// Package servicetest provides tests to ensure that implementations of
// platform/task/backend.Store and platform/task/backend.LogReader meet the requirements of platform.TaskService.
//
// Consumers of this package must import query/builtin.
// This package does not import it directly, to avoid requiring it too early.
package servicetest

import (
	"context"
	"fmt"
	"math"
	"runtime"
	"sync"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"github.com/influxdata/platform"
	"github.com/influxdata/platform/snowflake"
	"github.com/influxdata/platform/task"
	"github.com/influxdata/platform/task/backend"
	"github.com/influxdata/platform/task/options"
)

func init() {
	// TODO(mr): remove as part of https://github.com/influxdata/platform/issues/484.
	options.EnableScriptCacheForTest()
}

// BackendComponentFactory is supplied by consumers of the adaptertest package,
// to provide the values required to constitute a PlatformAdapter.
// The provided context.CancelFunc is called after the test,
// and it is the implementer's responsibility to clean up after that is called.
//
// If creating the System fails, the implementer should call t.Fatal.
type BackendComponentFactory func(t *testing.T) (*System, context.CancelFunc)

// TestTaskService should be called by consumers of the servicetest package.
// This will call fn once to create a single platform.TaskService
// used across all subtests in TestTaskService.
func TestTaskService(t *testing.T, fn BackendComponentFactory) {
	sys, cancel := fn(t)
	defer cancel()
	if sys.TaskServiceFunc == nil {
		sys.ts = task.PlatformAdapter(sys.S, sys.LR, sys.Sch)
	} else {
		sys.ts = sys.TaskServiceFunc()
	}

	t.Run("TaskService", func(t *testing.T) {
		// We're running the subtests in parallel, but if we don't use this wrapper,
		// the defer cancel() call above would return before the parallel subtests completed.
		//
		// Running the subtests in parallel might make them slightly faster,
		// but more importantly, it should exercise concurrency to catch data races.

		t.Run("Task CRUD", func(t *testing.T) {
			t.Parallel()
			testTaskCRUD(t, sys)
		})

		t.Run("Task Runs", func(t *testing.T) {
			t.Parallel()
			testTaskRuns(t, sys)
		})

		t.Run("Task Concurrency", func(t *testing.T) {
			if testing.Short() {
				t.Skip("skipping in short mode")
			}
			t.Parallel()
			testTaskConcurrency(t, sys)
		})

		t.Run("Task Meta Updates", func(t *testing.T) {
			t.Parallel()
			testMetaUpdate(t, sys)
		})
	})
}

// System, as in "system under test", encapsulates the required parts of a platform.TaskAdapter
// (the underlying Store, LogReader, and LogWriter) for low-level operations.
type System struct {
	S   backend.Store
	LR  backend.LogReader
	LW  backend.LogWriter
	Sch backend.Scheduler

	// Set this context, to be used in tests, so that any spawned goroutines watching Ctx.Done()
	// will clean up after themselves.
	Ctx context.Context

	// Override for how to create a TaskService.
	// Most callers should leave this nil, in which case the tests will call task.PlatformAdapter.
	TaskServiceFunc func() platform.TaskService

	// Override for accessing credentials for an individual test.
	// Callers can leave this nil and the test will create its own random IDs for each test.
	// However, if the system needs to verify a token, organization, or user,
	// the caller should set this value and return valid IDs and a token.
	// It is safe if this returns the same values every time it is called.
	CredsFunc func() (orgID, userID platform.ID, token string, err error)

	// Underlying task service, initialized inside TestTaskService,
	// either by instantiating a PlatformAdapter directly or by calling TaskServiceFunc.
	ts platform.TaskService
}

func testTaskCRUD(t *testing.T, sys *System) {
	orgID := idGen.ID()
	userID := idGen.ID()

	// Create a task.
	task := &platform.Task{Organization: orgID, Owner: platform.User{ID: userID}, Flux: fmt.Sprintf(scriptFmt, 0)}
	if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
		t.Fatal(err)
	}
	if !task.ID.Valid() {
		t.Fatal("no task ID set")
	}

	// Look up a task the different ways we can.
	// Map of method name to found task.
	found := make(map[string]*platform.Task)

