/*
 * Copyright 2025 CloudWeGo Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ttstream

import (
	"context"
	"sync/atomic"
)

// contextWithCancelReason implements context.Context
// with a cancel func for passing cancel reason
// NOTE: use context.WithCancelCause when go1.20?
type contextWithCancelReason struct {
	context.Context

	cancel context.CancelFunc
	reason atomic.Value
}

func (c *contextWithCancelReason) Err() error {
	err := c.reason.Load()
	if err != nil {
		return err.(error)
	}
	return c.Context.Err()
}

func (c *contextWithCancelReason) CancelWithReason(reason error) {
	if reason != nil {
		c.reason.CompareAndSwap(nil, reason)
	}
	c.cancel()
}

type cancelWithReason func(reason error)

func newContextWithCancelReason(ctx context.Context, cancel context.CancelFunc) (context.Context, cancelWithReason) {
	ret := &contextWithCancelReason{Context: ctx, cancel: cancel}
	return ret, ret.CancelWithReason
}
