import os
import json
import firebase_admin
from firebase_admin import credentials, auth as fb_auth, firestore
import requests as http_requests

_initialized = False
_db = None


def init_firebase() -> bool:
    global _initialized, _db
    if _initialized:
        return True

    creds_json = os.getenv("FIREBASE_CREDENTIALS", "")
    if not creds_json:
        print("[firebase] FIREBASE_CREDENTIALS not set — auth disabled.")
        return False

    try:
        cred = credentials.Certificate(json.loads(creds_json))
        firebase_admin.initialize_app(cred)
        _db = firestore.client()
        _initialized = True
        print("[firebase] Initialized successfully.")
        return True
    except Exception as exc:
        print(f"[firebase] Init error: {exc}")
        return False


def get_db():
    if not _initialized:
        init_firebase()
    return _db


# ── Auth helpers ────────────────────────────────────────────────────────────

def create_user(email: str, password: str) -> dict | None:
    """Create Firebase Auth user + Firestore profile. Returns uid or None."""
    try:
        user = fb_auth.create_user(email=email, password=password)
        db = get_db()
        if db:
            db.collection("users").document(user.uid).set({
                "email": email,
                "cg_api_key": "",
                "created_at": firestore.SERVER_TIMESTAMP,
            })
        return {"uid": user.uid, "email": email}
    except fb_auth.EmailAlreadyExistsError:
        return {"error": "email_taken"}
    except Exception as exc:
        print(f"[firebase] create_user error: {exc}")
        return {"error": str(exc)}


def sign_in(email: str, password: str) -> dict | None:
    """Sign in via Firebase REST API. Returns uid + email or None."""
    api_key = os.getenv("FIREBASE_WEB_API_KEY", "")
    if not api_key:
        return {"error": "no_web_api_key"}

    url = (
        "https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword"
        f"?key={api_key}"
    )
    try:
        resp = http_requests.post(
            url,
            json={"email": email, "password": password, "returnSecureToken": True},
            timeout=8,
        )
        if resp.status_code == 200:
            data = resp.json()
            return {"uid": data["localId"], "email": data["email"]}
        err = resp.json().get("error", {}).get("message", "INVALID_CREDENTIALS")
        return {"error": err}
    except Exception as exc:
        return {"error": str(exc)}


def get_user_profile(uid: str) -> dict | None:
    """Fetch user doc from Firestore."""
    db = get_db()
    if not db:
        return None
    doc = db.collection("users").document(uid).get()
    return {"uid": uid, **doc.to_dict()} if doc.exists else None


def update_user_profile(uid: str, data: dict) -> bool:
    """Merge-update user doc."""
    db = get_db()
    if not db:
        return False
    try:
        db.collection("users").document(uid).set(data, merge=True)
        return True
    except Exception as exc:
        print(f"[firebase] update_user_profile error: {exc}")
        return False


def get_watchlist(uid: str) -> list[str]:
    """Return the user's watchlist as a list of coin IDs."""
    db = get_db()
    if not db:
        return []
    doc = db.collection("users").document(uid).get()
    if not doc.exists:
        return []
    return doc.to_dict().get("watchlist", [])


def toggle_watchlist(uid: str, coin_id: str) -> dict:
    """Add or remove a coin from the user's watchlist. Returns {watchlist, starred}."""
    db = get_db()
    if not db:
        return {"error": "db_unavailable"}
    try:
        ref = db.collection("users").document(uid)
        doc = ref.get()
        current: list = (doc.to_dict() or {}).get("watchlist", [])
        if coin_id in current:
            current.remove(coin_id)
            starred = False
        else:
            current.append(coin_id)
            starred = True
        ref.set({"watchlist": current}, merge=True)
        return {"watchlist": current, "starred": starred}
    except Exception as exc:
        print(f"[firebase] toggle_watchlist error: {exc}")
        return {"error": str(exc)}


def delete_user_account(uid: str) -> bool:
    """Delete Firebase Auth user + Firestore doc."""
    try:
        fb_auth.delete_user(uid)
        db = get_db()
        if db:
            db.collection("users").document(uid).delete()
        return True
    except Exception as exc:
        print(f"[firebase] delete_user error: {exc}")
        return False