// Copyright 2018 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package issues

import (
	"context"
	"os"
	"runtime/pprof"
	"sync/atomic"
	"time"

	db_model "code.gitea.io/gitea/models/db"
	issues_model "code.gitea.io/gitea/models/issues"
	repo_model "code.gitea.io/gitea/models/repo"
	"code.gitea.io/gitea/modules/graceful"
	"code.gitea.io/gitea/modules/indexer/issues/bleve"
	"code.gitea.io/gitea/modules/indexer/issues/db"
	"code.gitea.io/gitea/modules/indexer/issues/elasticsearch"
	"code.gitea.io/gitea/modules/indexer/issues/internal"
	"code.gitea.io/gitea/modules/indexer/issues/meilisearch"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/process"
	"code.gitea.io/gitea/modules/queue"
	"code.gitea.io/gitea/modules/setting"
	"code.gitea.io/gitea/modules/util"
)

var (
	// issueIndexerQueue queue of issue ids to be updated
	issueIndexerQueue *queue.WorkerPoolQueue[*internal.IndexerData]
	// globalIndexer is the global indexer, it cannot be nil.
	// When the real indexer is not ready, it will be a dummy indexer which will return error to explain it's not ready.
	// So it's always safe use it as *globalIndexer.Load() and call its methods.
	globalIndexer atomic.Pointer[internal.Indexer]
	dummyIndexer  *internal.Indexer
)

func init() {
	i := internal.NewDummyIndexer()
	dummyIndexer = &i
	globalIndexer.Store(dummyIndexer)
}

// InitIssueIndexer initialize issue indexer, syncReindex is true then reindex until
// all issue index done.
func InitIssueIndexer(syncReindex bool) {
	ctx, _, finished := process.GetManager().AddTypedContext(context.Background(), "Service: IssueIndexer", process.SystemProcessType, false)

	indexerInitWaitChannel := make(chan time.Duration, 1)

	// Create the Queue
	switch setting.Indexer.IssueType {
	case "bleve", "elasticsearch", "meilisearch":
		handler := func(items ...*internal.IndexerData) (unhandled []*internal.IndexerData) {
			indexer := *globalIndexer.Load()
			toIndex := make([]*internal.IndexerData, 0, len(items))
			for _, indexerData := range items {
				log.Trace("IndexerData Process: %d %v %t", indexerData.ID, indexerData.IDs, indexerData.IsDelete)
				if indexerData.IsDelete {
					if err := indexer.Delete(ctx, indexerData.IDs...); err != nil {
						log.Error("Issue indexer handler: failed to from index: %v Error: %v", indexerData.IDs, err)
						unhandled = append(unhandled, indexerData)
					}
					continue
				}
				toIndex = append(toIndex, indexerData)
			}
			if err := indexer.Index(ctx, toIndex); err != nil {
				log.Error("Error whilst indexing: %v Error: %v", toIndex, err)
				unhandled = append(unhandled, toIndex...)
			}
			return unhandled
		}

		issueIndexerQueue = queue.CreateSimpleQueue(ctx, "issue_indexer", handler)

		if issueIndexerQueue == nil {
			log.Fatal("Unable to create issue indexer queue")
		}
	default:
		issueIndexerQueue = queue.CreateSimpleQueue[*internal.IndexerData](ctx, "issue_indexer", nil)
	}

	graceful.GetManager().RunAtTerminate(finished)

	// Create the Indexer
	go func() {
		pprof.SetGoroutineLabels(ctx)
		start := time.Now()
		log.Info("PID %d: Initializing Issue Indexer: %s", os.Getpid(), setting.Indexer.IssueType)
		var (
			issueIndexer internal.Indexer
			existed      bool
			err          error
		)
		switch setting.Indexer.IssueType {
		case "bleve":
			defer func() {
				if err := recover(); err != nil {
					log.Error("PANIC whilst initializing issue indexer: %v\nStacktrace: %s", err, log.Stack(2))
					log.Error("The indexer files are likely corrupted and may need to be deleted")
					log.Error("You can completely remove the %q directory to make Gitea recreate the indexes", setting.Indexer.IssuePath)
					globalIndexer.Store(dummyIndexer)
					log.Fatal("PID: %d Unable to initialize the Bleve Issue Indexer at path: %s Error: %v", os.Getpid(), setting.Indexer.IssuePath, err)
				}
			}()
			issueIndexer = bleve.NewIndexer(setting.Indexer.IssuePath)
			existed, err = issueIndexer.Init(ctx)
			if err != nil {
				log.Fatal("Unable to initialize Bleve Issue Indexer at path: %s Error: %v", setting.Indexer.IssuePath, err)
			}
		case "elasticsearch":
			issueIndexer = elasticsearch.NewIndexer(setting.Indexer.IssueConnStr, setting.Indexer.IssueIndexerName)
			existed, err = issueIndexer.Init(ctx)
			if err != nil {
				log.Fatal("Unable to issueIndexer.Init with connection %s Error: %v", setting.Indexer.IssueConnStr, err)
			}
		case "db":
			issueIndexer = db.NewIndexer()
		case "meilisearch":
			issueIndexer = meilisearch.NewIndexer(setting.Indexer.IssueConnStr, setting.Indexer.IssueConnAuth, setting.Indexer.IssueIndexerName)
			existed, err = issueIndexer.Init(ctx)
			if err != nil {
				log.Fatal("Unable to issueIndexer.Init with connection %s Error: %v", setting.Indexer.IssueConnStr, err)
			}
		default:
			log.Fatal("Unknown issue indexer type: %s", setting.Indexer.IssueType)
		}
		globalIndexer.Store(&issueIndexer)

		graceful.GetManager().RunAtTerminate(func() {
			log.Debug("Closing issue indexer")
			(*globalIndexer.Load()).Close()
			log.Info("PID: %d Issue Indexer closed", os.Getpid())
		})

