package sww

import (
	"log/slog"
	"net/url"
	"testing"
	"testing/synctest"
	"time"

	"sneak.berlin/go/smallwebwaf/internal/remotelog"
)

// The stop's tests run in a synctest bubble, where the time package runs
// on a clock of the test's own, so that how long the stop takes can be
// told exactly. The sender is held up by its process log, not by the
// network: a goroutine of the bubble that waits on the network keeps that
// clock from moving on.

func TestStopWaitsForTheSenderToFinish(t *testing.T) {
	t.Parallel()

	synctest.Test(t, func(t *testing.T) {
		took := stopHeldSender(t, time.Second)
		if took != time.Second {
			t.Errorf("the stop took %s, want the second the sender took", took)
		}
	})
}

func TestStopWaitsForTheSenderAtMostTwoSeconds(t *testing.T) {
	t.Parallel()

	synctest.Test(t, func(t *testing.T) {
		took := stopHeldSender(t, time.Minute)
		if took != 2*time.Second {
			t.Errorf("the stop took %s, want 2s", took)
		}
	})
}

// heldLog holds each line written to it until it is closed.
type heldLog chan struct{}

// Write waits until the log is closed.
func (l heldLog) Write(p []byte) (int, error) {
	<-l

	return len(p), nil
}

// stopHeldSender starts sending to an endpoint the sender cannot connect
// to, holds the sender as it logs that failure until release has passed,
// stops the sending, and returns how long the stop took. It returns once
// the sender has ended, as a bubble must.
func stopHeldSender(t *testing.T, release time.Duration) time.Duration {
	t.Helper()

	log := make(heldLog)
	sender := remotelog.New(remotelog.Params{
		// No port is 65536, so each attempt to connect fails at once,
		// before it reaches the network.
		URL:    &url.URL{Scheme: remotelog.SchemeTCP, Host: "127.0.0.1:65536"},
		Buffer: 1,
	})

	stopSending := startSending(t.Context(), sender,
		slog.New(slog.NewJSONHandler(log, nil)))

	synctest.Wait()
	time.AfterFunc(release, func() { close(log) })

	stopped := time.Now()

	stopSending()

	took := time.Since(stopped)

	time.Sleep(release)
	synctest.Wait()

	return took
}