// Copyright 2019 Drone IO, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package manager

import (
	"context"
	"encoding/json"
	"time"

	"github.com/drone/drone/core"
	"github.com/drone/drone/store/shared/db"
	"github.com/drone/go-scm/scm"

	"github.com/hashicorp/go-multierror"
	"github.com/sirupsen/logrus"
)

type teardown struct {
	Builds    core.BuildStore
	Events    core.Pubsub
	Logs      core.LogStream
	Scheduler core.Scheduler
	Repos     core.RepositoryStore
	Steps     core.StepStore
	Status    core.StatusService
	Stages    core.StageStore
	Users     core.UserStore
}

func (t *teardown) do(ctx context.Context, stage *core.Stage) error {
	logger := logrus.WithField("stage.id", stage.ID)
	logger.Debugln("manager: stage is complete. teardown")

	build, err := t.Builds.Find(noContext, stage.BuildID)
	if err != nil {
		logger.WithError(err).Warnln("manager: cannot find the build")
		return err
	}

	logger = logger.WithFields(
		logrus.Fields{
			"build.number": build.Number,
			"build.id":     build.ID,
			"repo.id":      build.RepoID,
		},
	)

	repo, err := t.Repos.Find(noContext, build.RepoID)
	if err != nil {
		logger.WithError(err).Warnln("manager: cannot find the repository")
		return err
	}

	for _, step := range stage.Steps {
		err := t.Steps.Update(noContext, step)
		if err != nil {
			logger.WithError(err).
				WithField("stage.status", stage.Status).
				WithField("step.name", step.Name).
				WithField("step.id", step.ID).
				Warnln("manager: cannot persist the step")
			return err
		}
	}

	stage.Updated = time.Now().Unix()
	err = t.Stages.Update(noContext, stage)
	if err != nil {
		logger.WithError(err).
			Warnln("manager: cannot update the stage")
		return err
	}

	for _, step := range stage.Steps {
		t.Logs.Delete(noContext, step.ID)
	}

	stages, err := t.Stages.ListSteps(noContext, build.ID)
	if err != nil {
		logger.WithError(err).Warnln("manager: cannot get stages")
		return err
	}

	err = t.cancelDownstream(ctx, stages)
	if err != nil {
		return err
	}
	err = t.scheduleDownstream(ctx, stage, stages)
	if err != nil {
		return err
	}

	if isBuildComplete(stages) == false {
		logger.Debugln("manager: build pending completion of additional stages")
		return nil
	}

	logger.Debugln("manager: build is finished, teardown")

	build.Status = core.StatusPassing
	build.Finished = time.Now().Unix()
	for _, sibling := range stages {
		if sibling.Status == core.StatusKilled {
			build.Status = core.StatusKilled
			break
		}
		if sibling.Status == core.StatusFailing {
			build.Status = core.StatusFailing
			break
		}
		if sibling.Status == core.StatusError {
			build.Status = core.StatusError
			break
		}
	}

	err = t.Builds.Update(noContext, build)
	if err == db.ErrOptimisticLock {
		logger.WithError(err).
			Warnln("manager: build updated by another goroutine")
		return nil
	}
	if err != nil {
		logger.WithError(err).
			Warnln("manager: cannot update the build")
		return err
	}

	// err = t.Watcher.Complete(noContext, build.ID)
	// if err != nil {
	// 	logger.WithError(err).
	// 		Warnln("manager: cannot remove the watcher")
	// }

	repo.Build = build
	repo.Build.Stages = stages
	data, _ := json.Marshal(repo)
	err = t.Events.Publish(noContext, &core.Message{
		Repository: repo.Slug,
		Visibility: repo.Visibility,
		Data:       data,
	})
	if err != nil {
		logger.WithError(err).
			Warnln("manager: cannot publish build event")
	}

	user, err := t.Users.Find(noContext, repo.UserID)
	if err != nil {
		logger.WithError(err).
			Warnln("manager: cannot find repository owner")
		return err
	}

	req := &core.StatusInput{
		Repo:  repo,
		Build: build,
	}
	err = t.Status.Send(noContext, user, req)
	if err != nil && err != scm.ErrNotSupported {
		logger.WithError(err).
			Warnln("manager: cannot publish status")
	}
	return nil
}

// cancelDownstream is a helper function that tests for
// downstream stages and cancels them based on the overall
// pipeline state.
func (t *teardown) cancelDownstream(
	ctx context.Context,
	stages []*core.Stage,
) error {
	failed := false
	for _, s := range stages {
		if s.IsFailed() {
			failed = true
		}
	}

	var errs error
	for _, s := range stages {
		if s.Status != core.StatusWaiting {
			continue
		}
		if failed == true && s.OnFailure == true {
			continue
		}
		if failed == false && s.OnSuccess == true {
			continue
		}

		logger := logrus.WithFields(
			logrus.Fields{
				"stage.id":         s.ID,
				"stage.on_success": s.OnSuccess,
				"stage.on_failure": s.OnFailure,
				"stage.is_failure": failed,
				"stage.depends_on": s.DependsOn,
			},
		)
		logger.Debugln("manager: skipping step")

		s.Status = core.StatusSkipped
		s.Started = time.Now().Unix()
		s.Stopped = time.Now().Unix()
		err := t.Stages.Update(noContext, s)
		if err != nil && err != db.ErrOptimisticLock {
			logger.WithError(err).
				Warnln("manager: cannot update stage status")
			errs = multierror.Append(errs, err)
		}
	}
	return errs
}

// scheduleDownstream is a helper function that tests for
// downstream stages and schedules stages if all dependencies
// and execution requirements are met.
func (t *teardown) scheduleDownstream(
	ctx context.Context,
	stage *core.Stage,
	stages []*core.Stage,
) error {

	var errs error
	for _, sibling := range stages {
		if sibling.Status == core.StatusWaiting {
			if len(sibling.DependsOn) == 0 {
				continue
			}
			if isDep(stage, sibling) == false {
				continue
			}
			if areDepsComplete(sibling, stages) == false {
				continue
			}
			if isLastDep(stage, sibling, stages) == false {
				continue
			}

			logger := logrus.WithFields(
				logrus.Fields{
					"stage.id":         sibling.ID,
					"stage.name":       sibling.Name,
					"stage.depends_on": sibling.DependsOn,
				},
			)
			logger.Debugln("manager: schedule next stage")

			sibling.Status = core.StatusPending
			sibling.Updated = time.Now().Unix()
			err := t.Stages.Update(noContext, sibling)
			if err != nil {
				logger.WithError(err).
					Warnln("manager: cannot update stage status")
				errs = multierror.Append(errs, err)
			}

			err = t.Scheduler.Schedule(noContext, sibling)
			if err != nil {
				logger.WithError(err).
					Warnln("manager: cannot schedule stage")
				errs = multierror.Append(errs, err)
			}
		}
	}
	return errs
}