		// Start processing the queue
		go graceful.GetManager().RunWithCancel(issueIndexerQueue)

		// Populate the index
		if !existed {
			if syncReindex {
				graceful.GetManager().RunWithShutdownContext(populateIssueIndexer)
			} else {
				go graceful.GetManager().RunWithShutdownContext(populateIssueIndexer)
			}
		}

		indexerInitWaitChannel <- time.Since(start)
		close(indexerInitWaitChannel)
	}()

	if syncReindex {
		select {
		case <-indexerInitWaitChannel:
		case <-graceful.GetManager().IsShutdown():
		}
	} else if setting.Indexer.StartupTimeout > 0 {
		go func() {
			pprof.SetGoroutineLabels(ctx)
			timeout := setting.Indexer.StartupTimeout
			if graceful.GetManager().IsChild() && setting.GracefulHammerTime > 0 {
				timeout += setting.GracefulHammerTime
			}
			select {
			case duration := <-indexerInitWaitChannel:
				log.Info("Issue Indexer Initialization took %v", duration)
			case <-graceful.GetManager().IsShutdown():
				log.Warn("Shutdown occurred before issue index initialisation was complete")
			case <-time.After(timeout):
				issueIndexerQueue.ShutdownWait(5 * time.Second)
				log.Fatal("Issue Indexer Initialization timed-out after: %v", timeout)
			}
		}()
	}
}

// populateIssueIndexer populate the issue indexer with issue data
func populateIssueIndexer(ctx context.Context) {
	ctx, _, finished := process.GetManager().AddTypedContext(ctx, "Service: PopulateIssueIndexer", process.SystemProcessType, true)
	defer finished()
	for page := 1; ; page++ {
		select {
		case <-ctx.Done():
			log.Warn("Issue Indexer population shutdown before completion")
			return
		default:
		}
		repos, _, err := repo_model.SearchRepositoryByName(ctx, &repo_model.SearchRepoOptions{
			ListOptions: db_model.ListOptions{Page: page, PageSize: repo_model.RepositoryListDefaultPageSize},
			OrderBy:     db_model.SearchOrderByID,
			Private:     true,
			Collaborate: util.OptionalBoolFalse,
		})
		if err != nil {
			log.Error("SearchRepositoryByName: %v", err)
			continue
		}
		if len(repos) == 0 {
			log.Debug("Issue Indexer population complete")
			return
		}

		for _, repo := range repos {
			select {
			case <-ctx.Done():
				log.Info("Issue Indexer population shutdown before completion")
				return
			default:
			}
			UpdateRepoIndexer(ctx, repo)
		}
	}
}

// UpdateRepoIndexer add/update all issues of the repositories
func UpdateRepoIndexer(ctx context.Context, repo *repo_model.Repository) {
	is, err := issues_model.Issues(ctx, &issues_model.IssuesOptions{
		RepoIDs:  []int64{repo.ID},
		IsClosed: util.OptionalBoolNone,
		IsPull:   util.OptionalBoolNone,
	})
	if err != nil {
		log.Error("Issues: %v", err)
		return
	}
	if err = issues_model.IssueList(is).LoadDiscussComments(ctx); err != nil {
		log.Error("LoadDiscussComments: %v", err)
		return
	}
	for _, issue := range is {
		UpdateIssueIndexer(issue)
	}
}

// UpdateIssueIndexer add/update an issue to the issue indexer
func UpdateIssueIndexer(issue *issues_model.Issue) {
	var comments []string
	for _, comment := range issue.Comments {
		if comment.Type == issues_model.CommentTypeComment {
			comments = append(comments, comment.Content)
		}
	}
	issueType := "issue"
	if issue.IsPull {
		issueType = "pull"
	}
	indexerData := &internal.IndexerData{
		ID:        issue.ID,
		RepoID:    issue.RepoID,
		State:     string(issue.State()),
		IssueType: issueType,
		Title:     issue.Title,
		Content:   issue.Content,
		Comments:  comments,
	}
	log.Debug("Adding to channel: %v", indexerData)
	if err := issueIndexerQueue.Push(indexerData); err != nil {
		log.Error("Unable to push to issue indexer: %v: Error: %v", indexerData, err)
	}
}

// DeleteRepoIssueIndexer deletes repo's all issues indexes
func DeleteRepoIssueIndexer(ctx context.Context, repo *repo_model.Repository) {
	var ids []int64
	ids, err := issues_model.GetIssueIDsByRepoID(ctx, repo.ID)
	if err != nil {
		log.Error("GetIssueIDsByRepoID failed: %v", err)
		return
	}

	if len(ids) == 0 {
		return
	}
	indexerData := &internal.IndexerData{
		IDs:      ids,
		IsDelete: true,
	}
	if err := issueIndexerQueue.Push(indexerData); err != nil {
		log.Error("Unable to push to issue indexer: %v: Error: %v", indexerData, err)
	}
}

// SearchIssuesByKeyword search issue ids by keywords and repo id
// WARNNING: You have to ensure user have permission to visit repoIDs' issues
func SearchIssuesByKeyword(ctx context.Context, repoIDs []int64, keyword, state string) ([]int64, error) {
	var issueIDs []int64
	indexer := *globalIndexer.Load()
	res, err := indexer.Search(ctx, keyword, repoIDs, 50, 0, state)
	if err != nil {
		return nil, err
	}
	for _, r := range res.Hits {
		issueIDs = append(issueIDs, r.ID)
	}
	return issueIDs, nil
}

// IsAvailable checks if issue indexer is available
func IsAvailable(ctx context.Context) bool {
	return (*globalIndexer.Load()).Ping(ctx) == nil
}