'use client';

import { useEffect, useState } from 'react';
import Link from 'next/link';
import { useParams, useRouter } from 'next/navigation';
import { ShieldCheck, GitFork, Activity, ExternalLink, ChevronDown, ChevronRight } from 'lucide-react';
import { apiFetch } from '@/lib/api';
import { Logo } from '@/components/logo';
import { Button } from '@/components/ui/button';
import { CodeBlock } from '@/components/code-block';

interface Tool {
  name: string;
  description: string;
  inputSchema: Record<string, unknown>;
}

interface SecretHint {
  key: string;
  description: string;
  howToGetUrl?: string;
}

interface TemplateDetail {
  id: string;
  slug: string;
  title: string;
  shortDescription: string;
  longDescription: string | null;
  category: string;
  status: 'draft' | 'public' | 'hidden' | 'takedown';
  verified: boolean;
  forkCount: number;
  activeDeployments: number;
  toolsSchema: Tool[];
  generatedCode: string;
  requiredSecrets: SecretHint[];
  scopes: string[];
  ownerName: string | null;
  ownerOrgName: string | null;
  sourceServerId: string | null;
  createdAt: string;
}

export default function TemplateDetail() {
  const params = useParams<{ slug: string }>();
  const router = useRouter();
  const [template, setTemplate] = useState<TemplateDetail | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [showCode, setShowCode] = useState(false);

  useEffect(() => {
    apiFetch<{ template: TemplateDetail }>(`/v1/templates/${params.slug}`)
      .then((r) => setTemplate(r.template))
      .catch((e) => {
        const detail = (e as { detail?: { error?: string } }).detail;
        setError(detail?.error ?? (e as Error).message);
      });
  }, [params.slug]);

  function useTemplate() {
    if (!template) return;
    router.push(`/servers/new?template=${template.slug}`);
  }

  if (error) {
    return (
      <div className="flex min-h-screen items-center justify-center px-6">
        <div className="text-center">
          <p className="text-[14px]">Template not found.</p>
          <Link href="/templates" className="mt-3 inline-block text-[12px] text-[--color-accent] underline">
            ← Back to marketplace
          </Link>
        </div>
      </div>
    );
  }

  if (!template) {
    return (
      <div className="px-8 py-20 text-center mono text-[12px] text-[--color-fg-muted]">Loading…</div>
    );
  }

  return (
    <div className="flex min-h-screen flex-col">
      <header className="sticky top-0 z-50 border-b border-[--color-border] bg-[--color-bg]/85 backdrop-blur-md">
        <div className="mx-auto flex h-12 max-w-5xl items-center justify-between px-6">
          <div className="flex items-center gap-3">
            <Logo />
            <span className="text-[12.5px] text-[--color-fg-subtle]">
              / <Link href="/templates" className="hover:text-[--color-fg]">templates</Link> / {template.slug}
            </span>
          </div>
          <Link
            href="/login"
            className="rounded-md bg-[--color-accent] px-3 py-1.5 text-[12.5px] font-medium text-white transition-colors duration-200 hover:bg-[#5557e8]"
          >
            Start building
          </Link>
        </div>
      </header>

      <main className="mx-auto w-full max-w-5xl flex-1 px-6 py-10">
        <div className="grid gap-10 lg:grid-cols-[1fr_300px]">
          <div>
            <div className="flex items-center gap-2">
              <span className="mono rounded-full border border-[--color-border] bg-[--color-bg-subtle] px-2 py-0.5 text-[11px] text-[--color-fg-muted]">
                {template.category}
              </span>
              {template.verified && (
                <span className="inline-flex items-center gap-1 rounded-full border border-[--color-accent]/40 bg-[--color-accent]/10 px-2 py-0.5 text-[11px] font-medium text-[--color-accent]">
                  <ShieldCheck size={10} /> verified
                </span>
              )}
            </div>
            <h1 className="mt-3 text-[28px] font-semibold tracking-tight">{template.title}</h1>
            <p className="mt-2 text-[14px] leading-relaxed text-[--color-fg-muted]">
              {template.shortDescription}
            </p>

            {template.longDescription && (
              <p className="mt-4 whitespace-pre-wrap text-[13.5px] leading-relaxed text-[--color-fg]">
                {template.longDescription}
              </p>
            )}

            <section className="mt-10">
              <h2 className="text-[16px] font-semibold tracking-tight">
                Tools ({template.toolsSchema.length})
              </h2>
              <div className="mt-3 space-y-3">
                {template.toolsSchema.map((tool) => (
                  <div key={tool.name} className="panel p-3">
                    <div className="flex items-baseline gap-2">
                      <span className="mono text-[13px] font-semibold">{tool.name}</span>
                      <span className="mono text-[10.5px] text-[--color-fg-subtle]">
                        {Object.keys(tool.inputSchema ?? {}).length} param
                        {Object.keys(tool.inputSchema ?? {}).length === 1 ? '' : 's'}
                      </span>
                    </div>
                    <p className="mt-1.5 text-[12.5px] text-[--color-fg-muted]">{tool.description}</p>
                    {Object.keys(tool.inputSchema ?? {}).length > 0 && (
                      <div className="mt-2">
                        <CodeBlock
                          label="input schema"
                          code={JSON.stringify(tool.inputSchema, null, 2)}
                        />
                      </div>
                    )}
                  </div>
                ))}
              </div>
            </section>

