import type Browserslist from "browserslist";
import { compare } from "./compare.js";
import { SUPPORTED_ESBUILD_TARGETS, UNSUPPORTED_BROWSERLIST_TARGETS } from "./constants.js";
import { compareSemver } from "./semver.js";

// Original: https://github.com/marcofugaro/browserslist-to-esbuild/blob/0875f1a4ec71f206a634ba406c3528ca5ecf04de/src/index.js
// License: MIT
/**
 * Loads and converts Browserslist into esbuild's `target` option.
 *
 * @param cwd
 * @returns
 */
export const browserslistToEsbuild = (browserslist: typeof Browserslist, cwd: string, defaultBrowserslist: string[]): string[] => {
  const browserslistConfig = browserslist.loadConfig({ path: cwd }) ?? defaultBrowserslist;
  return (
    browserslist(browserslistConfig)
      // Filter out legacy Android webview to avoid converting them into Chrome targets
      .filter((query) => !UNSUPPORTED_BROWSERLIST_TARGETS.some((target) => query.startsWith(target)))
      .map((query) => {
        const modified = query === "safari TP" ? browserslist("last 1 safari version")[0] : query;
        const split = modified.split(" ");
        // https://github.com/browserslist/browserslist/blob/5cad191bc1a1e5beb7768ca263503cc15d0dcc7d/README.md?plain=1#L329-L350
        // https://esbuild.github.io/api/#target
        if (split[0] === "android" || split[0] === "and_chr") {
          split[0] = "chrome";
        }
        if (split[0] === "and_ff") {
          split[0] = "firefox";
        }
        if (split[0] === "ios_saf" || split[0] === "ios") {
          split[0] = "safari";
        }
        // Remove upper version bound
        if (split[1].includes("-")) {
          split[1] = split[1].slice(0, split[1].indexOf("-"));
        }
        // Trim ending .0
        if (split[1].endsWith(".0")) {
          split[1] = split[1].slice(0, -2);
        }
        return split;
      })
      // Remove unsupported browsers and invalid versions
      .filter((split) => SUPPORTED_ESBUILD_TARGETS.includes(split[0]) && /^\d+(\.\d+)*$/.test(split[1]))
      // Re-sort the result such that the oldest versions end up the latest, same as how
      // Browserslist does it.
      .sort((a, b) => {
        if (a[0] === b[0]) {
          return compareSemver(b[1].split("."), a[1].split("."));
        } else {
          return compare(a[0], b[0]);
        }
      })
      // Only pick the oldest included version for each browser to avoid duplications.
      .reduce((acc, browser) => {
        const existingIndex = acc.findIndex((br) => br[0] === browser[0]);
        if (existingIndex !== -1) {
          acc[existingIndex][1] = browser[1];
        } else {
          acc.push(browser);
        }
        return acc;
      }, [] as string[][])
      .map((split) => split.join(""))
  );
};