"""
config_loader.py – lädt Verbindungsparameter aus config/config.ini (primär)
oder .env (Fallback / Migration).
Umgebungsvariablen haben immer Vorrang.
"""
import os
import sys
import pathlib
import configparser

_BASE = pathlib.Path(sys.executable).parent if getattr(sys, "frozen", False) else pathlib.Path(__file__).parent

CONFIG_SECTION_CONNECTION = "connection"
CONFIG_SECTION_PRINT      = "print"
CONFIG_SECTION_BRIDGE     = "bridge"


def _find_config_file() -> pathlib.Path | None:
    for base in (_BASE, _BASE.parent):
        p = base / "config" / "config.ini"
        if p.is_file():
            return p
    return None


def _find_env_file() -> pathlib.Path | None:
    for base in (_BASE, _BASE.parent):
        p = base / ".env"
        if p.is_file():
            return p
    return None


def _load_env_file(path: pathlib.Path):
    """Lädt .env-Datei als Fallback – setzt nur Keys die noch nicht in os.environ sind."""
    with open(path, encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith("#") or "=" not in line:
                continue
            key, _, val = line.partition("=")
            key = key.strip()
            val = val.strip()
            if key and key not in os.environ:
                os.environ[key] = val


def _load_config_file(path: pathlib.Path):
    """Lädt config.ini und setzt Keys in os.environ (nur wenn nicht bereits gesetzt)."""
    cfg = configparser.ConfigParser()
    cfg.read(path, encoding="utf-8")

    mapping = {
        "PRINTER_IP":       (CONFIG_SECTION_CONNECTION, "printer_ip"),
        "MQTT_PORT":        (CONFIG_SECTION_CONNECTION, "mqtt_port"),
        "MQTT_USERNAME":    (CONFIG_SECTION_CONNECTION, "username"),
        "MQTT_PASSWORD":    (CONFIG_SECTION_CONNECTION, "password"),
        "MODE_ID":          (CONFIG_SECTION_CONNECTION, "mode_id"),
        "DEVICE_ID":        (CONFIG_SECTION_CONNECTION, "device_id"),
        "DEFAULT_AMS_SLOT": (CONFIG_SECTION_PRINT,      "default_ams_slot"),
        "AUTO_LEVELING":    (CONFIG_SECTION_PRINT,      "auto_leveling"),
    }
    for env_key, (section, option) in mapping.items():
        if env_key not in os.environ:
            try:
                val = cfg.get(section, option)
                if val:
                    os.environ[env_key] = val
            except (configparser.NoSectionError, configparser.NoOptionError):
                pass


def migrate_env_to_config(env_path: pathlib.Path, config_path: pathlib.Path):
    """Einmalige Migration: .env → config.ini anlegen."""
    env_vals: dict[str, str] = {}
    with open(env_path, encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith("#") or "=" not in line:
                continue
            k, _, v = line.partition("=")
            env_vals[k.strip()] = v.strip()

    config_path.parent.mkdir(parents=True, exist_ok=True)
    cfg = configparser.ConfigParser()
    cfg[CONFIG_SECTION_CONNECTION] = {
        "printer_ip": env_vals.get("PRINTER_IP", ""),
        "mqtt_port":  env_vals.get("MQTT_PORT",  "9883"),
        "username":   env_vals.get("MQTT_USERNAME", ""),
        "password":   env_vals.get("MQTT_PASSWORD", ""),
        "mode_id":    env_vals.get("MODE_ID",    ""),
        "device_id":  env_vals.get("DEVICE_ID",  ""),
    }
    cfg[CONFIG_SECTION_PRINT] = {
        "default_ams_slot": env_vals.get("DEFAULT_AMS_SLOT", "auto"),
        "auto_leveling":    env_vals.get("AUTO_LEVELING",    "1"),
    }
    cfg[CONFIG_SECTION_BRIDGE] = {
        "poll_interval": "3",
    }
    with open(config_path, "w", encoding="utf-8") as f:
        f.write("# KX-Bridge Konfigurationsdatei\n")
        f.write("# Automatisch migriert aus .env\n\n")
        cfg.write(f)


def find_config_path() -> pathlib.Path:
    """Gibt den Pfad zur config.ini zurück (auch wenn sie noch nicht existiert)."""
    for base in (_BASE, _BASE.parent):
        config_dir = base / "config"
        if config_dir.is_dir():
            return config_dir / "config.ini"
    return _BASE / "config" / "config.ini"


# ─── Laden ───────────────────────────────────────────────────────────────────

_config_path = _find_config_file()
_env_path    = _find_env_file()

if _config_path:
    _load_config_file(_config_path)
elif _env_path:
    # Kein config.ini vorhanden → aus .env migrieren
    _target = find_config_path()
    migrate_env_to_config(_env_path, _target)
    _load_config_file(_target)
    _config_path = _target


def get(key: str, default: str = "") -> str:
    return os.environ.get(key, default)


# Häufig verwendete Shortcuts
PRINTER_IP       = get("PRINTER_IP",       "")
MQTT_PORT        = int(get("MQTT_PORT",    "9883"))
USERNAME         = get("MQTT_USERNAME",    "")
PASSWORD         = get("MQTT_PASSWORD",    "")
MODE_ID          = get("MODE_ID",          "")
DEVICE_ID        = get("DEVICE_ID",        "")
DEFAULT_AMS_SLOT = get("DEFAULT_AMS_SLOT", "auto")
AUTO_LEVELING    = int(get("AUTO_LEVELING","1"))