// Copyright (c) 2024 Mattermost Community Enterprise
// Bleve Search Engine Implementation - Lightweight alternative to Elasticsearch

package searchengine

import (
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/blevesearch/bleve/v2"
	"github.com/blevesearch/bleve/v2/analysis/analyzer/custom"
	"github.com/blevesearch/bleve/v2/analysis/analyzer/keyword"
	"github.com/blevesearch/bleve/v2/analysis/analyzer/standard"
	"github.com/blevesearch/bleve/v2/analysis/lang/cjk"
	"github.com/blevesearch/bleve/v2/analysis/token/lowercase"
	"github.com/blevesearch/bleve/v2/analysis/token/porter"
	"github.com/blevesearch/bleve/v2/analysis/tokenizer/unicode"
	"github.com/blevesearch/bleve/v2/mapping"
	"github.com/blevesearch/bleve/v2/search/query"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/shared/mlog"
	"github.com/mattermost/mattermost/server/public/shared/request"
)

const (
	BleveEngineName    = "bleve"
	BleveEngineVersion = 2

	PostIndexName    = "posts"
	ChannelIndexName = "channels"
	UserIndexName    = "users"
	FileIndexName    = "files"
)

// BleveConfig holds configuration for Bleve search engine
type BleveConfig struct {
	Config func() *model.Config
	Logger mlog.LoggerIFace
}

// BleveSettings holds Bleve-specific settings
type BleveSettings struct {
	IndexDir            string
	EnableIndexing      bool
	EnableSearching     bool
	EnableAutocomplete  bool
	BulkIndexingTimeWindowSeconds int
}

// BleveEngine implements SearchEngineInterface using Bleve
type BleveEngine struct {
	config   func() *model.Config
	logger   mlog.LoggerIFace
	settings *BleveSettings

	postIndex    bleve.Index
	channelIndex bleve.Index
	userIndex    bleve.Index
	fileIndex    bleve.Index

	mutex    sync.RWMutex
	started  bool
}

// Indexed document types
type PostDocument struct {
	ID        string    `json:"id"`
	TeamID    string    `json:"team_id"`
	ChannelID string    `json:"channel_id"`
	UserID    string    `json:"user_id"`
	Message   string    `json:"message"`
	CreateAt  time.Time `json:"create_at"`
	Type      string    `json:"type"`
	Hashtags  string    `json:"hashtags"`
}

type ChannelDocument struct {
	ID          string   `json:"id"`
	TeamID      string   `json:"team_id"`
	Type        string   `json:"type"`
	Name        string   `json:"name"`
	DisplayName string   `json:"display_name"`
	Header      string   `json:"header"`
	Purpose     string   `json:"purpose"`
	UserIDs     []string `json:"user_ids"`
	TeamMemberIDs []string `json:"team_member_ids"`
}

type UserDocument struct {
	ID          string   `json:"id"`
	Username    string   `json:"username"`
	Nickname    string   `json:"nickname"`
	FirstName   string   `json:"first_name"`
	LastName    string   `json:"last_name"`
	Email       string   `json:"email"`
	TeamIDs     []string `json:"team_ids"`
	ChannelIDs  []string `json:"channel_ids"`
	DeleteAt    int64    `json:"delete_at"`
}

type FileDocument struct {
	ID        string    `json:"id"`
	ChannelID string    `json:"channel_id"`
	PostID    string    `json:"post_id"`
	UserID    string    `json:"user_id"`
	Name      string    `json:"name"`
	Extension string    `json:"extension"`
	Content   string    `json:"content"`
	CreateAt  time.Time `json:"create_at"`
}

// NewBleveEngine creates a new Bleve search engine
func NewBleveEngine(cfg *BleveConfig) *BleveEngine {
	return &BleveEngine{
		config: cfg.Config,
		logger: cfg.Logger,
		settings: &BleveSettings{
			IndexDir:           "/var/mattermost/bleve-indexes",
			EnableIndexing:     true,
			EnableSearching:    true,
			EnableAutocomplete: true,
			BulkIndexingTimeWindowSeconds: 60,
		},
	}
}

