// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package actions

import (
	"context"
	"errors"
	"fmt"
	"slices"

	actions_model "gitea.dev/models/actions"
	"gitea.dev/models/db"
	"gitea.dev/modules/container"
	"gitea.dev/modules/graceful"
	"gitea.dev/modules/log"
	"gitea.dev/modules/queue"
	"gitea.dev/modules/setting"
	"gitea.dev/modules/timeutil"

	"xorm.io/builder"
)

var jobEmitterQueue *queue.WorkerPoolQueue[*jobUpdate]

type jobUpdate struct {
	RunID int64
}

var EmitJobsIfReadyByRun = func(runID int64) error {
	err := jobEmitterQueue.Push(&jobUpdate{
		RunID: runID,
	})
	if errors.Is(err, queue.ErrAlreadyInQueue) {
		return nil
	}
	return err
}

func EmitJobsIfReadyByJobs(jobs []*actions_model.ActionRunJob) {
	checkedRuns := make(container.Set[int64])
	for _, job := range jobs {
		if !job.Status.IsDone() || checkedRuns.Contains(job.RunID) {
			continue
		}
		if err := EmitJobsIfReadyByRun(job.RunID); err != nil {
			log.Error("Check jobs of run %d: %v", job.RunID, err)
		}
		checkedRuns.Add(job.RunID)
	}
}

func jobEmitterQueueHandler(items ...*jobUpdate) []*jobUpdate {
	ctx := graceful.GetManager().ShutdownContext()
	var ret []*jobUpdate
	for _, update := range items {
		if err := checkJobsByRunID(ctx, update.RunID); err != nil {
			log.Error("check run %d: %v", update.RunID, err)
			ret = append(ret, update)
		}
	}
	return ret
}

func checkJobsByRunID(ctx context.Context, runID int64) error {
	run, exist, err := db.GetByID[actions_model.ActionRun](ctx, runID)
	if !exist {
		return fmt.Errorf("run %d does not exist", runID)
	}
	if err != nil {
		return fmt.Errorf("get action run: %w", err)
	}
	var result jobsCheckResult
	if err := db.WithTx(ctx, func(ctx context.Context) error {
		// check jobs of the current run
		r, err := checkJobsOfCurrentRunAttempt(ctx, run)
		if err != nil {
			return err
		}
		result.merge(r)

		r, err = checkRunConcurrency(ctx, run)
		if err != nil {
			return err
		}
		result.merge(r)
		return nil
	}); err != nil {
		return err
	}
	// Re-emit AFTER the transaction commits; doing this inside WithTx would deadlock under
	// immediate-mode queues (the inline handler reopens checkJobsByRunID and asks for a
	// nested writer transaction while the outer one is still open).
	emitted := make(container.Set[int64])
	for _, rid := range result.RunIDsToReEmit {
		if !emitted.Add(rid) {
			continue
		}
		if err := EmitJobsIfReadyByRun(rid); err != nil {
			log.Error("re-emit run %d: %v", rid, err)
		}
	}
	NotifyWorkflowJobsAndRunsStatusUpdate(ctx, result.CancelledJobs)
	EmitJobsIfReadyByJobs(result.CancelledJobs)
	if err := createCommitStatusesForJobsByRun(ctx, result.Jobs); err != nil {
		return err
	}
	NotifyWorkflowJobsStatusUpdate(ctx, result.UpdatedJobs...)
	runJobs := make(map[int64][]*actions_model.ActionRunJob)
	for _, job := range result.Jobs {
		runJobs[job.RunID] = append(runJobs[job.RunID], job)
	}
	runUpdatedJobs := make(map[int64][]*actions_model.ActionRunJob)
	for _, uj := range result.UpdatedJobs {
		runUpdatedJobs[uj.RunID] = append(runUpdatedJobs[uj.RunID], uj)
	}
	for runID, js := range runJobs {
		if len(runUpdatedJobs[runID]) == 0 {
			continue
		}
		runUpdated := true
		for _, job := range js {
			if !job.Status.IsDone() {
				runUpdated = false
				break
			}
		}
		if runUpdated {
			NotifyWorkflowRunStatusUpdateWithReload(ctx, js[0].RepoID, js[0].RunID)
		}
	}
	return nil
}

