"""
JSON file-based database module

Handles:
- JSON file storage for users, tokens, and blacklisted tokens
- User management and authentication
- Token blacklist management
- Refresh token storage
- Thread-safe JSON operations with file locking
- Hugging Face friendly seeding + writable fallback
"""

import os
import json
import threading
import shutil
from typing import Optional, Dict, Any, List, Tuple
from pathlib import Path
from datetime import datetime

# =========================================================
# PATHS
# =========================================================

def _project_root() -> Path:
    # auth/json_database.py -> auth (parent) -> project root (parent)
    return Path(__file__).resolve().parent.parent

DEFAULT_DB_DIR = str((_project_root() / "data").resolve())  # <project>/data
DB_DIR_ENV = os.getenv("AUTH_DB_DIR", DEFAULT_DB_DIR)

# Seed dir (where your repo JSON files exist)
SEED_DIR_ENV = os.getenv("AUTH_SEED_DIR", DEFAULT_DB_DIR)

# Seeding controls
SEED_ON_START = os.getenv("AUTH_SEED_ON_START", "1") == "1"
SEED_IF_EMPTY = os.getenv("AUTH_SEED_IF_EMPTY", "1") == "1"

# Initialize DB files on startup
RUN_INIT_DB = os.getenv("RUN_INIT_DB", "1") == "1"

# Resolve target db dir
DB_DIR = str(Path(DB_DIR_ENV).expanduser().resolve())
SEED_DIR = str(Path(SEED_DIR_ENV).expanduser().resolve())

USERS_FILE = os.path.join(DB_DIR, "users.json")
BLACKLISTED_TOKENS_FILE = os.path.join(DB_DIR, "blacklisted_tokens.json")
REFRESH_TOKENS_FILE = os.path.join(DB_DIR, "refresh_tokens.json")

# Thread locks
_file_locks = {
    "users": threading.Lock(),
    "blacklisted_tokens": threading.Lock(),
    "refresh_tokens": threading.Lock(),
}

_db_init_done = False
_db_init_lock = threading.Lock()

# =========================================================
# HELPERS
# =========================================================

def _log(msg: str):
    # Simple stdout logging (Hugging Face logs show this)
    print(msg, flush=True)

def ensure_data_directory():
    """
    Create DB directory. If not writable, fallback to /tmp/auth_db.
    """
    global DB_DIR, USERS_FILE, BLACKLISTED_TOKENS_FILE, REFRESH_TOKENS_FILE

    try:
        Path(DB_DIR).mkdir(parents=True, exist_ok=True)
        # write test
        test_file = os.path.join(DB_DIR, ".write_test")
        with open(test_file, "w", encoding="utf-8") as f:
            f.write("ok")
        os.remove(test_file)
        return
    except Exception as e:
        _log(f"[AUTH][WARN] DB_DIR not writable: {DB_DIR}. Error: {e}")
        fallback = "/tmp/auth_db"
        _log(f"[AUTH][WARN] Falling back to: {fallback}")
        DB_DIR = fallback
        Path(DB_DIR).mkdir(parents=True, exist_ok=True)

        USERS_FILE = os.path.join(DB_DIR, "users.json")
        BLACKLISTED_TOKENS_FILE = os.path.join(DB_DIR, "blacklisted_tokens.json")
        REFRESH_TOKENS_FILE = os.path.join(DB_DIR, "refresh_tokens.json")

def load_json_file(filepath: str) -> Dict[str, Any]:
    """
    Load JSON file with error handling.
    Returns {} if file does not exist.
    """
    if not os.path.exists(filepath):
        return {}

    try:
        with open(filepath, "r", encoding="utf-8") as f:
            return json.load(f)
    except (json.JSONDecodeError, IOError) as e:
        _log(f"[AUTH][ERROR] Error loading {filepath}: {e}")
        return {}

def save_json_file(filepath: str, data: Dict[str, Any]):
    """
    Atomic save JSON file (prevents partial writes).
    """
    parent = os.path.dirname(filepath)
    os.makedirs(parent, exist_ok=True)

