// Package persistence provides the database interface for Flamenco Manager.
package persistence

// SPDX-License-Identifier: GPL-3.0-or-later

import (
	"fmt"
	"math"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"golang.org/x/net/context"

	"git.blender.org/flamenco/internal/manager/job_compilers"
	"git.blender.org/flamenco/internal/uuid"
	"git.blender.org/flamenco/pkg/api"
)

func TestStoreAuthoredJob(t *testing.T) {
	ctx, cancel, db := persistenceTestFixtures(t, 1*time.Second)
	defer cancel()

	job := createTestAuthoredJobWithTasks()
	err := db.StoreAuthoredJob(ctx, job)
	assert.NoError(t, err)

	fetchedJob, err := db.FetchJob(ctx, job.JobID)
	assert.NoError(t, err)
	assert.NotNil(t, fetchedJob)

	// Test contents of fetched job
	assert.Equal(t, job.JobID, fetchedJob.UUID)
	assert.Equal(t, job.Name, fetchedJob.Name)
	assert.Equal(t, job.JobType, fetchedJob.JobType)
	assert.Equal(t, job.Priority, fetchedJob.Priority)
	assert.Equal(t, api.JobStatusUnderConstruction, fetchedJob.Status)
	assert.EqualValues(t, map[string]interface{}(job.Settings), fetchedJob.Settings)
	assert.EqualValues(t, map[string]string(job.Metadata), fetchedJob.Metadata)
	assert.Equal(t, "", fetchedJob.Storage.ShamanCheckoutID)

	// Fetch tasks of job.
	var dbJob Job
	tx := db.gormDB.Where(&Job{UUID: job.JobID}).Find(&dbJob)
	assert.NoError(t, tx.Error)
	var tasks []Task
	tx = db.gormDB.Where("job_id = ?", dbJob.ID).Find(&tasks)
	assert.NoError(t, tx.Error)

	if len(tasks) != 3 {
		t.Fatalf("expected 3 tasks, got %d", len(tasks))
	}

	// TODO: test task contents.
	assert.Equal(t, api.TaskStatusQueued, tasks[0].Status)
	assert.Equal(t, api.TaskStatusQueued, tasks[1].Status)
	assert.Equal(t, api.TaskStatusQueued, tasks[2].Status)
}

func TestStoreAuthoredJobWithShamanCheckoutID(t *testing.T) {
	ctx, cancel, db := persistenceTestFixtures(t, 1*time.Second)
	defer cancel()

	job := createTestAuthoredJobWithTasks()
	job.Storage.ShamanCheckoutID = "één/twee"

	err := db.StoreAuthoredJob(ctx, job)
	require.NoError(t, err)

	fetchedJob, err := db.FetchJob(ctx, job.JobID)
	require.NoError(t, err)
	require.NotNil(t, fetchedJob)

	assert.Equal(t, job.Storage.ShamanCheckoutID, fetchedJob.Storage.ShamanCheckoutID)
}

func TestSaveJobStorageInfo(t *testing.T) {
	// Test that saving job storage info doesn't count as "update".
	// This is necessary for `cmd/shaman-checkout-id-setter` to do its work quietly.
	ctx, cancel, db := persistenceTestFixtures(t, 1*time.Second)
	defer cancel()

	startTime := time.Date(2023, time.February, 7, 15, 0, 0, 0, time.Local)
	mockNow := startTime
	db.gormDB.NowFunc = func() time.Time { return mockNow }

	authoredJob := createTestAuthoredJobWithTasks()
	err := db.StoreAuthoredJob(ctx, authoredJob)
	require.NoError(t, err)

	dbJob, err := db.FetchJob(ctx, authoredJob.JobID)
	require.NoError(t, err)
	assert.NotNil(t, dbJob)
	assert.EqualValues(t, startTime, dbJob.UpdatedAt)

	// Move the clock forward.
	updateTime := time.Date(2023, time.February, 7, 15, 10, 0, 0, time.Local)
	mockNow = updateTime

	// Save the storage info.
	dbJob.Storage.ShamanCheckoutID = "shaman/checkout/id"
	require.NoError(t, db.SaveJobStorageInfo(ctx, dbJob))

