// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package bots

import (
	"context"
	"fmt"

	bots_model "code.gitea.io/gitea/models/bots"
	"code.gitea.io/gitea/models/db"
	"code.gitea.io/gitea/modules/graceful"
	"code.gitea.io/gitea/modules/queue"
	"xorm.io/builder"
)

var jobEmitterQueue queue.UniqueQueue

type jobUpdate struct {
	RunID int64
}

func InitJobEmitter() {
	jobEmitterQueue = queue.CreateUniqueQueue("bots_ready_job", jobEmitterQueueHandle, new(jobUpdate))
	go graceful.GetManager().RunWithShutdownFns(jobEmitterQueue.Run)
}

func EmitJobsIfReady(runID int64) error {
	return jobEmitterQueue.Push(&jobUpdate{
		RunID: runID,
	})
}

func jobEmitterQueueHandle(data ...queue.Data) []queue.Data {
	ctx := graceful.GetManager().ShutdownContext()
	var ret []queue.Data
	for _, d := range data {
		update := d.(*jobUpdate)
		if err := checkJobsOfRun(ctx, update.RunID); err != nil {
			ret = append(ret, d)
		}
	}
	return ret
}

func checkJobsOfRun(ctx context.Context, runID int64) error {
	return db.WithTx(func(ctx context.Context) error {
		jobs, _, err := bots_model.FindRunJobs(ctx, bots_model.FindRunJobOptions{RunID: runID})
		if err != nil {
			return err
		}
		idToJobs := make(map[string][]*bots_model.RunJob, len(jobs))
		for _, job := range jobs {
			idToJobs[job.JobID] = append(idToJobs[job.JobID], job)
		}

		updates := newJobStatusResolver(jobs).Resolve()
		for _, job := range jobs {
			if status, ok := updates[job.ID]; ok {
				job.Status = status
				if n, err := bots_model.UpdateRunJob(ctx, job, builder.Eq{"status": bots_model.StatusBlocked}, "status"); err != nil {
					return err
				} else if n != 1 {
					return fmt.Errorf("no affected for updating blocked job %v", job.ID)
				}
			}
		}
		return nil
	}, ctx)
}

type jobStatusResolver struct {
	statuses map[int64]bots_model.Status
	needs    map[int64][]int64
}

func newJobStatusResolver(jobs bots_model.RunJobList) *jobStatusResolver {
	idToJobs := make(map[string][]*bots_model.RunJob, len(jobs))
	for _, job := range jobs {
		idToJobs[job.JobID] = append(idToJobs[job.JobID], job)
	}

	statuses := make(map[int64]bots_model.Status, len(jobs))
	needs := make(map[int64][]int64, len(jobs))
	for _, job := range jobs {
		statuses[job.ID] = job.Status
		for _, need := range job.Needs {
			for _, v := range idToJobs[need] {
				needs[job.ID] = append(needs[job.ID], v.ID)
			}
		}
	}
	return &jobStatusResolver{
		statuses: statuses,
		needs:    needs,
	}
}

func (r *jobStatusResolver) Resolve() map[int64]bots_model.Status {
	ret := map[int64]bots_model.Status{}
	for i := 0; i < len(r.statuses); i++ {
		updated := r.resolve()
		if len(updated) == 0 {
			return ret
		}
		for k, v := range updated {
			ret[k] = v
			r.statuses[k] = v
		}
	}
	return ret
}

func (r *jobStatusResolver) resolve() map[int64]bots_model.Status {
	ret := map[int64]bots_model.Status{}
	for id, status := range r.statuses {
		if status != bots_model.StatusBlocked {
			continue
		}
		allDone, allSucceed := true, true
		for _, need := range r.needs[id] {
			needStatus := r.statuses[need]
			if !needStatus.IsDone() {
				allDone = false
			}
			if needStatus.In(bots_model.StatusFailure, bots_model.StatusCancelled, bots_model.StatusSkipped) {
				allSucceed = false
			}
		}
		if allDone {
			if allSucceed {
				ret[id] = bots_model.StatusWaiting
			} else {
				ret[id] = bots_model.StatusSkipped
			}
		}
	}
	return ret
}