package main

import (
	"context"
	"fmt"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/containerd/containerd"
	"github.com/containerd/containerd/cio"
	"github.com/containerd/containerd/oci"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/sirupsen/logrus"
)

type worker struct {
	id       int
	wg       *sync.WaitGroup
	count    int
	failures int

	client *containerd.Client
	image  containerd.Image
	spec   *specs.Spec
	commit string
}

func (w *worker) run(ctx, tctx context.Context) {
	defer func() {
		w.wg.Done()
		logrus.Infof("worker %d finished", w.id)
	}()
	for {
		select {
		case <-tctx.Done():
			return
		default:
		}

		w.count++
		id := w.getID()
		logrus.Debugf("starting container %s", id)
		start := time.Now()
		if err := w.runContainer(ctx, id); err != nil {
			if err != context.DeadlineExceeded ||
				!strings.Contains(err.Error(), context.DeadlineExceeded.Error()) {
				w.failures++
				logrus.WithError(err).Errorf("running container %s", id)
				errCounter.WithValues(err.Error()).Inc()

			}
			continue
		}
		// only log times are success so we don't scew the results from failures that go really fast
		ct.WithValues(w.commit).UpdateSince(start)
	}
}

func (w *worker) runContainer(ctx context.Context, id string) (err error) {
	// fix up cgroups path for a default config
	w.spec.Linux.CgroupsPath = filepath.Join("/", "stress", id)
	c, err := w.client.NewContainer(ctx, id,
		containerd.WithNewSnapshot(id, w.image),
		containerd.WithSpec(w.spec, oci.WithUsername("games")),
	)
	if err != nil {
		return err
	}
	defer func() {
		if derr := c.Delete(ctx, containerd.WithSnapshotCleanup); err == nil {
			err = derr
		}
	}()
	task, err := c.NewTask(ctx, cio.NullIO)
	if err != nil {
		return err
	}
	defer func() {
		if _, derr := task.Delete(ctx, containerd.WithProcessKill); err == nil {
			err = derr
		}
	}()
	statusC, err := task.Wait(ctx)
	if err != nil {
		return err
	}
	if err := task.Start(ctx); err != nil {
		return err
	}
	status := <-statusC
	_, _, err = status.Result()
	if err != nil {
		if err == context.DeadlineExceeded || err == context.Canceled {
			return nil
		}
		w.failures++
		errCounter.WithValues(err.Error()).Inc()
	}
	return nil
}

func (w *worker) getID() string {
	return fmt.Sprintf("%d-%d", w.id, w.count)
}