menu.ts

import * as vscode from "vscode";

import { Context } from "./context";
import { keypress, promptLocked, promptOne } from "./prompt";
import { CancellationError } from "./errors";

export interface Menu {
  readonly title?: string;
  /**
    * `hotkey` menus are built into a tree of hotkey characters, to
    * implement kakoune's multi-key commands/menus, like [g]oto → [l]ine-end.
    *
    * `palette` menus are just stock-standard VSCode QuickPicks.
    */
  readonly type?: "hotkey" | "palette"
  readonly items: Menu.Items;
}

export declare namespace Menu {
  export interface Items {
    [keys: string]: Item;
  }

  export interface Item {
    readonly text: string;
    readonly command: string;
    readonly args?: any[];
  }
}

/**
 * Validates the given menu and returns a list of strings representing errors
 * with the given menu. If that list is empty, the menu is valid and can be
 * used.
 */
export function validateMenu(menu: Menu) {
  if (typeof menu !== "object" || menu === null) {
    return ["menu must be an object"];
  }

  if (typeof menu.items !== "object" || Object.keys(menu.items ?? {}).length === 0) {
    return ['menu must have an subobject "items" with at least two entries.'];
  }

  const seenKeyCodes = new Map<number, string>(),
        errors = [] as string[];

  if (menu.title !== undefined && typeof menu.title !== "string") {
    errors.push("menu title must be a string");
  }

  if (menu.type !== undefined && menu.type !== "hotkey" && menu.type !== "palette") {
    errors.push("menu.type must be 'hotkey' (default) or 'palette'");
  }

  const isHotkey = (menu.type ?? "hotkey") === "hotkey";

  for (const key in menu.items) {
    const item = menu.items[key],
          itemDisplay = JSON.stringify(key);

    if (typeof item !== "object" || item === null) {
      errors.push(`item ${itemDisplay} must be an object.`);
      continue;
    }

    if (typeof item.text !== "string" || item.text.length === 0) {
      errors.push(`item ${itemDisplay} must have a non-empty "text" property.`);
      continue;
    }

    if (typeof item.command !== "string" || item.command.length === 0) {
      errors.push(`item ${itemDisplay} must have a non-empty "command" property.`);
      continue;
    }

    if (key.length === 0) {
      errors.push(`item ${itemDisplay} must be a non-empty string key.`);
      continue;
    }

    if (isHotkey) {
      for (let i = 0; i < key.length; i++) {
        const keyCode = key.charCodeAt(i),
              prevKey = seenKeyCodes.get(keyCode);

        if (prevKey) {
          errors.push(`menu has duplicate key '${key[i]}' (specified by '${prevKey}' and '${key}').`);
          continue;
        }

        seenKeyCodes.set(keyCode, key);
      }
    }
  }

  return errors;
}

/**
 * Returns the menu with the given name. If no such menu exists, an exception
 * will be thrown.
 */
export function findMenu(menuName: string, context = Context.WithoutActiveEditor.current) {
  const menu = context.extension.menus.get(menuName);

  if (menu === undefined) {
    throw new Error(`menu ${JSON.stringify(menuName)} does not exist`);
  }

  return menu;
}

/**
 * Shows the given menu to the user, awaiting a choice.
 */
export async function showMenu(
  menu: Menu,
  additionalArgs: readonly any[] = [],
  prefix?: string,
) {
  const entries = Object.entries(menu.items);
  const items = entries.map((x) => [x[0], x[1].text] as const);

  let choice: string | number;
  if ((menu.type ?? "hotkey") === "hotkey") {
    choice = await promptOne(items, (quickPick) => quickPick.title = menu.title);
  } else {
    choice = await promptPalette(items, { title: menu.title });
  }

  if (typeof choice === "string") {
    if (prefix !== undefined) {
      await vscode.commands.executeCommand("default:type", { text: prefix + choice });
    }

    return;
  }

  const pickedItem = entries[choice][1],
        args = mergeArgs(pickedItem.args, additionalArgs);

  return Context.WithoutActiveEditor.wrap(
    vscode.commands.executeCommand(pickedItem.command, ...args),
  );
}

