package ping

import (
	"context"
	"net"
	"testing"
	"time"

	"internetpressure.io/probe-agent/internal/protocol"
)

func TestSummarise(t *testing.T) {
	m := protocol.Measurement{}
	summarise(&m, []time.Duration{10 * time.Millisecond, 12 * time.Millisecond, 11 * time.Millisecond, 13 * time.Millisecond}, 5)
	if !m.OK || m.Error != "" || *m.Sent != 5 || *m.Received != 4 {
		t.Fatalf("%+v", m)
	}
	if *m.PacketLoss != 0.2 || *m.RTTMinMs != 10 || *m.RTTMaxMs != 13 || *m.RTTAvgMs != 11.5 {
		t.Fatalf("stats: loss=%v min=%v avg=%v max=%v", *m.PacketLoss, *m.RTTMinMs, *m.RTTAvgMs, *m.RTTMaxMs)
	}
	// successive diffs: |12-10|=2, |11-12|=1, |13-11|=2 → mean 5/3
	if got := *m.JitterMs; got < 1.666 || got > 1.667 {
		t.Fatalf("jitter=%v", got)
	}

	m = protocol.Measurement{}
	summarise(&m, nil, 5)
	if m.OK || m.Error != protocol.ErrUnreachable || *m.PacketLoss != 1 {
		t.Fatalf("unreachable: %+v", m)
	}
}

func TestTCPConnects(t *testing.T) {
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()
	go func() {
		for {
			c, err := ln.Accept()
			if err != nil {
				return
			}
			c.Close()
		}
	}()
	port := ln.Addr().(*net.TCPAddr).Port
	c := &Checker{}
	m := c.RunTCP(context.Background(), protocol.Target{TargetID: "t", Hostname: "localhost", IP: strPtr("127.0.0.1"), Port: port})
	if !m.OK || m.Kind != "tcp" || *m.Received != Count || m.ResolvedIP != "127.0.0.1" {
		t.Fatalf("%+v", m)
	}
	// Closed port → refused → unreachable
	ln.Close()
	m = c.RunTCP(context.Background(), protocol.Target{TargetID: "t", Hostname: "localhost", IP: strPtr("127.0.0.1"), Port: port})
	if m.OK || m.Error != protocol.ErrUnreachable {
		t.Fatalf("closed port: %+v", m)
	}
}

// Loopback ICMP echo; skipped when the platform does not allow unprivileged ICMP sockets.
func TestICMPLoopback(t *testing.T) {
	if !Detect() {
		t.Skip("unprivileged ICMP not available here")
	}
	c := &Checker{ICMP: true}
	m := c.Run(context.Background(), protocol.Target{TargetID: "lo", Hostname: "localhost", IP: strPtr("127.0.0.1")})
	if m.Kind != "ping" {
		t.Fatalf("expected icmp ping, got %+v", m)
	}
	if !m.OK || *m.Received == 0 {
		t.Fatalf("loopback ping failed: %+v", m)
	}
}

func strPtr(s string) *string { return &s }