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_fsq.go

@@ -0,0 +1,159 @@
+// 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
+
+// FunctionScoreQuery allows you to modify the score of documents that
+// are retrieved by a query. This can be useful if, for example,
+// a score function is computationally expensive and it is sufficient
+// to compute the score on a filtered set of documents.
+//
+// For more details, see
+// https://www.elastic.co/guide/en/elasticsearch/reference/7.0/query-dsl-function-score-query.html
+type FunctionScoreQuery struct {
+	query      Query
+	filter     Query
+	boost      *float64
+	maxBoost   *float64
+	scoreMode  string
+	boostMode  string
+	filters    []Query
+	scoreFuncs []ScoreFunction
+	minScore   *float64
+}
+
+// NewFunctionScoreQuery creates and initializes a new function score query.
+func NewFunctionScoreQuery() *FunctionScoreQuery {
+	return &FunctionScoreQuery{
+		filters:    make([]Query, 0),
+		scoreFuncs: make([]ScoreFunction, 0),
+	}
+}
+
+// Query sets the query for the function score query.
+func (q *FunctionScoreQuery) Query(query Query) *FunctionScoreQuery {
+	q.query = query
+	return q
+}
+
+// Filter sets the filter for the function score query.
+func (q *FunctionScoreQuery) Filter(filter Query) *FunctionScoreQuery {
+	q.filter = filter
+	return q
+}
+
+// Add adds a score function that will execute on all the documents
+// matching the filter.
+func (q *FunctionScoreQuery) Add(filter Query, scoreFunc ScoreFunction) *FunctionScoreQuery {
+	q.filters = append(q.filters, filter)
+	q.scoreFuncs = append(q.scoreFuncs, scoreFunc)
+	return q
+}
+
+// AddScoreFunc adds a score function that will execute the function on all documents.
+func (q *FunctionScoreQuery) AddScoreFunc(scoreFunc ScoreFunction) *FunctionScoreQuery {
+	q.filters = append(q.filters, nil)
+	q.scoreFuncs = append(q.scoreFuncs, scoreFunc)
+	return q
+}
+
+// ScoreMode defines how results of individual score functions will be aggregated.
+// Can be first, avg, max, sum, min, or multiply.
+func (q *FunctionScoreQuery) ScoreMode(scoreMode string) *FunctionScoreQuery {
+	q.scoreMode = scoreMode
+	return q
+}
+
+// BoostMode defines how the combined result of score functions will
+// influence the final score together with the sub query score.
+func (q *FunctionScoreQuery) BoostMode(boostMode string) *FunctionScoreQuery {
+	q.boostMode = boostMode
+	return q
+}
+
+// MaxBoost is the maximum boost that will be applied by function score.
+func (q *FunctionScoreQuery) MaxBoost(maxBoost float64) *FunctionScoreQuery {
+	q.maxBoost = &maxBoost
+	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 *FunctionScoreQuery) Boost(boost float64) *FunctionScoreQuery {
+	q.boost = &boost
+	return q
+}
+
+// MinScore sets the minimum score.
+func (q *FunctionScoreQuery) MinScore(minScore float64) *FunctionScoreQuery {
+	q.minScore = &minScore
+	return q
+}
+
+// Source returns JSON for the function score query.
+func (q *FunctionScoreQuery) Source() (interface{}, error) {
+	source := make(map[string]interface{})
+	query := make(map[string]interface{})
+	source["function_score"] = query
+
+	if q.query != nil {
+		src, err := q.query.Source()
+		if err != nil {
+			return nil, err
+		}
+		query["query"] = src
+	}
+	if q.filter != nil {
+		src, err := q.filter.Source()
+		if err != nil {
+			return nil, err
+		}
+		query["filter"] = src
+	}
+
+	if len(q.filters) > 0 {
+		funcs := make([]interface{}, len(q.filters))
+		for i, filter := range q.filters {
+			hsh := make(map[string]interface{})
+			if filter != nil {
+				src, err := filter.Source()
+				if err != nil {
+					return nil, err
+				}
+				hsh["filter"] = src
+			}
+			// Weight needs to be serialized on this level.
+			if weight := q.scoreFuncs[i].GetWeight(); weight != nil {
+				hsh["weight"] = weight
+			}
+			// Serialize the score function
+			src, err := q.scoreFuncs[i].Source()
+			if err != nil {
+				return nil, err
+			}
+			hsh[q.scoreFuncs[i].Name()] = src
+			funcs[i] = hsh
+		}
+		query["functions"] = funcs
+	}
+
+	if q.scoreMode != "" {
+		query["score_mode"] = q.scoreMode
+	}
+	if q.boostMode != "" {
+		query["boost_mode"] = q.boostMode
+	}
+	if q.maxBoost != nil {
+		query["max_boost"] = *q.maxBoost
+	}
+	if q.boost != nil {
+		query["boost"] = *q.boost
+	}
+	if q.minScore != nil {
+		query["min_score"] = *q.minScore
+	}
+
+	return source, nil
+}