import fs from "fs";
import path from "path";
import Link from "next/link";
import { notFound } from "next/navigation";
import { Card, CardContent } from "@/components/ui/card";
import { PageHeader } from "@/components/page-header";

function formatTitle(filename: string) {
  return filename
    .replace(/\.RTF$/i, "")
    .replace(/-/g, " ")
    .replace(/\b\w/g, (c) => c.toUpperCase());
}

function formatSize(bytes: number) {
  if (bytes < 1024) return `${bytes} B`;
  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
}

export default function RtfsPage() {
  if (process.env.ALLOW_RTF !== "true") notFound();

  const rtfDir = path.join(process.cwd(), "public/rtfs");
  const files = fs.readdirSync(rtfDir).filter((f) => /\.rtf$/i.test(f));

  const fileList = files.map((f) => {
    const stat = fs.statSync(path.join(rtfDir, f));
    return {
      filename: f,
      slug: f.replace(/\.RTF$/i, ""),
      title: formatTitle(f),
      size: stat.size,
    };
  });

  fileList.sort((a, b) => a.title.localeCompare(b.title));

  return (
    <div className="min-h-screen bg-background">
      <PageHeader>
        <Link
          href="/"
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Home
        </Link>
        <h1 className="mt-3 text-2xl font-bold text-foreground">
          RTF Document Viewer
        </h1>
        <p className="mt-1 text-muted-foreground">
          {files.length} original documents from the pre-1978 Vedabase
        </p>
      </PageHeader>
      <main className="max-w-3xl mx-auto px-6 py-8">
        <Card className="py-0">
          <CardContent className="p-0 divide-y divide-border">
            {fileList.map((file) => (
              <Link
                key={file.slug}
                href={`/rtfs/${file.slug}`}
                className="flex items-center justify-between px-5 py-4 hover:bg-muted transition-colors first:rounded-t-xl last:rounded-b-xl"
              >
                <span className="font-medium text-foreground">
                  {file.title}
                </span>
                <span className="text-sm text-muted-foreground shrink-0 ml-4">
                  {formatSize(file.size)}
                </span>
              </Link>
            ))}
          </CardContent>
        </Card>
      </main>
    </div>
  );
}