	// Find by ID should return the right task.
	f, err := sys.ts.FindTaskByID(sys.Ctx, task.ID)
	if err != nil {
		t.Fatal(err)
	}
	found["FindTaskByID"] = f

	fs, _, err := sys.ts.FindTasks(sys.Ctx, platform.TaskFilter{Organization: &orgID})
	if err != nil {
		t.Fatal(err)
	}
	if len(fs) != 1 {
		t.Fatalf("expected 1 task returned, got %d: %#v", len(fs), fs)
	}
	found["FindTasks with Organization filter"] = fs[0]

	fs, _, err = sys.ts.FindTasks(sys.Ctx, platform.TaskFilter{User: &userID})
	if err != nil {
		t.Fatal(err)
	}
	if len(fs) != 1 {
		t.Fatalf("expected 1 task returned, got %d: %#v", len(fs), fs)
	}
	found["FindTasks with User filter"] = fs[0]

	for fn, f := range found {
		if f.Organization != orgID {
			t.Fatalf("%s: wrong organization returned; want %s, got %s", fn, orgID.String(), f.Organization.String())
		}
		if f.Owner.ID != userID {
			t.Fatalf("%s: wrong user returned; want %s, got %s", fn, userID.String(), f.Owner.ID.String())
		}

		if f.Name != "task #0" {
			t.Fatalf(`%s: wrong name returned; want "task #0", got %q`, fn, f.Name)
		}
		if f.Cron != "* * * * *" {
			t.Fatalf(`%s: wrong cron returned; want "* * * * *", got %q`, fn, f.Cron)
		}
		if f.Offset != "5s" {
			t.Fatalf(`%s: wrong offset returned; want "5s", got %q`, fn, f.Offset)
		}
		if f.Every != "" {
			t.Fatalf(`%s: wrong every returned; want "", got %q`, fn, f.Every)
		}
		if f.Status != string(backend.DefaultTaskStatus) {
			t.Fatalf(`%s: wrong default task status; want %q, got %q`, fn, backend.DefaultTaskStatus, f.Status)
		}
	}

	// Update task: script only.
	newFlux := fmt.Sprintf(scriptFmt, 99)
	origID := f.ID
	f, err = sys.ts.UpdateTask(sys.Ctx, origID, platform.TaskUpdate{Flux: &newFlux})
	if err != nil {
		t.Fatal(err)
	}

	if origID != f.ID {
		t.Fatalf("task ID unexpectedly changed during update, from %s to %s", origID.String(), f.ID.String())
	}
	if f.Flux != newFlux {
		t.Fatalf("wrong flux from update; want %q, got %q", newFlux, f.Flux)
	}
	if f.Status != string(backend.TaskActive) {
		t.Fatalf("expected task to be created active, got %q", f.Status)
	}

	// Update task: status only.
	newStatus := string(backend.TaskInactive)
	f, err = sys.ts.UpdateTask(sys.Ctx, origID, platform.TaskUpdate{Status: &newStatus})
	if err != nil {
		t.Fatal(err)
	}
	if f.Flux != newFlux {
		t.Fatalf("flux unexpected updated: %s", f.Flux)
	}
	if f.Status != newStatus {
		t.Fatalf("expected task status to be inactive, got %q", f.Status)
	}

	// Update task: reactivate status and update script.
	newStatus = string(backend.TaskActive)
	newFlux = fmt.Sprintf(scriptFmt, 98)
	f, err = sys.ts.UpdateTask(sys.Ctx, origID, platform.TaskUpdate{Flux: &newFlux, Status: &newStatus})
	if err != nil {
		t.Fatal(err)
	}
	if f.Flux != newFlux {
		t.Fatalf("flux unexpected updated: %s", f.Flux)
	}
	if f.Status != newStatus {
		t.Fatalf("expected task status to be inactive, got %q", f.Status)
	}

	// Delete task.
	if err := sys.ts.DeleteTask(sys.Ctx, origID); err != nil {
		t.Fatal(err)
	}

	// Task should not be returned.
	if _, err := sys.ts.FindTaskByID(sys.Ctx, origID); err != backend.ErrTaskNotFound {
		t.Fatalf("expected %v, got %v", backend.ErrTaskNotFound, err)
	}
}

func testMetaUpdate(t *testing.T, sys *System) {
	orgID, userID, _ := creds(t, sys)

	task := &platform.Task{Organization: orgID, Owner: platform.User{ID: userID}, Flux: fmt.Sprintf(scriptFmt, 0)}
	if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
		t.Fatal(err)
	}

	now := time.Now()
	st, err := sys.ts.FindTaskByID(sys.Ctx, task.ID)
	if err != nil {
		t.Fatal(err)
	}

	ti, err := time.Parse(time.RFC3339, st.LatestCompleted)
	if err != nil {
		t.Fatal(err)
	}

