import { serveFile } from '@std/http/file-server';
import { transpile } from 'deno/emit';
import sass from 'sass';

async function transpileTs(content: string, specifier: URL) {
  const urlStr = specifier.toString();
  const result = await transpile(specifier, {
    load(specifier: string) {
      if (specifier !== urlStr) {
        return Promise.resolve({ kind: 'module', specifier, content: '' });
      }
      return Promise.resolve({ kind: 'module', specifier, content });
    },
  });
  return result.get(urlStr) || '';
}

export async function serveFileWithTs(request: Request, filePath: string, extraHeaders?: ResponseInit['headers']) {
  const response = await serveFile(request, filePath);

  if (response.status !== 200) {
    return response;
  }

  const tsCode = await response.text();
  const jsCode = await transpileTs(tsCode, new URL('file:///src.ts'));
  const { headers } = response;
  headers.set('content-type', 'application/javascript; charset=utf-8');
  headers.delete('content-length');

  return new Response(jsCode, {
    status: response.status,
    statusText: response.statusText,
    headers,
    ...(extraHeaders || {}),
  });
}

function transpileSass(content: string) {
  const compiler = sass(content);

  return compiler.to_string('compressed') as string;
}

export async function serveFileWithSass(request: Request, filePath: string, extraHeaders?: ResponseInit['headers']) {
  const response = await serveFile(request, filePath);

  if (response.status !== 200) {
    return response;
  }

  const sassCode = await response.text();
  const cssCode = transpileSass(sassCode);
  const { headers } = response;
  headers.set('content-type', 'text/css; charset=utf-8');
  headers.delete('content-length');

  return new Response(cssCode, {
    status: response.status,
    statusText: response.statusText,
    headers,
    ...(extraHeaders || {}),
  });
}