Add multi-line chat and help menu (#152)

# PR Description
Given that `arcade chat` is the entry point for all users, this PR makes
the developer's first experience with Arcade a better experience.

1. Add multi-line & pasting support to `arcade chat`. To start a
multi-line chat message, start your message with `"""`. To end the
multi-line chat message, end your line with `"""`.

![image](https://github.com/user-attachments/assets/f190f487-d8d6-4c1d-ab73-29e811528d16)

2. Added chat commands
  - `/?` displays all available chat commands that are available
- `/show` shows all of the tools available. This uses `arcade show`.
Currently no option to specify the toolkit, or tool.
  - `/clear` clears the chat conversation history of the current session
  - `/exit` exits the chat. (ctrl+c still works of course!)
  

![image](https://github.com/user-attachments/assets/265b9977-5621-441a-9b80-5f33f5be5681)

arcade/arcade/cli/main.py

@@ -31,8 +31,10 @@ from arcade.cli.utils import (
     delete_deprecated_config_file,
     get_eval_files,
     get_tools_from_engine,
+    get_user_input,
     handle_chat_interaction,
     handle_tool_authorization,
+    handle_user_command,
     is_authorization_pending,
     load_eval_suites,
     log_engine_health,
@@ -270,16 +272,19 @@ def chat(
         log_engine_health(client)
 
         while True:
-            console.print(f"\n[magenta][bold]User[/bold] ({user_email}):[/magenta] ")
+            console.print(
+                f"\n[magenta][bold]User[/bold] {user_email}: [/magenta]"
+                + "([bold][default]/?[/default][/bold] for help)"
+            )
 
-            # Use input() instead of console.input() to leverage readline history
-            user_input = input()
-            while not user_input.strip():
-                user_input = input()
+            user_input = get_user_input()
 
             # Add the input to history
             readline.add_history(user_input)
 
+            if handle_user_command(user_input, history, host, port, force_tls, force_no_tls, show):
+                continue
+
             history.append({"role": "user", "content": user_input})
 
             try:

arcade/arcade/cli/utils.py

@@ -3,7 +3,9 @@ import ipaddress
 import os
 import webbrowser
 from dataclasses import dataclass
+from enum import Enum
 from pathlib import Path
+from textwrap import dedent
 from typing import Any, Callable, Union, cast
 from urllib.parse import urlencode, urlparse
 
@@ -36,6 +38,13 @@ class OrderCommands(TyperGroup):
         return list(self.commands)  # get commands using self.commands
 
 
+class ChatCommand(str, Enum):
+    HELP = "/?"
+    CLEAR = "/clear"
+    SHOW = "/show"
+    EXIT = "/exit"
+
+
 def create_cli_catalog(
     toolkit: str | None = None,
     show_toolkits: bool = False,
@@ -587,3 +596,89 @@ def delete_deprecated_config_file() -> None:
 
     if os.path.exists(deprecated_config_file_path):
         os.remove(deprecated_config_file_path)
+
+
+def get_user_input() -> str:
+    """
+    Get input from the user, handling multi-line input.
+    """
+    MULTI_LINE_PROMPT = '"""'
+    user_input = input()
+    # Handle multi-line input
+    if user_input.startswith(MULTI_LINE_PROMPT):
+        user_input = user_input[len(MULTI_LINE_PROMPT) :]
+
+        while not user_input.endswith(MULTI_LINE_PROMPT):
+            line = input()
+            if not line:
+                print()
+            user_input += "\n" + line
+
+        user_input = user_input.rstrip(MULTI_LINE_PROMPT)
+    else:
+        # Handle single-line input
+        while not user_input.strip():
+            user_input = input()
+
+    return user_input.strip()
+
+
+def display_chat_help() -> None:
+    """Display the help message for arcade chat."""
+    help_message = dedent(f"""\
+        [default]
+        Available Commands:
+          {ChatCommand.SHOW:<10} Show all available tools
+          {ChatCommand.CLEAR:<10} Clear the chat history
+          {ChatCommand.HELP:<10} Help for a command
+          {ChatCommand.EXIT:<10} Exit the chat
+
+        Use \"\"\" to begin & end a multi-line message[/default]
+    """)
+    console.print(help_message)
+
+
+def handle_user_command(
+    user_input: str,
+    history: list,
+    host: str,
+    port: int,
+    force_tls: bool,
+    force_no_tls: bool,
+    show: Callable,
+) -> bool:
+    """
+    Handle user commands during `arcade chat` and return True if a command was processed, otherwise False.
+    """
+    if user_input == ChatCommand.HELP:
+        display_chat_help()
+        return True
+    elif user_input == ChatCommand.EXIT:
+        raise KeyboardInterrupt
+    elif user_input == ChatCommand.CLEAR:
+        console.print("Chat history cleared.", style="bold green")
+        history.clear()
+        return True
+    elif user_input == ChatCommand.SHOW:
+        show(
+            toolkit=None,
+            tool=None,
+            host=host,
+            port=port,
+            force_tls=force_tls,
+            force_no_tls=force_no_tls,
+            debug=False,
+        )
+        return True
+    return False
+
+
+def parse_user_command(user_input: str) -> ChatCommand | None:
+    """
+    Parse the user command and return the corresponding ChatCommand enum.
+    Returns None if the input is not a valid chat command.
+    """
+    try:
+        return ChatCommand(user_input)
+    except ValueError:
+        return None