	// Check that the UpdatedAt field wasn't touched.
	updatedJob, err := db.FetchJob(ctx, authoredJob.JobID)
	require.NoError(t, err)
	assert.Equal(t, startTime, updatedJob.UpdatedAt, "SaveJobStorageInfo should not touch UpdatedAt")
}

func TestDeleteJob(t *testing.T) {
	ctx, cancel, db := persistenceTestFixtures(t, 1*time.Second)
	defer cancel()

	authJob := createTestAuthoredJobWithTasks()
	persistAuthoredJob(t, ctx, db, authJob)

	// Delete the job.
	err := db.DeleteJob(ctx, authJob.JobID)
	assert.NoError(t, err)

	// Test it cannot be found via the API.
	_, err = db.FetchJob(ctx, authJob.JobID)
	assert.ErrorIs(t, err, ErrJobNotFound, "deleted jobs should not be found")

	// Test that the job is really gone.
	var numJobs int64
	tx := db.gormDB.Model(&Job{}).Count(&numJobs)
	assert.NoError(t, tx.Error)
	assert.Equal(t, int64(0), numJobs, "the job should have been deleted")

	// Test that the tasks are gone too.
	var numTasks int64
	tx = db.gormDB.Model(&Task{}).Count(&numTasks)
	assert.NoError(t, tx.Error)
	assert.Equal(t, int64(0), numTasks, "tasks should have been deleted along with their job")

	// TODO: test that blocklist entries and task dependencies are gone too.
}

func TestRequestJobDeletion(t *testing.T) {
	ctx, close, db, job1, authoredJob1 := jobTasksTestFixtures(t)
	defer close()

	// Create another job, to see it's not touched by deleting the first one.
	authoredJob2 := duplicateJobAndTasks(authoredJob1)
	persistAuthoredJob(t, ctx, db, authoredJob2)

	mockNow := time.Now()
	db.gormDB.NowFunc = func() time.Time { return mockNow }

	err := db.RequestJobDeletion(ctx, job1)
	assert.NoError(t, err)
	assert.True(t, job1.DeleteRequested())
	assert.True(t, job1.DeleteRequestedAt.Valid)
	assert.Equal(t, job1.DeleteRequestedAt.Time, mockNow)

	dbJob1, err := db.FetchJob(ctx, job1.UUID)
	assert.NoError(t, err)
	assert.True(t, job1.DeleteRequested())
	assert.True(t, dbJob1.DeleteRequestedAt.Valid)
	assert.WithinDuration(t, mockNow, dbJob1.DeleteRequestedAt.Time, time.Second)

	// Other jobs shouldn't be touched.
	dbJob2, err := db.FetchJob(ctx, authoredJob2.JobID)
	assert.NoError(t, err)
	assert.False(t, dbJob2.DeleteRequested())
	assert.False(t, dbJob2.DeleteRequestedAt.Valid)
}

func TestFetchJobsDeletionRequested(t *testing.T) {
	ctx, close, db, job1, authoredJob1 := jobTasksTestFixtures(t)
	defer close()

	now := time.Now()
	db.gormDB.NowFunc = func() time.Time { return now }

	authoredJob2 := duplicateJobAndTasks(authoredJob1)
	job2 := persistAuthoredJob(t, ctx, db, authoredJob2)
	authoredJob3 := duplicateJobAndTasks(authoredJob1)
	job3 := persistAuthoredJob(t, ctx, db, authoredJob3)
	authoredJob4 := duplicateJobAndTasks(authoredJob1)
	persistAuthoredJob(t, ctx, db, authoredJob4)

	// Ensure different requests get different timestamps,
	// out of chronological order.
	timestamps := []time.Time{
		// timestamps for 'delete requested at' and 'updated at'
		now.Add(-3 * time.Second), now.Add(-3 * time.Second),
		now.Add(-1 * time.Second), now.Add(-1 * time.Second),
		now.Add(-5 * time.Second), now.Add(-5 * time.Second),
	}
	currentTimestampIndex := 0
	db.gormDB.NowFunc = func() time.Time {
		now := timestamps[currentTimestampIndex]
		currentTimestampIndex++
		return now
	}

	err := db.RequestJobDeletion(ctx, job1)
	assert.NoError(t, err)
	err = db.RequestJobDeletion(ctx, job2)
	assert.NoError(t, err)
	err = db.RequestJobDeletion(ctx, job3)
	assert.NoError(t, err)

	actualUUIDs, err := db.FetchJobsDeletionRequested(ctx)
	assert.NoError(t, err)
	assert.Len(t, actualUUIDs, 3, "3 out of 4 jobs were marked for deletion")

