"use client"

import { useState } from "react"
import { Card, CardContent, CardHeader, CardTitle, CardDescription, CardFooter } from "@/components/ui/card"
import { Button } from "@/components/ui/button"
import { Check, X, ShieldCheck, Loader2, Minus, CheckCircle2 } from "lucide-react"

import { useActiveUser } from "@/hooks/useActiveUser"

const WEBHOOK_SECRET = "local_webhook_secret"

export default function UpgradePage() {
  const { userId, loading: userLoading, refreshUser } = useActiveUser()
  const [loadingTier, setLoadingTier] = useState<string | null>(null)
  const [showModal, setShowModal] = useState(false)
  const [orderData, setOrderData] = useState<any>(null)
  const [processing, setProcessing] = useState(false)
  const [success, setSuccess] = useState(false)

  const handleUpgrade = async (tier: string) => {
    if (userLoading || !userId) return
    setLoadingTier(tier)
    try {
      const res = await fetch(`/api/billing/create-order?user_id=${userId}&plan_tier=${tier}`, {
        method: "POST"
      })
      if (!res.ok) throw new Error("Order creation failed")
      const order = await res.json()
      setOrderData({ ...order, tier })
      setShowModal(true)
    } catch (err) {
      console.error(err)
      alert("Failed to create order")
    } finally {
      setLoadingTier(null)
    }
  }

  const generateMockSignature = async (payloadStr: string) => {
    const encoder = new TextEncoder();
    const key = await crypto.subtle.importKey(
      'raw',
      encoder.encode(WEBHOOK_SECRET),
      { name: 'HMAC', hash: 'SHA-256' },
      false,
      ['sign']
    );
    const signature = await crypto.subtle.sign('HMAC', key, encoder.encode(payloadStr));
    return Array.from(new Uint8Array(signature)).map(b => b.toString(16).padStart(2, '0')).join('');
  }

  const simulatePayment = async () => {
    if (!userId) return
    setProcessing(true)
    try {
      const payloadObj = {
        event: "payment.captured",
        payload: {
          payment: {
            entity: {
              id: `pay_mock_${Date.now()}`,
              amount: orderData.amount,
              notes: {
                user_id: userId,
                tier_requested: orderData.tier
              }
            }
          }
        }
      }
      
      const payloadStr = JSON.stringify(payloadObj)
      const signature = await generateMockSignature(payloadStr)

      const res = await fetch(`/api/billing/webhook/razorpay`, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          "X-Razorpay-Signature": signature
        },
        body: payloadStr
      })

      if (!res.ok) throw new Error("Webhook failed")
      
      setSuccess(true)
      await refreshUser()
      setTimeout(() => {
        window.location.href = "/dashboard"
      }, 2000)

    } catch (err) {
      console.error(err)
      alert("Payment simulation failed")
      setProcessing(false)
    }
  }

  return (
    <div className="p-8 max-w-7xl mx-auto animate-in fade-in duration-500 min-h-screen">
      <div className="text-center max-w-2xl mx-auto mb-16">
        <h1 className="text-4xl font-extrabold tracking-tight mb-4">Upgrade Your Preparation</h1>
        <p className="text-xl text-muted-foreground">Unlock the full power of PragatiVeer to master JEE & NEET.</p>
      </div>

      <div className="grid grid-cols-1 lg:grid-cols-2 gap-8 max-w-5xl mx-auto items-stretch">
        {/* Free Tier 
        <Card className="bg-background/80 backdrop-blur-md border border-border p-6 rounded-[2rem] flex flex-col justify-between h-full z-10 relative shadow-xl hover:border-border/80 transition-colors">
          <div>
            <h3 className="text-3xl font-bold mb-2 text-foreground">Free</h3>
            <p className="text-muted-foreground mb-6 text-base">Perfect to get started.</p>
            <div className="text-6xl font-bold tracking-tighter mb-6 text-foreground">
              ₹0<span className="text-xl text-white/60 font-medium tracking-normal ml-1">/year</span>
            </div>
            <ul className="space-y-3 mb-6 font-medium text-lg">
              <li className="flex items-center gap-4"><CheckCircle2 className="text-foreground shrink-0" size={24}/> 1 Daily Practice Sheet</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-foreground shrink-0" size={24}/> Basic Performance Analytics</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-foreground shrink-0" size={24}/> Community Access</li>
            </ul>
          </div>
          <Button variant="outline" className="w-full rounded-2xl h-12 border-border text-foreground font-bold text-lg hover:bg-secondary" disabled>Get Started Free</Button>
        </Card>
        */}

