package media

import (
	"context"
	"slices"

	"git.mstar.dev/mstar/goutils/sliceutils"
	"github.com/minio/minio-go/v7"
	"github.com/rs/zerolog/log"

	"git.mstar.dev/mstar/linstrom/config"
	"git.mstar.dev/mstar/linstrom/storage-new/dbgen"
	"git.mstar.dev/mstar/linstrom/storage-new/models"
)

// ServiceEnsureFileSynchronisation is a service function for ensuring data synchronicity between
// the db's metadata for the files and the actual files in s3.
// All files without matching metadata will be deleted. Same for all metadata without a matching file.
// No attempt at restoring a connection will be made
func (s *Server) ServiceEnsureFileSynchronisation() {
	allFiles, err := dbgen.MediaMetadata.Select(dbgen.MediaMetadata.ID, dbgen.MediaMetadata.OwnedById, dbgen.MediaMetadata.Name).
		Find()
	if err != nil {
		log.Error().Err(err).Msg("Failed to get a list of all known media")
		return
	}
	foundInDb := []string{}
	objectMissingInDb := []minio.ObjectInfo{}
	// Go over all objects in the bucket. Note down if it has an entry in the db or not
	for obj := range s.client.ListObjects(context.TODO(), config.GlobalConfig.S3.BucketName, minio.ListObjectsOptions{}) {
		if slices.ContainsFunc(allFiles, func(e *models.MediaMetadata) bool {
			return UsernameFilename(e.OwnedById.String, e.Name) == obj.Key
		}) {
			foundInDb = append(foundInDb, obj.Key)
		} else {
			objectMissingInDb = append(objectMissingInDb, obj)
		}
	}

	// Find every db entry not in the list of found objects
	entryMissingAnObject := []string{}
	for _, dbFile := range allFiles {
		if !slices.ContainsFunc(foundInDb, func(e string) bool {
			return UsernameFilename(dbFile.OwnedById.String, dbFile.Name) == e
		}) {
			entryMissingAnObject = append(entryMissingAnObject, dbFile.ID)
		}
	}

	// For every object missing in the db, delete it
	minioErrChan := s.client.RemoveObjects(
		context.TODO(),
		config.GlobalConfig.S3.BucketName,
		sliceutils.ToChannel(objectMissingInDb),
		minio.RemoveObjectsOptions{GovernanceBypass: true},
	)
	s3Errors := sliceutils.FromChannel(minioErrChan, 0)
	s3Errors = sliceutils.Filter(
		s3Errors,
		func(t minio.RemoveObjectError) bool { return t.Err != nil },
	)
	for _, s3Err := range s3Errors {
		log.Error().
			Err(s3Err.Err).
			Str("object-name", s3Err.ObjectName).
			Msg("Failed to delete object missing in db")
	}
	// And perform a batch delete
	_, err = dbgen.MediaMetadata.Where(dbgen.MediaMetadata.ID.In(entryMissingAnObject...)).Delete()
	if err != nil {
		log.Error().
			Err(err).
			Strs("media-ids", entryMissingAnObject).
			Msg("Failed to batch delete all media metadata without a matching object in s3")
	}
}