import { useState } from 'react';
import { Download, Copy, Eye, EyeOff, Shield, AlertTriangle, CheckCircle, ExternalLink, KeyRound, QrCode } from 'lucide-react';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { QRCodeCanvas } from '@/components/ui/qrcode';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useLocalStorage } from '@/hooks/useLocalStorage';
import { useNostrLogin } from '@nostrify/react/login';
import { toast } from '@/hooks/useToast';

const sanitizeFilename = (filename: string) => filename.replace(/[^a-z0-9_.-]/gi, '_');

export function SecuritySettings() {
  const { user } = useCurrentUser();
  const { logins } = useNostrLogin();
  const [confirmed, setConfirmed] = useLocalStorage('backup-confirmed', false);
  const [showWarning, setShowWarning] = useState(!confirmed);

  // Recovery reveal state
  const [revealed, setRevealed] = useState(false);
  const [showQr, setShowQr] = useState(false);

  // The active login. For nsec logins, the recovery code (nsec) is stored on
  // the login object itself — this is how we can reveal it later for users who
  // skipped backup at signup. For bunker/extension/Amber logins, the app never
  // held the key, so there is nothing to reveal here.
  const activeLogin = logins[0] as
    | (typeof logins[number] & { nsec?: string; data?: { nsec?: string } })
    | undefined;
  const loginType = activeLogin?.type;
  // Nostrify stores the bech32 nsec directly on the login (older builds nested
  // it under `data`), so check both to be safe.
  const recoveryCode = loginType === 'nsec'
    ? (activeLogin?.nsec ?? activeLogin?.data?.nsec)
    : undefined;

  const handleReveal = () => setRevealed(true);

  const handleCopyRecovery = () => {
    if (!recoveryCode) return;
    navigator.clipboard.writeText(recoveryCode);
    // Copying the recovery code counts as a real backup — mark confirmed so the
    // gentle reminder stops nagging a user who has genuinely saved their login.
    setConfirmed(true);
    setShowWarning(false);
    toast({ title: 'Copied!', description: 'Recovery code copied. Store it somewhere safe.' });
  };

  const handleDownloadRecovery = () => {
    if (!recoveryCode) return;
    try {
      const blob = new Blob([recoveryCode], { type: 'text/plain; charset=utf-8' });
      const url = globalThis.URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = sanitizeFilename('skatespots-recovery-code.txt');
      a.style.display = 'none';
      document.body.appendChild(a);
      a.click();
      globalThis.URL.revokeObjectURL(url);
      document.body.removeChild(a);
      // A downloaded recovery file is a genuine backup — mark confirmed so the
      // reminder stops for good.
      setConfirmed(true);
      setShowWarning(false);
      toast({ title: 'Saved!', description: 'Recovery code downloaded. Keep it somewhere safe.' });
    } catch {
      toast({ title: 'Download failed', description: 'Please copy it manually instead.', variant: 'destructive' });
    }
  };

  if (!user) {
    return (
      <Card className="border-dashed">
        <CardContent className="py-12 text-center">
          <Shield className="h-12 w-12 mx-auto mb-4 text-muted-foreground/50" />
          <h3 className="text-lg font-medium mb-2">Login Required</h3>
          <p className="text-muted-foreground">
            Log in to access security settings.
          </p>
        </CardContent>
      </Card>
    );
  }

  const handleConfirmBackup = () => {
    setConfirmed(true);
    setShowWarning(false);
    toast({
      title: 'Backup Confirmed! ✅',
      description: 'Great! Your keys are safe.',
    });
  };

  return (
    <div className="space-y-6">
      {/* Recover / reveal recovery code — the real backup path for skaters who
          skipped it at signup. Only possible for nsec logins. */}
      <Card className="bg-black/90 border-2 border-amber-500/40">
        <CardHeader>
          <CardTitle className="flex items-center gap-2 text-amber-400">
            <KeyRound className="h-5 w-5" />
            Your Recovery Code
          </CardTitle>
          <CardDescription>
            Didn't save it when you signed up? You can grab it here anytime.
          </CardDescription>
        </CardHeader>
        <CardContent className="space-y-4">
          {recoveryCode ? (
            <>
              <p className="text-sm text-gray-300">
                This code is the <strong className="text-white">only</strong> way to log back in on a
                new device or browser. Save it somewhere safe (a password manager, or written on paper).
                Anyone who has it controls your account — never share it.
              </p>