        {/* Pro Tier */}
        <Card className="bg-background/80 backdrop-blur-md border border-border p-6 rounded-[2rem] flex flex-col justify-between h-full z-10 relative shadow-xl hover:border-border/80 transition-colors">
          <div>
            <h3 className="text-3xl font-bold mb-2 text-yellow-500">Pro</h3>
            <p className="text-muted-foreground mb-6 text-base">Perfect for self-paced practice.</p>
            <div className="text-6xl font-bold tracking-tighter mb-6 text-yellow-500">
              ₹3,499<span className="text-xl text-yellow-500/60 font-medium tracking-normal ml-1">/year</span>
            </div>
            <ul className="space-y-3 mb-6 font-medium text-lg">
              <li className="flex items-center gap-4"><CheckCircle2 className="text-yellow-500 shrink-0" size={24}/> Unlimited Daily Practice Sheets</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-yellow-500 shrink-0" size={24}/> Weekly Test Series & Mock Tests</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-yellow-500 shrink-0" size={24}/> Detailed Performance Analytics</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-yellow-500 shrink-0" size={24}/> Parent Dashboard Access</li>
            </ul>
          </div>
          <Button 
            className="w-full bg-yellow-500 text-black hover:bg-yellow-400 font-bold text-lg rounded-2xl h-12" 
            onClick={() => handleUpgrade("Pro")}
            disabled={!!loadingTier}
          >
            {loadingTier === "Pro" ? <Loader2 className="animate-spin" /> : "Get Pro"}
          </Button>
        </Card>

        {/* AI Coach Tier */}
        <Card className="bg-background/80 backdrop-blur-md border border-border p-6 rounded-[2rem] flex flex-col justify-between h-full z-10 relative shadow-xl hover:border-border/80 transition-colors">
          <div>
            <h3 className="text-3xl font-bold mb-2 text-[#00F0FF]">AI Coach</h3>
            <p className="text-muted-foreground mb-6 text-base">The complete AI-driven system.</p>
            <div className="text-6xl font-bold tracking-tighter mb-6 text-[#00F0FF]">
              ₹11,999<span className="text-xl text-[#00F0FF]/60 font-medium tracking-normal ml-1">/year</span>
            </div>
            <ul className="space-y-3 mb-6 font-medium text-lg">
              <li className="flex items-center gap-4"><CheckCircle2 className="text-[#00F0FF] shrink-0" size={24}/> Everything in Pro</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-[#00F0FF] shrink-0" size={24}/> AI Spaced Repetition (Mistakes)</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-[#00F0FF] shrink-0" size={24}/> 24/7 Streaming AI Tutor Chat</li>
              <li className="flex items-center gap-4"><CheckCircle2 className="text-[#00F0FF] shrink-0" size={24}/> Predictive Rank & College Predictor</li>
            </ul>
          </div>
          <Button 
            className="w-full font-bold text-lg rounded-2xl h-12 bg-[#00F0FF] text-black hover:bg-[#00F0FF]/90 transition-all" 
            onClick={() => handleUpgrade("Al_Coach")}
            disabled={!!loadingTier}
          >
            {loadingTier === "Al_Coach" ? <Loader2 className="animate-spin" /> : "Get AI Coach"}
          </Button>
        </Card>
      </div>

      <p className="text-center mt-8 text-sm text-muted-foreground font-medium w-full">
        * All above prices are inclusive of GST.
      </p>

      {/* ── Tier Comparison Matrix ── */}
      <section className="mt-20 py-8">
        <div className="text-center mb-12">
          <h2 className="text-3xl md:text-4xl font-extrabold tracking-tight mb-3">Compare All Features</h2>
          <p className="text-muted-foreground text-base md:text-lg max-w-2xl mx-auto">
            Detailed breakdown of capabilities across Free, Pro, and AI Coach tiers.
          </p>
        </div>

