Add validator lib

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

pkg/validator/validator_conditional.go

@@ -0,0 +1,71 @@
+// 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 (
+	"reflect"
+	"time"
+)
+
+// EqualTo validates that a value equals another value using deep equality.
+// Special handling for time.Time to compare instants rather than internal structure.
+func EqualTo(other any) ValidatorFunc {
+	return func(value any) *ValidationError {
+		if !areEqual(value, other) {
+			return newValidationError(ErrorCodeInvalidFormat, "values must match")
+		}
+		return nil
+	}
+}
+
+// NotEqualTo validates that a value does not equal another value using deep equality.
+// Special handling for time.Time to compare instants rather than internal structure.
+func NotEqualTo(other any) ValidatorFunc {
+	return func(value any) *ValidationError {
+		if areEqual(value, other) {
+			return newValidationError(ErrorCodeInvalidFormat, "values must not match")
+		}
+		return nil
+	}
+}
+
+// areEqual compares two values for equality with special handling for time.Time.
+func areEqual(a, b any) bool {
+	// Dereference both values
+	aVal, aIsNil := dereferenceValue(a)
+	bVal, bIsNil := dereferenceValue(b)
+
+	// If both are nil, they're equal
+	if aIsNil && bIsNil {
+		return true
+	}
+
+	// If only one is nil, they're not equal
+	if aIsNil || bIsNil {
+		return false
+	}
+
+	// Special handling for time.Time
+	aTime, aIsTime := aVal.(time.Time)
+	bTime, bIsTime := bVal.(time.Time)
+
+	if aIsTime && bIsTime {
+		// Use time.Time.Equal() which compares the instant, ignoring location and monotonic clock
+		return aTime.Equal(bTime)
+	}
+
+	// Fall back to reflect.DeepEqual for all other types
+	return reflect.DeepEqual(aVal, bVal)
+}