// SPDX-FileCopyrightText: 2026 Echolot contributors
// SPDX-License-Identifier: GPL-3.0-or-later

package tcpecho

import (
	"bufio"
	"encoding/json"
	"net"
	"testing"
	"time"
)

// Plain echo must be server-speaks-first: a client that sends nothing still
// gets the greeting (via the peek timeout), then its bytes are echoed.
func TestPlainEchoServerSpeaksFirst(t *testing.T) {
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()
	go (&Server{}).Serve(ln)

	c, err := net.Dial("tcp", ln.Addr().String())
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()
	c.SetDeadline(time.Now().Add(3 * time.Second))

	line, err := bufio.NewReader(c).ReadBytes('\n')
	if err != nil {
		t.Fatalf("no greeting: %v", err)
	}
	var g struct {
		TLS bool   `json:"tls"`
		Src string `json:"observed_src"`
	}
	if err := json.Unmarshal(line, &g); err != nil {
		t.Fatal(err)
	}
	if g.TLS {
		t.Fatal("plain connection reported tls=true")
	}
	if g.Src == "" {
		t.Fatal("greeting missing observed_src")
	}
	c.Write([]byte("xyz"))
	buf := make([]byte, 3)
	if _, err := c.Read(buf); err != nil || string(buf) != "xyz" {
		t.Fatalf("echo failed: %q %v", buf, err)
	}
}