func createCommitStatusesForJobsByRun(ctx context.Context, jobs []*actions_model.ActionRunJob) error {
	runJobs := make(map[int64][]*actions_model.ActionRunJob)
	for _, job := range jobs {
		runJobs[job.RunID] = append(runJobs[job.RunID], job)
	}

	for jobRunID, jobList := range runJobs {
		run, err := actions_model.GetRunByRepoAndID(ctx, jobList[0].RepoID, jobRunID)
		if err != nil {
			return fmt.Errorf("get action run %d: %w", jobRunID, err)
		}
		CreateCommitStatusForRunJobs(ctx, run, jobList...)
	}
	return nil
}

// findConcurrencyWaiterToWake returns a run (other than excludeRunID) blocked on the group that can be woken now
func findConcurrencyWaiterToWake(ctx context.Context, repoID, excludeRunID int64, concurrencyGroup string) (int64, error) {
	if concurrencyGroup == "" {
		return 0, nil
	}

	// The slot should be free before any waiter can proceed.
	holderAttempts, holderJobs, err := actions_model.GetConcurrentRunAttemptsAndJobs(ctx, repoID, concurrencyGroup, []actions_model.Status{actions_model.StatusRunning, actions_model.StatusCancelling})
	if err != nil {
		return 0, fmt.Errorf("find concurrency-group holders: %w", err)
	}
	if len(holderAttempts) > 0 || len(holderJobs) > 0 {
		return 0, nil
	}

	cAttempts, cJobs, err := actions_model.GetConcurrentRunAttemptsAndJobs(ctx, repoID, concurrencyGroup, []actions_model.Status{actions_model.StatusBlocked})
	if err != nil {
		return 0, fmt.Errorf("find blocked concurrent runs: %w", err)
	}
	for _, a := range cAttempts {
		if a.RunID != excludeRunID {
			return a.RunID, nil
		}
	}
	for _, j := range cJobs {
		if j.RunID != excludeRunID {
			return j.RunID, nil
		}
	}
	return 0, nil
}

// checkRunConcurrency wakes a run blocked by concurrency that may become runnable now that
// the current run's activity may have freed a workflow-level or job-level concurrency group.
func checkRunConcurrency(ctx context.Context, run *actions_model.ActionRun) (*jobsCheckResult, error) {
	result := &jobsCheckResult{}
	checkedConcurrencyGroup := make(container.Set[string])

	collect := func(concurrencyGroup string) error {
		checkedConcurrencyGroup.Add(concurrencyGroup)

		// Exclude run.ID: this run's own jobs are resolved by checkJobsOfCurrentRunAttempt, no need to re-emit.
		concurrentRunID, err := findConcurrencyWaiterToWake(ctx, run.RepoID, run.ID, concurrencyGroup)
		if err != nil {
			return err
		}
		if concurrentRunID == 0 {
			return nil
		}

		concurrentRun, err := actions_model.GetRunByRepoAndID(ctx, run.RepoID, concurrentRunID)
		if err != nil {
			return fmt.Errorf("get concurrent run %d: %w", concurrentRunID, err)
		}
		// A run awaiting approval is not advanced by concurrency; ApproveRuns emits it once approved.
		if concurrentRun.NeedApproval {
			return nil
		}

		result.RunIDsToReEmit = append(result.RunIDsToReEmit, concurrentRunID)
		return nil
	}

	// check run (workflow-level) concurrency
	runConcurrencyGroup, _, err := run.GetEffectiveConcurrency(ctx)
	if err != nil {
		return nil, fmt.Errorf("GetEffectiveConcurrency: %w", err)
	}
	if runConcurrencyGroup != "" {
		if err := collect(runConcurrencyGroup); err != nil {
			return nil, err
		}
	}

