Create chat.exs

Author: danglinhanh

chat.exs

@@ -0,0 +1,121 @@
+defmodule ChatSimulator do
+  defmodule User do
+    defstruct [:username, :password]
+  end
+
+  defmodule Message do
+    defstruct [:from, :to, :content, :timestamp]
+  end
+
+  def start do
+    IO.puts("Welcome to Terminal Chat!")
+    loop([], [], nil)
+  end
+
+  # Main loop
+  defp loop(users, messages, current_user) do
+    if current_user do
+      IO.puts("\nLogged in as: #{current_user.username}")
+      IO.puts("Commands: send | inbox | logout | quit")
+    else
+      IO.puts("\nCommands: register | login | quit")
+    end
+
+    case IO.gets("> ") |> String.trim() do
+      "register" ->
+        {users, current_user} = register_user(users)
+        loop(users, messages, current_user)
+
+      "login" ->
+        case login_user(users) do
+          {:ok, user} -> loop(users, messages, user)
+          :error -> loop(users, messages, nil)
+        end
+
+      "send" when current_user != nil ->
+        messages = send_message(current_user, users, messages)
+        loop(users, messages, current_user)
+
+      "inbox" when current_user != nil ->
+        view_inbox(current_user, messages)
+        loop(users, messages, current_user)
+
+      "logout" when current_user != nil ->
+        IO.puts("Logged out.")
+        loop(users, messages, nil)
+
+      "quit" ->
+        IO.puts("Exiting chat.")
+        :ok
+
+      _ ->
+        IO.puts("Invalid command.")
+        loop(users, messages, current_user)
+    end
+  end
+
+  # User registration
+  defp register_user(users) do
+    username = IO.gets("Choose a username: ") |> String.trim()
+    if Enum.any?(users, &(&1.username == username)) do
+      IO.puts("Username already taken.")
+      {users, nil}
+    else
+      password = IO.gets("Choose a password: ") |> String.trim()
+      user = %User{username: username, password: password}
+      IO.puts("Registered successfully and logged in.")
+      {[user | users], user}
+    end
+  end
+
+  # User login
+  defp login_user(users) do
+    username = IO.gets("Username: ") |> String.trim()
+    password = IO.gets("Password: ") |> String.trim()
+
+    case Enum.find(users, &(&1.username == username && &1.password == password)) do
+      nil ->
+        IO.puts("Login failed.")
+        :error
+      user ->
+        IO.puts("Login successful.")
+        {:ok, user}
+    end
+  end
+
+  # Sending a message
+  defp send_message(from_user, users, messages) do
+    to_user = IO.gets("To: ") |> String.trim()
+    if Enum.any?(users, &(&1.username == to_user)) do
+      content = IO.gets("Message: ") |> String.trim()
+      msg = %Message{
+        from: from_user.username,
+        to: to_user,
+        content: content,
+        timestamp: DateTime.utc_now() |> DateTime.to_string()
+      }
+      IO.puts("Message sent.")
+      [msg | messages]
+    else
+      IO.puts("User not found.")
+      messages
+    end
+  end
+
+  # Viewing inbox
+  defp view_inbox(user, messages) do
+    user_messages =
+      Enum.filter(messages, fn m -> m.to == user.username end)
+
+    if user_messages == [] do
+      IO.puts("No messages.")
+    else
+      IO.puts("\nYour messages:")
+      Enum.each(Enum.reverse(user_messages), fn m ->
+        IO.puts("[#{m.timestamp}] #{m.from}: #{m.content}")
+      end)
+    end
+  end
+end
+
+ChatSimulator.start()