	if now.Sub(ti) > 10*time.Second {
		t.Fatalf("latest completed not accurate, expected: ~%s, got %s", now, ti)
	}

	requestedAtUnix := time.Now().Add(5 * time.Minute).UTC().Unix()

	rc, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
	if err != nil {
		t.Fatal(err)
	}

	if err := sys.S.FinishRun(sys.Ctx, task.ID, rc.Created.RunID); err != nil {
		t.Fatal(err)
	}

	st2, err := sys.ts.FindTaskByID(sys.Ctx, task.ID)
	if err != nil {
		t.Fatal(err)
	}

	if st2.LatestCompleted <= st.LatestCompleted {
		t.Fatalf("executed task has not updated latest complete: expected > %s", st2.LatestCompleted)
	}
}

func testTaskRuns(t *testing.T, sys *System) {
	orgID, userID, _ := creds(t, sys)

	t.Run("FindRuns and FindRunByID", func(t *testing.T) {
		t.Parallel()

		// Script is set to run every minute. The platform adapter is currently hardcoded to schedule after "now",
		// which makes timing of runs somewhat difficult.
		task := &platform.Task{Organization: orgID, Owner: platform.User{ID: userID}, Flux: fmt.Sprintf(scriptFmt, 0)}
		if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
			t.Fatal(err)
		}
		st, err := sys.S.FindTaskByID(sys.Ctx, task.ID)
		if err != nil {
			t.Fatal(err)
		}

		requestedAtUnix := time.Now().Add(5 * time.Minute).UTC().Unix() // This should guarantee we can make two runs.

		rc0, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
		if err != nil {
			t.Fatal(err)
		}
		if rc0.Created.TaskID != task.ID {
			t.Fatalf("wrong task ID on created task: got %s, want %s", rc0.Created.TaskID, task.ID)
		}

		startedAt := time.Now().UTC()

		// Update the run state to Started; normally the scheduler would do this.
		rlb0 := backend.RunLogBase{
			Task:            st,
			RunID:           rc0.Created.RunID,
			RunScheduledFor: rc0.Created.Now,
			RequestedAt:     requestedAtUnix,
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb0, startedAt, backend.RunStarted); err != nil {
			t.Fatal(err)
		}

		rc1, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
		if err != nil {
			t.Fatal(err)
		}
		if rc1.Created.TaskID != task.ID {
			t.Fatalf("wrong task ID on created task: got %s, want %s", rc1.Created.TaskID, task.ID)
		}

		// Update the run state to Started; normally the scheduler would do this.
		rlb1 := backend.RunLogBase{
			Task:            st,
			RunID:           rc1.Created.RunID,
			RunScheduledFor: rc1.Created.Now,
			RequestedAt:     requestedAtUnix,
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb1, startedAt, backend.RunStarted); err != nil {
			t.Fatal(err)
		}
		// Mark the second run finished.
		if err := sys.S.FinishRun(sys.Ctx, task.ID, rlb1.RunID); err != nil {
			t.Fatal(err)
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb1, startedAt.Add(time.Second), backend.RunSuccess); err != nil {
			t.Fatal(err)
		}

		runs, _, err := sys.ts.FindRuns(sys.Ctx, platform.RunFilter{Org: &orgID, Task: &task.ID})
		if err != nil {
			t.Fatal(err)
		}
		if len(runs) != 2 {
			t.Fatalf("expected 2 runs, got %v", runs)
		}
		if runs[0].ID != rc0.Created.RunID {
			t.Fatalf("retrieved wrong run ID; want %s, got %s", rc0.Created.RunID, runs[0].ID)
		}
		if exp := startedAt.Format(time.RFC3339Nano); runs[0].StartedAt != exp {
			t.Fatalf("unexpectedStartedAt; want %s, got %s", exp, runs[0].StartedAt)
		}
		if runs[0].Status != backend.RunStarted.String() {
			t.Fatalf("unexpected run status; want %s, got %s", backend.RunStarted.String(), runs[0].Status)
		}
		if runs[0].FinishedAt != "" {
			t.Fatalf("expected empty FinishedAt, got %q", runs[0].FinishedAt)
		}

		if runs[1].ID != rc1.Created.RunID {
			t.Fatalf("retrieved wrong run ID; want %s, got %s", rc1.Created.RunID, runs[1].ID)
		}
		if runs[1].StartedAt != runs[0].StartedAt {
			t.Fatalf("unexpected StartedAt; want %s, got %s", runs[0].StartedAt, runs[1].StartedAt)
		}
		if runs[1].Status != backend.RunSuccess.String() {
			t.Fatalf("unexpected run status; want %s, got %s", backend.RunSuccess.String(), runs[0].Status)
		}
		if exp := startedAt.Add(time.Second).Format(time.RFC3339Nano); runs[1].FinishedAt != exp {
			t.Fatalf("unexpected FinishedAt; want %s, got %s", exp, runs[1].FinishedAt)
		}