            {template.requiredSecrets.length > 0 && (
              <section className="mt-10">
                <h2 className="text-[16px] font-semibold tracking-tight">
                  Credentials you&apos;ll need
                </h2>
                <p className="mt-1 text-[12.5px] text-[--color-fg-muted]">
                  When you fork, the wizard asks you for these. Your values stay in your container —
                  the template author never sees them.
                </p>
                <div className="mt-3 space-y-2">
                  {template.requiredSecrets.map((s) => (
                    <div key={s.key} className="panel p-3">
                      <div className="flex items-baseline justify-between gap-2">
                        <span className="mono text-[13px] font-semibold">{s.key}</span>
                        {s.howToGetUrl && (
                          <a
                            href={s.howToGetUrl}
                            target="_blank"
                            rel="noreferrer"
                            className="inline-flex items-center gap-1 text-[11.5px] text-[--color-accent] hover:underline"
                          >
                            How to get one <ExternalLink size={10} />
                          </a>
                        )}
                      </div>
                      <p className="mt-1.5 text-[12.5px] text-[--color-fg-muted]">
                        {s.description}
                      </p>
                    </div>
                  ))}
                </div>
              </section>
            )}

            <section className="mt-10">
              <button
                type="button"
                onClick={() => setShowCode((s) => !s)}
                className="inline-flex items-center gap-1 text-[14px] font-semibold tracking-tight text-[--color-fg] transition-colors hover:text-[--color-fg-muted]"
              >
                {showCode ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
                Generated code ({template.generatedCode.length} chars)
              </button>
              <p className="mt-1 text-[12px] text-[--color-fg-muted]">
                Audit before you fork. We re-scan every published template for banned patterns
                (eval, child_process, prompt-injection markers).
              </p>
              {showCode && (
                <div className="mt-3">
                  <CodeBlock label="src/server.ts" code={template.generatedCode} />
                </div>
              )}
            </section>
          </div>

          <aside className="space-y-3">
            <div className="panel p-4">
              {template.status === 'public' ? (
                <>
                  <Button variant="primary" size="lg" className="w-full" onClick={useTemplate}>
                    Fork this template →
                  </Button>
                  <p className="mt-2 text-[11.5px] text-[--color-fg-muted]">
                    One click → your own isolated container.
                  </p>
                </>
              ) : (
                <>
                  <div className="rounded-md border border-amber-400/30 bg-amber-400/5 p-2.5 text-[12px] text-amber-200/90">
                    This template is <span className="mono">{template.status}</span> — not
                    forkable. {template.sourceServerId ? 'Re-share it from the server’s Publish tab to allow forks.' : ''}
                  </div>
                  {template.sourceServerId && (
                    <a
                      href={`/servers/${template.sourceServerId}`}
                      className="mt-2 inline-flex h-8 w-full items-center justify-center rounded-md border border-[--color-border] bg-[--color-bg-elevated] text-[12.5px] text-[--color-fg] transition-colors hover:bg-[--color-bg-subtle]"
                    >
                      Manage in server →
                    </a>
                  )}
                </>
              )}
            </div>

            <div className="panel p-3 text-[12px]">
              <Row label="Forks" value={template.forkCount} icon={<GitFork size={11} />} />
              <Row
                label="Live deployments"
                value={template.activeDeployments}
                icon={<Activity size={11} />}
              />
              <Row label="Category" value={template.category} mono />
              <Row
                label="Published"
                value={new Date(template.createdAt).toLocaleDateString()}
              />
              <Row label="Author" value={template.ownerName ?? template.ownerOrgName ?? 'anonymous'} />
            </div>

            <div className="panel p-3 text-[11.5px] leading-relaxed text-[--color-fg-muted]">
              <strong className="text-[--color-fg]">Forking is safe.</strong> Your fork gets its own
              Docker container, its own port, its own AES-256-encrypted secrets. The template
              author has no visibility into your traffic or data.
            </div>
          </aside>
        </div>
      </main>
    </div>
  );
}

function Row({
  label,
  value,
  mono,
  icon,
}: {
  label: string;
  value: string | number;
  mono?: boolean;
  icon?: React.ReactNode;
}) {
  return (
    <div className="flex items-baseline justify-between gap-3 py-1">
      <span className="text-[--color-fg-subtle]">{label}</span>
      <span className={`inline-flex items-center gap-1.5 ${mono ? 'mono' : ''} text-[--color-fg]`}>
        {icon}
        {value}
      </span>
    </div>
  );
}
