Standardize email-diagnostics.sh menu formatting and add input validation

IMPROVEMENTS:
- Added input validation for check type (1-2) with retry loop
- Added input validation for time period (1-5) with retry loop
- Added email format validation (user@domain.com pattern)
- Added domain format validation (example.com pattern)
- Added color codes to menu options (${CYAN}1)${NC} format)
- Improved error messages for invalid input

VALIDATION DETAILS:
- Check type: Only accepts 1 or 2, rejects invalid input with clear error
- Time period: Only accepts 1-5, rejects invalid input with clear error
- Email format: Validates user@domain.com pattern
- Domain format: Validates domain.com pattern (alphanumeric, dots, hyphens)
- All inputs with defaults continue to work seamlessly

MENU STANDARDS COMPLIANCE:
✓ Input validation (CRITICAL)
✓ Default values (already had)
✓ Color codes (CRITICAL)
✓ Error messages on invalid input (IMPORTANT)
✓ Retry logic for failed validation (IMPORTANT)

Lines modified: ~60 (input validation + color codes)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

modules/email/email-diagnostics.sh

@@ -27,40 +27,90 @@ echo ""
 # Ask what to check
 echo -e "${BOLD}What would you like to check?${NC}"
 echo ""
-echo "  1) Specific email address (e.g., user@example.com)"
-echo "  2) Entire domain (e.g., example.com)"
+echo -e "  ${CYAN}1)${NC} Specific email address (e.g., user@example.com)"
+echo -e "  ${CYAN}2)${NC} Entire domain (e.g., example.com)"
 echo ""
-read -p "Enter choice [1]: " check_type
-check_type=${check_type:-1}
+
+# Validate check_type input
+while true; do
+    read -p "Enter choice [1]: " check_type
+    check_type=${check_type:-1}
+
+    if ! [[ "$check_type" =~ ^[1-2]$ ]]; then
+        print_error "Invalid choice. Please enter 1 or 2"
+        continue
+    fi
+    break
+done
 
 # Get email/domain to check
 echo ""
-if [ "$check_type" = "2" ]; then
-    read -p "Enter domain to check (e.g., example.com): " target
-    search_pattern="@${target}"
-    check_label="domain $target"
-else
-    read -p "Enter email address to check: " target
-    search_pattern="$target"
-    check_label="email $target"
-fi
 
-if [ -z "$target" ]; then
-    print_error "No email/domain provided"
-    exit 1
+if [ "$check_type" = "2" ]; then
+    # Domain input with validation
+    while true; do
+        read -p "Enter domain to check (e.g., example.com): " target
+
+        # Validate domain format (basic check)
+        if [ -z "$target" ]; then
+            print_error "Domain cannot be empty"
+            continue
+        fi
+
+        # Check for invalid characters (allow alphanumeric, dots, hyphens)
+        if ! [[ "$target" =~ ^[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ ]]; then
+            print_error "Invalid domain format. Use format like: example.com"
+            continue
+        fi
+
+        search_pattern="@${target}"
+        check_label="domain $target"
+        break
+    done
+else
+    # Email address input with validation
+    while true; do
+        read -p "Enter email address to check: " target
+
+        # Validate email format (basic check)
+        if [ -z "$target" ]; then
+            print_error "Email address cannot be empty"
+            continue
+        fi
+
+        # Check for valid email format (user@domain.com)
+        if ! [[ "$target" =~ ^[a-zA-Z0-9._+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ ]]; then
+            print_error "Invalid email format. Use format like: user@example.com"
+            continue
+        fi
+
+        search_pattern="$target"
+        check_label="email $target"
+        break
+    done
 fi
 
 # Time period to check
 echo ""
 echo "Check logs from:"
-echo "  1) Last 1 hour"
-echo "  2) Last 6 hours"
-echo "  3) Last 24 hours (recommended)"
-echo "  4) Last 48 hours"
-echo "  5) Last week"
+echo -e "  ${CYAN}1)${NC} Last 1 hour"
+echo -e "  ${CYAN}2)${NC} Last 6 hours"
+echo -e "  ${CYAN}3)${NC} Last 24 hours (recommended)"
+echo -e "  ${CYAN}4)${NC} Last 48 hours"
+echo -e "  ${CYAN}5)${NC} Last week"
 echo ""
-read -p "Enter choice [3]: " time_choice
-time_choice=${time_choice:-3}
+
+# Validate time_choice input
+while true; do
+    read -p "Enter choice [3]: " time_choice
+    time_choice=${time_choice:-3}
+
+    if ! [[ "$time_choice" =~ ^[1-5]$ ]]; then
+        print_error "Invalid choice. Please enter 1-5"
+        continue
+    fi
+    break
+done
 
 case "$time_choice" in
     1) hours=1 ;;
@@ -68,7 +118,6 @@ case "$time_choice" in
     3) hours=24 ;;
     4) hours=48 ;;
     5) hours=168 ;;
-    *) hours=24 ;;
 esac
 
 echo ""