// 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)
}