esbuild-plugin-lit-css.ts

import type { Plugin } from 'esbuild';
import type { Options } from '@pwrs/lit-css/lit-css';
import { transform } from '@pwrs/lit-css';
import { readFile } from 'node:fs/promises';

export interface LitCSSOptions extends Omit<Options, 'css'> {
  filter: RegExp;
}

export function litCssPlugin(options?: LitCSSOptions): Plugin {
  const { filter = /\.css$/, specifier, tag, ...rest } = options ?? {};
  return {
    name: 'lit-css',
    setup(build) {
      const loader = 'js';
      build.onLoad({ filter }, async args => {
        const css = await readFile(args.path, 'utf8');
        const filePath = args.path;
        try {
          const contents = await transform({ css, specifier, tag, filePath, ...rest });
          return { contents, loader };
        } catch (error) {
          return {
            errors: [{
              text: error.message,
              detail: error,
              location: {
                file: error.file,
                line: error.line,
                column: error.column,
              },
            }],
          };
        }
      });
    },
  };
}