[feat] Add the command usage syntax hint

apps/playground-web/components/Shell/Shell.tsx

@@ -1,13 +1,21 @@
 // src/components/Shell/Shell.tsx
 'use client';
 
+import React from 'react';
 // hooks
 import { useShell } from './hooks/useShell';
+import { SyntaxPart } from '@/data/commandSyntaxMap';
 
 interface ShellProps {
   decreaseCommandsLeft: () => void;
 }
 
+const InlineHint = ({ part }: { part: SyntaxPart }) => (
+  <span className="border-b border-dotted border-gray-600">
+    {' ' + part.syntax}
+  </span>
+);
+
 export default function Shell({ decreaseCommandsLeft }: ShellProps) {
   const {
     handleInputChange,
@@ -16,7 +24,9 @@ export default function Shell({ decreaseCommandsLeft }: ShellProps) {
     inputRef,
     output,
     command,
+    remainingSyntax,
   } = useShell(decreaseCommandsLeft);
+
   return (
     <div
       ref={terminalRef}
@@ -34,8 +44,8 @@ export default function Shell({ decreaseCommandsLeft }: ShellProps) {
         </div>
       ))}
       <div className="flex items-center">
-        <p className="text-green-500 mr-2 p-1">dice ~$</p>
-        <div className="flex-grow">
+        <p className="text-green-500 mr-2 p-1 flex-shrink-0">dice ~$</p>
+        <div className="flex-grow relative">
           <input
             ref={inputRef}
             type="text"
@@ -45,6 +55,18 @@ export default function Shell({ decreaseCommandsLeft }: ShellProps) {
             data-testid="shell-input"
             className="w-full bg-transparent outline-none text-white"
           />
+          <div
+            className="absolute top-0 left-0 text-gray-500 pointer-events-none whitespace-wrap overflow-x-auto"
+            style={{ paddingLeft: `${command.length + 1}ch ` }}
+            data-testid="inline-hint"
+          >
+            {remainingSyntax.map((part, index) => (
+              <React.Fragment key={index}>
+                {index > 0}
+                <InlineHint part={part} />
+              </React.Fragment>
+            ))}
+          </div>
         </div>
       </div>
     </div>

apps/playground-web/components/Shell/__tests__/index.test.tsx

@@ -109,4 +109,52 @@ describe('Shell Component', () => {
     await user.keyboard('[ArrowDown]');
     expect(cliInputElement.value).toBe(newCommand);
   });
+
+  it('should show syntax usage hint for SET', async () => {
+    const { cliInputElement, user, getByTestId } = setupTest();
+
+    const newCommand = 'set';
+    await user.type(cliInputElement, newCommand);
+
+    const inlineHint = getByTestId('inline-hint');
+    expect(inlineHint.childElementCount).toBe(4);
+
+    const inlineHintChild = inlineHint.childNodes;
+
+    expect(inlineHintChild[0]).toHaveTextContent('Key');
+    expect(inlineHintChild[1]).toHaveTextContent('Value');
+    expect(inlineHintChild[2]).toHaveTextContent('[NX | XX]');
+    expect(inlineHintChild[3]).toHaveTextContent(
+      '[EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix-time-milliseconds | KEEPTTL]',
+    );
+  });
+
+  it('should show syntax usage hint for GET', async () => {
+    const { cliInputElement, user, getByTestId } = setupTest();
+
+    const newCommand = 'get';
+    await user.type(cliInputElement, newCommand);
+
+    const inlineHint = getByTestId('inline-hint');
+    expect(inlineHint.childElementCount).toBe(1);
+
+    const inlineHintChild = inlineHint.childNodes;
+
+    expect(inlineHintChild[0]).toHaveTextContent('Key');
+  });
+
+  it('should show syntax usage hint for DEL', async () => {
+    const { cliInputElement, user, getByTestId } = setupTest();
+
+    const newCommand = 'del';
+    await user.type(cliInputElement, newCommand);
+
+    const inlineHint = getByTestId('inline-hint');
+    expect(inlineHint.childElementCount).toBe(2);
+
+    const inlineHintChild = inlineHint.childNodes;
+
+    expect(inlineHintChild[0]).toHaveTextContent('Key');
+    expect(inlineHintChild[1]).toHaveTextContent('[Key ...]');
+  });
 });

apps/playground-web/components/Shell/hooks/useShell.tsx

@@ -3,7 +3,8 @@ import { useState, useEffect, useRef, KeyboardEvent, ChangeEvent } from 'react';
 
