Add email validation to library

utils/regex.go

@@ -0,0 +1,17 @@
+// Copyright © 2025 Prabhjot Singh Sethi, All Rights reserved
+// Author: Prabhjot Singh Sethi <prabhjot.sethi@gmail.com>
+
+package utils
+
+import "regexp"
+
+// IsValidEmail returns true if the provided string is a valid email address format.
+// Usage:
+//
+//	valid := utils.IsValidEmail("user@example.com") // returns true
+//	valid := utils.IsValidEmail("not-an-email")     // returns false
+func IsValidEmail(email string) bool {
+	// This is a reasonably strict regex for email validation
+	var emailRegex = regexp.MustCompile(`^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$`)
+	return emailRegex.MatchString(email)
+}

utils/regex_test.go

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+// Copyright © 2025 Prabhjot Singh Sethi, All Rights reserved
+// Author: Prabhjot Singh Sethi <prabhjot.sethi@gmail.com>
+
+package utils
+
+import (
+	"testing"
+)
+
+func TestIsValidEmail(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected bool
+	}{
+		{"test@example.com", true},
+		{"invalid-email", false},
+		{"user@localhost", false}, // usually considered invalid in public contexts
+		{"name.lastname@domain.co.uk", true},
+		{"user@domain", false}, // missing TLD
+		{"user@sub.domain.com", true},
+		{"user+alias@domain.com", true},
+		{"", false},
+		{"@domain.com", false},
+		{"user@.com", false},
+		{"user@domain.c", false}, // TLD too short
+	}
+
+	for _, test := range tests {
+		result := IsValidEmail(test.input)
+		if result != test.expected {
+			t.Errorf("IsValidEmail(%q) = %v; want %v", test.input, result, test.expected)
+		}
+	}
+}