    tmp_path = filepath + ".tmp"
    try:
        with open(tmp_path, "w", encoding="utf-8") as f:
            json.dump(data, f, indent=2, ensure_ascii=False)
        os.replace(tmp_path, filepath)
    except Exception as e:
        _log(f"[AUTH][ERROR] Error saving {filepath}: {e}")
        # cleanup temp if exists
        try:
            if os.path.exists(tmp_path):
                os.remove(tmp_path)
        except Exception:
            pass
        raise

def _file_is_empty_json(filepath: str) -> bool:
    if not os.path.exists(filepath):
        return True
    try:
        data = load_json_file(filepath)
        return not bool(data)
    except Exception:
        return True

def _seed_file_if_needed(target_path: str, seed_path: str):
    """
    Copy seed file -> target if:
    - target missing, OR
    - target exists but empty AND SEED_IF_EMPTY=1
    """
    if not SEED_ON_START:
        return

    seed_exists = os.path.exists(seed_path)
    target_exists = os.path.exists(target_path)

    if (not target_exists and seed_exists) or (target_exists and SEED_IF_EMPTY and seed_exists and _file_is_empty_json(target_path)):
        os.makedirs(os.path.dirname(target_path), exist_ok=True)
        shutil.copy2(seed_path, target_path)
        _log(f"[AUTH][SEED] Copied seed: {seed_path} -> {target_path}")

# =========================================================
# STORAGE CLASSES
# =========================================================

class JSONUsers:
    @staticmethod
    def load_all() -> Dict[str, Any]:
        with _file_locks["users"]:
            return load_json_file(USERS_FILE)

    @staticmethod
    def find_by_username(username: str) -> Optional[Dict[str, Any]]:
        users = JSONUsers.load_all()
        return users.get(username.lower())

    @staticmethod
    def create_user(username: str, password_hash: str, role: str = "user") -> bool:
        username_lower = username.lower()

        with _file_locks["users"]:
            users = load_json_file(USERS_FILE)

            if username_lower in users:
                return False

            users[username_lower] = {
                "id": len(users) + 1,
                "username": username_lower,
                "password_hash": password_hash,
                "role": role,
                "created_at": datetime.now().isoformat(),
            }

            save_json_file(USERS_FILE, users)
            return True

    @staticmethod
    def get_all_users() -> List[Dict[str, Any]]:
        users = JSONUsers.load_all()
        return [
            {"id": u.get("id"), "username": u.get("username"), "role": u.get("role")}
            for u in users.values()
        ]

    @staticmethod
    def promote_to_admin(username: str) -> bool:
        username_lower = username.lower()
        with _file_locks["users"]:
            users = load_json_file(USERS_FILE)
            if username_lower not in users:
                return False
            users[username_lower]["role"] = "admin"
            save_json_file(USERS_FILE, users)
            return True

    @staticmethod
    def user_count() -> int:
        return len(JSONUsers.load_all())

class JSONBlacklistedTokens:
    @staticmethod
    def load_all() -> Dict[str, Any]:
        with _file_locks["blacklisted_tokens"]:
            return load_json_file(BLACKLISTED_TOKENS_FILE)

    @staticmethod
    def is_blacklisted(token: str) -> bool:
        tokens = JSONBlacklistedTokens.load_all()
        return token in tokens

    @staticmethod
    def add_to_blacklist(token: str) -> bool:
        with _file_locks["blacklisted_tokens"]:
            tokens = load_json_file(BLACKLISTED_TOKENS_FILE)
            if token in tokens:
                return True

            tokens[token] = {"token": token, "created_at": datetime.now().isoformat()}
            save_json_file(BLACKLISTED_TOKENS_FILE, tokens)
            return True

class JSONRefreshTokens:
    @staticmethod
    def load_all() -> Dict[str, Any]:
        with _file_locks["refresh_tokens"]:
            return load_json_file(REFRESH_TOKENS_FILE)

    @staticmethod
    def find_by_token(token: str) -> Optional[str]:
        tokens = JSONRefreshTokens.load_all()
        for token_data in tokens.values():
            if token_data.get("token") == token:
                return token_data.get("username")
        return None

