import { useQuery } from '@tanstack/react-query';
import api from '../api/client';

// ─── Types ───────────────────────────────────────────────────────────────────

export type Tier = 'starter' | 'launch' | 'growth' | 'command';

export type Feature =
  | 'dashboard'
  | 'forecasting'
  | 'cascading_goals'
  | 'strategic_intelligence'
  | 'scale_optimization'
  | 'multi_market'
  | 'enterprise';

export interface TierLimits {
  markets: number;
  seats: number;
  connectors: number;
}

export interface TierInfo {
  tier: Tier;
  features: Feature[];
  limits: TierLimits;
}

// Tier ordering, lowest → highest (mirrors app/utils/feature_gate.py)
export const TIER_ORDER: Tier[] = ['starter', 'launch', 'growth', 'command'];

// Minimum tier that unlocks each feature (for upgrade prompts)
export const FEATURE_MIN_TIER: Record<Feature, Tier> = {
  dashboard: 'starter',
  forecasting: 'starter',
  cascading_goals: 'launch',
  strategic_intelligence: 'growth',
  scale_optimization: 'growth',
  multi_market: 'growth',
  enterprise: 'command',
};

export const TIER_LABELS: Record<Tier, string> = {
  starter: 'Starter',
  launch: 'Launch',
  growth: 'Growth',
  command: 'Command',
};

const FALLBACK: TierInfo = {
  tier: 'starter',
  features: ['dashboard', 'forecasting'],
  limits: { markets: 1, seats: 2, connectors: 1 },
};

// ─── Hook ────────────────────────────────────────────────────────────────────

/**
 * useFeatureGate — fetches the current user's subscription tier and exposes
 * feature-check helpers.
 *
 * const { hasFeature, tier, isLoading, requiredTier } = useFeatureGate();
 * if (!hasFeature('multi_market')) return <UpgradePrompt feature="multi_market" />;
 */
export function useFeatureGate() {
  const { data, isLoading, isError } = useQuery<TierInfo>({
    queryKey: ['billing', 'tier'],
    queryFn: async () => {
      const res = await api.get<TierInfo>('/api/billing/tier');
      return res.data;
    },
    staleTime: 5 * 60 * 1000,
    retry: 1,
  });

  const info = data ?? FALLBACK;

  const hasFeature = (feature: Feature): boolean => {
    // While loading, don't flash upgrade prompts — treat as unlocked until we know.
    if (isLoading) return true;
    if (isError) return info.features.includes(feature);
    return info.features.includes(feature);
  };

  const requiredTier = (feature: Feature): Tier => FEATURE_MIN_TIER[feature];

  return {
    tier: info.tier,
    tierLabel: TIER_LABELS[info.tier],
    features: info.features,
    limits: info.limits,
    hasFeature,
    requiredTier,
    isLoading,
    isError,
  };
}