#!/usr/bin/env python3
from __future__ import annotations

import json
import os
import time
from pathlib import Path
from typing import Dict, List, Optional, Tuple
import urllib.error
import urllib.request

SINGBOX_INSTANCE_DROPIN = "10-selective-vpn.conf"


def fail(msg: str) -> int:
    print(f"[transport_systemd_real_e2e] ERROR: {msg}")
    return 1


def request_json(api_url: str, method: str, path: str, payload: Optional[Dict] = None) -> Tuple[int, Dict]:
    data = None
    headers = {"Accept": "application/json"}
    if payload is not None:
        data = json.dumps(payload).encode("utf-8")
        headers["Content-Type"] = "application/json"
    req = urllib.request.Request(
        f"{api_url.rstrip('/')}{path}",
        data=data,
        method=method.upper(),
        headers=headers,
    )
    try:
        with urllib.request.urlopen(req, timeout=30.0) as resp:
            raw = resp.read().decode("utf-8", errors="replace")
            status = int(resp.getcode() or 200)
    except urllib.error.HTTPError as e:
        raw = e.read().decode("utf-8", errors="replace")
        status = int(e.code or 500)
    except Exception:
        return 0, {}

    try:
        data_json = json.loads(raw) if raw else {}
    except Exception:
        data_json = {}
    if not isinstance(data_json, dict):
        data_json = {}
    return status, data_json


def ensure_client_deleted(api_url: str, client_id: str) -> None:
    request_json(api_url, "DELETE", f"/api/v1/transport/clients/{client_id}?force=true")


def is_systemd_unavailable(resp: Dict) -> bool:
    text = (
        str(resp.get("message") or "")
        + " "
        + str(resp.get("stderr") or "")
        + " "
        + str(resp.get("stdout") or "")
    ).lower()
    checks = (
        "not been booted with systemd",
        "failed to connect to bus",
        "systemctl daemon-reload failed",
        "operation not permitted",
    )
    return any(c in text for c in checks)


def unit_file_path(unit: str) -> Path:
    return Path("/etc/systemd/system") / unit


def unit_dropin_path(unit: str, file_name: str = SINGBOX_INSTANCE_DROPIN) -> Path:
    return Path("/etc/systemd/system") / f"{unit}.d" / file_name


def assert_unit_owned(unit: str, client_id: str) -> None:
    marker = f"Environment=SVPN_TRANSPORT_ID={client_id}"
    unit_path = unit_file_path(unit)
    if unit_path.exists():
        body = unit_path.read_text(encoding="utf-8", errors="replace")
        if marker in body:
            return

    dropin_path = unit_dropin_path(unit)
    if dropin_path.exists():
        body = dropin_path.read_text(encoding="utf-8", errors="replace")
        if marker in body:
            return

    if unit_path.exists() and not dropin_path.exists():
        raise AssertionError(f"ownership marker {marker} not found in unit: {unit_path}")
    raise AssertionError(f"unit artifacts are missing for ownership check: {unit_path} {dropin_path}")


def assert_unit_removed(unit: str, client_id: str) -> None:
    marker = f"Environment=SVPN_TRANSPORT_ID={client_id}"
    unit_path = unit_file_path(unit)
    dropin_path = unit_dropin_path(unit)
    if dropin_path.exists():
        raise AssertionError(f"drop-in file still exists after cleanup: {dropin_path}")
    if unit_path.exists():
        body = unit_path.read_text(encoding="utf-8", errors="replace")
        if marker in body:
            raise AssertionError(f"owned unit file still exists after cleanup: {unit_path}")


def assert_file_exists(path: str) -> None:
    p = Path(path)
    if not p.exists():
        raise AssertionError(f"expected file missing: {p}")


def create_client(api_url: str, payload: Dict) -> Tuple[int, Dict]:
    return request_json(api_url, "POST", "/api/v1/transport/clients", payload)


def run_case(
    api_url: str,
    *,
    client_id: str,
    name: str,
    kind: str,
    cfg: Dict,
    units: List[str],
    template_units: Optional[List[str]] = None,
) -> Tuple[bool, str]:
    ensure_client_deleted(api_url, client_id)
    status, created = create_client(
        api_url,
        {
            "id": client_id,
            "name": name,
            "kind": kind,
            "enabled": False,
            "config": cfg,
        },
    )
    if status != 200 or not bool(created.get("ok", False)):
        raise AssertionError(f"create failed status={status} payload={created}")

    try:
        status, provision = request_json(api_url, "POST", f"/api/v1/transport/clients/{client_id}/provision")
        if status == 404:
            return False, "provision endpoint is not available on current backend build"
        if status != 200:
            raise AssertionError(f"provision failed status={status} payload={provision}")
        if not bool(provision.get("ok", False)):
            if is_systemd_unavailable(provision):
                return False, f"systemd is unavailable: {provision}"
            raise AssertionError(f"provision returned ok=false payload={provision}")

        for unit in units:
            assert_unit_owned(unit, client_id)
        for t_unit in (template_units or []):
            assert_file_exists(str(unit_file_path(t_unit)))

        status, started = request_json(api_url, "POST", f"/api/v1/transport/clients/{client_id}/start")
        if status != 200 or not bool(started.get("ok", False)):
            raise AssertionError(f"start failed status={status} payload={started}")
        if str(started.get("status_after") or "").strip().lower() != "up":
            raise AssertionError(f"start did not set status_after=up payload={started}")