// Start initializes and starts the Bleve engine
func (b *BleveEngine) Start() *model.AppError {
	b.mutex.Lock()
	defer b.mutex.Unlock()

	if b.started {
		return nil
	}

	// Create index directory if not exists
	if err := os.MkdirAll(b.settings.IndexDir, 0755); err != nil {
		return model.NewAppError("BleveEngine.Start", "searchengine.bleve.create_dir", nil, err.Error(), http.StatusInternalServerError)
	}

	// Open or create indexes
	var err error

	b.postIndex, err = b.openOrCreateIndex(PostIndexName, b.createPostMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.Start", "searchengine.bleve.open_post_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.channelIndex, err = b.openOrCreateIndex(ChannelIndexName, b.createChannelMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.Start", "searchengine.bleve.open_channel_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.userIndex, err = b.openOrCreateIndex(UserIndexName, b.createUserMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.Start", "searchengine.bleve.open_user_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.fileIndex, err = b.openOrCreateIndex(FileIndexName, b.createFileMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.Start", "searchengine.bleve.open_file_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.started = true
	b.logger.Info("Bleve search engine started",
		mlog.String("index_dir", b.settings.IndexDir),
	)

	return nil
}

// Stop closes all indexes
func (b *BleveEngine) Stop() *model.AppError {
	b.mutex.Lock()
	defer b.mutex.Unlock()

	if !b.started {
		return nil
	}

	if b.postIndex != nil {
		b.postIndex.Close()
	}
	if b.channelIndex != nil {
		b.channelIndex.Close()
	}
	if b.userIndex != nil {
		b.userIndex.Close()
	}
	if b.fileIndex != nil {
		b.fileIndex.Close()
	}

	b.started = false
	b.logger.Info("Bleve search engine stopped")

	return nil
}

func (b *BleveEngine) GetFullVersion() string {
	return fmt.Sprintf("%s.%d", BleveEngineName, BleveEngineVersion)
}

func (b *BleveEngine) GetVersion() int {
	return BleveEngineVersion
}

func (b *BleveEngine) GetPlugins() []string {
	return []string{}
}

func (b *BleveEngine) UpdateConfig(cfg *model.Config) {
	// Update settings from config if needed
}

func (b *BleveEngine) GetName() string {
	return BleveEngineName
}

func (b *BleveEngine) IsEnabled() bool {
	return b.settings.EnableIndexing || b.settings.EnableSearching
}

func (b *BleveEngine) IsActive() bool {
	return b.started
}

func (b *BleveEngine) IsIndexingEnabled() bool {
	return b.settings.EnableIndexing
}

func (b *BleveEngine) IsSearchEnabled() bool {
	return b.settings.EnableSearching
}

func (b *BleveEngine) IsAutocompletionEnabled() bool {
	return b.settings.EnableAutocomplete
}

func (b *BleveEngine) IsIndexingSync() bool {
	return true // Bleve indexes synchronously
}

// Post operations
func (b *BleveEngine) IndexPost(post *model.Post, teamId string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.postIndex == nil {
		return model.NewAppError("BleveEngine.IndexPost", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	doc := PostDocument{
		ID:        post.Id,
		TeamID:    teamId,
		ChannelID: post.ChannelId,
		UserID:    post.UserId,
		Message:   post.Message,
		CreateAt:  time.Unix(0, post.CreateAt*int64(time.Millisecond)),
		Type:      post.Type,
		Hashtags:  post.Hashtags,
	}

	if err := b.postIndex.Index(post.Id, doc); err != nil {
		return model.NewAppError("BleveEngine.IndexPost", "searchengine.bleve.index_post", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) SearchPosts(channels model.ChannelList, searchParams []*model.SearchParams, page, perPage int) ([]string, model.PostSearchMatches, *model.AppError) {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.postIndex == nil {
		return nil, nil, model.NewAppError("BleveEngine.SearchPosts", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	// Build channel ID filter
	channelIDs := make([]string, len(channels))
	for i, ch := range channels {
		channelIDs[i] = ch.Id
	}