	// Expect UUIDs in chronological order of deletion requests, so that the
	// oldest request is handled first.
	expectUUIDs := []string{job3.UUID, job1.UUID, job2.UUID}
	assert.Equal(t, expectUUIDs, actualUUIDs)
}

func TestJobHasTasksInStatus(t *testing.T) {
	ctx, close, db, job, _ := jobTasksTestFixtures(t)
	defer close()

	hasTasks, err := db.JobHasTasksInStatus(ctx, job, api.TaskStatusQueued)
	assert.NoError(t, err)
	assert.True(t, hasTasks, "expected freshly-created job to have queued tasks")

	hasTasks, err = db.JobHasTasksInStatus(ctx, job, api.TaskStatusActive)
	assert.NoError(t, err)
	assert.False(t, hasTasks, "expected freshly-created job to have no active tasks")
}

func TestCountTasksOfJobInStatus(t *testing.T) {
	ctx, close, db, job, authoredJob := jobTasksTestFixtures(t)
	defer close()

	numQueued, numTotal, err := db.CountTasksOfJobInStatus(ctx, job, api.TaskStatusQueued)
	assert.NoError(t, err)
	assert.Equal(t, 3, numQueued)
	assert.Equal(t, 3, numTotal)

	// Make one task failed.
	task, err := db.FetchTask(ctx, authoredJob.Tasks[0].UUID)
	assert.NoError(t, err)
	task.Status = api.TaskStatusFailed
	assert.NoError(t, db.SaveTask(ctx, task))

	numQueued, numTotal, err = db.CountTasksOfJobInStatus(ctx, job, api.TaskStatusQueued)
	assert.NoError(t, err)
	assert.Equal(t, 2, numQueued)
	assert.Equal(t, 3, numTotal)

	numFailed, numTotal, err := db.CountTasksOfJobInStatus(ctx, job, api.TaskStatusFailed)
	assert.NoError(t, err)
	assert.Equal(t, 1, numFailed)
	assert.Equal(t, 3, numTotal)

	numActive, numTotal, err := db.CountTasksOfJobInStatus(ctx, job, api.TaskStatusActive)
	assert.NoError(t, err)
	assert.Equal(t, 0, numActive)
	assert.Equal(t, 3, numTotal)
}

func TestFetchJobsInStatus(t *testing.T) {
	ctx, close, db, job1, _ := jobTasksTestFixtures(t)
	defer close()

	ajob2 := createTestAuthoredJob("1f08e20b-ce24-41c2-b237-36120bd69fc6")
	ajob3 := createTestAuthoredJob("3ac2dbb4-0c34-410e-ad3b-652e6d7e65a5")
	job2 := persistAuthoredJob(t, ctx, db, ajob2)
	job3 := persistAuthoredJob(t, ctx, db, ajob3)

	// Sanity check
	if !assert.Equal(t, api.JobStatusUnderConstruction, job1.Status) {
		return
	}

	// Query single status
	jobs, err := db.FetchJobsInStatus(ctx, api.JobStatusUnderConstruction)
	assert.NoError(t, err)
	assert.Equal(t, []*Job{job1, job2, job3}, jobs)

	// Query two statuses, where only one matches all jobs.
	jobs, err = db.FetchJobsInStatus(ctx, api.JobStatusCanceled, api.JobStatusUnderConstruction)
	assert.NoError(t, err)
	assert.Equal(t, []*Job{job1, job2, job3}, jobs)

	// Update a job status, query for two of the three used statuses.
	job1.Status = api.JobStatusQueued
	assert.NoError(t, db.SaveJobStatus(ctx, job1))
	job2.Status = api.JobStatusRequeueing
	assert.NoError(t, db.SaveJobStatus(ctx, job2))

	jobs, err = db.FetchJobsInStatus(ctx, api.JobStatusQueued, api.JobStatusUnderConstruction)
	assert.NoError(t, err)
	if assert.Len(t, jobs, 2) {
		assert.Equal(t, job1.UUID, jobs[0].UUID)
		assert.Equal(t, job3.UUID, jobs[1].UUID)
	}
}

func TestFetchTasksOfJobInStatus(t *testing.T) {
	ctx, close, db, job, authoredJob := jobTasksTestFixtures(t)
	defer close()

	allTasks, err := db.FetchTasksOfJob(ctx, job)
	if !assert.NoError(t, err) {
		return
	}
	assert.Equal(t, job, allTasks[0].Job, "FetchTasksOfJob should set job pointer")

	tasks, err := db.FetchTasksOfJobInStatus(ctx, job, api.TaskStatusQueued)
	assert.NoError(t, err)
	assert.Equal(t, allTasks, tasks)
	assert.Equal(t, job, tasks[0].Job, "FetchTasksOfJobInStatus should set job pointer")

