feat(search): search with meilisearch (#6060)

* feat(search): search with meilisearch.

* feat(search): meilisearch supports auto update.

* chores: remove utils.Log.

* fix(search): the null pointer caused by deleting non-existing file/folder indexes.

---------

Co-authored-by: Andy Hsu <i@nn.ci>

internal/search/meilisearch/init.go

@@ -0,0 +1,89 @@
+package meilisearch
+
+import (
+	"errors"
+	"fmt"
+	"github.com/alist-org/alist/v3/internal/conf"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/search/searcher"
+	"github.com/alist-org/alist/v3/pkg/utils"
+	"github.com/meilisearch/meilisearch-go"
+)
+
+var config = searcher.Config{
+	Name:       "meilisearch",
+	AutoUpdate: true,
+}
+
+func init() {
+	searcher.RegisterSearcher(config, func() (searcher.Searcher, error) {
+		m := Meilisearch{
+			Client: meilisearch.NewClient(meilisearch.ClientConfig{
+				Host:   conf.Conf.Meilisearch.Host,
+				APIKey: conf.Conf.Meilisearch.APIKey,
+			}),
+			IndexUid:             conf.Conf.Meilisearch.IndexPrefix + "alist",
+			FilterableAttributes: []string{"parent", "is_dir", "name"},
+			SearchableAttributes: []string{"name"},
+		}
+
+		_, err := m.Client.GetIndex(m.IndexUid)
+		if err != nil {
+			var mErr *meilisearch.Error
+			ok := errors.As(err, &mErr)
+			if ok && mErr.MeilisearchApiError.Code == "index_not_found" {
+				task, err := m.Client.CreateIndex(&meilisearch.IndexConfig{
+					Uid:        m.IndexUid,
+					PrimaryKey: "id",
+				})
+				if err != nil {
+					return nil, err
+				}
+				forTask, err := m.Client.WaitForTask(task.TaskUID)
+				if err != nil {
+					return nil, err
+				}
+				if forTask.Status != meilisearch.TaskStatusSucceeded {
+					return nil, fmt.Errorf("index creation failed, task status is %s", forTask.Status)
+				}
+			} else {
+				return nil, err
+			}
+		}
+		attributes, err := m.Client.Index(m.IndexUid).GetFilterableAttributes()
+		if err != nil {
+			return nil, err
+		}
+		if attributes == nil || !utils.SliceAllContains(*attributes, m.FilterableAttributes...) {
+			_, err = m.Client.Index(m.IndexUid).UpdateFilterableAttributes(&m.FilterableAttributes)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		attributes, err = m.Client.Index(m.IndexUid).GetSearchableAttributes()
+		if err != nil {
+			return nil, err
+		}
+		if attributes == nil || !utils.SliceAllContains(*attributes, m.SearchableAttributes...) {
+			_, err = m.Client.Index(m.IndexUid).UpdateSearchableAttributes(&m.SearchableAttributes)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		pagination, err := m.Client.Index(m.IndexUid).GetPagination()
+		if err != nil {
+			return nil, err
+		}
+		if pagination.MaxTotalHits != int64(model.MaxInt) {
+			_, err := m.Client.Index(m.IndexUid).UpdatePagination(&meilisearch.Pagination{
+				MaxTotalHits: int64(model.MaxInt),
+			})
+			if err != nil {
+				return nil, err
+			}
+		}
+		return &m, nil
+	})
+}