package swarming_metrics

/*
	Package swarming_metrics generates metrics from Swarming data.
*/

import (
	"bytes"
	"context"
	"encoding/gob"
	"fmt"
	"strconv"
	"time"

	swarming_api "go.chromium.org/luci/common/api/swarming/swarming/v1"
	"go.skia.org/infra/go/common"
	"go.skia.org/infra/go/metrics2"
	"go.skia.org/infra/go/metrics2/events"
	"go.skia.org/infra/go/sklog"
	"go.skia.org/infra/go/swarming"
	"go.skia.org/infra/go/taskname"
	"go.skia.org/infra/go/util"
	"go.skia.org/infra/perf/go/ingest/format"
	"go.skia.org/infra/perf/go/perfclient"
	"golang.org/x/oauth2"
)

const (
	MEASUREMENT_SWARMING_TASKS = "swarming_task_events"
	STREAM_SWARMING_TASKS_TMPL = "swarming-tasks-%s"
)

var (
	includeDimensions = util.NewStringSet([]string{
		"os",
		"model",
		"cpu",
		"gpu",
		"device_type",
		"device_os",
	})

	errNoValue = fmt.Errorf("no value")
)

func streamForPool(pool string) string {
	return fmt.Sprintf(STREAM_SWARMING_TASKS_TMPL, pool)
}

// loadSwarmingTasks loads the Swarming tasks which were created within the
// given time range, plus any tasks we're explicitly told to load. Inserts all
// completed tasks into the EventDB and perf. Then, it returns any unfinished
// tasks so that they can be revisited later.
func loadSwarmingTasks(s swarming.ApiClient, pool string, edb events.EventDB, perfClient perfclient.ClientInterface, tnp taskname.TaskNameParser, lastLoad, now time.Time, revisit []string) ([]string, error) {
	sklog.Info("Loading swarming tasks.")

	tasks, err := s.ListTasks(lastLoad, now, []string{fmt.Sprintf("pool:%s", pool)}, "")
	if err != nil {
		return nil, err
	}
	for _, id := range revisit {
		task, err := s.GetTaskMetadata(id)
		if err != nil {
			return nil, err
		}
		tasks = append(tasks, task)
	}
	revisitLater := []string{}
	loaded := 0
	for _, t := range tasks {
		// Only include finished tasks. This includes completed success
		// and completed failures.
		if t.TaskResult.State != swarming.TASK_STATE_COMPLETED {
			// Check back on Pending/Running tasks
			if t.TaskResult.State == swarming.TASK_STATE_PENDING ||
				t.TaskResult.State == swarming.TASK_STATE_RUNNING {
				revisitLater = append(revisitLater, t.TaskId)
			}
			continue
		}

		// Don't send deduped tasks to Perf, since that would double-
		// count the deduped-from task.
		if t.TaskResult.DedupedFrom == "" {
			if err := reportDurationToPerf(t, perfClient, now, tnp); err != nil {
				sklog.Errorf("Error reporting task duration to perf: %s", err)
				revisitLater = append(revisitLater, t.TaskId)
			}
		}

		var buf bytes.Buffer
		if err := gob.NewEncoder(&buf).Encode(t); err != nil {
			return nil, fmt.Errorf("Failed to serialize Swarming task: %s", err)
		}
		created, err := swarming.Created(t)
		if err != nil {
			return nil, fmt.Errorf("Failed to parse Created time: %s", err)
		}
		if err := edb.Insert(&events.Event{
			Stream:    streamForPool(pool),
			Timestamp: created,
			Data:      buf.Bytes(),
		}); err != nil {
			return nil, fmt.Errorf("Failed to insert event: %s", err)
		}
		loaded++
	}
	sklog.Infof("... loaded %d swarming tasks.", loaded)
	return revisitLater, nil
}

func reportDurationToPerf(t *swarming_api.SwarmingRpcsTaskRequestMetadata, perfClient perfclient.ClientInterface, now time.Time, tnp taskname.TaskNameParser) error {