		// look for a run that doesn't exit.
		_, err = sys.ts.FindRunByID(sys.Ctx, task.ID, platform.ID(math.MaxUint64))
		if err == nil {
			t.Fatalf("expected %s but got %s instead", backend.ErrRunNotFound, err)
		}

		// look for a taskID that doesn't exist.
		_, err = sys.ts.FindRunByID(sys.Ctx, platform.ID(math.MaxUint64), runs[0].ID)
		if err == nil {
			t.Fatalf("expected %s but got %s instead", backend.ErrRunNotFound, err)
		}

		foundRun0, err := sys.ts.FindRunByID(sys.Ctx, task.ID, runs[0].ID)
		if err != nil {
			t.Fatal(err)
		}

		if diff := cmp.Diff(foundRun0, runs[0]); diff != "" {
			t.Fatalf("difference between listed run and found run: %s", diff)
		}

		foundRun1, err := sys.ts.FindRunByID(sys.Ctx, task.ID, runs[1].ID)
		if err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(foundRun1, runs[1]); diff != "" {
			t.Fatalf("difference between listed run and found run: %s", diff)
		}
	})

	t.Run("RetryRun", func(t *testing.T) {
		t.Parallel()

		// Script is set to run every minute. The platform adapter is currently hardcoded to schedule after "now",
		// which makes timing of runs somewhat difficult.
		task := &platform.Task{Organization: orgID, Owner: platform.User{ID: userID}, Flux: fmt.Sprintf(scriptFmt, 0)}
		if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
			t.Fatal(err)
		}
		st, err := sys.S.FindTaskByID(sys.Ctx, task.ID)
		if err != nil {
			t.Fatal(err)
		}

		// Non-existent ID should return the right error.
		_, err = sys.ts.RetryRun(sys.Ctx, task.ID, platform.ID(math.MaxUint64))
		if err != backend.ErrRunNotFound {
			t.Errorf("expected retrying run that doesn't exist to return %v, got %v", backend.ErrRunNotFound, err)
		}

		requestedAtUnix := time.Now().Add(5 * time.Minute).UTC().Unix() // This should guarantee we can make a run.

		rc, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
		if err != nil {
			t.Fatal(err)
		}
		if rc.Created.TaskID != task.ID {
			t.Fatalf("wrong task ID on created task: got %s, want %s", rc.Created.TaskID, task.ID)
		}

		startedAt := time.Now().UTC()

		// Update the run state to Started then Failed; normally the scheduler would do this.
		rlb := backend.RunLogBase{
			Task:            st,
			RunID:           rc.Created.RunID,
			RunScheduledFor: rc.Created.Now,
			RequestedAt:     requestedAtUnix,
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb, startedAt, backend.RunStarted); err != nil {
			t.Fatal(err)
		}
		if err := sys.S.FinishRun(sys.Ctx, task.ID, rlb.RunID); err != nil {
			t.Fatal(err)
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb, startedAt.Add(time.Second), backend.RunFail); err != nil {
			t.Fatal(err)
		}

		// Now retry the run.
		m, err := sys.ts.RetryRun(sys.Ctx, task.ID, rlb.RunID)
		if err != nil {
			t.Fatal(err)
		}
		if m.TaskID != task.ID {
			t.Fatalf("wrong task ID on retried run: got %s, want %s", m.TaskID, task.ID)
		}
		if m.Status != "scheduled" {
			t.Fatal("expected new retried run to have status of scheduled")
		}
		nowTime, err := time.Parse(time.RFC3339, m.ScheduledFor)
		if err != nil {
			t.Fatalf("expected scheduledFor to be a parsable time in RFC3339, but got %s", m.ScheduledFor)
		}
		if nowTime.Unix() != rc.Created.Now {
			t.Fatalf("wrong scheduledFor on task: got %s, want %s", m.ScheduledFor, time.Unix(rc.Created.Now, 0).Format(time.RFC3339))
		}