	// Make one task failed.
	task, err := db.FetchTask(ctx, authoredJob.Tasks[0].UUID)
	assert.NoError(t, err)
	task.Status = api.TaskStatusFailed
	assert.NoError(t, db.SaveTask(ctx, task))

	tasks, err = db.FetchTasksOfJobInStatus(ctx, job, api.TaskStatusQueued)
	assert.NoError(t, err)
	assert.Equal(t, []*Task{allTasks[1], allTasks[2]}, tasks)

	// Check the failed task. This cannot directly compare to `allTasks[0]`
	// because saving the task above changed some of its fields.
	tasks, err = db.FetchTasksOfJobInStatus(ctx, job, api.TaskStatusFailed)
	assert.NoError(t, err)
	assert.Len(t, tasks, 1)
	assert.Equal(t, allTasks[0].ID, tasks[0].ID)

	tasks, err = db.FetchTasksOfJobInStatus(ctx, job, api.TaskStatusActive)
	assert.NoError(t, err)
	assert.Empty(t, tasks)
}

func TestTaskAssignToWorker(t *testing.T) {
	ctx, close, db, _, authoredJob := jobTasksTestFixtures(t)
	defer close()

	task, err := db.FetchTask(ctx, authoredJob.Tasks[1].UUID)
	assert.NoError(t, err)

	w := createWorker(ctx, t, db)
	assert.NoError(t, db.TaskAssignToWorker(ctx, task, w))

	if task.Worker == nil {
		t.Error("task.Worker == nil")
	} else {
		assert.Equal(t, w, task.Worker)
	}
	if task.WorkerID == nil {
		t.Error("task.WorkerID == nil")
	} else {
		assert.Equal(t, w.ID, *task.WorkerID)
	}
}

func TestFetchTasksOfWorkerInStatus(t *testing.T) {
	ctx, close, db, _, authoredJob := jobTasksTestFixtures(t)
	defer close()

	task, err := db.FetchTask(ctx, authoredJob.Tasks[1].UUID)
	assert.NoError(t, err)

	w := createWorker(ctx, t, db)
	assert.NoError(t, db.TaskAssignToWorker(ctx, task, w))

	tasks, err := db.FetchTasksOfWorkerInStatus(ctx, w, task.Status)
	assert.NoError(t, err)
	assert.Len(t, tasks, 1, "worker should have one task in status %q", task.Status)
	assert.Equal(t, task.ID, tasks[0].ID)
	assert.Equal(t, task.UUID, tasks[0].UUID)

	assert.NotEqual(t, api.TaskStatusCanceled, task.Status)
	tasks, err = db.FetchTasksOfWorkerInStatus(ctx, w, api.TaskStatusCanceled)
	assert.NoError(t, err)
	assert.Empty(t, tasks, "worker should have no task in status %q", w)
}

func TestTaskTouchedByWorker(t *testing.T) {
	ctx, close, db, _, authoredJob := jobTasksTestFixtures(t)
	defer close()

	task, err := db.FetchTask(ctx, authoredJob.Tasks[1].UUID)
	assert.NoError(t, err)
	assert.True(t, task.LastTouchedAt.IsZero())

	now := db.gormDB.NowFunc()
	err = db.TaskTouchedByWorker(ctx, task)
	assert.NoError(t, err)

	// Test the task instance as well as the database entry.
	dbTask, err := db.FetchTask(ctx, task.UUID)
	assert.NoError(t, err)
	assert.WithinDuration(t, now, task.LastTouchedAt, time.Second)
	assert.WithinDuration(t, now, dbTask.LastTouchedAt, time.Second)
}

func TestAddWorkerToTaskFailedList(t *testing.T) {
	ctx, close, db, _, authoredJob := jobTasksTestFixtures(t)
	defer close()

	task, err := db.FetchTask(ctx, authoredJob.Tasks[1].UUID)
	assert.NoError(t, err)

	worker1 := createWorker(ctx, t, db)

