import json
import os
import hashlib
import secrets
import bcrypt
from copy import deepcopy
from typing import Any
from app.utils.platform_utils import get_config_dir


_CONFIG_FILE = "config.json"

_WG_DEFAULT: dict[str, Any] = {
    "interface_name": "wgs0",
    "server_endpoint": "",
    "server_port": 51820,
    "server_public_key": "",
    # Drapeau explicite : une PSK vide ne veut pas dire « oubliée ». Sans lui,
    # le diagnostic criait au champ manquant sur tout serveur qui n'en utilise
    # pas — c'est-à-dire la configuration WireGuard par défaut.
    #
    # Le défaut est `None`, pas `False` : `_merge()` recopie le défaut dans
    # toute configuration antérieure au drapeau, et `False` aurait désactivé
    # la clé pré-partagée d'un tunnel qui fonctionnait. `None` signifie
    # « jamais renseigné » et laisse `uses_preshared_key()` déduire l'état de
    # la présence de la clé.
    "use_preshared_key": None,
    "preshared_key": "",
    "client_private_key": "",
    "client_public_key": "",
    "client_address": "10.8.0.2/24",
    "dns": "1.1.1.1",
    "allowed_ips": "10.8.0.0/24",
    "keepalive": 25,
    "mtu": 0,
    # Split-DNS : serveur DNS dédié pour les noms du réseau distant,
    # avec liste de domaines à résoudre via ce serveur (ex: ["local", "internal"]).
    # Laisser vide pour utiliser le DNS par défaut pour tout le trafic.
    # Authentification auprès du serveur après montage du tunnel : identifiant
    # du compte VPN tel que connu du serveur, et URL de son API. Laissée vide,
    # celle-ci est déduite de l'adresse du client (cf. vpn_session.py).
    "vpn_username": "",
    "api_url": "",
    "split_dns_server": "",
    "split_dns_domains": [],
}

_DEFAULT: dict[str, Any] = {
    "version": "0.7.3",
    "admin_password_hash": "",
    "admin_salt": "",
    "mfa_enabled": False,
    "mfa_secret": "",
    "active_profile": "H3",
    "profiles": {},
    "wg": deepcopy(_WG_DEFAULT),
    "ui": {
        "minimize_to_tray": True,
        "autostart": True,
        "auto_connect_on_startup": False,
        "auto_reconnect": True,
        "reconnect_interval": 15,
    },
}


class Config:
    def __init__(self):
        self._path = os.path.join(get_config_dir(), _CONFIG_FILE)
        self._data: dict[str, Any] = {}
        self.load()

    def load(self):
        if os.path.exists(self._path):
            try:
                with open(self._path, "r", encoding="utf-8") as f:
                    saved = json.load(f)
                self._data = self._merge(_DEFAULT, saved)
            except Exception:
                self._data = deepcopy(_DEFAULT)
        else:
            # Première exécution : le défaut « autostart activé » n'a d'effet
            # que si on l'applique réellement (fichier .desktop / clé de
            # registre), sinon la case reste cochée sans rien avoir installé.
            self._data = deepcopy(_DEFAULT)
            self._apply_autostart(self._data["ui"]["autostart"])

    def save(self):
        os.makedirs(os.path.dirname(self._path), exist_ok=True)
        with open(self._path, "w", encoding="utf-8") as f:
            json.dump(self._data, f, indent=2, ensure_ascii=False)

    def _merge(self, base: dict, override: dict) -> dict:
        result = dict(base)
        for k, v in override.items():
            if k in result and isinstance(result[k], dict) and isinstance(v, dict):
                result[k] = self._merge(result[k], v)
            else:
                result[k] = v
        return result

    def get(self, *keys: str, default=None) -> Any:
        node = self._data
        for k in keys:
            if not isinstance(node, dict) or k not in node:
                return default
            node = node[k]
        return node

    def set(self, *keys_and_value) -> None:
        *keys, value = keys_and_value
        node = self._data
        for k in keys[:-1]:
            node = node.setdefault(k, {})
        node[keys[-1]] = value

