from fastapi import Depends, HTTPException, status, Header
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from typing import Optional
from dataclasses import dataclass, field
from app.database import get_supabase
from app.config import settings
import base64
import hashlib
import hmac
import json
import logging
import time

logger = logging.getLogger(__name__)
security = HTTPBearer(auto_error=False)


@dataclass
class _LocalUser:
    """Minimal user object built from JWT claims — mirrors the fields used downstream."""
    id: str
    email: str
    role: str = "authenticated"
    app_metadata: dict = field(default_factory=dict)
    user_metadata: dict = field(default_factory=dict)


def _verify_jwt_local(token: str) -> Optional[_LocalUser]:
    """Verify a Supabase HS256 JWT using the local secret (no network call).
    Returns None if the secret is not configured, the signature is wrong, or the token is expired."""
    secret = settings.supabase_jwt_secret
    if not secret:
        return None
    try:
        parts = token.split(".")
        if len(parts) != 3:
            return None
        header_b64, payload_b64, sig_b64 = parts

        # Verify HMAC-SHA256 signature
        message = f"{header_b64}.{payload_b64}".encode()
        expected = hmac.new(secret.encode(), message, hashlib.sha256).digest()
        padding = "=" * (-len(sig_b64) % 4)
        actual = base64.urlsafe_b64decode(sig_b64 + padding)
        if not hmac.compare_digest(expected, actual):
            return None

        # Decode payload
        padding = "=" * (-len(payload_b64) % 4)
        payload = json.loads(base64.urlsafe_b64decode(payload_b64 + padding))

        # Check expiry
        if payload.get("exp", 0) < time.time():
            return None

        return _LocalUser(
            id=payload["sub"],
            email=payload.get("email", ""),
            role=payload.get("role", "authenticated"),
            app_metadata=payload.get("app_metadata", {}),
            user_metadata=payload.get("user_metadata", {}),
        )
    except Exception:
        return None


async def get_current_user(
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(security),
):
    """Extract and verify the current user from a Supabase JWT.

    Tries local HS256 verification first (no network call, no SSL risk).
    Falls back to supabase.auth.get_user() only when the JWT secret is not configured.
    """
    if not credentials:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
        )

    token = credentials.credentials

    # ── Fast path: local verification ────────────────────────────────────────
    user = _verify_jwt_local(token)

    # ── Slow path: network call (only if SUPABASE_JWT_SECRET is not set) ─────
    if user is None:
        supabase = get_supabase()
        try:
            response = supabase.auth.get_user(token)
            if not response or not response.user:
                raise HTTPException(
                    status_code=status.HTTP_401_UNAUTHORIZED,
                    detail="Invalid or expired token",
                )
            user = response.user
        except HTTPException:
            raise
        except Exception as e:
            logger.error(f"Auth error: {e}")
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid or expired token",
            )

    # ── Suspension check (DB, not network-auth, so still fast) ───────────────
    try:
        supabase = get_supabase()
        profile = supabase.table("user_profiles").select("suspended_at").eq("user_id", user.id).execute()
        if profile.data and profile.data[0].get("suspended_at"):
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Account suspended. Please contact support.",
            )
    except HTTPException:
        raise
    except Exception:
        pass  # Never block login if profile lookup fails

    return user


async def get_admin_user(
    current_user=Depends(get_current_user),
):
    """Require the current user to be an admin."""
    supabase = get_supabase()
    try:
        profile = supabase.table("user_profiles").select("is_admin").eq("user_id", current_user.id).execute()
        if not profile.data or not profile.data[0].get("is_admin"):
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Admin access required",
            )
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Admin check failed: {e}")
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin access required",
        )
    return current_user


async def get_optional_user(
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(security),
):
    """Optional auth - returns None if not authenticated"""
    if not credentials:
        return None
    try:
        return await get_current_user(credentials)
    except HTTPException:
        return None


async def get_user_subscription(user=Depends(get_current_user)):
    """Get user's subscription plan"""
    supabase = get_supabase()
    try:
        result = (
            supabase.table("subscriptions")
            .select("*")
            .eq("user_id", user.id)
            .eq("status", "active")
            .execute()
        )
        if result.data:
            return result.data[0]
        return {"plan": "free", "status": "active", "user_id": user.id}
    except Exception:
        return {"plan": "free", "status": "active", "user_id": user.id}


async def require_plan(min_plan: str, user=Depends(get_current_user)):
    """Require a minimum plan level"""
    plan_order = ["free", "starter", "business", "agency", "enterprise"]
    subscription = await get_user_subscription(user)
    user_plan = subscription.get("plan", "free")

    if plan_order.index(user_plan) < plan_order.index(min_plan):
        raise HTTPException(
            status_code=status.HTTP_402_PAYMENT_REQUIRED,
            detail=f"This feature requires {min_plan} plan or higher",
        )
    return user