	// Create another worker, using the 1st as template:
	newWorker := *worker1
	newWorker.ID = 0
	newWorker.UUID = "89ed2b02-b51b-4cd4-b44a-4a1c8d01db85"
	newWorker.Name = "Worker 2"
	assert.NoError(t, db.SaveWorker(ctx, &newWorker))
	worker2, err := db.FetchWorker(ctx, newWorker.UUID)
	assert.NoError(t, err)

	// First failure should be registered just fine.
	numFailed, err := db.AddWorkerToTaskFailedList(ctx, task, worker1)
	assert.NoError(t, err)
	assert.Equal(t, 1, numFailed)

	// Calling again should be a no-op and not cause any errors.
	numFailed, err = db.AddWorkerToTaskFailedList(ctx, task, worker1)
	assert.NoError(t, err)
	assert.Equal(t, 1, numFailed)

	// Another worker should be able to fail this task as well.
	numFailed, err = db.AddWorkerToTaskFailedList(ctx, task, worker2)
	assert.NoError(t, err)
	assert.Equal(t, 2, numFailed)

	// Deleting the task should also delete the failures.
	assert.NoError(t, db.DeleteJob(ctx, authoredJob.JobID))
	var num int64
	tx := db.gormDB.Model(&TaskFailure{}).Count(&num)
	assert.NoError(t, tx.Error)
	assert.Zero(t, num)
}

func TestClearFailureListOfTask(t *testing.T) {
	ctx, close, db, _, authoredJob := jobTasksTestFixtures(t)
	defer close()

	task1, _ := db.FetchTask(ctx, authoredJob.Tasks[1].UUID)
	task2, _ := db.FetchTask(ctx, authoredJob.Tasks[2].UUID)

	worker1 := createWorker(ctx, t, db)

	// Create another worker, using the 1st as template:
	newWorker := *worker1
	newWorker.ID = 0
	newWorker.UUID = "89ed2b02-b51b-4cd4-b44a-4a1c8d01db85"
	newWorker.Name = "Worker 2"
	assert.NoError(t, db.SaveWorker(ctx, &newWorker))
	worker2, err := db.FetchWorker(ctx, newWorker.UUID)
	assert.NoError(t, err)

	// Store some failures for different tasks.
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1, worker1)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1, worker2)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task2, worker1)

	// Clearing should just update this one task.
	assert.NoError(t, db.ClearFailureListOfTask(ctx, task1))
	var failures = []TaskFailure{}
	tx := db.gormDB.Model(&TaskFailure{}).Scan(&failures)
	assert.NoError(t, tx.Error)
	if assert.Len(t, failures, 1) {
		assert.Equal(t, task2.ID, failures[0].TaskID)
		assert.Equal(t, worker1.ID, failures[0].WorkerID)
	}
}

func TestClearFailureListOfJob(t *testing.T) {
	ctx, close, db, dbJob1, authoredJob1 := jobTasksTestFixtures(t)
	defer close()

	// Construct a cloned version of the job.
	authoredJob2 := duplicateJobAndTasks(authoredJob1)
	persistAuthoredJob(t, ctx, db, authoredJob2)

	task1_1, _ := db.FetchTask(ctx, authoredJob1.Tasks[1].UUID)
	task1_2, _ := db.FetchTask(ctx, authoredJob1.Tasks[2].UUID)
	task2_1, _ := db.FetchTask(ctx, authoredJob2.Tasks[1].UUID)

	worker1 := createWorker(ctx, t, db)
	worker2 := createWorkerFrom(ctx, t, db, *worker1)

	// Store some failures for different tasks and jobs
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_1, worker1)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_1, worker2)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_2, worker1)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task2_1, worker1)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task2_1, worker2)

	// Sanity check: there should be 5 failures registered now.
	assert.Equal(t, 5, countTaskFailures(db))

	// Clearing should be limited to the given job.
	assert.NoError(t, db.ClearFailureListOfJob(ctx, dbJob1))
	var failures = []TaskFailure{}
	tx := db.gormDB.Model(&TaskFailure{}).Scan(&failures)
	assert.NoError(t, tx.Error)
	if assert.Len(t, failures, 2) {
		assert.Equal(t, task2_1.ID, failures[0].TaskID)
		assert.Equal(t, worker1.ID, failures[0].WorkerID)
		assert.Equal(t, task2_1.ID, failures[1].TaskID)
		assert.Equal(t, worker2.ID, failures[1].WorkerID)
	}
}

func TestFetchTaskFailureList(t *testing.T) {
	ctx, close, db, _, authoredJob1 := jobTasksTestFixtures(t)
	defer close()

