package app

import (
	"context"
	"sync"
	"time"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
)

// Watches contexts and channels for the
// app to be finished and calls shutdown once
// the app is done
func (a *App) run() {
	select {
	case <-a.AppContext.Done():
		a.l.Warn().Str("reason", a.AppContext.Err().Error()).
			Msg("shutting down on context done")
	case <-a.HTTP.HTTPDone: // TODO: return error on this channel
		a.l.Warn().Msg("shutting down early on http server done")
	case err := <-a.GRPC.GRPCDone:
		a.l.Warn().Err(err).Msg("shutting down early on grpc server done")
	}

	a.Shutdown()     // Run through all shutdown funcs
	a.appDone <- nil // Notify app
}

// Typically invoked when AppContext is done
// or Server has exited. Not intended to be called
// manually
func (a *App) Shutdown() {
	now := time.Now()

	doneCtx, cncl := context.WithTimeout(context.Background(), 15*time.Second)
	defer func() {
		if doneCtx.Err() == context.DeadlineExceeded {
			a.l.Err(doneCtx.Err()).
				Dur("shutdownTime", time.Since(now)).
				Msg("app shutdown aborted")
		} else {
			a.l.Info().
				Int("shutdownFuncsCalled", len(a.shutdownFuncs)).
				Dur("shutdownTime", time.Since(now)).
				Msg("app shutdown normally")
		}
		cncl()
	}()

	doneCtx, span := a.tracer.Start(doneCtx, "shutdown")
	defer span.End()

	span.SetAttributes(attribute.Int("shutdown.funcs", len(a.shutdownFuncs)))

	var wg sync.WaitGroup
	wg.Add(len(a.shutdownFuncs))

	for _, f := range a.shutdownFuncs {
		go func() {
			defer wg.Done()
			err := f(doneCtx)
			if err != nil {
				span.SetStatus(codes.Error, "shutdown failed")
				span.RecordError(err)
				a.l.Err(err).Send()
			}
		}()
	}

	wg.Wait()
}