// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

package twcc

import (
	"io"
	"sync"
	"testing"
	"time"

	"github.com/pion/interceptor"
	"github.com/pion/interceptor/internal/test"
	"github.com/pion/rtp"
	"github.com/stretchr/testify/assert"
)

func TestHeaderExtensionInterceptor(t *testing.T) {
	t.Run("if header is nil, return error", func(t *testing.T) {
		factory, err := NewHeaderExtensionInterceptor()
		assert.NoError(t, err)

		inter, err := factory.NewInterceptor("")
		assert.NoError(t, err)

		fn := inter.BindLocalStream(&interceptor.StreamInfo{RTPHeaderExtensions: []interceptor.RTPHeaderExtension{
			{
				URI: transportCCURI,
				ID:  1,
			},
		}}, interceptor.RTPWriterFunc(func(*rtp.Header, []byte, interceptor.Attributes) (int, error) {
			return 0, io.EOF
		}))

		_, err = fn.Write(nil, []byte{}, interceptor.Attributes{})
		assert.Equal(t, errHeaderIsNil, err)
	})

	t.Run("add transport wide cc to each packet", func(t *testing.T) {
		factory, err := NewHeaderExtensionInterceptor()
		assert.NoError(t, err)

		inter, err := factory.NewInterceptor("")
		assert.NoError(t, err)

		pChan := make(chan *rtp.Packet, 10*5)
		go func() {
			// start some parallel streams using the same interceptor to test for race conditions
			var wg sync.WaitGroup
			num := 10
			wg.Add(num)
			for i := 0; i < num; i++ {
				go func(ch chan *rtp.Packet, id uint16) {
					stream := test.NewMockStream(&interceptor.StreamInfo{RTPHeaderExtensions: []interceptor.RTPHeaderExtension{
						{
							URI: transportCCURI,
							ID:  1,
						},
					}}, inter)
					defer func() {
						wg.Done()
						assert.NoError(t, stream.Close())
					}()

					for _, seqNum := range []uint16{id * 1, id * 2, id * 3, id * 4, id * 5} {
						assert.NoError(t, stream.WriteRTP(&rtp.Packet{Header: rtp.Header{SequenceNumber: seqNum}}))
						select {
						case p := <-stream.WrittenRTP():
							assert.Equal(t, seqNum, p.SequenceNumber)
							ch <- p
						case <-time.After(10 * time.Millisecond):
							assert.FailNow(t, "written rtp packet not found")
						}
					}
				}(pChan, uint16(i+1)) //nolint:gosec // G115
			}
			wg.Wait()
			close(pChan)
		}()

		for p := range pChan {
			// Can't check for increasing transport cc sequence number, since we can't ensure ordering between the streams
			// on pChan is same as in the interceptor, but at least make sure each packet has a seq nr.
			extensionHeader := p.GetExtension(1)
			twcc := &rtp.TransportCCExtension{}
			err = twcc.Unmarshal(extensionHeader)
			assert.NoError(t, err)
		}
	})
}