	// check job concurrency
	runJobs, err := actions_model.GetLatestAttemptJobsByRepoAndRunID(ctx, run.RepoID, run.ID)
	if err != nil {
		return nil, fmt.Errorf("find run %d jobs: %w", run.ID, err)
	}
	for _, job := range runJobs {
		if !job.Status.IsDone() {
			continue
		}
		if job.ConcurrencyGroup == "" || checkedConcurrencyGroup.Contains(job.ConcurrencyGroup) {
			continue
		}
		if err := collect(job.ConcurrencyGroup); err != nil {
			return nil, err
		}
	}
	return result, nil
}

// checkJobsOfCurrentRunAttempt resolves blocked jobs of the run's latest attempt.
func checkJobsOfCurrentRunAttempt(ctx context.Context, run *actions_model.ActionRun) (*jobsCheckResult, error) {
	jobs, err := actions_model.GetRunJobsByRunAndAttemptID(ctx, run.ID, run.LatestAttemptID)
	if err != nil {
		return nil, err
	}
	result := &jobsCheckResult{Jobs: jobs}

	var attempt *actions_model.ActionRunAttempt
	if run.LatestAttemptID > 0 {
		attempt, err = actions_model.GetRunAttemptByRepoAndID(ctx, run.RepoID, run.LatestAttemptID)
		if err != nil {
			return nil, err
		}
	}

	// The resolver below only considers needs and job-level concurrency, so a run blocked
	// solely by run-level concurrency would have its jobs unblocked here. checkRunConcurrency
	// re-evaluates when the holding run finishes.
	if run.Status.IsBlocked() && attempt != nil {
		shouldBlock, err := shouldBlockRunByConcurrency(ctx, attempt)
		if err != nil {
			return nil, fmt.Errorf("shouldBlockRunByConcurrency: %w", err)
		}
		if shouldBlock {
			return result, nil
		}
	}

	vars, err := actions_model.GetVariablesOfRun(ctx, run)
	if err != nil {
		return nil, err
	}
	resolver := newJobStatusResolver(jobs, vars)

	expandedAnyCaller := false
	if err = db.WithTx(ctx, func(ctx context.Context) error {
		for _, job := range jobs {
			job.Run = run
		}

		updates, err := resolver.Resolve(ctx)
		if err != nil {
			return err
		}
		for _, job := range jobs {
			status, ok := updates[job.ID]
			if !ok {
				continue
			}

			if job.IsReusableCaller {
				switch status {
				case actions_model.StatusWaiting:
					if err := expandReusableWorkflowCaller(ctx, run, attempt, job, vars); err != nil {
						// Terminal expansion failure (an invalid/unresolvable reusable workflow): fail this caller.
						log.Warn("caller %d cannot be expanded: %v", job.ID, err)
						job.Status = actions_model.StatusFailure
						job.Stopped = timeutil.TimeStampNow()
						if n, uerr := actions_model.UpdateRunJob(ctx, job, builder.Eq{"status": actions_model.StatusBlocked, "is_expanded": false}, "status", "stopped"); uerr != nil {
							return fmt.Errorf("mark unexpandable caller %d failed: %w", job.ID, uerr)
						} else if n == 1 {
							log.Warn("unexpandable caller %d has been marked as failed", job.ID)
							result.UpdatedJobs = append(result.UpdatedJobs, job)
							// Re-emit so the failed caller's dependents get resolved on the next pass.
							expandedAnyCaller = true
						} else {
							// A concurrent writer advanced the caller; restore the in-memory state.
							log.Warn("unexpandable caller %d has been advanced by a concurrent writer, not marking it failed", job.ID)
							job.Status = actions_model.StatusBlocked
							job.Stopped = 0
						}
					} else {
						expandedAnyCaller = true
					}
				case actions_model.StatusSkipped:
					job.Status = actions_model.StatusSkipped
					if _, err := actions_model.UpdateRunJob(ctx, job, nil, "status"); err != nil {
						return err
					}
				}
				continue
			}