	// Test with non-existing task.
	fakeTask := Task{Model: Model{ID: 327}}
	failures, err := db.FetchTaskFailureList(ctx, &fakeTask)
	assert.NoError(t, err)
	assert.Empty(t, failures)

	task1_1, _ := db.FetchTask(ctx, authoredJob1.Tasks[1].UUID)
	task1_2, _ := db.FetchTask(ctx, authoredJob1.Tasks[2].UUID)

	// Test without failures.
	failures, err = db.FetchTaskFailureList(ctx, task1_1)
	assert.NoError(t, err)
	assert.Empty(t, failures)

	worker1 := createWorker(ctx, t, db)
	worker2 := createWorkerFrom(ctx, t, db, *worker1)

	// Store some failures for different tasks and jobs
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_1, worker1)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_1, worker2)
	_, _ = db.AddWorkerToTaskFailedList(ctx, task1_2, worker1)

	// Fetch one task's failure list.
	failures, err = db.FetchTaskFailureList(ctx, task1_1)
	assert.NoError(t, err)

	if assert.Len(t, failures, 2) {
		assert.Equal(t, worker1.UUID, failures[0].UUID)
		assert.Equal(t, worker1.Name, failures[0].Name)
		assert.Equal(t, worker1.Address, failures[0].Address)

		assert.Equal(t, worker2.UUID, failures[1].UUID)
		assert.Equal(t, worker2.Name, failures[1].Name)
		assert.Equal(t, worker2.Address, failures[1].Address)
	}
}

func createTestAuthoredJobWithTasks() job_compilers.AuthoredJob {
	task1 := job_compilers.AuthoredTask{
		Name: "render-1-3",
		Type: "blender",
		UUID: "db1f5481-4ef5-4084-8571-8460c547ecaa",
		Commands: []job_compilers.AuthoredCommand{
			{
				Name: "blender-render",
				Parameters: job_compilers.AuthoredCommandParameters{
					"exe":       "{blender}",
					"blendfile": "/path/to/file.blend",
					"args": []interface{}{
						"--render-output", "/path/to/output/######.png",
						"--render-format", "PNG",
						"--render-frame", "1-3",
					},
				}},
		},
	}

	task2 := task1
	task2.Name = "render-4-6"
	task2.UUID = "d75ac779-151b-4bc2-b8f1-d153a9c4ac69"
	task2.Commands[0].Parameters["frames"] = "4-6"

	task3 := job_compilers.AuthoredTask{
		Name: "preview-video",
		Type: "ffmpeg",
		UUID: "4915fb05-72f5-463e-a2f4-7efdb2584a1e",
		Commands: []job_compilers.AuthoredCommand{
			{
				Name: "merge-frames-to-video",
				Parameters: job_compilers.AuthoredCommandParameters{
					"images":       "/path/to/output/######.png",
					"output":       "/path/to/output/preview.mkv",
					"ffmpegParams": "-c:v hevc -crf 31",
				}},
		},
		Dependencies: []*job_compilers.AuthoredTask{&task1, &task2},
	}

	return createTestAuthoredJob("263fd47e-b9f8-4637-b726-fd7e47ecfdae", task1, task2, task3)
}

func createTestAuthoredJob(jobID string, tasks ...job_compilers.AuthoredTask) job_compilers.AuthoredJob {
	job := job_compilers.AuthoredJob{
		JobID:    jobID,
		Name:     "Test job",
		Status:   api.JobStatusUnderConstruction,
		Priority: 50,
		Settings: job_compilers.JobSettings{
			"frames":     "1-6",
			"chunk_size": 3.0, // The roundtrip to JSON in the database can make this a float.
		},
		Metadata: job_compilers.JobMetadata{
			"author":  "Sybren",
			"project": "Sprite Fright",
		},
		Tasks: tasks,
	}

	return job
}

func persistAuthoredJob(t *testing.T, ctx context.Context, db *DB, authoredJob job_compilers.AuthoredJob) *Job {
	err := db.StoreAuthoredJob(ctx, authoredJob)
	if err != nil {
		t.Fatalf("error storing authored job in DB: %v", err)
	}

	dbJob, err := db.FetchJob(ctx, authoredJob.JobID)
	if err != nil {
		t.Fatalf("error fetching job from DB: %v", err)
	}
	if dbJob == nil {
		t.Fatalf("nil job obtained from DB but with no error!")
	}
	return dbJob
}

