feat: multiple search indexes (#2514)

* refactor: abstract search interface

* wip: ~

* fix cycle import

* objs update hook

* wip: ~

* Delete search/none

* auto update index while cache changed

* db searcher

TODO: bleve init issue

cannot open index, metadata missing

* fix size type

why float64??

* fix typo

* fix nil pointer using

* api adapt ui

* bleve: fix clear & change struct

internal/search/build.go

@@ -0,0 +1,100 @@
+package search
+
+import (
+	"context"
+	"path"
+	"path/filepath"
+	"time"
+
+	"github.com/alist-org/alist/v3/internal/db"
+	"github.com/alist-org/alist/v3/internal/fs"
+	"github.com/alist-org/alist/v3/internal/model"
+	log "github.com/sirupsen/logrus"
+)
+
+var (
+	Running = false
+)
+
+func BuildIndex(ctx context.Context, indexPaths, ignorePaths []string, maxDepth int, count bool) error {
+	var objCount uint64 = 0
+	Running = true
+	var (
+		err error
+		fi  model.Obj
+	)
+	defer func() {
+		Running = false
+		now := time.Now()
+		eMsg := ""
+		if err != nil {
+			log.Errorf("build index error: %+v", err)
+			eMsg = err.Error()
+		} else {
+			log.Infof("success build index, count: %d", objCount)
+		}
+		if count {
+			WriteProgress(&model.IndexProgress{
+				ObjCount:     objCount,
+				IsDone:       err == nil,
+				LastDoneTime: &now,
+				Error:        eMsg,
+			})
+		}
+	}()
+	admin, err := db.GetAdmin()
+	if err != nil {
+		return err
+	}
+	if count {
+		WriteProgress(&model.IndexProgress{
+			ObjCount: 0,
+			IsDone:   false,
+		})
+	}
+	for _, indexPath := range indexPaths {
+		walkFn := func(indexPath string, info model.Obj, err error) error {
+			for _, avoidPath := range ignorePaths {
+				if indexPath == avoidPath {
+					return filepath.SkipDir
+				}
+			}
+			// ignore root
+			if indexPath == "/" {
+				return nil
+			}
+			err = instance.Index(ctx, path.Dir(indexPath), info)
+			if err != nil {
+				return err
+			} else {
+				objCount++
+			}
+			if objCount%100 == 0 {
+				log.Infof("index obj count: %d", objCount)
+				log.Debugf("current success index: %s", indexPath)
+				if count {
+					WriteProgress(&model.IndexProgress{
+						ObjCount:     objCount,
+						IsDone:       false,
+						LastDoneTime: nil,
+					})
+				}
+			}
+			return nil
+		}
+		fi, err = fs.Get(ctx, indexPath)
+		if err != nil {
+			return err
+		}
+		// TODO: run walkFS concurrently
+		err = fs.WalkFS(context.WithValue(ctx, "user", admin), maxDepth, indexPath, fi, walkFn)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func Clear(ctx context.Context) error {
+	return instance.Clear(ctx)
+}