              {!revealed ? (
                <Button
                  onClick={handleReveal}
                  className="w-full bg-amber-500 hover:bg-amber-600 text-black font-bold"
                >
                  <Eye className="h-4 w-4 mr-2" />
                  Reveal my recovery code
                </Button>
              ) : (
                <div className="space-y-3">
                  <div className="p-3 bg-black rounded-lg border border-amber-500/30 font-mono text-xs break-all text-white select-all">
                    {recoveryCode}
                  </div>

                  <div className="grid grid-cols-3 gap-2">
                    <Button
                      variant="outline"
                      size="sm"
                      className="border-amber-500/40 text-amber-300 hover:bg-amber-500/10"
                      onClick={handleCopyRecovery}
                    >
                      <Copy className="h-3.5 w-3.5 mr-1.5" />
                      Copy
                    </Button>
                    <Button
                      variant="outline"
                      size="sm"
                      className="border-amber-500/40 text-amber-300 hover:bg-amber-500/10"
                      onClick={handleDownloadRecovery}
                    >
                      <Download className="h-3.5 w-3.5 mr-1.5" />
                      Save
                    </Button>
                    <Button
                      variant="outline"
                      size="sm"
                      className="border-amber-500/40 text-amber-300 hover:bg-amber-500/10"
                      onClick={() => setShowQr((v) => !v)}
                    >
                      <QrCode className="h-3.5 w-3.5 mr-1.5" />
                      QR
                    </Button>
                  </div>

                  {showQr && (
                    <div className="flex flex-col items-center gap-2 pt-2">
                      <div className="bg-white p-3 rounded-xl">
                        <QRCodeCanvas value={recoveryCode} size={200} level="M" />
                      </div>
                      <p className="text-xs text-gray-500 text-center max-w-xs">
                        Scan with another Nostr app to log in. Keep this screen private.
                      </p>
                    </div>
                  )}

                  <div className="flex items-center justify-between">
                    <p className="text-xs text-amber-300/80">⚠️ Never share this. Hide it when you're done.</p>
                    <Button
                      variant="ghost"
                      size="sm"
                      className="text-gray-500 hover:text-gray-300 h-auto py-1"
                      onClick={() => { setRevealed(false); setShowQr(false); }}
                    >
                      <EyeOff className="h-3.5 w-3.5 mr-1.5" />
                      Hide
                    </Button>
                  </div>
                </div>
              )}
            </>
          ) : (
            <Alert className="bg-blue-950/30 border border-blue-500/30">
              <Shield className="h-4 w-4 text-blue-400" />
              <AlertDescription className="text-sm text-gray-300">
                {loginType === 'x-amber' && (
                  <>You're logged in with <strong className="text-white">Amber</strong>. Your recovery code lives inside Amber — open the Amber app to back it up. SkateSpots never sees your key.</>
                )}
                {loginType === 'bunker' && (
                  <>You're logged in with a <strong className="text-white">remote signer (bunker)</strong>. Your recovery code is held by your signer service, not SkateSpots. Back it up there.</>
                )}
                {(loginType as string) === 'extension' && (
                  <>You're logged in with a <strong className="text-white">browser extension</strong>. Your recovery code lives in the extension — use its own backup/export option. SkateSpots never sees your key.</>
                )}
                {!loginType && (
                  <>Your recovery code is managed by your signer app, not SkateSpots. Back it up there.</>
                )}
              </AlertDescription>
            </Alert>
          )}
        </CardContent>
      </Card>

      {/* Backup Warning */}
      {showWarning && (
        <Alert className="bg-gradient-to-r from-amber-500/10 to-red-500/10 border-2 border-amber-500/50">
          <AlertTriangle className="h-5 w-5 text-amber-500" />
          <AlertDescription>
            <div className="space-y-3">
              <p className="font-bold text-amber-400">
                ⚠️ Have you backed up your recovery phrase or secret key?
              </p>
              <p className="text-sm text-gray-300">
                Your keys are the ONLY way to access your account. If you lose them, you lose everything - 
                there's no password reset!
              </p>
              <Button
                onClick={handleConfirmBackup}
                size="sm"
                className="bg-amber-500 hover:bg-amber-600 text-black font-bold"
              >
                <CheckCircle className="h-4 w-4 mr-2" />
                I've Backed Up My Keys
              </Button>
            </div>
          </AlertDescription>
        </Alert>
      )}

