Improve issue search (#2387)

* Improve issue indexer

* Fix new issue sqlite bug

* Different test indexer paths for each db

* Add integration indexer paths to make clean

modules/indexer/indexer.go

@@ -5,10 +5,39 @@
 package indexer
 
 import (
-	"code.gitea.io/gitea/models"
+	"fmt"
+	"strconv"
+
+	"github.com/blevesearch/bleve"
+	"github.com/blevesearch/bleve/search/query"
 )
 
-// NewContext start indexer service
-func NewContext() {
-	models.InitIssueIndexer()
+// indexerID a bleve-compatible unique identifier for an integer id
+func indexerID(id int64) string {
+	return strconv.FormatInt(id, 36)
+}
+
+// idOfIndexerID the integer id associated with an indexer id
+func idOfIndexerID(indexerID string) (int64, error) {
+	id, err := strconv.ParseInt(indexerID, 36, 64)
+	if err != nil {
+		return 0, fmt.Errorf("Unexpected indexer ID %s: %v", indexerID, err)
+	}
+	return id, nil
+}
+
+// numericEqualityQuery a numeric equality query for the given value and field
+func numericEqualityQuery(value int64, field string) *query.NumericRangeQuery {
+	f := float64(value)
+	tru := true
+	q := bleve.NewNumericRangeInclusiveQuery(&f, &f, &tru, &tru)
+	q.SetField(field)
+	return q
+}
+
+func newMatchPhraseQuery(matchPhrase, field, analyzer string) *query.MatchPhraseQuery {
+	q := bleve.NewMatchPhraseQuery(matchPhrase)
+	q.FieldVal = field
+	q.Analyzer = analyzer
+	return q
 }