/**
 * Shows the menu with the given name.
 */
export function showMenuByName(
  menuName: string,
  additionalArgs: readonly any[] = [],
  prefix?: string,
) {
  return showMenu(findMenu(menuName), additionalArgs, prefix);
}

/**
 * Same as {@link showMenu}, but only displays the menu after a specified delay.
 */
export async function showMenuAfterDelay(
  delayMs: number,
  menu: Menu,
  additionalArgs: readonly any[] = [],
  prefix?: string,
) {
  const cancellationTokenSource = new vscode.CancellationTokenSource(),
        currentContext = Context.current;

  currentContext.cancellationToken.onCancellationRequested(() =>
    cancellationTokenSource.cancel());

  const keypressContext = currentContext.withCancellationToken(cancellationTokenSource.token),
        timeout = setTimeout(() => cancellationTokenSource.cancel(), delayMs);

  try {
    const key = await keypress(keypressContext);

    clearTimeout(timeout);

    for (const itemKeys in menu.items) {
      if (!itemKeys.includes(key)) {
        continue;
      }

      // found a match, run it and finish the loop
      const pickedItem = menu.items[itemKeys],
            args = mergeArgs(pickedItem.args, additionalArgs);

      await Context.WithoutActiveEditor.wrap(
        vscode.commands.executeCommand(pickedItem.command, ...args),
      );

      return;
    }

    if (prefix !== undefined) {
      await vscode.commands.executeCommand("default:type", { text: prefix + key });
    }
  } catch (e) {
    if (!currentContext.cancellationToken.isCancellationRequested) {
      await showMenu(menu, additionalArgs, prefix);
      return;
    }

    throw e;
  } finally {
    cancellationTokenSource.dispose();
  }
}

async function promptPalette(
  items: readonly (readonly [string, string])[],
  quickPickOptions: vscode.QuickPickOptions,
  context = Context.WithoutActiveEditor.current,
): Promise<number> {
  const result = await vscode.window.showQuickPick(
    items.map(([label, description], i) => ({
        label,
        description,
        _i: i,
      } satisfies vscode.QuickPickItem & {_i: number})),
      { ...quickPickOptions },
    context.cancellationToken,
  );

  if (result === undefined) {
    throw new CancellationError(CancellationError.Reason.PressedEscape);
  }
  return result._i;
}

/**
 * Shows the given menu to the user, not dismissing it when a key is pressed.
 */
export async function showLockedMenu(
  menu: Menu,
  additionalArgs: readonly any[] = [],
) {
  const entries = Object.entries(menu.items),
        items = entries.map(([keys, item]) =>
          [keys, item.text, () =>
            vscode.commands.executeCommand(
              item.command, ...mergeArgs(item.args, additionalArgs))] as const);

  await promptLocked(items, (quickPick) => quickPick.title = menu.title);
}

/**
 * Shows the menu with the given name.
 */
export function showLockedMenyByName(
  menuName: string,
  additionalArgs: readonly any[] = [],
) {
  return showLockedMenu(findMenu(menuName), additionalArgs);
}

function mergeArgs(args: readonly any[] | undefined, additionalArgs: readonly any[]) {
  if (args == null) {
    return additionalArgs;
  }

  if (!Array.isArray(args)) {
    args = [args];
  }

  if (additionalArgs.length > 0) {
    return args.length > additionalArgs.length
      ? args.map((arg, i) =>
        i < additionalArgs.length && additionalArgs[i]
          ? Object.assign({}, additionalArgs[i], arg)
          : arg)
      : additionalArgs.map((arg, i) =>
        i < args!.length ? Object.assign({}, arg, args![i]) : arg);
  } else {
    return args;
  }
}