	// Pull taskName from tags, because the task name could be changed (e.g. retries)
	// and that would make ParseTaskName not happy.
	tags, err := swarming.ParseTags(t.Request.Tags)
	if err != nil {
		sklog.Errorf("Can not parse tags for task %q: %s", t.TaskId, err)
		return nil
	}
	getTag := func(key string) string {
		vals := tags[key]
		if len(vals) > 0 {
			return vals[0]
		}
		return ""
	}
	taskName := getTag("sk_name")
	taskRevision := getTag("sk_revision")
	taskIssue := getTag("sk_issue")
	taskPatchSet := getTag("sk_patchset")
	taskPatchStorage := ""
	if getTag("sk_issue_server") == "https://skia-review.googlesource.com" {
		taskPatchStorage = "gerrit"
	}
	repo := getTag("sk_repo")
	if repo != common.REPO_SKIA {
		// The schema parser only supports the Skia repo, not, for example, the Infra repo
		// which would also show up here.
		return nil
	}
	if taskName == "" || taskRevision == "" {
		sklog.Errorf("Task %q has sk_repo tag but not sk_name and sk_revision.", t.TaskId)
		// If these tags are missing, there is no useful data.
		return nil
	}
	parsed, err := tnp.ParseTaskName(taskName)
	if err != nil {
		sklog.Errorf("Could not parse task name of %s: %s", taskName, err)
		// return nil here instead of error because the calling code will attempt to
		// retry errors. Presumably parsing the task name would always fail.
		return nil
	}
	if t.TaskResult.InternalFailure {
		// Skip bots that died because of infra reasons (e.g. bot lost power)
		return nil
	}
	parsed["failure"] = strconv.FormatBool(t.TaskResult.Failure)

	casOverhead := float64(0.0)
	if t.TaskResult.PerformanceStats.IsolatedDownload != nil {
		casOverhead += t.TaskResult.PerformanceStats.IsolatedDownload.Duration
	}
	if t.TaskResult.PerformanceStats.IsolatedUpload != nil {
		casOverhead += t.TaskResult.PerformanceStats.IsolatedUpload.Duration
	}
	durations := format.BenchResults{
		"task_duration": {
			"task_step_s":    t.TaskResult.Duration,
			"all_overhead_s": t.TaskResult.PerformanceStats.BotOverhead,
			"cas_overhead_s": casOverhead,
			"total_s":        t.TaskResult.Duration + t.TaskResult.PerformanceStats.BotOverhead,
		},
	}
	toReport := format.BenchData{
		Hash:     taskRevision,
		Issue:    taskIssue,
		PatchSet: taskPatchSet,
		Source:   "datahopper",
		Key:      parsed,
		Results: map[string]format.BenchResults{
			taskName: durations,
		},
		PatchStorage: taskPatchStorage,
	}

	sklog.Debugf("Reporting that %s had these durations: %#v ms", taskName, durations)

	if err := perfClient.PushToPerf(now, taskName, "task_duration", toReport); err != nil {
		return fmt.Errorf("Ran into error while pushing task duration to perf: %s", err)
	}
	return nil

}

// decodeTasks decodes a slice of events.Event into a slice of Swarming task
// metadata.
func decodeTasks(ev []*events.Event) ([]*swarming_api.SwarmingRpcsTaskRequestMetadata, error) {
	rv := make([]*swarming_api.SwarmingRpcsTaskRequestMetadata, 0, len(ev))
	for _, e := range ev {
		var t swarming_api.SwarmingRpcsTaskRequestMetadata
		if err := gob.NewDecoder(bytes.NewBuffer(e.Data)).Decode(&t); err != nil {
			return nil, err
		}
		rv = append(rv, &t)
	}
	return rv, nil
}

// addMetric adds a dynamic metric to the given event stream with the given
// metric name. It aggregates the data points returned by the given helper
// function and computes the mean for each tag set. This simplifies the addition
// of metrics in StartSwarmingTaskMetrics.
func addMetric(s *events.EventStream, metric, pool string, period time.Duration, fn func(*swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error)) error {
	tags := map[string]string{
		"metric": metric,
		"pool":   pool,
	}
	f := func(ev []*events.Event) ([]map[string]string, []float64, error) {
		sklog.Infof("Computing value(s) for metric %q", metric)
		if len(ev) == 0 {
			return []map[string]string{}, []float64{}, nil
		}
		tasks, err := decodeTasks(ev)
		if err != nil {
			return nil, nil, err
		}
		tagSets := map[string]map[string]string{}
		totals := map[string]int64{}
		counts := map[string]int{}
		for _, t := range tasks {
			// Don't include de-duped tasks, as they'll skew the metrics down.
			if t.TaskResult.DedupedFrom != "" {
				continue
			}

			val, err := fn(t)
			if err == errNoValue {
				continue
			}
			if err != nil {
				return nil, nil, err
			}
			tags := map[string]string{
				"task_name": t.TaskResult.Name,
			}
			for d := range includeDimensions {
				tags[d] = ""
			}
			for _, dim := range swarming.GetTaskRequestProperties(t).Dimensions {
				if _, ok := includeDimensions[dim.Key]; ok {
					tags[dim.Key] = dim.Value
				}
			}
			key, err := util.MD5Sum(tags)
			if err != nil {
				return nil, nil, err
			}
			tagSets[key] = tags
			totals[key] += val
			counts[key]++
		}
		tagSetsList := make([]map[string]string, 0, len(tagSets))
		vals := make([]float64, 0, len(tagSets))
		for key, tags := range tagSets {
			tagSetsList = append(tagSetsList, tags)
			vals = append(vals, float64(totals[key])/float64(counts[key]))
		}
		return tagSetsList, vals, nil
	}
	return s.DynamicMetric(tags, period, f)
}

