Add validator lib

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/validator/errors.go

@@ -0,0 +1,107 @@
+// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package validator
+
+import (
+	"fmt"
+	"strings"
+)
+
+type ErrorCode string
+
+const (
+	ErrorCodeRequired      ErrorCode = "REQUIRED"
+	ErrorCodeInvalidFormat ErrorCode = "INVALID_FORMAT"
+	ErrorCodeOutOfRange    ErrorCode = "OUT_OF_RANGE"
+	ErrorCodeTooShort      ErrorCode = "TOO_SHORT"
+	ErrorCodeTooLong       ErrorCode = "TOO_LONG"
+	ErrorCodeInvalidEmail  ErrorCode = "INVALID_EMAIL"
+	ErrorCodeInvalidURL    ErrorCode = "INVALID_URL"
+	ErrorCodeInvalidEnum   ErrorCode = "INVALID_ENUM"
+	ErrorCodeInvalidGID    ErrorCode = "INVALID_GID"
+	ErrorCodeUnsafeContent ErrorCode = "UNSAFE_CONTENT"
+	ErrorCodeCustom        ErrorCode = "CUSTOM"
+)
+
+type ValidationError struct {
+	Field   string
+	Code    ErrorCode
+	Message string
+	Value   any
+}
+
+func (e *ValidationError) Error() string {
+	return fmt.Sprintf("%s %s", e.Field, e.Message)
+}
+
+type ValidationErrors []*ValidationError
+
+func (ve ValidationErrors) Error() string {
+	if len(ve) == 0 {
+		return ""
+	}
+
+	var messages []string
+	for _, err := range ve {
+		messages = append(messages, err.Error())
+	}
+	return strings.Join(messages, "; ")
+}
+
+func (ve ValidationErrors) HasErrors() bool {
+	return len(ve) > 0
+}
+
+func (ve ValidationErrors) Fields() []string {
+	fields := make([]string, 0, len(ve))
+	for _, err := range ve {
+		fields = append(fields, err.Field)
+	}
+	return fields
+}
+
+func (ve ValidationErrors) ByField(field string) ValidationErrors {
+	var errors ValidationErrors
+	for _, err := range ve {
+		if err.Field == field {
+			errors = append(errors, err)
+		}
+	}
+	return errors
+}
+
+func (ve ValidationErrors) ByCode(code ErrorCode) ValidationErrors {
+	var errors ValidationErrors
+	for _, err := range ve {
+		if err.Code == code {
+			errors = append(errors, err)
+		}
+	}
+	return errors
+}
+
+func (ve ValidationErrors) First() *ValidationError {
+	if len(ve) == 0 {
+		return nil
+	}
+	return ve[0]
+}
+
+func newValidationError(code ErrorCode, message string) *ValidationError {
+	return &ValidationError{
+		Code:    code,
+		Message: message,
+	}
+}