	// Build query from search params
	queries := []query.Query{}

	for _, params := range searchParams {
		// Main terms query
		if params.Terms != "" {
			terms := strings.Fields(params.Terms)
			for _, term := range terms {
				if params.IsHashtag {
					// Hashtag search
					q := bleve.NewTermQuery(term)
					q.SetField("hashtags")
					queries = append(queries, q)
				} else {
					// Full text search
					q := bleve.NewMatchQuery(term)
					q.SetField("message")
					queries = append(queries, q)
				}
			}
		}

		// Channel filter
		if len(params.InChannels) > 0 {
			for _, ch := range params.InChannels {
				q := bleve.NewTermQuery(ch)
				q.SetField("channel_id")
				queries = append(queries, q)
			}
		}

		// User filter
		if len(params.FromUsers) > 0 {
			for _, user := range params.FromUsers {
				q := bleve.NewTermQuery(user)
				q.SetField("user_id")
				queries = append(queries, q)
			}
		}
	}

	// Must be in allowed channels
	channelQueries := make([]query.Query, len(channelIDs))
	for i, chID := range channelIDs {
		q := bleve.NewTermQuery(chID)
		q.SetField("channel_id")
		channelQueries[i] = q
	}
	channelFilter := bleve.NewDisjunctionQuery(channelQueries...)

	// Combine all queries
	var finalQuery query.Query
	if len(queries) > 0 {
		mainQuery := bleve.NewConjunctionQuery(queries...)
		finalQuery = bleve.NewConjunctionQuery(mainQuery, channelFilter)
	} else {
		finalQuery = channelFilter
	}

	// Execute search
	searchRequest := bleve.NewSearchRequestOptions(finalQuery, perPage, page*perPage, false)
	searchRequest.SortBy([]string{"-create_at"})

	result, err := b.postIndex.Search(searchRequest)
	if err != nil {
		return nil, nil, model.NewAppError("BleveEngine.SearchPosts", "searchengine.bleve.search_posts", nil, err.Error(), http.StatusInternalServerError)
	}

	// Extract post IDs
	postIDs := make([]string, len(result.Hits))
	matches := make(model.PostSearchMatches)

	for i, hit := range result.Hits {
		postIDs[i] = hit.ID
		// Add match info if available
		if len(hit.Fragments) > 0 {
			matches[hit.ID] = hit.Fragments["message"]
		}
	}

	return postIDs, matches, nil
}

func (b *BleveEngine) DeletePost(post *model.Post) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.postIndex == nil {
		return nil
	}

	if err := b.postIndex.Delete(post.Id); err != nil {
		return model.NewAppError("BleveEngine.DeletePost", "searchengine.bleve.delete_post", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) DeleteChannelPosts(rctx request.CTX, channelID string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.postIndex == nil {
		return nil
	}

	// Find all posts in channel
	q := bleve.NewTermQuery(channelID)
	q.SetField("channel_id")
	searchRequest := bleve.NewSearchRequest(q)
	searchRequest.Size = 10000

	result, err := b.postIndex.Search(searchRequest)
	if err != nil {
		return model.NewAppError("BleveEngine.DeleteChannelPosts", "searchengine.bleve.search_channel_posts", nil, err.Error(), http.StatusInternalServerError)
	}

	// Delete each post
	batch := b.postIndex.NewBatch()
	for _, hit := range result.Hits {
		batch.Delete(hit.ID)
	}

	if err := b.postIndex.Batch(batch); err != nil {
		return model.NewAppError("BleveEngine.DeleteChannelPosts", "searchengine.bleve.delete_channel_posts", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) DeleteUserPosts(rctx request.CTX, userID string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.postIndex == nil {
		return nil
	}

