Make meilisearch do exact search for issues (#29740 & #29671) (#29846)

Backport https://github.com/go-gitea/gitea/pull/29740 (based on #29671
...)

(cherry picked from commit 0cbbcf20e3f83413a88fe3d436451d707639fe55)

modules/indexer/issues/meilisearch/meilisearch.go

@@ -5,6 +5,7 @@ package meilisearch
 
 import (
 	"context"
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -210,7 +211,11 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 
 	skip, limit := indexer_internal.ParsePaginator(options.Paginator, maxTotalHits)
 
-	searchRes, err := b.inner.Client.Index(b.inner.VersionedIndexName()).Search(options.Keyword, &meilisearch.SearchRequest{
+	// to make it non fuzzy ("typo tolerance" in meilisearch terms), we have to quote the keyword(s)
+	// https://www.meilisearch.com/docs/reference/api/search#phrase-search
+	keyword := doubleQuoteKeyword(options.Keyword)
+
+	searchRes, err := b.inner.Client.Index(b.inner.VersionedIndexName()).Search(keyword, &meilisearch.SearchRequest{
 		Filter:           query.Statement(),
 		Limit:            int64(limit),
 		Offset:           int64(skip),
@@ -241,3 +246,16 @@ func parseSortBy(sortBy internal.SortBy) string {
 	}
 	return field + ":asc"
 }
+
+func doubleQuoteKeyword(k string) string {
+	kp := strings.Split(k, " ")
+	parts := 0
+	for i := range kp {
+		part := strings.Trim(kp[i], "\"")
+		if part != "" {
+			kp[parts] = fmt.Sprintf(`"%s"`, part)
+			parts++
+		}
+	}
+	return strings.Join(kp[:parts], " ")
+}

modules/indexer/issues/meilisearch/meilisearch_test.go

@@ -11,6 +11,8 @@ import (
 	"time"
 
 	"code.gitea.io/gitea/modules/indexer/issues/internal/tests"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestMeilisearchIndexer(t *testing.T) {
@@ -49,3 +51,11 @@ func TestMeilisearchIndexer(t *testing.T) {
 
 	tests.TestIndexer(t, indexer)
 }
+
+func TestDoubleQuoteKeyword(t *testing.T) {
+	assert.EqualValues(t, "", doubleQuoteKeyword(""))
+	assert.EqualValues(t, `"a" "b" "c"`, doubleQuoteKeyword("a b c"))
+	assert.EqualValues(t, `"a" "d" "g"`, doubleQuoteKeyword("a  d g"))
+	assert.EqualValues(t, `"a" "d" "g"`, doubleQuoteKeyword("a  d g"))
+	assert.EqualValues(t, `"a" "d" "g"`, doubleQuoteKeyword(`a  "" "d" """g`))
+}