			// Non-caller: standard status update.
			job.Status = status
			if n, err := actions_model.UpdateRunJob(ctx, job, builder.Eq{"status": actions_model.StatusBlocked}, "status"); err != nil {
				return err
			} else if n != 1 {
				return fmt.Errorf("no affected for updating blocked job %v", job.ID)
			}
			result.UpdatedJobs = append(result.UpdatedJobs, job)
		}
		return nil
	}); err != nil {
		return nil, err
	}

	result.UpdatedJobs = append(result.UpdatedJobs, resolver.matrixUpdatedJobs...)
	// Caller and matrix expansion both insert Blocked jobs, which only a follow-up pass resolves.
	// Like the caller's children, matrix siblings are left out of result.Jobs and picked up there.
	if expandedAnyCaller || resolver.matrixChanged {
		result.RunIDsToReEmit = append(result.RunIDsToReEmit, run.ID)
	}
	result.CancelledJobs = resolver.cancelledJobs
	return result, nil
}

type jobStatusResolver struct {
	statuses map[int64]actions_model.Status
	// sortedIDs are the keys of statuses, so blocked jobs are resolved in insertion order.
	// Resolve only ever rewrites statuses values, never its key set.
	sortedIDs     []int64
	needs         map[int64][]int64
	jobMap        map[int64]*actions_model.ActionRunJob
	vars          map[string]string
	cancelledJobs []*actions_model.ActionRunJob
	// matrixChanged is set when matrix expansion inserted siblings or failed a placeholder, both of
	// which need a follow-up pass to resolve the dependents.
	matrixChanged bool
	// matrixInserted is set when matrix expansion inserted sibling rows, which Resolve stops on.
	matrixInserted bool
	// matrixUpdatedJobs holds jobs whose status matrix expansion persisted itself, so they are
	// notified like the ones the caller updates from the resolved status map.
	matrixUpdatedJobs []*actions_model.ActionRunJob
}

func newJobStatusResolver(jobs actions_model.ActionJobList, vars map[string]string) *jobStatusResolver {
	// Scope-aware: needs are resolved within the same ParentJobID scope so the same
	// JobID in different reusable workflow calls does not cross-link.
	scopedIDToJobs := make(map[int64]map[string][]*actions_model.ActionRunJob)
	jobMap := make(map[int64]*actions_model.ActionRunJob)
	for _, job := range jobs {
		scope := scopedIDToJobs[job.ParentJobID]
		if scope == nil {
			scope = make(map[string][]*actions_model.ActionRunJob)
			scopedIDToJobs[job.ParentJobID] = scope
		}
		scope[job.JobID] = append(scope[job.JobID], job)
		jobMap[job.ID] = job
	}

	statuses := make(map[int64]actions_model.Status, len(jobs))
	needs := make(map[int64][]int64, len(jobs))
	sortedIDs := make([]int64, 0, len(jobs))
	for _, job := range jobs {
		statuses[job.ID] = job.Status
		sortedIDs = append(sortedIDs, job.ID)
		scope := scopedIDToJobs[job.ParentJobID]
		for _, need := range job.Needs {
			for _, v := range scope[need] {
				needs[job.ID] = append(needs[job.ID], v.ID)
			}
		}
	}
	slices.Sort(sortedIDs)
	return &jobStatusResolver{
		statuses:  statuses,
		sortedIDs: sortedIDs,
		needs:     needs,
		jobMap:    jobMap,
		vars:      vars,
	}
}

func (r *jobStatusResolver) Resolve(ctx context.Context) (map[int64]actions_model.Status, error) {
	ret := map[int64]actions_model.Status{}
	for i := 0; i < len(r.statuses); i++ {
		updated, err := r.resolve(ctx)
		if err != nil {
			return nil, err
		}
		if len(updated) == 0 {
			return ret, nil
		}
		for k, v := range updated {
			ret[k] = v
			r.statuses[k] = v
		}
		if r.matrixInserted {
			// Matrix expansion inserted sibling rows this round. They are not in statuses/needs, so
			// another round would resolve a dependent of the expanded job against the placeholder's
			// own combination alone: if that combination was just skipped by its `if:`, the dependent
			// sees all its needs done and gets skipped before any sibling has even started. Stop here
			// and let the re-emit, which reloads the full job set, resolve them.
			return ret, nil
		}
	}
	return ret, nil
}