        status, health = request_json(api_url, "GET", f"/api/v1/transport/clients/{client_id}/health")
        if status != 200 or not bool(health.get("ok", False)):
            raise AssertionError(f"health failed status={status} payload={health}")
        if str(health.get("status") or "").strip().lower() not in ("up", "degraded"):
            raise AssertionError(f"health status is unexpected payload={health}")

        status, metrics = request_json(api_url, "GET", f"/api/v1/transport/clients/{client_id}/metrics")
        if status != 200 or not bool(metrics.get("ok", False)):
            raise AssertionError(f"metrics failed status={status} payload={metrics}")
        m = metrics.get("metrics") or {}
        if not isinstance(m, dict):
            raise AssertionError(f"metrics payload is invalid: {metrics}")
        if int(m.get("state_changes", 0) or 0) < 1:
            raise AssertionError(f"state_changes must be >=1 after start: {metrics}")

        status, restarted = request_json(api_url, "POST", f"/api/v1/transport/clients/{client_id}/restart")
        if status != 200 or not bool(restarted.get("ok", False)):
            raise AssertionError(f"restart failed status={status} payload={restarted}")

        status, stopped = request_json(api_url, "POST", f"/api/v1/transport/clients/{client_id}/stop")
        if status != 200 or not bool(stopped.get("ok", False)):
            raise AssertionError(f"stop failed status={status} payload={stopped}")
        if str(stopped.get("status_after") or "").strip().lower() != "down":
            raise AssertionError(f"stop did not set status_after=down payload={stopped}")
    finally:
        status, deleted = request_json(api_url, "DELETE", f"/api/v1/transport/clients/{client_id}?force=true")
        if status != 200 or not bool(deleted.get("ok", False)):
            raise AssertionError(f"delete failed status={status} payload={deleted}")
        for unit in units:
            assert_unit_removed(unit, client_id)
        for t_unit in (template_units or []):
            assert_file_exists(str(unit_file_path(t_unit)))

    return True, "ok"


def main() -> int:
    api_url = os.environ.get("API_URL", "http://127.0.0.1:8080").strip()
    if not api_url:
        return fail("empty API_URL")
    print(f"[transport_systemd_real_e2e] API_URL={api_url}")

    status, caps = request_json(api_url, "GET", "/api/v1/transport/capabilities")
    if status == 404:
        print("[transport_systemd_real_e2e] SKIP: transport endpoints are not available on this backend")
        return 0
    if status != 200 or not bool(caps.get("ok", False)):
        return fail(f"capabilities failed status={status} payload={caps}")
    runtime_modes = caps.get("runtime_modes") or {}
    if isinstance(runtime_modes, dict) and runtime_modes:
        if not bool(runtime_modes.get("exec", False)):
            return fail(f"runtime_modes.exec is not supported: {caps}")

    ts = int(time.time())
    pid = os.getpid()
    tag = f"{ts}-{pid}"

    cases = [
        {
            "client_id": f"e2e-sys-singbox-{tag}",
            "name": "E2E Systemd Singbox",
            "kind": "singbox",
            "cfg": {
                "runner": "systemd",
                "runtime_mode": "exec",
                "exec_start": "/usr/bin/sleep 120",
                "hardening_enabled": False,
            },
            "units": [f"singbox@e2e-sys-singbox-{tag}.service"],
            "template_units": ["singbox@.service"],
        },
        {
            "client_id": f"e2e-sys-phoenix-{tag}",
            "name": "E2E Systemd Phoenix",
            "kind": "phoenix",
            "cfg": {
                "runner": "systemd",
                "runtime_mode": "exec",
                "unit": f"svpn-e2e-phoenix-{tag}.service",
                "exec_start": "/usr/bin/sleep 120",
                "hardening_enabled": False,
            },
            "units": [f"svpn-e2e-phoenix-{tag}.service"],
        },
        {
            "client_id": f"e2e-sys-dnstt-{tag}",
            "name": "E2E Systemd DNSTT",
            "kind": "dnstt",
            "cfg": {
                "runner": "systemd",
                "runtime_mode": "exec",
                "unit": f"svpn-e2e-dnstt-{tag}.service",
                "exec_start": "/usr/bin/sleep 120",
                "ssh_tunnel": True,
                "ssh_unit": f"svpn-e2e-dnstt-ssh-{tag}.service",
                "ssh_exec_start": "/usr/bin/sleep 120",
                "hardening_enabled": False,
                "ssh_hardening_enabled": False,
            },
            "units": [
                f"svpn-e2e-dnstt-{tag}.service",
                f"svpn-e2e-dnstt-ssh-{tag}.service",
            ],
        },
    ]

    for case in cases:
        try:
            ok, reason = run_case(
                api_url,
                client_id=case["client_id"],
                name=case["name"],
                kind=case["kind"],
                cfg=case["cfg"],
                units=case["units"],
                template_units=case.get("template_units"),
            )
        except AssertionError as e:
            return fail(f"{case['kind']} failed: {e}")
        if not ok:
            print(f"[transport_systemd_real_e2e] SKIP: {reason}")
            return 0
        print(f"[transport_systemd_real_e2e] {case['kind']} real-systemd lifecycle: ok")

    print("[transport_systemd_real_e2e] passed")
    return 0


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