_task_scheduler.bat",
            "stop_task_scheduler.bat",
            "status_task_scheduler.bat",
            "uninstall_task_scheduler.bat",
        ):
            src = staged / name
            if src.exists():
                shutil.copy2(src, INSTALL_ROOT / name)

    @staticmethod
    def _install_requirements_and_verify() -> None:
        py = _python(console=True)
        req = INSTALL_ROOT / "requirements.txt"
        result = subprocess.run(
            [str(py), "-m", "pip", "install", "-r", str(req)],
            cwd=str(INSTALL_ROOT),
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            text=True,
            creationflags=_create_no_window(),
            timeout=300,
        )
        if result.returncode != 0:
            raise RuntimeError("Dependency installation failed:\n" + result.stdout[-4000:])

        code = (
            "import erp_local_agent;"
            "from erp_local_agent import accounting_store,commands,tally,updater;"
            "print(erp_local_agent.__version__)"
        )
        result = subprocess.run(
            [str(py), "-c", code],
            cwd=str(INSTALL_ROOT),
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            text=True,
            creationflags=_create_no_window(),
            timeout=60,
        )
        if result.returncode != 0:
            raise RuntimeError("Updated worker import verification failed:\n" + result.stdout[-4000:])

    @staticmethod
    def _restore_backup(backup: Path) -> None:
        target = INSTALL_ROOT / "erp_local_agent"
        backup_agent = backup / "erp_local_agent"
        if backup_agent.exists():
            shutil.rmtree(target, ignore_errors=True)
            shutil.copytree(backup_agent, target)
        for item in backup.iterdir():
            if item.name == "erp_local_agent":
                continue
            if item.is_file():
                shutil.copy2(item, INSTALL_ROOT / item.name)

    def apply_update(self, request: dict) -> None:
        version = str(request.get("version") or "").strip()
        staged_text = str(request.get("staged_dir") or "").strip()
        if not version or not staged_text:
            raise RuntimeError("Supervisor update request is missing version/staged_dir.")

        staged = Path(staged_text).resolve()
        self._validate_staged(staged)
        _state("installing", f"Installing ERP Local Agent {version}.", target_version=version)

        self.stop_worker()
        backup = self._backup_runtime(version)
        try:
            self._replace_worker_runtime(staged)
            self._install_requirements_and_verify()
            self.start_worker()

            deadline = time.time() + HEALTH_TIMEOUT_SECONDS
            while time.time() < deadline:
                if self.worker is not None and self.worker.poll() is not None:
                    raise RuntimeError(f"Updated worker exited with code {self.worker.returncode}.")
                if _dashboard_ready():
                    _state(
                        "updated",
                        f"ERP Local Agent {version} installed and restarted successfully.",
                        target_version=version,
                        worker_pid=(self.worker.pid if self.worker else None),
                        backup_path=str(backup),
                    )
                    return
                time.sleep(1)

            raise RuntimeError("Updated worker did not become healthy within the restart timeout.")
        except Exception:
            _state("rollback", f"Update {version} failed. Restoring previous worker.", target_version=version)
            self.stop_worker()
            self._restore_backup(backup)
            self.start_worker()
            raise

    def run(self) -> int:
        if not self.acquire_lock():
            return 0

        try:
            _state("starting", "ERP Local Agent supervisor starting.")
            self.start_worker()

            while self.running:
                request = self._read_request()
                if request and str(request.get("action") or "") == "install_update":
                    self._clear_request()
                    try:
                        self.apply_update(request)
                    except Exception as exc:
                        _state("error", f"Update failed and worker was restored/restarted: {exc}")

                if self.worker is None or self.worker.poll() is not None:
                    code = None if self.worker is None else self.worker.returncode
                    _state("restarting", f"ERP Local Agent worker stopped (exit={code}); restarting.")
                    time.sleep(RESTART_DELAY_SECONDS)
                    self.start_worker()

                time.sleep(1)

            return 0
        finally:
            self.stop_worker()
            self.release_lock()
            _state("stopped", "ERP Local Agent supervisor stopped.")


def main() -> int:
    parser = argparse.ArgumentParser(description="ERP Local Agent desktop/background supervisor")
    parser.add_argument("--background", action="store_true")
    parser.parse_args()

    supervisor = Supervisor()

    def stop_handler(*_args):
        supervisor.running = False

    try:
        signal.signal(signal.SIGTERM, stop_handler)
        signal.signal(signal.SIGINT, stop_handler)
    except Exception:
        pass

    return supervisor.run()


if __name__ == "__main__":
    raise SystemExit(main())