func (r *jobStatusResolver) resolveCheckNeeds(id int64) (allDone, allSucceed bool) {
	allDone, allSucceed = true, true
	for _, need := range r.needs[id] {
		needStatus := r.statuses[need]
		if !needStatus.IsDone() {
			allDone = false
		}
		// A failed need with continue-on-error:true is treated as success, matching AggregateJobStatus,
		// so a downstream job with an implicit `success()` is not skipped.
		if needJob := r.jobMap[need]; needJob != nil && needJob.ContinueOnError && needStatus == actions_model.StatusFailure {
			continue
		}
		if needStatus.In(actions_model.StatusFailure, actions_model.StatusCancelled, actions_model.StatusSkipped) {
			allSucceed = false
		}
	}
	return allDone, allSucceed
}

func (r *jobStatusResolver) resolve(ctx context.Context) (map[int64]actions_model.Status, error) {
	ret := map[int64]actions_model.Status{}

	slots := maxParallelSlots{}
	for id, status := range r.statuses {
		slots.hold(r.jobMap[id], status)
	}

	for _, id := range r.sortedIDs {
		status := r.statuses[id]
		actionRunJob := r.jobMap[id]
		if status != actions_model.StatusBlocked {
			continue
		}
		// An expanded caller has been resolved in an earlier pass, skip.
		if actionRunJob.IsReusableCaller && actionRunJob.IsExpanded {
			continue
		}
		// A child of a caller cannot start until the caller has become "ready" (children inserted, CallPayload populated).
		if actionRunJob.ParentJobID > 0 {
			if parent, ok := r.jobMap[actionRunJob.ParentJobID]; ok && !parent.IsExpanded {
				continue
			}
		}
		allDone, allSucceed := r.resolveCheckNeeds(id)
		if !allDone {
			continue
		}

		// Decide whether the job runs at all before expanding a deferred matrix: a job whose needs
		// failed or were skipped has to be skipped too, not failed for a matrix those needs never
		// produced the outputs for. An `if:` that reads `matrix.*` cannot be decided this early, so
		// evaluateJobIf reduces it to that needs gate and the pass below decides it per combination.
		shouldStartJob, err := evaluateJobIf(ctx, actionRunJob.Run, nil, actionRunJob, r.vars, allSucceed)
		if err != nil {
			// TODO: surface deterministic expression errors to users by failing the job with a message.
			log.Error("evaluateJobIf failed, job will stay blocked: job: %d, err: %v", id, err)
			continue
		}
		if !shouldStartJob {
			ret[id] = actions_model.StatusSkipped
			continue
		}

		// Expand a needs-dependent matrix now that its needs are done and the job is going to run.
		wasDeferred := actionRunJob.IsMatrixDeferred
		siblings, err := expandDeferredMatrix(ctx, actionRunJob, r.vars)
		if err != nil {
			// Aborting the pass is required: once the placeholder is claimed as the first combination,
			// committing here would drop the remaining ones for good. Before the claim it is what gets
			// the pass retried by the job-emitter queue, since a run whose needs are all done has
			// nothing left to trigger another pass on its own.
			return nil, fmt.Errorf("expand matrix of job %d: %w", id, err)
		}
		if actionRunJob.Status != actions_model.StatusBlocked {
			// expandDeferredMatrix already persisted the failure, so it bypasses `ret`.
			r.statuses[id] = actionRunJob.Status
			r.matrixUpdatedJobs = append(r.matrixUpdatedJobs, actionRunJob)
			r.matrixChanged = true
			continue
		}
		if actionRunJob.IsMatrixDeferred {
			continue // could not be expanded yet, it stays blocked and is retried on the next pass
		}
		if len(siblings) > 0 {
			r.matrixChanged, r.matrixInserted = true, true
		}
		if wasDeferred {
			// This row is now the first combination, and the `if:` can be evaluated.
			// Gate it on its own combination here, as the siblings will be on the next pass.
			shouldStartJob, err := evaluateJobIf(ctx, actionRunJob.Run, nil, actionRunJob, r.vars, allSucceed)
			if err != nil {
				log.Error("evaluateJobIf failed after matrix expansion, job will stay blocked: job: %d, err: %v", id, err)
				continue
			}
			if !shouldStartJob {
				ret[id] = actions_model.StatusSkipped
				continue
			}
		}

