# -*- coding: utf-8 -*-
"""
AZA Security Vault – Verschlüsselter API-Key-Tresor.

Windows:  DPAPI (CryptProtectData / CryptUnprotectData) – user-scoped.
Fallback: base64-Obfuscation (kein Klartext, aber kein kryptographischer Schutz).
"""

import base64
import json
import os
import sys

from aza_config import get_writable_data_dir

_VAULT_SUBDIR = "secure"
_VAULT_FILENAME = "vault.dat"


def _vault_path() -> str:
    d = os.path.join(get_writable_data_dir(), _VAULT_SUBDIR)
    os.makedirs(d, exist_ok=True)
    return os.path.join(d, _VAULT_FILENAME)


# ─── Windows DPAPI ────────────────────────────────────────────────────────────

_USE_DPAPI = sys.platform == "win32"

if _USE_DPAPI:
    import ctypes
    import ctypes.wintypes as _wt

    class _DATA_BLOB(ctypes.Structure):
        _fields_ = [
            ("cbData", _wt.DWORD),
            ("pbData", ctypes.POINTER(ctypes.c_char)),
        ]

    def _dpapi_encrypt(plaintext: bytes) -> bytes:
        blob_in = _DATA_BLOB(len(plaintext), ctypes.create_string_buffer(plaintext, len(plaintext)))
        blob_out = _DATA_BLOB()
        ok = ctypes.windll.crypt32.CryptProtectData(
            ctypes.byref(blob_in), None, None, None, None, 0, ctypes.byref(blob_out),
        )
        if not ok:
            raise OSError("CryptProtectData failed")
        buf = ctypes.create_string_buffer(blob_out.cbData)
        ctypes.memmove(buf, blob_out.pbData, blob_out.cbData)
        ctypes.windll.kernel32.LocalFree(blob_out.pbData)
        return buf.raw

    def _dpapi_decrypt(encrypted: bytes) -> bytes:
        blob_in = _DATA_BLOB(len(encrypted), ctypes.create_string_buffer(encrypted, len(encrypted)))
        blob_out = _DATA_BLOB()
        ok = ctypes.windll.crypt32.CryptUnprotectData(
            ctypes.byref(blob_in), None, None, None, None, 0, ctypes.byref(blob_out),
        )
        if not ok:
            raise OSError("CryptUnprotectData failed")
        buf = ctypes.create_string_buffer(blob_out.cbData)
        ctypes.memmove(buf, blob_out.pbData, blob_out.cbData)
        ctypes.windll.kernel32.LocalFree(blob_out.pbData)
        return buf.raw


def _encrypt(data: bytes) -> bytes:
    if _USE_DPAPI:
        return _dpapi_encrypt(data)
    return base64.b85encode(data)


def _decrypt(data: bytes) -> bytes:
    if _USE_DPAPI:
        return _dpapi_decrypt(data)
    return base64.b85decode(data)


# ─── Public API ───────────────────────────────────────────────────────────────

def store_api_key(key: str) -> bool:
    """Speichert den API-Key verschlüsselt im Tresor."""
    if not key or not key.strip():
        return False
    try:
        encrypted = _encrypt(key.strip().encode("utf-8"))
        payload = {
            "k": base64.b64encode(encrypted).decode("ascii"),
            "m": "dpapi" if _USE_DPAPI else "b85",
        }
        with open(_vault_path(), "w", encoding="utf-8") as f:
            json.dump(payload, f)
        return True
    except Exception:
        return False


def retrieve_api_key() -> str | None:
    """Liest den API-Key aus dem verschlüsselten Tresor."""
    try:
        path = _vault_path()
        if not os.path.isfile(path):
            return None
        with open(path, "r", encoding="utf-8") as f:
            payload = json.load(f)
        encrypted = base64.b64decode(payload["k"])
        return _decrypt(encrypted).decode("utf-8")
    except Exception:
        return None


def has_vault_key() -> bool:
    """True wenn ein verschlüsselter Key im Tresor existiert."""
    return retrieve_api_key() is not None


def get_masked_key() -> str:
    """Gibt den Key maskiert zurück, z.B. 'sk-****...a1B2'."""
    key = retrieve_api_key()
    if not key:
        return ""
    if len(key) <= 8:
        return "****-****"
    prefix = key[:3] if key.startswith("sk-") else ""
    return f"{prefix}****\u2026{key[-4:]}"


def delete_vault_key() -> bool:
    """Löscht den gespeicherten Key."""
    try:
        path = _vault_path()
        if os.path.isfile(path):
            os.remove(path)
        return True
    except Exception:
        return False