        <div className="overflow-x-auto rounded-2xl border border-border/50 bg-secondary/10 backdrop-blur-sm p-3 md:p-6 shadow-2xl">
          <table className="w-full text-left border-collapse min-w-[700px]">
            <thead>
              <tr className="border-b border-border/50 bg-background/50">
                <th className="p-4 md:p-6 font-bold text-lg w-1/2 border-l border-t border-border/50">Feature</th>
                {/* <th className="p-4 md:p-6 font-bold text-lg text-center w-1/5 border-x border-t border-white">Free</th> */}
                <th className="p-4 md:p-6 font-bold text-lg text-center w-1/4 text-yellow-500 border-x border-t border-yellow-500">Pro</th>
                <th className="p-4 md:p-6 font-bold text-lg text-center w-1/4 text-[#00F0FF] bg-[#00F0FF]/5 border-x border-t border-[#00F0FF]">AI Coach</th>
              </tr>
            </thead>
            <tbody className="divide-y divide-border/30 text-sm md:text-base">
              {[
                { name: "Daily Practice Sheets", free: "1/day", pro: "Unlimited", ai: "Unlimited" },
                { name: "Answer Keys", free: true, pro: true, ai: true },
                { name: "Basic Progress Dashboard", free: true, pro: true, ai: true },
                { name: "Streak Tracking", free: true, pro: true, ai: true },
                { name: "Leaderboard (City/School)", free: true, pro: true, ai: true },
                { name: "Topic-wise Micro-tests", free: "5/day", pro: "Unlimited", ai: "Unlimited" },
                { name: "Weekly Test Series", free: false, pro: true, ai: true },
                { name: "Full-Length Mock Tests", free: false, pro: "4/month", ai: "Unlimited" },
                { name: "Previous Year Papers", free: false, pro: true, ai: true },
                { name: "Detailed Performance Analytics", free: false, pro: true, ai: true },
                { name: "Chapter-wise Progress", free: false, pro: true, ai: true },
                { name: "Doubt Resolution (Community)", free: false, pro: true, ai: true },
                { name: "Parent Dashboard", free: false, pro: true, ai: true },
                { name: "Offline Mode (Download DPS)", free: false, pro: true, ai: true },
                { name: "AI Mistake Tracking", free: false, pro: false, ai: true },
                { name: "Spaced Repetition (SM-2)", free: false, pro: false, ai: true },
                { name: "Personalized Daily Study Plan", free: false, pro: false, ai: true },
                { name: "AI Tutor Chat", free: false, pro: false, ai: true },
                { name: "Exam Readiness Score", free: false, pro: false, ai: true },
                { name: "Exam Day Strategy", free: false, pro: false, ai: true },
                { name: "College Predictor", free: false, pro: false, ai: true },
                { name: "Study Time Optimization", free: false, pro: false, ai: true },
              ].map((feature, idx) => (
                <tr key={idx} className="hover:bg-background/40 transition-colors">
                  <td className="p-4 md:p-6 font-medium border-y border-l border-border/30">{feature.name}</td>
                  {/* <td className="p-4 md:p-6 text-center text-muted-foreground border border-white">
                    {typeof feature.free === 'boolean' ? (feature.free ? <CheckCircle2 className="mx-auto text-white" size={20} /> : <Minus className="mx-auto text-white/30" size={20} />) : <span className="font-semibold text-white">{feature.free}</span>}
                  </td> */}
                  <td className="p-4 md:p-6 text-center border border-yellow-500">
                    {typeof feature.pro === 'boolean' ? (feature.pro ? <CheckCircle2 className="mx-auto text-yellow-500" size={20} /> : <Minus className="mx-auto text-yellow-500/30" size={20} />) : <span className="font-semibold text-yellow-500">{feature.pro}</span>}
                  </td>
                  <td className="p-4 md:p-6 text-center bg-[#00F0FF]/5 border border-[#00F0FF]">
                    {typeof feature.ai === 'boolean' ? (feature.ai ? <CheckCircle2 className="mx-auto text-[#00F0FF]" size={20} /> : <Minus className="mx-auto text-[#00F0FF]/30" size={20} />) : <span className="font-semibold text-[#00F0FF]">{feature.ai}</span>}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>
      </section>

      {/* Mock Razorpay Modal */}
      {showModal && (
        <div className="fixed inset-0 bg-background/80 backdrop-blur-sm flex items-center justify-center z-50 p-4">
          <Card className="max-w-md w-full shadow-2xl border-primary">
            <CardHeader className="text-center pb-2">
              <div className="mx-auto w-16 h-12 bg-blue-600 rounded-lg flex items-center justify-center mb-4">
                <span className="text-white font-black text-2xl">RZP</span>
              </div>
              <CardTitle>Mock Checkout Window</CardTitle>
              <CardDescription>Razorpay Test Sandbox Simulation</CardDescription>
            </CardHeader>
            <CardContent className="space-y-4 mt-4">
              <div className="bg-secondary p-4 rounded-xl space-y-2 text-sm font-mono">
                <div className="flex justify-between">
                  <span className="text-muted-foreground">Order ID:</span>
                  <span className="font-bold">{orderData?.id}</span>
                </div>
                <div className="flex justify-between">
                  <span className="text-muted-foreground">Amount:</span>
                  <span className="font-bold">₹{(orderData?.amount / 100).toFixed(2)}</span>
                </div>
                <div className="flex justify-between">
                  <span className="text-muted-foreground">Tier:</span>
                  <span className="font-bold">{orderData?.tier}</span>
                </div>
              </div>
              
              {success ? (
                <div className="p-4 bg-green-500/10 text-green-500 rounded-xl text-center font-bold animate-in zoom-in">
                  Payment Captured! Redirecting...
                </div>
              ) : (
                <p className="text-sm text-muted-foreground text-center">
                  Clicking confirm will securely sign and POST a payment.captured webhook to the backend.
                </p>
              )}
            </CardContent>
            <CardFooter className="flex gap-3">
              <Button variant="outline" className="w-full" onClick={() => setShowModal(false)} disabled={processing || success}>
                Cancel
              </Button>
              <Button className="w-full bg-blue-600 hover:bg-blue-700 text-white" onClick={simulatePayment} disabled={processing || success}>
                {processing ? <Loader2 className="animate-spin" /> : "Confirm Payment"}
              </Button>
            </CardFooter>
          </Card>
        </div>
      )}

    </div>
  )
}