// taskDuration returns the duration of the task in milliseconds.
func taskDuration(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	completedTime, err := swarming.Completed(t)
	if err != nil {
		return 0.0, err
	}
	startTime, err := swarming.Started(t)
	if err != nil {
		return 0.0, err
	}
	return int64(completedTime.Sub(startTime).Seconds() * float64(1000.0)), nil
}

// taskPendingTime returns the pending time of the task in milliseconds.
func taskPendingTime(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	createdTime, err := swarming.Created(t)
	if err != nil {
		return 0.0, err
	}
	startTime, err := swarming.Started(t)
	if err != nil {
		return 0.0, err
	}
	return int64(startTime.Sub(createdTime).Seconds() * float64(1000.0)), nil
}

// taskOverheadBot returns the bot overhead for the task in milliseconds.
func taskOverheadBot(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	if t.TaskResult.PerformanceStats == nil {
		return 0, errNoValue
	} else {
		return int64(t.TaskResult.PerformanceStats.BotOverhead * float64(1000.0)), nil
	}
}

// taskOverheadUpload returns the upload overhead for the task in milliseconds.
func taskOverheadUpload(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	if t.TaskResult.PerformanceStats == nil {
		return 0, errNoValue
	} else if t.TaskResult.PerformanceStats.IsolatedUpload == nil {
		return 0, errNoValue
	} else {
		return int64(t.TaskResult.PerformanceStats.IsolatedUpload.Duration * float64(1000.0)), nil
	}
}

// taskOverheadDownload returns the download overhead for the task in milliseconds.
func taskOverheadDownload(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	if t.TaskResult.PerformanceStats == nil {
		return 0, errNoValue
	} else if t.TaskResult.PerformanceStats.IsolatedDownload == nil {
		return 0, errNoValue
	} else {
		return int64(t.TaskResult.PerformanceStats.IsolatedDownload.Duration * float64(1000.0)), nil
	}
}

// casCacheMissDownload returns the download overhead for the task in milliseconds.
func casCacheMissDownload(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	if t.TaskResult.PerformanceStats == nil {
		return 0, errNoValue
	} else if t.TaskResult.PerformanceStats.IsolatedDownload == nil {
		return 0, errNoValue
	} else {
		return int64(t.TaskResult.PerformanceStats.IsolatedDownload.TotalBytesItemsCold), nil
	}
}

// casCacheMissUpload returns the download overhead for the task in milliseconds.
func casCacheMissUpload(t *swarming_api.SwarmingRpcsTaskRequestMetadata) (int64, error) {
	if t.TaskResult.PerformanceStats == nil {
		return 0, errNoValue
	} else if t.TaskResult.PerformanceStats.IsolatedUpload == nil {
		return 0, errNoValue
	} else {
		return int64(t.TaskResult.PerformanceStats.IsolatedUpload.TotalBytesItemsCold), nil
	}
}

// dedupeMetrics generates metrics for deduplicated tasks.
func dedupeMetrics(ev []*events.Event) ([]map[string]string, []float64, error) {
	sklog.Info("Computing value(s) for dedupeMetrics")
	if len(ev) == 0 {
		return []map[string]string{}, []float64{}, nil
	}
	tasks, err := decodeTasks(ev)
	if err != nil {
		return nil, nil, err
	}

	// Total time taken by all tasks. Deduped tasks are not counted.
	totalTime := int64(0)
	// Total time taken by idempotent tasks. Deduped tasks are not counted.
	idempotentTime := int64(0)
	// Total time taken by original tasks referenced by deduped tasks.
	dedupedTime := int64(0)
	// Total number of tasks which ran. Deduped tasks are not counted.
	totalCount := int64(0)
	// Total number of idempotent tasks which ran. Deduped tasks are not counted.
	idempotentCount := int64(0)
	// Total number of deduped tasks.
	dedupedCount := int64(0)
	for _, t := range tasks {
		completedTime, err := swarming.Completed(t)
		if err != nil {
			return nil, nil, err
		}
		startTime, err := swarming.Started(t)
		if err != nil {
			return nil, nil, err
		}
		durationMs := int64(completedTime.Sub(startTime).Seconds() * float64(1000.0))
		if t.TaskResult.DedupedFrom == "" {
			totalTime += durationMs
			totalCount++
			if swarming.GetTaskRequestProperties(t).Idempotent {
				idempotentTime += durationMs
				idempotentCount++
			}
		} else {
			dedupedTime += durationMs
			dedupedCount++
		}
	}
	tagSets := []map[string]string{
		{"metric": "total_count"},
		{"metric": "total_time"},
		{"metric": "idempotent_count"},
		{"metric": "idempotent_time"},
		{"metric": "deduped_count"},
		{"metric": "deduped_time"},
	}
	// Because we're sharing a measurement with the other metrics in this
	// file, we have to provide exactly the same set of tags, even if
	// they're left empty.
	for _, tagSet := range tagSets {
		tagSet["task_name"] = ""
		for k := range includeDimensions {
			tagSet[k] = ""
		}
	}
	return tagSets, []float64{
		float64(totalCount),
		float64(totalTime),
		float64(idempotentCount),
		float64(idempotentTime),
		float64(dedupedCount),
		float64(dedupedTime),
	}, nil
}

