package prometheus_test

import (
	"strings"
	"testing"

	coreprom "github.com/datarhei/core/v16/prometheus"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/testutil"
)

// fakeStats implements coreprom.WebRTCStatsSource for testing.
type fakeStats struct{ s coreprom.WebRTCStats }

func (f *fakeStats) Stats() coreprom.WebRTCStats { return f.s }

func newReg(t *testing.T, source coreprom.WebRTCStatsSource) *prometheus.Registry {
	t.Helper()
	reg := prometheus.NewRegistry()
	if err := reg.Register(coreprom.NewWebRTCCollector("test", source)); err != nil {
		t.Fatalf("Register: %v", err)
	}
	return reg
}

func TestWebRTCCollector_NoStreams(t *testing.T) {
	reg := newReg(t, &fakeStats{})
	if err := testutil.GatherAndCompare(reg, strings.NewReader(`
# HELP dragonfork_webrtc_active_streams Streams currently registered (processes with webrtc.enabled=true running).
# TYPE dragonfork_webrtc_active_streams gauge
dragonfork_webrtc_active_streams{core="test"} 0
# HELP dragonfork_webrtc_udp_ports_in_use UDP ports currently allocated (2 per active stream).
# TYPE dragonfork_webrtc_udp_ports_in_use gauge
dragonfork_webrtc_udp_ports_in_use{core="test"} 0
`),
		"dragonfork_webrtc_active_streams",
		"dragonfork_webrtc_udp_ports_in_use",
	); err != nil {
		t.Fatal(err)
	}
}

func TestWebRTCCollector_OneStreamWithPeers(t *testing.T) {
	src := &fakeStats{s: coreprom.WebRTCStats{
		StreamCount:   1,
		PeersByStream: map[string]int{"live": 3},
		UDPPortsInUse: 2,
	}}
	reg := newReg(t, src)
	if err := testutil.GatherAndCompare(reg, strings.NewReader(`
# HELP dragonfork_webrtc_active_peers Currently subscribed WHEP peers per stream.
# TYPE dragonfork_webrtc_active_peers gauge
dragonfork_webrtc_active_peers{core="test",stream_id="live"} 3
# HELP dragonfork_webrtc_active_streams Streams currently registered (processes with webrtc.enabled=true running).
# TYPE dragonfork_webrtc_active_streams gauge
dragonfork_webrtc_active_streams{core="test"} 1
# HELP dragonfork_webrtc_udp_ports_in_use UDP ports currently allocated (2 per active stream).
# TYPE dragonfork_webrtc_udp_ports_in_use gauge
dragonfork_webrtc_udp_ports_in_use{core="test"} 2
`)); err != nil {
		t.Fatal(err)
	}
}

func TestWebRTCCollector_MultipleStreams(t *testing.T) {
	src := &fakeStats{s: coreprom.WebRTCStats{
		StreamCount:   2,
		PeersByStream: map[string]int{"live": 3, "cam": 1},
		UDPPortsInUse: 4,
	}}
	reg := newReg(t, src)
	mfs, err := reg.Gather()
	if err != nil {
		t.Fatalf("Gather: %v", err)
	}
	// Check stream count and udp ports
	for _, mf := range mfs {
		switch mf.GetName() {
		case "dragonfork_webrtc_active_streams":
			if got := mf.GetMetric()[0].GetGauge().GetValue(); got != 2 {
				t.Errorf("active_streams: want 2, got %v", got)
			}
		case "dragonfork_webrtc_udp_ports_in_use":
			if got := mf.GetMetric()[0].GetGauge().GetValue(); got != 4 {
				t.Errorf("udp_ports_in_use: want 4, got %v", got)
			}
		case "dragonfork_webrtc_active_peers":
			total := 0.0
			for _, m := range mf.GetMetric() {
				total += m.GetGauge().GetValue()
			}
			if total != 4 {
				t.Errorf("active_peers total: want 4, got %v", total)
			}
		}
	}
}