		// Ensure the retry is added on the store task meta.
		meta, err := sys.S.FindTaskMetaByID(sys.Ctx, task.ID)
		if err != nil {
			t.Fatal(err)
		}

		found := false
		for _, mr := range meta.ManualRuns {
			if mr.Start == mr.End && mr.Start == rc.Created.Now {
				found = true
				break
			}
		}
		if !found {
			t.Fatalf("didn't find matching manual run after successful RetryRun call; got: %v", meta.ManualRuns)
		}

		exp := backend.RetryAlreadyQueuedError{Start: rc.Created.Now, End: rc.Created.Now}

		// Retrying a run which has been queued but not started, should be rejected.
		if _, err = sys.ts.RetryRun(sys.Ctx, task.ID, rlb.RunID); err != exp {
			t.Fatalf("subsequent retry should have been rejected with %v; got %v", exp, err)
		}
	})

	t.Run("FindLogs", func(t *testing.T) {
		t.Parallel()

		task := &platform.Task{Organization: orgID, Owner: platform.User{ID: userID}, Flux: fmt.Sprintf(scriptFmt, 0)}
		if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
			t.Fatal(err)
		}
		st, err := sys.S.FindTaskByID(sys.Ctx, task.ID)
		if err != nil {
			t.Fatal(err)
		}

		requestedAtUnix := time.Now().Add(5 * time.Minute).UTC().Unix() // This should guarantee we can make a run.

		// Create two runs.
		rc1, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
		if err != nil {
			t.Fatal(err)
		}
		rlb1 := backend.RunLogBase{
			Task:            st,
			RunID:           rc1.Created.RunID,
			RunScheduledFor: rc1.Created.Now,
			RequestedAt:     requestedAtUnix,
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb1, time.Now(), backend.RunStarted); err != nil {
			t.Fatal(err)
		}

		rc2, err := sys.S.CreateNextRun(sys.Ctx, task.ID, requestedAtUnix)
		if err != nil {
			t.Fatal(err)
		}
		rlb2 := backend.RunLogBase{
			Task:            st,
			RunID:           rc2.Created.RunID,
			RunScheduledFor: rc2.Created.Now,
			RequestedAt:     requestedAtUnix,
		}
		if err := sys.LW.UpdateRunState(sys.Ctx, rlb2, time.Now(), backend.RunStarted); err != nil {
			t.Fatal(err)
		}

		// Add a log for the first run.
		log1Time := time.Now().UTC()
		if err := sys.LW.AddRunLog(sys.Ctx, rlb1, log1Time, "entry 1"); err != nil {
			t.Fatal(err)
		}

		// Ensure it is returned when filtering logs by run ID.
		logs, err := sys.LR.ListLogs(sys.Ctx, platform.LogFilter{
			Org:  &orgID,
			Task: &task.ID,
			Run:  &rc1.Created.RunID,
		})
		if err != nil {
			t.Fatal(err)
		}

		expLine1 := platform.Log(log1Time.Format(time.RFC3339Nano) + ": entry 1")
		exp := []platform.Log{expLine1}
		if diff := cmp.Diff(logs, exp); diff != "" {
			t.Fatalf("unexpected log: -got/+want: %s", diff)
		}

		// Add a log for the second run.
		log2Time := time.Now().UTC()
		if err := sys.LW.AddRunLog(sys.Ctx, rlb2, log2Time, "entry 2"); err != nil {
			t.Fatal(err)
		}

		// Ensure both returned when filtering logs by task ID.
		logs, err = sys.LR.ListLogs(sys.Ctx, platform.LogFilter{
			Org:  &orgID,
			Task: &task.ID,
		})
		if err != nil {
			t.Fatal(err)
		}

		expLine2 := platform.Log(log2Time.Format(time.RFC3339Nano) + ": entry 2")
		exp = []platform.Log{expLine1, expLine2}
		if diff := cmp.Diff(logs, exp); diff != "" {
			t.Fatalf("unexpected log: -got/+want: %s", diff)
		}
	})
}

func testTaskConcurrency(t *testing.T, sys *System) {
	orgID, userID, _ := creds(t, sys)

	const numTasks = 450 // Arbitrarily chosen to get a reasonable count of concurrent creates and deletes.
	taskCh := make(chan *platform.Task, numTasks)

