import os
import json
import firebase_admin
from firebase_admin import credentials, auth
import config


class FirebaseService:
    def __init__(self):
        self._initialized = False

    def _initialize(self):
        if not self._initialized:
            try:
                if not firebase_admin._apps:
                    cred = None
                    
                    # Priority 1: JSON content from environment variable (for Hugging Face Spaces)
                    if config.FIREBASE_CREDENTIALS_JSON:
                        try:
                            cred_dict = json.loads(config.FIREBASE_CREDENTIALS_JSON)
                            cred = credentials.Certificate(cred_dict)
                            print("[Firebase] Initialized with credentials from FIREBASE_CREDENTIALS_JSON")
                        except json.JSONDecodeError as e:
                            print(f"[Firebase] Error parsing FIREBASE_CREDENTIALS_JSON: {e}")
                    
                    # Priority 2: Credentials JSON file
                    if not cred and config.FIREBASE_CREDENTIALS_PATH and os.path.exists(config.FIREBASE_CREDENTIALS_PATH):
                        cred = credentials.Certificate(config.FIREBASE_CREDENTIALS_PATH)
                        print(f"[Firebase] Initialized with credentials file: {config.FIREBASE_CREDENTIALS_PATH}")
                    
                    # Initialize with credentials or fallback to project ID
                    if cred:
                        firebase_admin.initialize_app(cred)
                    elif config.FIREBASE_PROJECT_ID:
                        firebase_admin.initialize_app(options={
                            'projectId': config.FIREBASE_PROJECT_ID
                        })
                        print(f"[Firebase] Initialized with project ID only: {config.FIREBASE_PROJECT_ID}")
                    else:
                        print("[Firebase] No credentials or project ID configured")
                        return
                        
                self._initialized = True
            except Exception as e:
                print(f"[Firebase] Initialization error: {e}")

    def verify_token(self, id_token: str) -> dict:
        self._initialize()
        
        # If Firebase not initialized, skip verification (optional mode)
        if not self._initialized:
            print("[Firebase] Not initialized - skipping token verification (optional mode)")
            return {
                "uid": "anonymous",
                "email": None,
                "verified": False,
                "skipped": True
            }
        
        try:
            decoded_token = auth.verify_id_token(id_token)
            return {
                "uid": decoded_token.get("uid"),
                "email": decoded_token.get("email"),
                "verified": True
            }
        except auth.InvalidIdTokenError:
            raise Exception("Invalid Firebase token")
        except auth.ExpiredIdTokenError:
            raise Exception("Firebase token has expired")
        except Exception as e:
            error_str = str(e).lower()
            # If credentials error or connection error, return anonymous (optional mode)
            if any(keyword in error_str for keyword in ["credentials", "connection", "remote", "network", "timeout", "aborted"]):
                print(f"[Firebase] Connection/credentials error - skipping verification: {str(e)[:100]}")
                return {
                    "uid": "anonymous",
                    "email": None,
                    "verified": False,
                    "skipped": True
                }
            raise Exception(f"Firebase authentication failed: {str(e)}")


firebase_service = FirebaseService()