      {/* Backup Status */}
      <Card className={confirmed ? "bg-green-950/20 border-2 border-green-500/30" : "bg-red-950/20 border-2 border-red-500/30"}>
        <CardHeader>
          <CardTitle className={confirmed ? "text-green-400" : "text-red-400"}>
            {confirmed ? '✅ Backup Confirmed' : '⚠️ Backup Not Confirmed'}
          </CardTitle>
          <CardDescription>
            {confirmed 
              ? 'You\'ve confirmed that your keys are safely backed up.'
              : 'Make sure to backup your recovery phrase or secret key!'}
          </CardDescription>
        </CardHeader>
        {!confirmed && (
          <CardContent>
            <p className="text-sm text-gray-400 mb-4">
              Haven't saved your recovery code yet? No problem — grab it from the
              <strong className="text-amber-400"> Your Recovery Code</strong> section above, store it
              somewhere safe, then confirm below.
            </p>
            <Button
              onClick={handleConfirmBackup}
              variant="outline"
              className="border-green-500/50 text-green-400 hover:bg-green-500/20"
            >
              Yes, I've Backed Up My Keys
            </Button>
          </CardContent>
        )}
      </Card>

      {/* Security Information */}
      <Card className="bg-black/90 border-2 border-[#ccff00]/30">
        <CardHeader>
          <CardTitle className="flex items-center gap-2 text-[#ccff00]">
            <Shield className="h-5 w-5" />
            Key Security Best Practices
          </CardTitle>
          <CardDescription>
            How to keep your Nostr account safe
          </CardDescription>
        </CardHeader>
        <CardContent className="space-y-4">
          <div className="space-y-3 text-sm">
            <div className="flex items-start gap-3">
              <div className="text-2xl">✍️</div>
              <div>
                <p className="font-bold text-white">Write it down on paper</p>
                <p className="text-gray-400">Physical backup is the safest. Store in a secure location like a safe.</p>
              </div>
            </div>
            
            <div className="flex items-start gap-3">
              <div className="text-2xl">💾</div>
              <div>
                <p className="font-bold text-white">Multiple backups</p>
                <p className="text-gray-400">Keep copies in different secure locations (home safe, bank deposit box, etc.)</p>
              </div>
            </div>
            
            <div className="flex items-start gap-3">
              <div className="text-2xl">🔒</div>
              <div>
                <p className="font-bold text-white">Never share your keys</p>
                <p className="text-gray-400">Real Nostr apps NEVER ask for your nsec or recovery phrase after initial login</p>
              </div>
            </div>
            
            <div className="flex items-start gap-3">
              <div className="text-2xl">🚫</div>
              <div>
                <p className="font-bold text-white">Don't store in cloud unencrypted</p>
                <p className="text-gray-400">Avoid Google Docs, email drafts, or plain text cloud storage</p>
              </div>
            </div>
            
            <div className="flex items-start gap-3">
              <div className="text-2xl">🔐</div>
              <div>
                <p className="font-bold text-white">Consider using a browser extension</p>
                <p className="text-gray-400">Alby, nos2x, or Flamingo keep your keys secure and never expose them to websites</p>
              </div>
            </div>
          </div>

          <div className="pt-4 border-t border-[#ccff00]/20">
            <h4 className="font-bold text-[#ff0040] mb-2 uppercase text-sm">
              ⚠️ Important Reminders
            </h4>
            <ul className="text-xs text-gray-400 space-y-1">
              <li>• If you lose your keys, you lose your account permanently</li>
              <li>• No company or person can reset your password - not even us</li>
              <li>• Anyone with your keys has full control of your account</li>
              <li>• Your keys control all your Nostr data across ALL apps</li>
            </ul>
          </div>
        </CardContent>
      </Card>