// duplicateJobAndTasks constructs a copy of the given job and its tasks, ensuring new UUIDs.
// Does NOT copy settings, metadata, or commands. Just for testing with more than one job in the database.
func duplicateJobAndTasks(job job_compilers.AuthoredJob) job_compilers.AuthoredJob {
	// The function call already made a new AuthoredJob copy.
	// This function just needs to make the tasks are duplicated, make UUIDs
	// unique, and ensure that task pointers are pointing to the copy.

	// Duplicate task arrays.
	tasks := job.Tasks
	job.Tasks = []job_compilers.AuthoredTask{}
	job.Tasks = append(job.Tasks, tasks...)

	// Construct a mapping from old UUID to pointer-to-new-task
	taskPtrs := map[string]*job_compilers.AuthoredTask{}
	for idx := range job.Tasks {
		taskPtrs[job.Tasks[idx].UUID] = &job.Tasks[idx]
	}

	// Go over all task dependencies, as those are stored as pointers, and update them.
	for taskIdx := range job.Tasks {
		newDeps := make([]*job_compilers.AuthoredTask, len(job.Tasks[taskIdx].Dependencies))
		for depIdxs, oldTaskPtr := range job.Tasks[taskIdx].Dependencies {
			depUUID := oldTaskPtr.UUID
			newDeps[depIdxs] = taskPtrs[depUUID]
		}
		job.Tasks[taskIdx].Dependencies = newDeps
	}

	// Assign new UUIDs to the job & tasks.
	job.JobID = uuid.New()
	for idx := range job.Tasks {
		job.Tasks[idx].UUID = uuid.New()
	}

	return job
}

func jobTasksTestFixtures(t *testing.T) (context.Context, context.CancelFunc, *DB, *Job, job_compilers.AuthoredJob) {
	ctx, cancel, db := persistenceTestFixtures(t, schedulerTestTimeout)

	authoredJob := createTestAuthoredJobWithTasks()
	dbJob := persistAuthoredJob(t, ctx, db, authoredJob)

	return ctx, cancel, db, dbJob, authoredJob
}

func createWorker(ctx context.Context, t *testing.T, db *DB) *Worker {
	w := Worker{
		UUID:               "f0a123a9-ab05-4ce2-8577-94802cfe74a4",
		Name:               "дрон",
		Address:            "fe80::5054:ff:fede:2ad7",
		Platform:           "linux",
		Software:           "3.0",
		Status:             api.WorkerStatusAwake,
		SupportedTaskTypes: "blender,ffmpeg,file-management",
	}

	err := db.CreateWorker(ctx, &w)
	if err != nil {
		t.Fatalf("error creating worker: %v", err)
	}
	assert.NoError(t, err)

	fetchedWorker, err := db.FetchWorker(ctx, w.UUID)
	if err != nil {
		t.Fatalf("error fetching worker: %v", err)
	}
	if fetchedWorker == nil {
		t.Fatal("fetched worker is nil, but no error returned")
	}

	return fetchedWorker
}

// createWorkerFrom duplicates the given worker, ensuring new UUIDs.
func createWorkerFrom(ctx context.Context, t *testing.T, db *DB, worker Worker) *Worker {
	worker.ID = 0
	worker.UUID = uuid.New()
	worker.Name += " (copy)"

	err := db.SaveWorker(ctx, &worker)
	if !assert.NoError(t, err) {
		t.FailNow()
	}

	dbWorker, err := db.FetchWorker(ctx, worker.UUID)
	if !assert.NoError(t, err) {
		t.FailNow()
	}

	return dbWorker
}

func countTaskFailures(db *DB) int {
	var numFailures int64
	tx := db.gormDB.Model(&TaskFailure{}).Count(&numFailures)
	if tx.Error != nil {
		panic(tx.Error)
	}

	if numFailures > math.MaxInt {
		panic(fmt.Sprintf("too many failures: %v", numFailures))
	}
	return int(numFailures)
}