	// Since this test is run in parallel with other tests,
	// we need to keep a whitelist of IDs that are okay to delete.
	// This only matters when the creds function returns an identical user/org from another test.
	var idMu sync.Mutex
	taskIDs := make(map[platform.ID]struct{})

	var createWg sync.WaitGroup
	for i := 0; i < runtime.GOMAXPROCS(0); i++ {
		createWg.Add(1)
		go func() {
			defer createWg.Done()
			for task := range taskCh {
				if err := sys.ts.CreateTask(sys.Ctx, task); err != nil {
					t.Errorf("error creating task: %v", err)
				}
				idMu.Lock()
				taskIDs[task.ID] = struct{}{}
				idMu.Unlock()
			}
		}()
	}

	// Signal for non-creator goroutines to stop.
	quitCh := make(chan struct{})
	go func() {
		createWg.Wait()
		close(quitCh)
	}()

	var extraWg sync.WaitGroup
	// Get all the tasks, and delete the first one we find.
	extraWg.Add(1)
	go func() {
		defer extraWg.Done()

		deleted := 0
		defer func() {
			t.Logf("Concurrently deleted %d tasks", deleted)
		}()
		for {
			// Check if we need to quit.
			select {
			case <-quitCh:
				return
			default:
			}

			// Get all the tasks.
			tasks, _, err := sys.ts.FindTasks(sys.Ctx, platform.TaskFilter{Organization: &orgID})
			if err != nil {
				t.Errorf("error finding tasks: %v", err)
				return
			}
			if len(tasks) == 0 {
				continue
			}

			// Check again if we need to quit.
			select {
			case <-quitCh:
				return
			default:
			}

			for _, tsk := range tasks {
				// Was the retrieved task an ID we're allowed to delete?
				idMu.Lock()
				_, ok := taskIDs[tsk.ID]
				idMu.Unlock()
				if !ok {
					continue
				}

				// Task was in whitelist. Delete it from the TaskService.
				// We could remove it from the taskIDs map, but this test is short-lived enough
				// that clearing out the map isn't really worth taking the lock again.
				if err := sys.ts.DeleteTask(sys.Ctx, tsk.ID); err != nil {
					t.Errorf("error deleting task: %v", err)
					return
				}
				deleted++

				// Wait just a tiny bit.
				time.Sleep(time.Millisecond)
				break
			}
		}
	}()

	extraWg.Add(1)
	go func() {
		defer extraWg.Done()

		runsCreated := 0
		defer func() {
			t.Logf("Concurrently created %d runs", runsCreated)
		}()
		for {
			// Check if we need to quit.
			select {
			case <-quitCh:
				return
			default:
			}

			// Get all the tasks.
			tasks, _, err := sys.ts.FindTasks(sys.Ctx, platform.TaskFilter{Organization: &orgID})
			if err != nil {
				t.Errorf("error finding tasks: %v", err)
				return
			}
			if len(tasks) == 0 {
				continue
			}

			// Check again if we need to quit.
			select {
			case <-quitCh:
				return
			default:
			}

			// Create a run for the last task we found.
			// The script should run every minute, so use max now.
			tid := tasks[len(tasks)-1].ID
			if _, err := sys.S.CreateNextRun(sys.Ctx, tid, math.MaxInt64); err != nil {
				// This may have errored due to the task being deleted. Check if the task still exists.
				if _, err2 := sys.S.FindTaskByID(sys.Ctx, tid); err2 == backend.ErrTaskNotFound {
					// It was deleted. Just continue.
					continue
				}
				// Otherwise, we were able to find the task, so something went wrong here.
				t.Errorf("error creating next run: %v", err)
				return
			}
			runsCreated++

			// Wait just a tiny bit.
			time.Sleep(time.Millisecond)
		}
	}()

	// Start adding tasks.
	for i := 0; i < numTasks; i++ {
		taskCh <- &platform.Task{
			Organization: orgID,
			Owner:        platform.User{ID: userID},
			Flux:         fmt.Sprintf(scriptFmt, i),
		}
	}

	// Done adding. Wait for cleanup.
	close(taskCh)
	createWg.Wait()
	extraWg.Wait()
}

func creds(t *testing.T, s *System) (orgID, userID platform.ID, token string) {
	t.Helper()

	if s.CredsFunc == nil {
		return idGen.ID(), idGen.ID(), idGen.ID().String()
	}

	o, u, tok, err := s.CredsFunc()
	if err != nil {
		t.Fatal(err)
	}
	return o, u, tok
}

const scriptFmt = `option task = {
	name: "task #%d",
	cron: "* * * * *",
	offset: 5s,
	concurrency: 100,
}
from(bucket:"b") |> toHTTP(url:"http://example.com")`

var idGen = snowflake.NewIDGenerator()