	// Find all posts by user
	q := bleve.NewTermQuery(userID)
	q.SetField("user_id")
	searchRequest := bleve.NewSearchRequest(q)
	searchRequest.Size = 10000

	result, err := b.postIndex.Search(searchRequest)
	if err != nil {
		return model.NewAppError("BleveEngine.DeleteUserPosts", "searchengine.bleve.search_user_posts", nil, err.Error(), http.StatusInternalServerError)
	}

	// Delete each post
	batch := b.postIndex.NewBatch()
	for _, hit := range result.Hits {
		batch.Delete(hit.ID)
	}

	if err := b.postIndex.Batch(batch); err != nil {
		return model.NewAppError("BleveEngine.DeleteUserPosts", "searchengine.bleve.delete_user_posts", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

// Channel operations
func (b *BleveEngine) IndexChannel(rctx request.CTX, channel *model.Channel, userIDs, teamMemberIDs []string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.channelIndex == nil {
		return nil
	}

	doc := ChannelDocument{
		ID:            channel.Id,
		TeamID:        channel.TeamId,
		Type:          string(channel.Type),
		Name:          channel.Name,
		DisplayName:   channel.DisplayName,
		Header:        channel.Header,
		Purpose:       channel.Purpose,
		UserIDs:       userIDs,
		TeamMemberIDs: teamMemberIDs,
	}

	if err := b.channelIndex.Index(channel.Id, doc); err != nil {
		return model.NewAppError("BleveEngine.IndexChannel", "searchengine.bleve.index_channel", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) SyncBulkIndexChannels(rctx request.CTX, channels []*model.Channel, getUserIDsForChannel func(channel *model.Channel) ([]string, error), teamMemberIDs []string) *model.AppError {
	for _, channel := range channels {
		userIDs, _ := getUserIDsForChannel(channel)
		if err := b.IndexChannel(rctx, channel, userIDs, teamMemberIDs); err != nil {
			return err
		}
	}
	return nil
}

func (b *BleveEngine) SearchChannels(teamId, userID, term string, isGuest, includeDeleted bool) ([]string, *model.AppError) {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.channelIndex == nil {
		return nil, model.NewAppError("BleveEngine.SearchChannels", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	queries := []query.Query{}

	// Team filter
	if teamId != "" {
		q := bleve.NewTermQuery(teamId)
		q.SetField("team_id")
		queries = append(queries, q)
	}

	// Search term
	if term != "" {
		// Search in name and display_name
		nameQuery := bleve.NewMatchQuery(term)
		nameQuery.SetField("name")

		displayQuery := bleve.NewMatchQuery(term)
		displayQuery.SetField("display_name")

		termQuery := bleve.NewDisjunctionQuery(nameQuery, displayQuery)
		queries = append(queries, termQuery)
	}

	// For guests, filter by user_ids containing the user
	if isGuest && userID != "" {
		q := bleve.NewTermQuery(userID)
		q.SetField("user_ids")
		queries = append(queries, q)
	}

	var finalQuery query.Query
	if len(queries) > 0 {
		finalQuery = bleve.NewConjunctionQuery(queries...)
	} else {
		finalQuery = bleve.NewMatchAllQuery()
	}

	searchRequest := bleve.NewSearchRequest(finalQuery)
	searchRequest.Size = 100

	result, err := b.channelIndex.Search(searchRequest)
	if err != nil {
		return nil, model.NewAppError("BleveEngine.SearchChannels", "searchengine.bleve.search_channels", nil, err.Error(), http.StatusInternalServerError)
	}

	channelIDs := make([]string, len(result.Hits))
	for i, hit := range result.Hits {
		channelIDs[i] = hit.ID
	}

	return channelIDs, nil
}

func (b *BleveEngine) DeleteChannel(channel *model.Channel) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.channelIndex == nil {
		return nil
	}

	if err := b.channelIndex.Delete(channel.Id); err != nil {
		return model.NewAppError("BleveEngine.DeleteChannel", "searchengine.bleve.delete_channel", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

