package app

import (
	"bytes"
	"context"
	"errors"
	"io"
	"testing"

	"go.uber.org/fx"
)

var errTestStopFailed = errors.New("test stop hook failed")

// TestRunAppPrintsStopErrorOnce checks that when a stop hook fails, runApp
// prints the hook's error once and returns exit status 1.
func TestRunAppPrintsStopErrorOnce(t *testing.T) {
	t.Parallel()

	app := fx.New(
		fx.NopLogger,
		fx.Invoke(func(lifecycle fx.Lifecycle, shutdowner fx.Shutdowner) {
			lifecycle.Append(fx.Hook{
				// Ask to shut down as soon as the app has started, so
				// that runApp goes on to stop it.
				OnStart: func(context.Context) error { return shutdowner.Shutdown() },
				OnStop:  func(context.Context) error { return errTestStopFailed },
			})
		}),
	)

	var stderr bytes.Buffer

	exitCode := runApp(app, &stderr)
	if exitCode != 1 {
		t.Errorf("runApp() = %d, want 1", exitCode)
	}

	want := errTestStopFailed.Error() + "\n"
	if stderr.String() != want {
		t.Errorf("stderr = %q, want %q", stderr.String(), want)
	}
}

// TestRunAppReturnsShutdownExitCode checks that runApp returns the exit
// code a shutdown request names.
func TestRunAppReturnsShutdownExitCode(t *testing.T) {
	t.Parallel()

	app := fx.New(
		fx.NopLogger,
		fx.Invoke(func(lifecycle fx.Lifecycle, shutdowner fx.Shutdowner) {
			lifecycle.Append(fx.Hook{
				OnStart: func(context.Context) error {
					return shutdowner.Shutdown(fx.ExitCode(3))
				},
			})
		}),
	)

	exitCode := runApp(app, io.Discard)
	if exitCode != 3 {
		t.Errorf("runApp() = %d, want 3", exitCode)
	}
}