import browserslist from 'browserslist';
import { transform, browserslistToTargets, Features } from 'lightningcss';
import { readdir, rmdir, copyFile, mkdir, exists } from 'node:fs/promises';
import { type Dirent } from 'node:fs';

const assignmentDir = './assignments';
const outDir = './.out';

const ENABLE_TRANSPILE = false;

const targets = browserslistToTargets(browserslist('last 2 versions, > 0.1%'));

const handleAssignment = async (project: Dirent) => {
  console.log(`transpiling project ${project.name}`);
  if (!ENABLE_TRANSPILE) console.warn('WARNING: transpilation is disabled!!');

  await mkdir(`${outDir}/assignments/${project.name}`, { recursive: true });

  const files = await readdir(`${assignmentDir}/${project.name}`, { withFileTypes: true, recursive: true }).then(n =>
    n.filter(f => f.isFile()).map(f => (f.name.endsWith('.css') ? transpileCss(f) : copy(f))),
  );

  await Promise.all(files);
  console.log(`transpiled project ${project.name}`);
};

const copy = async ({ name, parentPath }: { name: string; parentPath: string }) => {
  console.log(`copying file ${name}`);
  if (!(await exists(`${outDir}/${parentPath}}`))) await mkdir(`${outDir}/${parentPath}`, { recursive: true });
  await copyFile(`./${parentPath}/${name}`, `${outDir}/${parentPath}/${name}`);
};

const transpileCss = async ({ name, parentPath }: { name: string; parentPath: string }) => {
  if (!ENABLE_TRANSPILE) return copy({ name, parentPath });

  console.log(`transpiling css file ${name}`);
  const content = await Bun.file(`./${parentPath}/${name}`).arrayBuffer();
  const { code, map } = transform({
    filename: name,
    code: Buffer.from(content),
    minify: false,
    sourceMap: false,
    exclude: Features.Nesting,
    targets,
  });

  await Bun.write(`${outDir}/${parentPath}/${name}`, code);
  if (map) await Bun.write(`${outDir}/${parentPath}/${name}.map`, map);
};

await rmdir(outDir, { recursive: true });

const ignores = await Bun.file('.gitignore')
  .text()
  .then(n =>
    n
      .split('\n')
      .filter(Boolean)
      .filter(n => !n.startsWith('#')),
  );
const assignments = await readdir(assignmentDir, { withFileTypes: true }).then(n =>
  n.filter(f => f.isDirectory() && !f.name.startsWith('.') && !ignores.includes(f.name)).map(handleAssignment),
);

await Promise.all(assignments);