// User operations
func (b *BleveEngine) IndexUser(rctx request.CTX, user *model.User, teamsIds, channelsIds []string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.userIndex == nil {
		return nil
	}

	doc := UserDocument{
		ID:         user.Id,
		Username:   user.Username,
		Nickname:   user.Nickname,
		FirstName:  user.FirstName,
		LastName:   user.LastName,
		Email:      user.Email,
		TeamIDs:    teamsIds,
		ChannelIDs: channelsIds,
		DeleteAt:   user.DeleteAt,
	}

	if err := b.userIndex.Index(user.Id, doc); err != nil {
		return model.NewAppError("BleveEngine.IndexUser", "searchengine.bleve.index_user", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) SearchUsersInChannel(teamId, channelId string, restrictedToChannels []string, term string, options *model.UserSearchOptions) ([]string, []string, *model.AppError) {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.userIndex == nil {
		return nil, nil, model.NewAppError("BleveEngine.SearchUsersInChannel", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	queries := []query.Query{}

	// Channel filter
	if channelId != "" {
		q := bleve.NewTermQuery(channelId)
		q.SetField("channel_ids")
		queries = append(queries, q)
	}

	// Search term
	if term != "" {
		termQueries := []query.Query{}

		usernameQuery := bleve.NewPrefixQuery(strings.ToLower(term))
		usernameQuery.SetField("username")
		termQueries = append(termQueries, usernameQuery)

		nicknameQuery := bleve.NewMatchQuery(term)
		nicknameQuery.SetField("nickname")
		termQueries = append(termQueries, nicknameQuery)

		firstQuery := bleve.NewMatchQuery(term)
		firstQuery.SetField("first_name")
		termQueries = append(termQueries, firstQuery)

		lastQuery := bleve.NewMatchQuery(term)
		lastQuery.SetField("last_name")
		termQueries = append(termQueries, lastQuery)

		queries = append(queries, bleve.NewDisjunctionQuery(termQueries...))
	}

	// Exclude deleted users
	if !options.AllowInactive {
		q := bleve.NewNumericRangeQuery(nil, floatPtr(0))
		q.SetField("delete_at")
		queries = append(queries, q)
	}

	var finalQuery query.Query
	if len(queries) > 0 {
		finalQuery = bleve.NewConjunctionQuery(queries...)
	} else {
		finalQuery = bleve.NewMatchAllQuery()
	}

	searchRequest := bleve.NewSearchRequest(finalQuery)
	searchRequest.Size = options.Limit

	result, err := b.userIndex.Search(searchRequest)
	if err != nil {
		return nil, nil, model.NewAppError("BleveEngine.SearchUsersInChannel", "searchengine.bleve.search_users", nil, err.Error(), http.StatusInternalServerError)
	}

	userIDs := make([]string, len(result.Hits))
	for i, hit := range result.Hits {
		userIDs[i] = hit.ID
	}

	// Return same list for both in-channel and out-of-channel for simplicity
	return userIDs, nil, nil
}

func (b *BleveEngine) SearchUsersInTeam(teamId string, restrictedToChannels []string, term string, options *model.UserSearchOptions) ([]string, *model.AppError) {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.userIndex == nil {
		return nil, model.NewAppError("BleveEngine.SearchUsersInTeam", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	queries := []query.Query{}

	// Team filter
	if teamId != "" {
		q := bleve.NewTermQuery(teamId)
		q.SetField("team_ids")
		queries = append(queries, q)
	}

