package main

import (
	"errors"
	"net"
	"net/http"
	"testing"
	"time"
)

func TestShutdownServerForceClosesAfterGracefulTimeout(t *testing.T) {
	handlerStarted := make(chan struct{})
	releaseHandler := make(chan struct{})
	server := &http.Server{
		Handler: http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
			close(handlerStarted)
			<-releaseHandler
		}),
		ReadHeaderTimeout: time.Second,
	}
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("net.Listen() error = %v", err)
	}
	serverErrors := make(chan error, 1)
	go func() {
		serverErrors <- server.Serve(listener)
	}()

	requestFinished := make(chan struct{})
	go func() {
		defer close(requestFinished)
		client := http.Client{Timeout: time.Second}
		response, err := client.Get("http://" + listener.Addr().String())
		if err == nil {
			_ = response.Body.Close()
		}
	}()
	select {
	case <-handlerStarted:
	case <-time.After(time.Second):
		t.Fatal("handler did not start")
	}

	err = shutdownServer(server, serverErrors, 10*time.Millisecond)
	if err == nil {
		t.Fatal("shutdownServer() error = nil")
	}
	close(releaseHandler)
	select {
	case <-requestFinished:
	case <-time.After(time.Second):
		t.Fatal("request did not finish after force close")
	}
	connection, dialErr := net.DialTimeout(
		"tcp",
		listener.Addr().String(),
		100*time.Millisecond,
	)
	if dialErr == nil {
		_ = connection.Close()
		t.Fatal("listener still accepted connections after force close")
	}
}

func TestShutdownServerAcceptsNormalServerClose(t *testing.T) {
	serverErrors := make(chan error, 1)
	serverErrors <- http.ErrServerClosed
	server := &http.Server{}

	if err := shutdownServer(server, serverErrors, time.Second); err != nil &&
		!errors.Is(err, http.ErrServerClosed) {
		t.Fatalf("shutdownServer() error = %v", err)
	}
}