"""Unified Clawdmeter configuration (Phase 7).

Single source of truth at ``%LOCALAPPDATA%\\Clawdmeter\\config.json``, shared by
the tray daemon and the FastAPI control panel. Replaces the Phase-6
``ha_config.json`` (auto-migrated on first load).

Shape::

    {
      "version": 1,
      "ha":       {"url": str, "token": str, "entities": [str, ...]},
      "buttons":  [{"id": str, "label": str, "icon": str,
                    "action": "toggle"|"bri"|"ct", "entity": str, "value": int|None}],
      "settings": {"device_address": str, "autostart": bool}
    }

The token is a secret: it lives only in this file (outside the repo, gitignored)
and is NEVER logged (only its length) — same discipline as ha_client.py. The
control panel masks it in API responses.
"""

import json
import os
from pathlib import Path

CONFIG_VERSION = 1
DEFAULT_PORT = 8723          # FastAPI control panel — bound to 127.0.0.1 only
VALID_ACTIONS = ("toggle", "bri", "ct")


def _dir() -> Path:
    base = Path(os.environ.get("LOCALAPPDATA", Path.home() / "AppData" / "Local"))
    return base / "Clawdmeter"


def config_path() -> Path:
    if override := os.environ.get("CLAWDMETER_CONFIG"):
        return Path(override)
    return _dir() / "config.json"


def _legacy_ha_path() -> Path:
    return _dir() / "ha_config.json"


def default_config() -> dict:
    return {
        "version": CONFIG_VERSION,
        "ha": {"url": "", "token": "", "entities": []},
        "buttons": [],
        "settings": {"device_address": "", "autostart": False, "low_battery_pct": 15},
    }


def _migrate_legacy(cfg: dict) -> dict:
    """Import the Phase-6 ha_config.json into the unified config when the unified
    HA section is still empty. Non-destructive: the old file is left in place."""
    legacy = _legacy_ha_path()
    if cfg["ha"]["url"] or not legacy.exists():
        return cfg
    try:
        # utf-8-sig: PowerShell's Out-File writes a BOM that json.loads chokes on.
        old = json.loads(legacy.read_text(encoding="utf-8-sig"))
    except (OSError, json.JSONDecodeError):
        return cfg
    cfg["ha"]["url"] = (old.get("url") or "").strip().rstrip("/")
    cfg["ha"]["token"] = (old.get("token") or "").strip()
    cfg["ha"]["entities"] = list(old.get("entities") or [])
    return cfg


def load_config() -> dict:
    """Load the unified config, filling defaults for any missing section so new
    keys added in later versions always resolve. Never raises."""
    cfg = default_config()
    try:
        loaded = json.loads(config_path().read_text(encoding="utf-8-sig"))
    except (OSError, json.JSONDecodeError):
        loaded = None
    if isinstance(loaded, dict):
        for section in ("ha", "settings"):
            if isinstance(loaded.get(section), dict):
                cfg[section].update(loaded[section])
        if isinstance(loaded.get("buttons"), list):
            cfg["buttons"] = loaded["buttons"]
    if not cfg["ha"]["url"] and not cfg["ha"]["token"]:
        cfg = _migrate_legacy(cfg)
    # Normalize the HA section the same way ha_client expects it.
    cfg["ha"]["url"] = (cfg["ha"].get("url") or "").strip().rstrip("/")
    cfg["ha"]["token"] = (cfg["ha"].get("token") or "").strip()
    cfg["ha"]["entities"] = list(cfg["ha"].get("entities") or [])
    return cfg


def save_config(cfg: dict) -> None:
    """Persist atomically (temp file + os.replace) so a crash mid-write can't
    leave a truncated config."""
    path = config_path()
    path.parent.mkdir(parents=True, exist_ok=True)
    tmp = path.with_name(path.name + ".tmp")
    tmp.write_text(json.dumps(cfg, ensure_ascii=False, indent=2), encoding="utf-8")
    os.replace(tmp, path)


def ha_settings(cfg: dict | None = None) -> dict | None:
    """Return {url, token, entities} when HA is configured (url + real token),
    else None — the shape the daemon needs to build an HAClient. Logging of the
    token is the caller's responsibility (ha_client logs only the length)."""
    if cfg is None:
        cfg = load_config()
    ha = cfg.get("ha", {})
    url = (ha.get("url") or "").strip().rstrip("/")
    token = (ha.get("token") or "").strip()
    if not url or not token or token.startswith("PASTE_"):
        return None
    return {"url": url, "token": token, "entities": list(ha.get("entities") or [])}