//  Copyright (c) 2014 Couchbase, Inc.
//  Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
//  except in compliance with the License. You may obtain a copy of the License at
//    http://www.apache.org/licenses/LICENSE-2.0
//  Unless required by applicable law or agreed to in writing, software distributed under the
//  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
//  either express or implied. See the License for the specific language governing permissions
//  and limitations under the License.

package query

import (
	"encoding/json"
	"fmt"

	"github.com/blevesearch/bleve/index"
	"github.com/blevesearch/bleve/mapping"
	"github.com/blevesearch/bleve/search"
	"github.com/blevesearch/bleve/search/searchers"
)

type DisjunctionQuery struct {
	Disjuncts []Query `json:"disjuncts"`
	Boost     *Boost  `json:"boost,omitempty"`
	Min       float64 `json:"min"`
}

// NewDisjunctionQuery creates a new compound Query.
// Result documents satisfy at least one Query.
func NewDisjunctionQuery(disjuncts []Query) *DisjunctionQuery {
	return &DisjunctionQuery{
		Disjuncts: disjuncts,
	}
}

// NewDisjunctionQueryMin creates a new compound Query.
// Result documents satisfy at least min Queries.
func NewDisjunctionQueryMin(disjuncts []Query, min float64) *DisjunctionQuery {
	return &DisjunctionQuery{
		Disjuncts: disjuncts,
		Min:       min,
	}
}

func (q *DisjunctionQuery) SetBoost(b float64) {
	boost := Boost(b)
	q.Boost = &boost
}

func (q *DisjunctionQuery) AddQuery(aq Query) {
	q.Disjuncts = append(q.Disjuncts, aq)
}

func (q *DisjunctionQuery) SetMin(m float64) {
	q.Min = m
}

func (q *DisjunctionQuery) Searcher(i index.IndexReader, m mapping.IndexMapping, explain bool) (search.Searcher, error) {
	ss := make([]search.Searcher, len(q.Disjuncts))
	for in, disjunct := range q.Disjuncts {
		var err error
		ss[in], err = disjunct.Searcher(i, m, explain)
		if err != nil {
			return nil, err
		}
	}
	return searchers.NewDisjunctionSearcher(i, ss, q.Min, explain)
}

func (q *DisjunctionQuery) Validate() error {
	if int(q.Min) > len(q.Disjuncts) {
		return fmt.Errorf("disjunction query has fewer than the minimum number of clauses to satisfy")
	}
	for _, q := range q.Disjuncts {
		if q, ok := q.(ValidatableQuery); ok {
			err := q.Validate()
			if err != nil {
				return err
			}
		}
	}
	return nil
}

func (q *DisjunctionQuery) UnmarshalJSON(data []byte) error {
	tmp := struct {
		Disjuncts []json.RawMessage `json:"disjuncts"`
		Boost     *Boost            `json:"boost,omitempty"`
		Min       float64           `json:"min"`
	}{}
	err := json.Unmarshal(data, &tmp)
	if err != nil {
		return err
	}
	q.Disjuncts = make([]Query, len(tmp.Disjuncts))
	for i, term := range tmp.Disjuncts {
		query, err := ParseQuery(term)
		if err != nil {
			return err
		}
		q.Disjuncts[i] = query
	}
	q.Boost = tmp.Boost
	q.Min = tmp.Min
	return nil
}