// Copyright 2016 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package indexer

import (
	"os"
	"strconv"

	"code.gitea.io/gitea/modules/setting"

	"github.com/blevesearch/bleve"
	"github.com/blevesearch/bleve/analysis/token/unicodenorm"
	"github.com/blevesearch/bleve/index/upsidedown"
	"github.com/blevesearch/bleve/mapping"
	"github.com/blevesearch/bleve/search/query"
	"github.com/ethantkoenig/rupture"
)

// indexerID a bleve-compatible unique identifier for an integer id
func indexerID(id int64) string {
	return strconv.FormatInt(id, 36)
}

// numericEqualityQuery a numeric equality query for the given value and field
func numericEqualityQuery(value int64, field string) *query.NumericRangeQuery {
	f := float64(value)
	tru := true
	q := bleve.NewNumericRangeInclusiveQuery(&f, &f, &tru, &tru)
	q.SetField(field)
	return q
}

const unicodeNormalizeName = "unicodeNormalize"

func addUnicodeNormalizeTokenFilter(m *mapping.IndexMappingImpl) error {
	return m.AddCustomTokenFilter(unicodeNormalizeName, map[string]interface{}{
		"type": unicodenorm.Name,
		"form": unicodenorm.NFC,
	})
}

const maxBatchSize = 16

// openIndexer open the index at the specified path, checking for metadata
// updates and bleve version updates.  If index needs to be created (or
// re-created), returns (nil, nil)
func openIndexer(path string, latestVersion int) (bleve.Index, error) {
	_, err := os.Stat(setting.Indexer.IssuePath)
	if err != nil && os.IsNotExist(err) {
		return nil, nil
	} else if err != nil {
		return nil, err
	}

	metadata, err := rupture.ReadIndexMetadata(path)
	if err != nil {
		return nil, err
	}
	if metadata.Version < latestVersion {
		// the indexer is using a previous version, so we should delete it and
		// re-populate
		return nil, os.RemoveAll(path)
	}

	index, err := bleve.Open(path)
	if err != nil && err == upsidedown.IncompatibleVersion {
		// the indexer was built with a previous version of bleve, so we should
		// delete it and re-populate
		return nil, os.RemoveAll(path)
	} else if err != nil {
		return nil, err
	}
	return index, nil
}