package ircserver_test

import (
	"bufio"
	"log/slog"
	"net"
	"os"
	"strings"
	"testing"
	"time"

	"sneak.berlin/go/neoirc/internal/config"
	"sneak.berlin/go/neoirc/internal/ircserver"
)

// newKillVictim returns a Conn for the nick victim whose
// socket is one end of a net.Pipe, and the other end, from
// which the test reads what the victim is sent. A write to
// the pipe blocks until the other end reads.
func newKillVictim(t *testing.T) (*ircserver.Conn, net.Conn) {
	t.Helper()

	serverSide, clientSide := net.Pipe()

	t.Cleanup(func() { _ = clientSide.Close() })

	log := slog.New(slog.NewTextHandler(
		os.Stderr,
		&slog.HandlerOptions{Level: slog.LevelError},
	))
	cfg := &config.Config{ServerName: testServerName}

	return ircserver.NewTestConn(
		log, cfg, serverSide, "victim",
	), clientSide
}

// TestDisconnectDoesNotBlockOnUnresponsiveVictim checks
// that Disconnect returns although the victim never reads,
// so a KILL cannot stall the operator who sent it. The
// limit is well below one KillWriteWindow, so a Disconnect
// that waits on any write to the victim fails.
func TestDisconnectDoesNotBlockOnUnresponsiveVictim(
	t *testing.T,
) {
	t.Parallel()

	victim, _ := newKillVictim(t)
	returned := make(chan struct{})

	go func() {
		victim.Disconnect("killed by oper")
		close(returned)
	}()

	select {
	case <-returned:
	case <-time.After(ircserver.KillWriteWindow / 4):
		t.Fatal("Disconnect waited for the victim to read")
	}
}

// TestDisconnectNotifiesAndClosesVictim checks that a
// victim that reads is sent KILL and ERROR, and that its
// connection is then closed.
func TestDisconnectNotifiesAndClosesVictim(t *testing.T) {
	t.Parallel()

	victim, clientSide := newKillVictim(t)
	received := make(chan []string, 1)

	go func() {
		var lines []string

		scanner := bufio.NewScanner(clientSide)
		for scanner.Scan() {
			lines = append(lines, scanner.Text())
		}

		received <- lines
	}()

	victim.Disconnect("killed by oper")

	var lines []string

	select {
	case lines = <-received:
	case <-time.After(testTimeout):
		t.Fatal("the victim's connection was not closed")
	}

	joined := strings.Join(lines, "\n")

	if !strings.Contains(joined, "KILL victim :killed by oper") {
		t.Errorf("missing KILL line, got: %q", joined)
	}

	if !strings.Contains(joined, "ERROR :Closing Link:") {
		t.Errorf("missing ERROR line, got: %q", joined)
	}
}