'use client';

import React, { createContext, useContext, useEffect, useMemo, useState } from 'react';

type SubscriptionState = {
  active: boolean;           // true if paid subscription is active
  trialEndsAt?: string | null; // ISO string when the trial ends
};

type SubscriptionContextValue = {
  state: SubscriptionState;
  isTrialActive: boolean;
  daysLeftInTrial: number;
  isEntitled: boolean; // active OR valid trial
  startTrial: (days?: number) => void;
  endTrial: () => void;
  purchase: () => void;     // placeholder “pay” success
  cancel: () => void;       // cancels paid sub (trial untouched)
  reset: () => void;        // dev helper
};

const STORAGE_KEYS = {
  ACTIVE: 'SUB_ACTIVE',
  TRIAL_END: 'SUB_TRIAL_ENDS_AT',
};

const SubscriptionContext = createContext<SubscriptionContextValue | null>(null);

export function SubscriptionProvider({ children }: { children: React.ReactNode }) {
  const [active, setActive] = useState<boolean>(false);
  const [trialEndsAt, setTrialEndsAt] = useState<string | null>(null);

  // Load from localStorage
  useEffect(() => {
    try {
      const a = localStorage.getItem(STORAGE_KEYS.ACTIVE);
      const t = localStorage.getItem(STORAGE_KEYS.TRIAL_END);
      setActive(a === '1');
      setTrialEndsAt(t || null);
    } catch {}
  }, []);

  // Persist changes
  useEffect(() => {
    try {
      localStorage.setItem(STORAGE_KEYS.ACTIVE, active ? '1' : '0');
      if (trialEndsAt) localStorage.setItem(STORAGE_KEYS.TRIAL_END, trialEndsAt);
      else localStorage.removeItem(STORAGE_KEYS.TRIAL_END);
    } catch {}
  }, [active, trialEndsAt]);

  const now = Date.now();
  const trialMsLeft = useMemo(() => {
    if (!trialEndsAt) return 0;
    const end = new Date(trialEndsAt).getTime();
    return Math.max(0, end - now);
  }, [trialEndsAt, now]);

  const daysLeftInTrial = Math.ceil(trialMsLeft / (1000 * 60 * 60 * 24));
  const isTrialActive = trialMsLeft > 0;
  const isEntitled = active || isTrialActive;

  const startTrial = (days = 7) => {
    const end = new Date(Date.now() + days * 24 * 60 * 60 * 1000).toISOString();
    setTrialEndsAt(end);
  };

  const endTrial = () => setTrialEndsAt(null);

  // Placeholder purchase: mark as active
  const purchase = () => setActive(true);

  // Cancel paid sub (keeps trial data as-is)
  const cancel = () => setActive(false);

  const reset = () => {
    setActive(false);
    setTrialEndsAt(null);
  };

  return (
    <SubscriptionContext.Provider
      value={{ state: { active, trialEndsAt }, isTrialActive, daysLeftInTrial, isEntitled, startTrial, endTrial, purchase, cancel, reset }}
    >
      {children}
    </SubscriptionContext.Provider>
  );
}

export function useSubscription() {
  const ctx = useContext(SubscriptionContext);
  if (!ctx) throw new Error('useSubscription must be used within SubscriptionProvider');
  return ctx;
}