Index: server/cli.go
===================================================================
--- server/cli.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
+++ server/cli.go	(revision b715712c7d5d3ee27c932a8a9d8e0a2bc6e85127)
@@ -0,0 +1,106 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// Session holds the currently-logged-in user, if any.
+type Session struct {
+	UserID   string
+	Username string
+}
+
+var stdin = bufio.NewReader(os.Stdin)
+
+func prompt(label string) string {
+	fmt.Print(label)
+	line, err := stdin.ReadString('\n')
+	// On EOF (Ctrl-D, or the end of a piped script) ReadString keeps returning
+	// an error forever. Without this the menu loop would spin printing
+	// "Unknown option." indefinitely instead of ending.
+	if err != nil && strings.TrimSpace(line) == "" {
+		fmt.Println("\nInput closed. Goodbye.")
+		os.Exit(0)
+	}
+	return strings.TrimSpace(line)
+}
+
+func RunCLI() {
+	fmt.Println("=========================================")
+	fmt.Println("  EduBerza - Crypto Exchange Simulation")
+	fmt.Println("=========================================")
+
+	var s Session
+	for {
+		if s.UserID == "" {
+			anonymousMenu(&s)
+		} else {
+			authenticatedMenu(&s)
+		}
+	}
+}
+
+func anonymousMenu(s *Session) {
+	fmt.Println()
+	fmt.Println("[1] Register")
+	fmt.Println("[2] Login")
+	fmt.Println("[3] Browse markets")
+	fmt.Println("[0] Exit")
+	switch prompt("> ") {
+	case "1":
+		Register()
+	case "2":
+		Login(s)
+	case "3":
+		ListMarkets()
+	case "0":
+		fmt.Println("Goodbye.")
+		os.Exit(0)
+	default:
+		fmt.Println("Unknown option.")
+	}
+}
+
+func authenticatedMenu(s *Session) {
+	fmt.Printf("\n--- Logged in as %s ---\n", s.Username)
+	fmt.Println("[1] View balance")
+	fmt.Println("[2] Deposit virtual funds")
+	fmt.Println("[3] Browse markets")
+	fmt.Println("[4] Place market BUY order")
+	fmt.Println("[5] Place market SELL order")
+	fmt.Println("[6] View portfolio")
+	fmt.Println("[7] View transaction history")
+	fmt.Println("[8] Manage watchlist")
+	fmt.Println("[9] Logout")
+	fmt.Println("[0] Exit")
+	switch prompt("> ") {
+	case "1":
+		ShowBalance(s)
+	case "2":
+		Deposit(s)
+	case "3":
+		ListMarkets()
+	case "4":
+		PlaceOrder(s, "buy")
+	case "5":
+		PlaceOrder(s, "sell")
+	case "6":
+		ShowPortfolio(s)
+	case "7":
+		ShowTransactions(s)
+	case "8":
+		ManageWatchlist(s)
+	case "9":
+		s.UserID = ""
+		s.Username = ""
+		fmt.Println("Logged out.")
+	case "0":
+		fmt.Println("Goodbye.")
+		os.Exit(0)
+	default:
+		fmt.Println("Unknown option.")
+	}
+}