    # ── Mot de passe admin ────────────────────────────────────────────────

    def set_admin_password(self, password: str):
        if not password:
            self._data["admin_salt"] = ""
            self._data["admin_password_hash"] = ""
        else:
            hashed = bcrypt.hashpw(password.encode("utf-8"), bcrypt.gensalt(rounds=12))
            self._data["admin_salt"] = ""
            self._data["admin_password_hash"] = hashed.decode("utf-8")
        self.save()

    def check_admin_password(self, password: str) -> bool:
        stored = self._data.get("admin_password_hash", "")
        if not stored:
            return True
        # Migration transparente : anciens hashes SHA-256 (64 hex chars, pas de $2b$)
        if not stored.startswith("$2"):
            salt = self._data.get("admin_salt", "")
            candidate = hashlib.sha256((salt + password).encode()).hexdigest()
            return secrets.compare_digest(candidate, stored)
        return bcrypt.checkpw(password.encode("utf-8"), stored.encode("utf-8"))

    def has_admin_password(self) -> bool:
        return bool(self._data.get("admin_password_hash", ""))

    # ── WireGuard ─────────────────────────────────────────────────────────

    @property
    def wg(self) -> dict:
        return self._data["wg"]

    @property
    def configured(self) -> bool:
        wg = self._data["wg"]
        return bool(wg.get("server_endpoint") and wg.get("client_private_key"))

    # ── MFA ───────────────────────────────────────────────────────────────

    @property
    def mfa_enabled(self) -> bool:
        return bool(self._data.get("mfa_enabled", False))

    @mfa_enabled.setter
    def mfa_enabled(self, value: bool):
        self._data["mfa_enabled"] = value

    @property
    def mfa_secret(self) -> str:
        return self._data.get("mfa_secret", "")

    @mfa_secret.setter
    def mfa_secret(self, value: str):
        self._data["mfa_secret"] = value

    # ── Multi-profils ─────────────────────────────────────────────────────

    @property
    def active_profile(self) -> str:
        return self._data.get("active_profile", "H3")

    def list_profiles(self) -> list[str]:
        return list(self._data.get("profiles", {}).keys())

    def save_profile(self, name: str) -> None:
        """Sauvegarde la config WireGuard courante sous un nom de profil."""
        self._data.setdefault("profiles", {})[name] = deepcopy(self._data["wg"])
        self._data["active_profile"] = name
        self.save()

    def load_profile(self, name: str) -> bool:
        """Charge un profil sauvegardé dans la config active."""
        profiles = self._data.get("profiles", {})
        if name not in profiles:
            return False
        self._data["wg"] = deepcopy(profiles[name])
        self._data["active_profile"] = name
        self.save()
        return True

    def delete_profile(self, name: str) -> bool:
        profiles = self._data.get("profiles", {})
        if name not in profiles:
            return False
        del profiles[name]
        if self._data.get("active_profile") == name:
            self._data["active_profile"] = "H3"
        self.save()
        return True

    def rename_profile(self, old: str, new: str) -> bool:
        profiles = self._data.get("profiles", {})
        if old not in profiles or new in profiles:
            return False
        profiles[new] = profiles.pop(old)
        if self._data.get("active_profile") == old:
            self._data["active_profile"] = new
        self.save()
        return True

    # ── Autostart ─────────────────────────────────────────────────────────

    def set_autostart(self, enabled: bool) -> None:
        self._data["ui"]["autostart"] = enabled
        self._apply_autostart(enabled)
        self.save()

    def _apply_autostart(self, enabled: bool) -> None:
        from app.utils.platform_utils import is_linux, is_windows, launch_command
        # launch_command() gère le cas du binaire PyInstaller, où main.py
        # n'existe pas : l'ancien « python3 <…>/main.py » ne démarrait jamais.
        command = launch_command()
        if is_linux():
            autostart_dir = os.path.expanduser("~/.config/autostart")
            desktop = os.path.join(autostart_dir, "wgsecure.desktop")
            if enabled:
                os.makedirs(autostart_dir, exist_ok=True)
                content = (
                    "[Desktop Entry]\nType=Application\nName=WGSecure\n"
                    f"Exec={command}\nIcon=wgsecure\n"
                    "Hidden=false\nX-GNOME-Autostart-enabled=true\n"
                )
                with open(desktop, "w") as f:
                    f.write(content)
            else:
                try:
                    os.unlink(desktop)
                except FileNotFoundError:
                    pass
        elif is_windows():
            import winreg
            key = r"Software\Microsoft\Windows\CurrentVersion\Run"
            try:
                reg = winreg.OpenKey(winreg.HKEY_CURRENT_USER, key, 0,
                                     winreg.KEY_SET_VALUE)
                if enabled:
                    winreg.SetValueEx(reg, "WGSecure", 0, winreg.REG_SZ, command)
                else:
                    winreg.DeleteValue(reg, "WGSecure")
                winreg.CloseKey(reg)
            except Exception:
                pass