	// Search term
	if term != "" {
		termQueries := []query.Query{}

		usernameQuery := bleve.NewPrefixQuery(strings.ToLower(term))
		usernameQuery.SetField("username")
		termQueries = append(termQueries, usernameQuery)

		nicknameQuery := bleve.NewMatchQuery(term)
		nicknameQuery.SetField("nickname")
		termQueries = append(termQueries, nicknameQuery)

		firstQuery := bleve.NewMatchQuery(term)
		firstQuery.SetField("first_name")
		termQueries = append(termQueries, firstQuery)

		lastQuery := bleve.NewMatchQuery(term)
		lastQuery.SetField("last_name")
		termQueries = append(termQueries, lastQuery)

		queries = append(queries, bleve.NewDisjunctionQuery(termQueries...))
	}

	var finalQuery query.Query
	if len(queries) > 0 {
		finalQuery = bleve.NewConjunctionQuery(queries...)
	} else {
		finalQuery = bleve.NewMatchAllQuery()
	}

	searchRequest := bleve.NewSearchRequest(finalQuery)
	searchRequest.Size = options.Limit

	result, err := b.userIndex.Search(searchRequest)
	if err != nil {
		return nil, model.NewAppError("BleveEngine.SearchUsersInTeam", "searchengine.bleve.search_users", nil, err.Error(), http.StatusInternalServerError)
	}

	userIDs := make([]string, len(result.Hits))
	for i, hit := range result.Hits {
		userIDs[i] = hit.ID
	}

	return userIDs, nil
}

func (b *BleveEngine) DeleteUser(user *model.User) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.userIndex == nil {
		return nil
	}

	if err := b.userIndex.Delete(user.Id); err != nil {
		return model.NewAppError("BleveEngine.DeleteUser", "searchengine.bleve.delete_user", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

// File operations
func (b *BleveEngine) IndexFile(file *model.FileInfo, channelId string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil
	}

	doc := FileDocument{
		ID:        file.Id,
		ChannelID: channelId,
		PostID:    file.PostId,
		UserID:    file.CreatorId,
		Name:      file.Name,
		Extension: file.Extension,
		Content:   file.Content,
		CreateAt:  time.Unix(0, file.CreateAt*int64(time.Millisecond)),
	}

	if err := b.fileIndex.Index(file.Id, doc); err != nil {
		return model.NewAppError("BleveEngine.IndexFile", "searchengine.bleve.index_file", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) SearchFiles(channels model.ChannelList, searchParams []*model.SearchParams, page, perPage int) ([]string, *model.AppError) {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil, model.NewAppError("BleveEngine.SearchFiles", "searchengine.bleve.not_started", nil, "", http.StatusServiceUnavailable)
	}

	// Build channel ID filter
	channelIDs := make([]string, len(channels))
	for i, ch := range channels {
		channelIDs[i] = ch.Id
	}

	queries := []query.Query{}

	for _, params := range searchParams {
		if params.Terms != "" {
			terms := strings.Fields(params.Terms)
			for _, term := range terms {
				// Search in name and content
				nameQuery := bleve.NewMatchQuery(term)
				nameQuery.SetField("name")

				contentQuery := bleve.NewMatchQuery(term)
				contentQuery.SetField("content")

				queries = append(queries, bleve.NewDisjunctionQuery(nameQuery, contentQuery))
			}
		}

		// Extension filter
		if len(params.Extensions) > 0 {
			extQueries := make([]query.Query, len(params.Extensions))
			for i, ext := range params.Extensions {
				q := bleve.NewTermQuery(ext)
				q.SetField("extension")
				extQueries[i] = q
			}
			queries = append(queries, bleve.NewDisjunctionQuery(extQueries...))
		}
	}

	// Channel filter
	channelQueries := make([]query.Query, len(channelIDs))
	for i, chID := range channelIDs {
		q := bleve.NewTermQuery(chID)
		q.SetField("channel_id")
		channelQueries[i] = q
	}
	channelFilter := bleve.NewDisjunctionQuery(channelQueries...)

