Implement History Command and the Shell Expansion Partially.

src/utils/bin/commands.ts

@@ -2,6 +2,7 @@
 
 import * as bin from './index';
 import config from '../../../config.json';
+import { list as listHistory } from '../history';
 
 // Help
 export const help = async (args: string[]): Promise<string> => {
@@ -138,6 +139,11 @@ export const sudo = async (args?: string[]): Promise<string> => {
   return `Permission denied: with little power comes... no responsibility? `;
 };
 
+// history
+export const history = async (args: string[]): Promise<string> => {
+  return listHistory();
+};
+
 // Banner
 export const banner = (args?: string[]): string => {
   return `

src/utils/history.ts

@@ -0,0 +1,69 @@
+type History = Record<number, string>;
+const history: History = {};
+let historyIndex = 0;
+
+export function list(): string {
+  const maximumNumberOfDigits = historyIndex.toString().length;
+
+  const array: Array<string> = [];
+  for (const index in history) {
+    const value = history[index];
+    const paddedIndex = index.toString().padStart(maximumNumberOfDigits, ' ');
+
+    array.push(`${paddedIndex}:  ${value}`);
+  }
+
+  return array.join('\n');
+}
+
+export function push(command: string): History {
+  if (getLast() !== command) {
+    history[++historyIndex] = command;
+  }
+
+  return history;
+}
+
+export function getCommandIfHistoryExpansion(input): string {
+  let command = undefined;
+  const regExpExecArray = /!(-?)(?:(\d+)|!)/.exec(input);
+  if (regExpExecArray) {
+    const isMinus =
+      Boolean(regExpExecArray[1]) && regExpExecArray[1].length > 0;
+
+    /**
+     * either digits or '!'
+     */
+    const n = regExpExecArray[2];
+    const index = parseInt(n);
+    if (Number.isNaN(index)) {
+      command = getLast();
+    } else {
+      /**
+       * !0, !-0 are invalid
+       */
+      if (index > 0) {
+        if (isMinus) {
+          command = getMinus(index);
+        } else {
+          command = get(index);
+        }
+      }
+    }
+  }
+
+  return command;
+}
+
+function get(index: number): string {
+  return history[index];
+}
+
+function getMinus(index: number): string {
+  // '!!' is a synonym for '!-1' so + 1
+  return history[historyIndex - index + 1];
+}
+
+function getLast(): string {
+  return history[historyIndex];
+}

src/utils/shell.ts

@@ -1,5 +1,6 @@
 import React from 'react';
 import * as bin from './bin';
+import { getCommandIfHistoryExpansion, push as pushHistory } from './history';
 
 export const shell = async (
   command: string,
@@ -8,17 +9,28 @@ export const shell = async (
   setCommand: React.Dispatch<React.SetStateAction<string>>,
 ) => {
   const args = command.split(' ');
-  args[0] = args[0].toLowerCase();
+  args[0] = args[0].toLowerCase().trim();
+
+  let expandedCommand = getCommandIfHistoryExpansion(args[0]);
+  if (expandedCommand) {
+    // like bash with histverify on or zsh default
+    setCommand(expandedCommand);
+    return;
+  }
 
   if (args[0] === 'clear') {
+    pushHistory(args[0]);
     clearHistory();
   } else if (command === '') {
     setHistory('');
   } else if (Object.keys(bin).indexOf(args[0]) === -1) {
+    pushHistory(args[0]);
     setHistory(
       `shell: command not found: ${args[0]}. Try 'help' to get started.`,
     );
   } else {
+    pushHistory(args[0]);
+
     const output = await bin[args[0]](args.slice(1));
     setHistory(output);
   }