// setupMetrics creates the event metrics for Swarming tasks.
func setupMetrics(ctx context.Context, btProject, btInstance, pool string, ts oauth2.TokenSource) (events.EventDB, *events.EventMetrics, error) {
	edb, err := events.NewBTEventDB(ctx, btProject, btInstance, ts)
	if err != nil {
		return nil, nil, err
	}
	em, err := events.NewEventMetrics(edb, MEASUREMENT_SWARMING_TASKS)
	if err != nil {
		return nil, nil, err
	}
	s := em.GetEventStream(streamForPool(pool))

	// Add metrics.
	for _, period := range []time.Duration{24 * time.Hour, 7 * 24 * time.Hour} {
		// Duration.
		if err := addMetric(s, "duration", pool, period, taskDuration); err != nil {
			return nil, nil, err
		}

		// Pending time.
		if err := addMetric(s, "pending-time", pool, period, taskPendingTime); err != nil {
			return nil, nil, err
		}

		// Overhead (bot).
		if err := addMetric(s, "overhead-bot", pool, period, taskOverheadBot); err != nil {
			return nil, nil, err
		}

		// Overhead (upload).
		if err := addMetric(s, "overhead-upload", pool, period, taskOverheadUpload); err != nil {
			return nil, nil, err
		}

		// Overhead (download).
		if err := addMetric(s, "overhead-download", pool, period, taskOverheadDownload); err != nil {
			return nil, nil, err
		}

		// CAS Cache Miss (download).
		if err := addMetric(s, "cas-cache-miss-download", pool, period, casCacheMissDownload); err != nil {
			return nil, nil, err
		}

		// CAS Cache Miss (upload).
		if err := addMetric(s, "cas-cache-miss-upload", pool, period, casCacheMissUpload); err != nil {
			return nil, nil, err
		}

		// Deduplicated tasks (duration and count).
		if err := s.DynamicMetric(map[string]string{
			"pool": pool,
		}, period, dedupeMetrics); err != nil {
			return nil, nil, err
		}
	}
	return edb, em, nil
}

// startLoadingTasks initiates the goroutine which periodically loads Swarming
// tasks into the EventDB.
func startLoadingTasks(swarm swarming.ApiClient, pool string, ctx context.Context, edb events.EventDB, perfClient perfclient.ClientInterface, tnp taskname.TaskNameParser) {
	// Start collecting the metrics.
	lv := metrics2.NewLiveness("last_successful_swarming_task_metrics", map[string]string{
		"pool": pool,
	})
	lastLoad := time.Now().Add(-2 * time.Minute)
	revisitTasks := []string{}
	go util.RepeatCtx(ctx, 10*time.Minute, func(ctx context.Context) {
		now := time.Now()
		revisit, err := loadSwarmingTasks(swarm, pool, edb, perfClient, tnp, lastLoad, now, revisitTasks)
		if err != nil {
			sklog.Errorf("Failed to load swarming tasks into metrics: %s", err)
		} else {
			lastLoad = now
			revisitTasks = revisit
			lv.Reset()
		}
	})
}

// StartSwarmingTaskMetrics initiates a goroutine which loads Swarming task
// results and computes metrics.
func StartSwarmingTaskMetrics(ctx context.Context, btProject, btInstance string, swarm swarming.ApiClient, pools []string, perfClient perfclient.ClientInterface, tnp taskname.TaskNameParser, ts oauth2.TokenSource) error {
	for _, pool := range pools {
		edb, em, err := setupMetrics(ctx, btProject, btInstance, pool, ts)
		if err != nil {
			return err
		}
		em.Start(ctx)
		startLoadingTasks(swarm, pool, ctx, edb, perfClient, tnp)
	}
	return nil
}