      {/* Browser Extension & Mobile App Recommendations */}
      <Card className="bg-black/90 border-2 border-purple-500/30">
        <CardHeader>
          <CardTitle className="text-purple-400">🔌 Recommended Nostr Signers</CardTitle>
          <CardDescription>
            Use a Nostr signer for better security and convenience
          </CardDescription>
        </CardHeader>
        <CardContent>
          <div className="space-y-3">
            {/* Amber - Android */}
            <a 
              href="https://github.com/greenart7c3/Amber" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-gradient-to-r from-[#ccff00]/10 to-green-500/10 border border-[#ccff00]/30 hover:border-[#ccff00]/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white flex items-center gap-2">
                    Amber
                    <span className="text-xs px-2 py-0.5 bg-[#ccff00]/20 text-[#ccff00] rounded-full">Android</span>
                  </div>
                  <p className="text-xs text-gray-400 mt-1">
                    Secure Nostr signer for Android. Keeps your keys safe on your phone and signs events without exposing them.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>
            <a 
              href="https://getalby.com" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-gradient-to-r from-amber-500/10 to-yellow-500/10 border border-amber-500/30 hover:border-amber-500/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white flex items-center gap-2">
                    Alby
                    <span className="text-xs px-2 py-0.5 bg-green-500/20 text-green-400 rounded-full">Recommended</span>
                  </div>
                  <p className="text-xs text-gray-400 mt-1">
                    Full-featured extension with Lightning wallet, WebLN, and NWC support.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>

            <a 
              href="https://www.getflamingo.org/" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-black/50 border border-purple-500/30 hover:border-purple-500/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white">Flamingo</div>
                  <p className="text-xs text-gray-400 mt-1">
                    Simple, clean interface. Focuses on Nostr signing without wallet features.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>

            <a 
              href="https://github.com/fiatjaf/nos2x" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-black/50 border border-purple-500/30 hover:border-purple-500/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white">nos2x</div>
                  <p className="text-xs text-gray-400 mt-1">
                    Minimal, lightweight extension for advanced users.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>
          </div>
        </CardContent>
      </Card>

      {/* Nostr Connect (Bunkers) */}
      <Card className="bg-black/90 border-2 border-blue-500/30">
        <CardHeader>
          <CardTitle className="text-blue-400">☁️ Nostr Connect (Remote Signers)</CardTitle>
          <CardDescription>
            Use a remote signer to access your account from any device
          </CardDescription>
        </CardHeader>
        <CardContent>
          <p className="text-sm text-gray-400 mb-4">
            Nostr Connect (also called "bunkers") lets you store your keys on a secure server and sign in from any device. 
            Your keys never leave the server, but you can use your account anywhere!
          </p>

          <div className="space-y-3">
            <a 
              href="https://nsec.app" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-gradient-to-r from-blue-500/10 to-cyan-500/10 border border-blue-500/30 hover:border-blue-500/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white flex items-center gap-2">
                    nsec.app
                    <span className="text-xs px-2 py-0.5 bg-blue-500/20 text-blue-400 rounded-full">Popular</span>
                  </div>
                  <p className="text-xs text-gray-400 mt-1">
                    Free, secure remote signer. Create bunker:// URI and paste when logging in.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>

            <a 
              href="https://nostrum.social" 
              target="_blank" 
              rel="noopener noreferrer"
              className="block p-4 rounded-lg bg-black/50 border border-blue-500/30 hover:border-blue-500/60 transition-all"
            >
              <div className="flex items-start justify-between gap-3">
                <div className="flex-1">
                  <div className="font-bold text-white">Nostrum</div>
                  <p className="text-xs text-gray-400 mt-1">
                    Another remote signer option with mobile support.
                  </p>
                </div>
                <ExternalLink className="h-4 w-4 text-gray-500" />
              </div>
            </a>
          </div>

          <div className="mt-4 p-3 rounded-lg bg-blue-950/30 border border-blue-500/30 text-sm text-gray-300">
            <p><strong className="text-blue-400">💡 How to use:</strong> Create an account on one of these services, 
            get your bunker:// connection string, then paste it in the "Nostr Connect" tab when logging in.</p>
          </div>
        </CardContent>
      </Card>
    </div>
  );
}