import type { Transform } from "node:stream";

import PluginError from "plugin-error";
import replaceExt from "replace-ext";
import slm from "slm";
import through from "through2";

export type Options = {
  filename?: string;
  extension?: string;
  data?: any;
  locals?: any;
};

const gulpSlm: (opts?: Options) => Transform = (opts: Options = {}) =>
  through.obj((file, _enc, cb) => {
    opts.filename = file.path;

    if (file.data) {
      opts.data = file.data;
    }

    file.path = replaceExt(file.path, opts.extension !== undefined ? opts.extension : ".html");

    if (file.isStream()) {
      return cb(new PluginError("gulp-slm", "Streaming not supported"));
    }

    if (file.isBuffer()) {
      try {
        const contents = String(file.contents);
        const compiled = slm.compile(contents, opts)(opts.locals || opts.data);
        file.contents = Buffer.from(compiled);
      } catch (e) {
        return cb(new PluginError("gulp-slm", e as any));
      }
    }

    cb(null, file);
  });

export default gulpSlm;