Issue search support elasticsearch (#9428)

* Issue search support elasticsearch

* Fix lint

* Add indexer name on app.ini

* add a warnning on SearchIssuesByKeyword

* improve code

vendor/github.com/olivere/elastic/v7/search_queries_fuzzy.go

@@ -0,0 +1,120 @@
+// Copyright 2012-present Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+// FuzzyQuery uses similarity based on Levenshtein edit distance for
+// string fields, and a +/- margin on numeric and date fields.
+//
+// For more details, see
+// https://www.elastic.co/guide/en/elasticsearch/reference/7.0/query-dsl-fuzzy-query.html
+type FuzzyQuery struct {
+	name           string
+	value          interface{}
+	boost          *float64
+	fuzziness      interface{}
+	prefixLength   *int
+	maxExpansions  *int
+	transpositions *bool
+	rewrite        string
+	queryName      string
+}
+
+// NewFuzzyQuery creates a new fuzzy query.
+func NewFuzzyQuery(name string, value interface{}) *FuzzyQuery {
+	q := &FuzzyQuery{
+		name:  name,
+		value: value,
+	}
+	return q
+}
+
+// Boost sets the boost for this query. Documents matching this query will
+// (in addition to the normal weightings) have their score multiplied by
+// the boost provided.
+func (q *FuzzyQuery) Boost(boost float64) *FuzzyQuery {
+	q.boost = &boost
+	return q
+}
+
+// Fuzziness can be an integer/long like 0, 1 or 2 as well as strings
+// like "auto", "0..1", "1..4" or "0.0..1.0".
+func (q *FuzzyQuery) Fuzziness(fuzziness interface{}) *FuzzyQuery {
+	q.fuzziness = fuzziness
+	return q
+}
+
+func (q *FuzzyQuery) PrefixLength(prefixLength int) *FuzzyQuery {
+	q.prefixLength = &prefixLength
+	return q
+}
+
+func (q *FuzzyQuery) MaxExpansions(maxExpansions int) *FuzzyQuery {
+	q.maxExpansions = &maxExpansions
+	return q
+}
+
+func (q *FuzzyQuery) Transpositions(transpositions bool) *FuzzyQuery {
+	q.transpositions = &transpositions
+	return q
+}
+
+func (q *FuzzyQuery) Rewrite(rewrite string) *FuzzyQuery {
+	q.rewrite = rewrite
+	return q
+}
+
+// QueryName sets the query name for the filter that can be used when
+// searching for matched filters per hit.
+func (q *FuzzyQuery) QueryName(queryName string) *FuzzyQuery {
+	q.queryName = queryName
+	return q
+}
+
+// Source returns JSON for the function score query.
+func (q *FuzzyQuery) Source() (interface{}, error) {
+	// {
+	//	"fuzzy" : {
+	//		"user" : {
+	//      "value" : "ki",
+	//      "boost" : 1.0,
+	//      "fuzziness" : 2,
+	//      "prefix_length" : 0,
+	//      "max_expansions" : 100
+	//    }
+	// }
+
+	source := make(map[string]interface{})
+	query := make(map[string]interface{})
+	source["fuzzy"] = query
+
+	fq := make(map[string]interface{})
+	query[q.name] = fq
+
+	fq["value"] = q.value
+
+	if q.boost != nil {
+		fq["boost"] = *q.boost
+	}
+	if q.transpositions != nil {
+		fq["transpositions"] = *q.transpositions
+	}
+	if q.fuzziness != nil {
+		fq["fuzziness"] = q.fuzziness
+	}
+	if q.prefixLength != nil {
+		fq["prefix_length"] = *q.prefixLength
+	}
+	if q.maxExpansions != nil {
+		fq["max_expansions"] = *q.maxExpansions
+	}
+	if q.rewrite != "" {
+		fq["rewrite"] = q.rewrite
+	}
+	if q.queryName != "" {
+		fq["_name"] = q.queryName
+	}
+
+	return source, nil
+}