	var finalQuery query.Query
	if len(queries) > 0 {
		mainQuery := bleve.NewConjunctionQuery(queries...)
		finalQuery = bleve.NewConjunctionQuery(mainQuery, channelFilter)
	} else {
		finalQuery = channelFilter
	}

	searchRequest := bleve.NewSearchRequestOptions(finalQuery, perPage, page*perPage, false)
	searchRequest.SortBy([]string{"-create_at"})

	result, err := b.fileIndex.Search(searchRequest)
	if err != nil {
		return nil, model.NewAppError("BleveEngine.SearchFiles", "searchengine.bleve.search_files", nil, err.Error(), http.StatusInternalServerError)
	}

	fileIDs := make([]string, len(result.Hits))
	for i, hit := range result.Hits {
		fileIDs[i] = hit.ID
	}

	return fileIDs, nil
}

func (b *BleveEngine) DeleteFile(fileID string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil
	}

	if err := b.fileIndex.Delete(fileID); err != nil {
		return model.NewAppError("BleveEngine.DeleteFile", "searchengine.bleve.delete_file", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) DeletePostFiles(rctx request.CTX, postID string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil
	}

	q := bleve.NewTermQuery(postID)
	q.SetField("post_id")
	searchRequest := bleve.NewSearchRequest(q)
	searchRequest.Size = 1000

	result, err := b.fileIndex.Search(searchRequest)
	if err != nil {
		return model.NewAppError("BleveEngine.DeletePostFiles", "searchengine.bleve.search_post_files", nil, err.Error(), http.StatusInternalServerError)
	}

	batch := b.fileIndex.NewBatch()
	for _, hit := range result.Hits {
		batch.Delete(hit.ID)
	}

	if err := b.fileIndex.Batch(batch); err != nil {
		return model.NewAppError("BleveEngine.DeletePostFiles", "searchengine.bleve.delete_post_files", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) DeleteUserFiles(rctx request.CTX, userID string) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil
	}

	q := bleve.NewTermQuery(userID)
	q.SetField("user_id")
	searchRequest := bleve.NewSearchRequest(q)
	searchRequest.Size = 10000

	result, err := b.fileIndex.Search(searchRequest)
	if err != nil {
		return model.NewAppError("BleveEngine.DeleteUserFiles", "searchengine.bleve.search_user_files", nil, err.Error(), http.StatusInternalServerError)
	}

	batch := b.fileIndex.NewBatch()
	for _, hit := range result.Hits {
		batch.Delete(hit.ID)
	}

	if err := b.fileIndex.Batch(batch); err != nil {
		return model.NewAppError("BleveEngine.DeleteUserFiles", "searchengine.bleve.delete_user_files", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

func (b *BleveEngine) DeleteFilesBatch(rctx request.CTX, endTime, limit int64) *model.AppError {
	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if !b.started || b.fileIndex == nil {
		return nil
	}

	endTimeFloat := float64(endTime)
	q := bleve.NewNumericRangeQuery(nil, &endTimeFloat)
	q.SetField("create_at")
	searchRequest := bleve.NewSearchRequest(q)
	searchRequest.Size = int(limit)

	result, err := b.fileIndex.Search(searchRequest)
	if err != nil {
		return model.NewAppError("BleveEngine.DeleteFilesBatch", "searchengine.bleve.search_files_batch", nil, err.Error(), http.StatusInternalServerError)
	}

	batch := b.fileIndex.NewBatch()
	for _, hit := range result.Hits {
		batch.Delete(hit.ID)
	}

	if err := b.fileIndex.Batch(batch); err != nil {
		return model.NewAppError("BleveEngine.DeleteFilesBatch", "searchengine.bleve.delete_files_batch", nil, err.Error(), http.StatusInternalServerError)
	}

	return nil
}

// Admin operations
func (b *BleveEngine) TestConfig(rctx request.CTX, cfg *model.Config) *model.AppError {
	// Test if we can create/access the index directory
	testDir := b.settings.IndexDir
	if err := os.MkdirAll(testDir, 0755); err != nil {
		return model.NewAppError("BleveEngine.TestConfig", "searchengine.bleve.test_config", nil, err.Error(), http.StatusInternalServerError)
	}
	return nil
}

func (b *BleveEngine) PurgeIndexes(rctx request.CTX) *model.AppError {
	b.mutex.Lock()
	defer b.mutex.Unlock()

