// Copyright 2012-2015 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

// FiltersAggregation defines a multi bucket aggregations where each bucket
// is associated with a filter. Each bucket will collect all documents that
// match its associated filter.
// See: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-aggregations-bucket-filters-aggregation.html
type FiltersAggregation struct {
	filters         []Query
	subAggregations map[string]Aggregation
	meta            map[string]interface{}
}

func NewFiltersAggregation() *FiltersAggregation {
	return &FiltersAggregation{
		filters:         make([]Query, 0),
		subAggregations: make(map[string]Aggregation),
	}
}

func (a *FiltersAggregation) Filter(filter Query) *FiltersAggregation {
	a.filters = append(a.filters, filter)
	return a
}

func (a *FiltersAggregation) Filters(filters ...Query) *FiltersAggregation {
	if len(filters) > 0 {
		a.filters = append(a.filters, filters...)
	}
	return a
}

func (a *FiltersAggregation) SubAggregation(name string, subAggregation Aggregation) *FiltersAggregation {
	a.subAggregations[name] = subAggregation
	return a
}

// Meta sets the meta data to be included in the aggregation response.
func (a *FiltersAggregation) Meta(metaData map[string]interface{}) *FiltersAggregation {
	a.meta = metaData
	return a
}

func (a *FiltersAggregation) Source() (interface{}, error) {
	// Example:
	//	{
	//  "aggs" : {
	//    "messages" : {
	//      "filters" : {
	//        "filters" : {
	//          "errors" :   { "term" : { "body" : "error"   }},
	//          "warnings" : { "term" : { "body" : "warning" }}
	//        }
	//      }
	//    }
	//  }
	//	}
	// This method returns only the (outer) { "filters" : {} } part.

	source := make(map[string]interface{})
	filters := make(map[string]interface{})
	source["filters"] = filters

	arr := make([]interface{}, len(a.filters))
	for i, filter := range a.filters {
		src, err := filter.Source()
		if err != nil {
			return nil, err
		}
		arr[i] = src
	}
	filters["filters"] = arr

	// AggregationBuilder (SubAggregations)
	if len(a.subAggregations) > 0 {
		aggsMap := make(map[string]interface{})
		source["aggregations"] = aggsMap
		for name, aggregate := range a.subAggregations {
			src, err := aggregate.Source()
			if err != nil {
				return nil, err
			}
			aggsMap[name] = src
		}
	}

	// Add Meta data if available
	if len(a.meta) > 0 {
		source["meta"] = a.meta
	}

	return source, nil
}