 // utils
 import { handleCommand } from '@/shared/utils/shellUtils';
-import blacklistedCommands from '@/shared/utils/blacklist';
+import blacklistedCommands from '@/shared/utils/blacklist'; // Assuming you added blacklist here
+import { syntaxMap, SyntaxPart } from '@/data/commandSyntaxMap';
 
 export const useShell = (decreaseCommandsLeft: () => void) => {
   // states
@@ -13,6 +14,7 @@ export const useShell = (decreaseCommandsLeft: () => void) => {
   // Initialise the command history with sessionStorage
   const [commandHistory, setCommandHistory] = useState<string[]>([]);
   const [historyIndex, setHistoryIndex] = useState<number>(-1);
+  const [remainingSyntax, setRemainingSyntax] = useState<SyntaxPart[]>([]);
 
   // useRefs
   const terminalRef = useRef<HTMLDivElement>(null);
@@ -39,6 +41,24 @@ export const useShell = (decreaseCommandsLeft: () => void) => {
     decreaseCommandsLeft(); // Call to update remaining commands
   };
 
+  const updateSyntax = (value: string) => {
+    const inputParts = value.trim().split(' ');
+    const command = inputParts[0].toUpperCase();
+    if (syntaxMap[command]) {
+      const parts = syntaxMap[command].parts;
+      if (inputParts.length === 1) {
+        // Only command typed, show all parts
+        setRemainingSyntax(parts);
+      } else {
+        // Show remaining parts based on what's already typed
+        const remainingParts = parts.slice(inputParts.length - 1);
+        setRemainingSyntax(remainingParts);
+      }
+    } else {
+      setRemainingSyntax([]);
+    }
+  };
+
   useEffect(() => {
     if (terminalRef.current) {
       terminalRef.current.scrollTop = terminalRef.current.scrollHeight;
@@ -64,9 +84,10 @@ export const useShell = (decreaseCommandsLeft: () => void) => {
   }, []);
 
   const handleInputChange = (e: ChangeEvent<HTMLInputElement>) => {
-    setCommand(e.target.value);
-    // Save current input when starting to navigate history
+    const value = e.target.value;
+    setCommand(value);
     setTempCommand(e.target.value);
+    updateSyntax(value);
   };
 
   const handleKeyDown = (e: KeyboardEvent<HTMLInputElement>) => {
@@ -76,6 +97,7 @@ export const useShell = (decreaseCommandsLeft: () => void) => {
         setCommandHistory((prev) => [...prev, command]);
         setHistoryIndex(-1);
       }
+      setRemainingSyntax([]);
       return;
     }
 
@@ -125,5 +147,6 @@ export const useShell = (decreaseCommandsLeft: () => void) => {
     command,
     tempCommand,
     setTempCommand,
+    remainingSyntax,
   };
 };

apps/playground-web/data/commandSyntaxMap.ts

@@ -0,0 +1,56 @@
+export type SyntaxPart = {
+  syntax: string;
+  doc: string;
+};
+
+export type CommandSyntax = {
+  parts: SyntaxPart[];
+};
+
+export type SyntaxMap = {
+  [command: string]: CommandSyntax;
+};
+
+export const syntaxMap: SyntaxMap = {
+  SET: {
+    parts: [
+      {
+        syntax: 'Key',
+        doc: 'The key under which to store the value',
+      },
+      {
+        syntax: 'Value',
+        doc: 'The value to be stored',
+      },
+      {
+        syntax: '[NX | XX]',
+        doc: 'NX - Only set if key does not exist. XX - Only set if key exists',
+      },
+      {
+        syntax:
+          '[EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix-time-milliseconds | KEEPTTL]',
+        doc: 'Options to set the key expiration: EX (seconds), PX (milliseconds), EXAT/PXAT (unix timestamp), or KEEPTTL to retain existing TTL',
+      },
+    ],
+  },
+  GET: {
+    parts: [
+      {
+        syntax: 'Key',
+        doc: 'Key of the value you want to retrive',
+      },
+    ],
+  },
+  DEL: {
+    parts: [
+      {
+        syntax: 'Key',
+        doc: 'Key that you want to delete',
+      },
+      {
+        syntax: '[Key ...]',
+        doc: 'Multiple keys you want to delete',
+      },
+    ],
+  },
+};