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/suggest_field.go

@@ -0,0 +1,90 @@
+// 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
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+// SuggestField can be used by the caller to specify a suggest field
+// at index time. For a detailed example, see e.g.
+// https://www.elastic.co/blog/you-complete-me.
+type SuggestField struct {
+	inputs         []string
+	weight         int
+	contextQueries []SuggesterContextQuery
+}
+
+func NewSuggestField(input ...string) *SuggestField {
+	return &SuggestField{
+		inputs: input,
+		weight: -1,
+	}
+}
+
+func (f *SuggestField) Input(input ...string) *SuggestField {
+	if f.inputs == nil {
+		f.inputs = make([]string, 0)
+	}
+	f.inputs = append(f.inputs, input...)
+	return f
+}
+
+func (f *SuggestField) Weight(weight int) *SuggestField {
+	f.weight = weight
+	return f
+}
+
+func (f *SuggestField) ContextQuery(queries ...SuggesterContextQuery) *SuggestField {
+	f.contextQueries = append(f.contextQueries, queries...)
+	return f
+}
+
+// MarshalJSON encodes SuggestField into JSON.
+func (f *SuggestField) MarshalJSON() ([]byte, error) {
+	source := make(map[string]interface{})
+
+	if f.inputs != nil {
+		switch len(f.inputs) {
+		case 1:
+			source["input"] = f.inputs[0]
+		default:
+			source["input"] = f.inputs
+		}
+	}
+
+	if f.weight >= 0 {
+		source["weight"] = f.weight
+	}
+
+	switch len(f.contextQueries) {
+	case 0:
+	case 1:
+		src, err := f.contextQueries[0].Source()
+		if err != nil {
+			return nil, err
+		}
+		source["contexts"] = src
+	default:
+		ctxq := make(map[string]interface{})
+		for _, query := range f.contextQueries {
+			src, err := query.Source()
+			if err != nil {
+				return nil, err
+			}
+			m, ok := src.(map[string]interface{})
+			if !ok {
+				return nil, errors.New("SuggesterContextQuery must be of type map[string]interface{}")
+			}
+			for k, v := range m {
+				ctxq[k] = v
+			}
+		}
+		source["contexts"] = ctxq
+	}
+
+	return json.Marshal(source)
+}