import * as fs from "fs";
import * as path from "path";
import { minify } from "html-minifier";
import { isExist, getListFromBundle } from "./utils";
import { InjectTag } from "./constants";
import { OutputBundle } from "./types/rollup";

interface Options {
  target?: string;
}

const replace = (
  source: string,
  pattern: RegExp,
  replacement: string
): string => {
  return source.replace(pattern, replacement);
};

const bundleInject = function (options: Options): object {
  const target: string | undefined = options.target;
  if (!target) throw new Error(`options.target cannot be empty`);
  const fileName: string = path.basename(target);

  return {
    name: "rollup-plugin-bundle-inject",
    generateBundle(options: object = {}, bundle: OutputBundle = {}) {
      // found the target html
      if (fs.statSync(target)) {
        // read the html code
        let code: string = fs.readFileSync(target, { encoding: "utf-8" });
        const { cssList, jsList } = getListFromBundle(bundle);
        const isExistInjectCSSTag: boolean = isExist("inject:css", code);
        const isExistInjectJSTag: boolean = isExist("inject:js", code);
        let pattern: RegExp;
        let replacement: string | Uint8Array;
        if (isExistInjectCSSTag) {
          // if exist css tag
          pattern = InjectTag.CSS;
          replacement = cssList.reduce(
            (acc: string, source: string | Uint8Array) =>
              `${acc}<style>${source}</style>`,
            ""
          );
          code = replace(code, pattern, replacement);
        }
        if (isExistInjectJSTag) {
          // else if exist js tag
          pattern = InjectTag.JS;
          replacement = jsList.reduce(
            (acc: string, source: string) => `${acc}<script>${source}</script>`,
            ""
          );
          code = replace(code, pattern, replacement);
        }
        if (!isExistInjectCSSTag && !isExistInjectJSTag) {
          // else default insert into the end of the head / body tag
          const headPattern: RegExp = InjectTag.HEAD_TAG;
          const headReplacement: string =
            cssList.reduce(
              (acc: string, source: string | Uint8Array) =>
                `${acc}<style>${source}</style>`,
              ""
            ) + "</head>";
          const bodyPattern: RegExp = InjectTag.BODY_TAG;
          const bodyReplacement: string =
            jsList.reduce(
              (acc: string, source: string) =>
                `${acc}<script>${source}</script>`,
              ""
            ) + "</body>";
          code = replace(code, headPattern, headReplacement);
          code = replace(code, bodyPattern, bodyReplacement);
        }
        code = minify(code, {
          removeComments: true,
          removeCommentsFromCDATA: true,
          collapseWhitespace: true,
          collapseBooleanAttributes: true,
          removeAttributeQuotes: true,
          removeRedundantAttributes: true,
          useShortDoctype: true,
          removeEmptyAttributes: true,
          removeEmptyElements: true,
        });
        this.emitFile({
          type: "asset",
          fileName,
          source: code,
        });
      }
    },
  };
};

module.exports = bundleInject;