		// A slot-starved job cannot start, skip the following checks.
		if !slots.available(actionRunJob) {
			continue
		}

		// update concurrency and check whether the job can run now
		err = updateConcurrencyEvaluationForJobWithNeeds(ctx, actionRunJob, r.vars)
		if err != nil {
			// The err can be caused by different cases: database error, or syntax error, or the needed jobs haven't completed
			// At the moment there is no way to distinguish them.
			// TODO: if workflow or concurrency expression has syntax error, there should be a user error message, need to show it to end users
			log.Debug("updateConcurrencyEvaluationForJobWithNeeds failed, this job will stay blocked: job: %d, err: %v", id, err)
			continue
		}

		newStatus, cancelledJobs, err := PrepareToStartJobWithConcurrency(ctx, actionRunJob)
		if err != nil {
			log.Error("ShouldBlockJobByConcurrency failed, this job will stay blocked: job: %d, err: %v", id, err)
		} else {
			r.cancelledJobs = append(r.cancelledJobs, cancelledJobs...)
		}

		if newStatus == actions_model.StatusWaiting && !slots.take(actionRunJob) {
			continue // no free slot, leave blocked
		}

		if newStatus != actions_model.StatusBlocked {
			ret[id] = newStatus
		}
	}
	return ret, nil
}

func updateConcurrencyEvaluationForJobWithNeeds(ctx context.Context, actionRunJob *actions_model.ActionRunJob, vars map[string]string) error {
	if setting.IsInTesting && actionRunJob.RepoID == 0 {
		return nil // for testing purpose only, no repo, no evaluation
	}

	// Legacy jobs (created before migration v331) have RunAttemptID=0 and no attempt record.
	var attempt *actions_model.ActionRunAttempt
	if actionRunJob.RunAttemptID > 0 {
		var err error
		attempt, err = actions_model.GetRunAttemptByRepoAndID(ctx, actionRunJob.RepoID, actionRunJob.RunAttemptID)
		if err != nil {
			return fmt.Errorf("GetRunAttemptByRepoAndID: %w", err)
		}
	}
	if err := EvaluateJobConcurrencyFillModel(ctx, actionRunJob.Run, attempt, actionRunJob, vars, nil); err != nil {
		return fmt.Errorf("evaluate job concurrency: %w", err)
	}

	if _, err := actions_model.UpdateRunJob(ctx, actionRunJob, nil, "concurrency_group", "concurrency_cancel", "is_concurrency_evaluated"); err != nil {
		return fmt.Errorf("update run job: %w", err)
	}
	return nil
}

// jobsCheckResult bundles the output of the per-run job-check helpers.
type jobsCheckResult struct {
	// Jobs are all jobs of the run's latest attempt that were inspected.
	Jobs []*actions_model.ActionRunJob
	// UpdatedJobs are jobs whose status was transitioned out of Blocked in this pass.
	UpdatedJobs []*actions_model.ActionRunJob
	// CancelledJobs are jobs cancelled by job-level concurrency while preparing to start.
	CancelledJobs []*actions_model.ActionRunJob
	// RunIDsToReEmit are runs that need another resolver pass in their own transaction.
	RunIDsToReEmit []int64
}

// merge appends another result's contents into r in place.
func (r *jobsCheckResult) merge(other *jobsCheckResult) {
	r.Jobs = append(r.Jobs, other.Jobs...)
	r.UpdatedJobs = append(r.UpdatedJobs, other.UpdatedJobs...)
	r.CancelledJobs = append(r.CancelledJobs, other.CancelledJobs...)
	r.RunIDsToReEmit = append(r.RunIDsToReEmit, other.RunIDsToReEmit...)
}