// Firefox stores Mac shortcuts with Command, MacCtrl, and Alt, and reads a
// manifest's Ctrl as Command there (ShortcutUtils' chromeModifierKeyMap).
const MAC_KEY_NAMES = { Ctrl: "Cmd", Command: "Cmd", MacCtrl: "Ctrl", Alt: "Option", Enter: "Return" };
const OTHER_KEY_NAMES = { Command: "Ctrl", MacCtrl: "Ctrl" };

// The keys of a Firefox shortcut such as "Alt+Shift+G", named for the platform.
export function shortcutKeys(shortcut, os) {
  const names = os === "mac" ? MAC_KEY_NAMES : OTHER_KEY_NAMES;
  return shortcut.split("+").map((key) => names[key] ?? key);
}

// Writes a shortcut the way the page does: named keys in angle brackets and
// single characters plain, "<Alt>+<Shift>+G".
export function formatShortcut(shortcut, os) {
  return shortcutKeys(shortcut, os)
    .map((name) => (name.length > 1 ? `<${name}>` : name))
    .join("+");
}

// The page's static hotkeys are written for Windows and Linux.
export function renderStaticShortcuts(document, os) {
  for (const element of document.querySelectorAll("[data-shortcut]")) {
    element.textContent = formatShortcut(element.dataset.shortcut, os);
  }
}

// Firefox owns shortcut preferences; never copy them into extension storage.
export async function initializeShortcut({ commands, document, window, os }) {
  const field = (id) => document.getElementById(id);
  let refreshId = 0;

  // One key cap per key for the drawing, joined by plain "+" text.
  function keycaps(shortcut) {
    return shortcutKeys(shortcut, os).flatMap((name, index) => {
      const key = document.createElement("kbd");
      key.className = "drawing-key";
      key.textContent = name;
      return index ? ["+", key] : [key];
    });
  }

  function render(shortcut) {
    const keys = shortcut ? formatShortcut(shortcut, os) : "";
    field("shortcut-intro").hidden = !keys;
    field("shortcut-intro-key").textContent = keys;
    field("shortcut-keycaps").replaceChildren(...(keys ? keycaps(shortcut) : []));
    field("shortcut-current").textContent = shortcut === null
      ? "Could not read the keyboard shortcut. Check Manage Extension Shortcuts in Add-ons."
      : keys ? `Current shortcut: ${keys}` : "No keyboard shortcut assigned.";
  }

  async function refresh() {
    const requestId = ++refreshId;
    try {
      const all = await commands.getAll();
      const command = all.find(({ name }) => name === "ask-chatgpt");
      if (requestId === refreshId) render(command?.shortcut ?? "");
    } catch {
      if (requestId === refreshId) render(null);
    }
  }

  const button = field("change-shortcut");
  button.hidden = typeof commands?.openShortcutSettings !== "function";
  button.addEventListener("click", async () => {
    try {
      await commands.openShortcutSettings();
    } catch {
      field("shortcut-current").textContent =
        "Open Add-ons, then the gear menu → Manage Extension Shortcuts to change your shortcut.";
    }
  });

  commands?.onChanged?.addListener(({ name }) => {
    if (name === "ask-chatgpt") void refresh();
  });
  window.addEventListener("focus", refresh);
  document.addEventListener("visibilitychange", () => {
    if (document.visibilityState === "visible") void refresh();
  });
  await refresh();
}