"""Mutable debug snapshot for ``zkac-node serve`` (optional, thread-safe)."""

from __future__ import annotations

import base64
import json
import threading
import time
import uuid
from collections import deque
from pathlib import Path
from typing import Any

import zkac


class ServerDebugState:
    """
    Live server introspection for an admin dashboard.

    Connection records are updated from worker threads; readers take a consistent
    snapshot via :meth:`snapshot`.
    """

    def __init__(self, *, userid: str, data_dir: str) -> None:
        self.userid = userid
        self.data_dir = str(Path(data_dir).resolve())
        self._lock = threading.Lock()
        self._started_wall = time.time()
        self._started_mono = time.monotonic()
        self._listen: tuple[str, int] = ("", 0)
        self._server_pk_hex: str | None = None
        self._registries_loaded = 0
        self._active: dict[str, dict[str, Any]] = {}
        self._history: deque[dict[str, Any]] = deque(maxlen=64)

    def set_listen(self, host: str, port: int) -> None:
        with self._lock:
            self._listen = (host, port)

    def set_boot_info(self, *, server_pk_hex: str, registries_loaded: int) -> None:
        with self._lock:
            self._server_pk_hex = server_pk_hex
            self._registries_loaded = registries_loaded

    def open_connection(self, peer: str) -> str:
        cid = uuid.uuid4().hex[:10]
        rec: dict[str, Any] = {
            "id": cid,
            "peer": peer,
            "opened_wall": time.time(),
            "opened_mono": time.monotonic(),
            "phase": "accepted",
            "hello_op": None,
            "transcript_hash_hex": None,
            "auth_registry_hex": None,
            "auth_role_hex": None,
            "auth_ok": None,
            "last_mgmt_cmd": None,
            "mgmt_commands": 0,
            "bytes_echoed": 0,
            "error": None,
        }
        with self._lock:
            self._active[cid] = rec
        return cid

    def update_connection(self, cid: str, **fields: Any) -> None:
        with self._lock:
            rec = self._active.get(cid)
            if rec is None:
                return
            rec.update(fields)

    def note_mgmt_command(self, cid: str, cmd: dict) -> None:
        name = cmd.get("cmd")
        with self._lock:
            rec = self._active.get(cid)
            if rec is None:
                return
            rec["last_mgmt_cmd"] = name
            rec["mgmt_commands"] = int(rec.get("mgmt_commands") or 0) + 1

    def note_echo_chunk(self, cid: str, n: int) -> None:
        with self._lock:
            rec = self._active.get(cid)
            if rec is None:
                return
            rec["bytes_echoed"] = int(rec.get("bytes_echoed") or 0) + n

    def close_connection(self, cid: str, *, error: str | None = None) -> None:
        with self._lock:
            rec = self._active.pop(cid, None)
            if rec is None:
                return
            rec = {**rec, "closed_wall": time.time(), "closed_mono": time.monotonic()}
            if error:
                rec["error"] = error
            self._history.appendleft(rec)

    def snapshot(self) -> dict[str, Any]:
        with self._lock:
            uptime = time.monotonic() - self._started_mono
            return {
                "userid": self.userid,
                "data_dir": self.data_dir,
                "started_wall": self._started_wall,
                "uptime_s": round(uptime, 3),
                "listen": {"host": self._listen[0], "port": self._listen[1]},
                "server_public_key_hex": self._server_pk_hex,
                "registries_loaded_boot": self._registries_loaded,
                "active_connections": list(self._active.values()),
                "recent_connections": list(self._history),
                "active_connection_count": len(self._active),
            }


def server_key_meta(data_dir: Path) -> dict[str, Any]:
    """Non-secret metadata from ``server_key.json``."""
    path = data_dir / "server_key.json"
    if not path.is_file():
        return {"present": False, "path": str(path)}
    try:
        data = json.loads(path.read_text())
        pub = base64.b64decode(data["public_b64"])
        sec = base64.b64decode(data["secret_b64"])
        return {
            "present": True,
            "path": str(path),
            "public_key_hex": pub.hex(),
            "secret_key_stored_bytes": len(sec),
        }
    except Exception as exc:
        return {"present": True, "path": str(path), "error": str(exc)}


def collect_registry_debug(data_dir: Path) -> list[dict[str, Any]]:
    """Per-registry rows from on-disk state (deserialized for version / ids)."""
    reg_dir = data_dir / "registries"
    if not reg_dir.is_dir():
        return []
    rows: list[dict[str, Any]] = []
    for p in sorted(reg_dir.glob("*.state")):
        rid_file = p.stem
        cert_path = reg_dir / f"{rid_file}.cert"
        raw = p.read_bytes()
        row: dict[str, Any] = {
            "file_registry_id_hex": rid_file,
            "state_path": str(p),
            "state_bytes": len(raw),
            "cert_path": str(cert_path) if cert_path.exists() else None,
            "cert_bytes": cert_path.stat().st_size if cert_path.exists() else 0,
        }
        try:
            st = zkac.RegistryState.deserialize(raw)
            row["parsed_ok"] = True
            row["version"] = st.version()
            row["registry_id_hex"] = st.registry_id().hex()
            row["state_hash_hex"] = st.state_hash().hex()
        except Exception as exc:
            row["parsed_ok"] = False
            row["parse_error"] = str(exc)
        rows.append(row)
    return rows


def data_dir_tree(data_dir: Path, *, max_files: int = 200) -> list[dict[str, Any]]:
    """Small file listing for transparency (names + sizes only)."""
    out: list[dict[str, Any]] = []
    root = data_dir.resolve()
    if not root.is_dir():
        return out
    n = 0
    for path in sorted(root.rglob("*")):
        if not path.is_file():
            continue
        if n >= max_files:
            out.append({"truncated": True, "note": f"listing capped at {max_files} files"})
            break
        rel = path.relative_to(root)
        try:
            out.append({"path": str(rel).replace("\\", "/"), "bytes": path.stat().st_size})
            n += 1
        except OSError:
            continue
    return out