    @staticmethod
    def create_token(username: str, token: str) -> bool:
        with _file_locks["refresh_tokens"]:
            tokens = load_json_file(REFRESH_TOKENS_FILE)
            token_key = f"{username.lower()}_{len(tokens) + 1}"
            tokens[token_key] = {
                "username": username.lower(),
                "token": token,
                "created_at": datetime.now().isoformat(),
            }
            save_json_file(REFRESH_TOKENS_FILE, tokens)
            return True

    @staticmethod
    def delete_user_tokens(username: str) -> bool:
        username_lower = username.lower()
        with _file_locks["refresh_tokens"]:
            tokens = load_json_file(REFRESH_TOKENS_FILE)
            to_remove = [k for k, v in tokens.items() if v.get("username") == username_lower]
            for k in to_remove:
                del tokens[k]
            save_json_file(REFRESH_TOKENS_FILE, tokens)
            return True

# =========================================================
# INIT / DIAG
# =========================================================

def init_db():
    """
    Initialize JSON database files.
    If AUTH_SEED_ON_START=1, seed from AUTH_SEED_DIR when missing or empty.
    """
    ensure_data_directory()

    # seed paths
    seed_users = os.path.join(SEED_DIR, "users.json")
    seed_blacklist = os.path.join(SEED_DIR, "blacklisted_tokens.json")
    seed_refresh = os.path.join(SEED_DIR, "refresh_tokens.json")

    # Seed (if needed)
    _seed_file_if_needed(USERS_FILE, seed_users)
    _seed_file_if_needed(BLACKLISTED_TOKENS_FILE, seed_blacklist)
    _seed_file_if_needed(REFRESH_TOKENS_FILE, seed_refresh)

    # Ensure files exist (create empty if still missing)
    if not os.path.exists(USERS_FILE):
        save_json_file(USERS_FILE, {})
        _log(f"[AUTH][INIT] Created empty {USERS_FILE}")

    if not os.path.exists(BLACKLISTED_TOKENS_FILE):
        save_json_file(BLACKLISTED_TOKENS_FILE, {})
        _log(f"[AUTH][INIT] Created empty {BLACKLISTED_TOKENS_FILE}")

    if not os.path.exists(REFRESH_TOKENS_FILE):
        save_json_file(REFRESH_TOKENS_FILE, {})
        _log(f"[AUTH][INIT] Created empty {REFRESH_TOKENS_FILE}")

    # Startup log (very useful in HF logs)
    try:
        users_count = len(load_json_file(USERS_FILE))
        _log(f"[AUTH][READY] DB_DIR={DB_DIR} | users={users_count}")
    except Exception as e:
        _log(f"[AUTH][WARN] Could not read users count: {e}")

def ensure_database_initialized() -> bool:
    """
    Ensure JSON DB is initialized once (thread-safe).
    Controlled by RUN_INIT_DB.
    """
    global _db_init_done

    if not RUN_INIT_DB:
        return False

    if not _db_init_done:
        with _db_init_lock:
            if not _db_init_done:
                init_db()
                _db_init_done = True
    return True

def get_database_info() -> Dict[str, Any]:
    info = {
        "database_type": "JSON",
        "storage_location": DB_DIR,
        "seed_location": SEED_DIR,
        "files": {},
    }

    def _file_info(path: str, label: str):
        if not os.path.exists(path):
            info["files"][label] = {"exists": False}
            return
        data = load_json_file(path)
        info["files"][label] = {
            "exists": True,
            "path": path,
            "size_bytes": os.path.getsize(path),
            "count": len(data) if isinstance(data, dict) else 0,
        }

    try:
        _file_info(USERS_FILE, "users")
        _file_info(BLACKLISTED_TOKENS_FILE, "blacklisted_tokens")
        _file_info(REFRESH_TOKENS_FILE, "refresh_tokens")
        info["connection_status"] = "ok"
    except Exception as e:
        info["connection_status"] = "error"
        info["error"] = str(e)

    return info

def test_database_connection() -> Tuple[bool, str]:
    try:
        ensure_data_directory()
        _ = JSONUsers.load_all()

        test_file = os.path.join(DB_DIR, ".test")
        save_json_file(test_file, {"test": "ok"})
        os.remove(test_file)

        return True, "JSON database connection successful"
    except Exception as e:
        return False, f"JSON database connection failed: {str(e)}"