LeetCode Custom Mapping

Apply custom vim mappings to LeetCode's built-in Monaco Vim mode
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// ==UserScript==
// @name         LeetCode Custom Mapping
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Apply custom vim mappings to LeetCode's built-in Monaco Vim mode
// @author       thraxis
// @match        https://leetcode.com/problems/*
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_registerMenuCommand
// @license      MIT
// ==/UserScript==
(function () {
  "use strict";

  const defaultMappings = [
    { lhs: "jk", rhs: "<Esc>", mode: "insert" },
    { lhs: "jj", rhs: "<Esc>", mode: "insert" },
    { lhs: "H", rhs: "^", mode: "normal" },
    { lhs: "L", rhs: "$", mode: "normal" },
    { lhs: "J", rhs: "5j", mode: "normal" },
    { lhs: "K", rhs: "5k", mode: "normal" },
  ];

  function normalizeEntry(entry) {
    if (entry && typeof entry === "object" && !Array.isArray(entry)) {
      const { lhs, rhs, mode } = entry;
      if (typeof lhs === "string" && typeof rhs === "string" && typeof mode === "string") {
        return { lhs, rhs, mode };
      }
      return null;
    }
    if (typeof entry === "string") {
      const parts = entry.trim().split(/\s+/);
      if (parts[0] === "map" && parts.length >= 4) {
        return { lhs: parts[1], rhs: parts[2], mode: parts[3] };
      }
      return null;
    }
    return null;
  }

  function getMappings() {
    const stored = GM_getValue("mappings", defaultMappings);
    if (!Array.isArray(stored)) {
      GM_setValue("mappings", defaultMappings);
      return defaultMappings;
    }
    return stored.map(normalizeEntry).filter(Boolean);
  }

  function applyMappings() {
    if (!unsafeWindow.monacoVim?.VimMode?.Vim) return false;
    const V = unsafeWindow.monacoVim.VimMode.Vim;
    getMappings().forEach(({ lhs, rhs, mode }) => {
      try {
        V.map(lhs, rhs, mode);
      } catch (e) {
        console.error("Map failed:", lhs, rhs, mode, e);
      }
    });
    return true;
  }

  function startPolling() {
    let tries = 0;
    const maxTries = 60;
    const interval = setInterval(() => {
      tries++;
      if (applyMappings() || tries >= maxTries) {
        clearInterval(interval);
      }
    }, 1000);
  }

  startPolling();

  let lastUrl = location.href;
  new MutationObserver(() => {
    if (location.href !== lastUrl) {
      lastUrl = location.href;
      startPolling();
    }
  }).observe(document.body, { childList: true, subtree: true });

  function mappingsToText(mappings) {
    return mappings.map((m) => `map ${m.lhs} ${m.rhs} ${m.mode}`).join("\n");
  }

  function textToMappings(text) {
    return text.split("\n").map(normalizeEntry).filter(Boolean);
  }

  GM_registerMenuCommand("Edit Mappings", () => {
    const current = mappingsToText(getMappings());
    const newText = prompt('Enter mappings, one per line (e.g. "map jk <Esc> insert"):', current);
    if (newText !== null) {
      GM_setValue("mappings", textToMappings(newText));
      alert("Saved. Reload the page for changes to take effect.");
    }
  });

  GM_registerMenuCommand("Reset Mappings to Defaults", () => {
    GM_setValue("mappings", defaultMappings);
    alert("Reset to defaults. Reload the page.");
  });
})();