	// Close existing indexes
	if b.postIndex != nil {
		b.postIndex.Close()
	}
	if b.channelIndex != nil {
		b.channelIndex.Close()
	}
	if b.userIndex != nil {
		b.userIndex.Close()
	}
	if b.fileIndex != nil {
		b.fileIndex.Close()
	}

	// Remove index directories
	indexes := []string{PostIndexName, ChannelIndexName, UserIndexName, FileIndexName}
	for _, idx := range indexes {
		indexPath := filepath.Join(b.settings.IndexDir, idx+".bleve")
		if err := os.RemoveAll(indexPath); err != nil {
			b.logger.Warn("Failed to remove index directory",
				mlog.String("index", idx),
				mlog.Err(err),
			)
		}
	}

	// Recreate indexes
	var err error
	b.postIndex, err = b.openOrCreateIndex(PostIndexName, b.createPostMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.PurgeIndexes", "searchengine.bleve.recreate_post_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.channelIndex, err = b.openOrCreateIndex(ChannelIndexName, b.createChannelMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.PurgeIndexes", "searchengine.bleve.recreate_channel_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.userIndex, err = b.openOrCreateIndex(UserIndexName, b.createUserMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.PurgeIndexes", "searchengine.bleve.recreate_user_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.fileIndex, err = b.openOrCreateIndex(FileIndexName, b.createFileMapping())
	if err != nil {
		return model.NewAppError("BleveEngine.PurgeIndexes", "searchengine.bleve.recreate_file_index", nil, err.Error(), http.StatusInternalServerError)
	}

	b.logger.Info("Purged all Bleve indexes")
	return nil
}

func (b *BleveEngine) PurgeIndexList(rctx request.CTX, indexes []string) *model.AppError {
	// For Bleve, we just purge all indexes
	return b.PurgeIndexes(rctx)
}

func (b *BleveEngine) RefreshIndexes(rctx request.CTX) *model.AppError {
	// Bleve doesn't need explicit refresh like Elasticsearch
	return nil
}

func (b *BleveEngine) DataRetentionDeleteIndexes(rctx request.CTX, cutoff time.Time) *model.AppError {
	// Delete posts before cutoff
	cutoffMs := cutoff.UnixMilli()
	cutoffFloat := float64(cutoffMs)

	b.mutex.RLock()
	defer b.mutex.RUnlock()

	if b.postIndex != nil {
		q := bleve.NewNumericRangeQuery(nil, &cutoffFloat)
		q.SetField("create_at")
		searchRequest := bleve.NewSearchRequest(q)
		searchRequest.Size = 10000

		result, err := b.postIndex.Search(searchRequest)
		if err == nil {
			batch := b.postIndex.NewBatch()
			for _, hit := range result.Hits {
				batch.Delete(hit.ID)
			}
			b.postIndex.Batch(batch)
		}
	}

	if b.fileIndex != nil {
		q := bleve.NewNumericRangeQuery(nil, &cutoffFloat)
		q.SetField("create_at")
		searchRequest := bleve.NewSearchRequest(q)
		searchRequest.Size = 10000

		result, err := b.fileIndex.Search(searchRequest)
		if err == nil {
			batch := b.fileIndex.NewBatch()
			for _, hit := range result.Hits {
				batch.Delete(hit.ID)
			}
			b.fileIndex.Batch(batch)
		}
	}

	b.logger.Info("Data retention delete completed",
		mlog.Time("cutoff", cutoff),
	)

	return nil
}

// Helper functions
func (b *BleveEngine) openOrCreateIndex(name string, indexMapping mapping.IndexMapping) (bleve.Index, error) {
	indexPath := filepath.Join(b.settings.IndexDir, name+".bleve")

	// Try to open existing index
	index, err := bleve.Open(indexPath)
	if err == nil {
		return index, nil
	}

	// Create new index
	return bleve.New(indexPath, indexMapping)
}

func (b *BleveEngine) createPostMapping() mapping.IndexMapping {
	// Create custom analyzer for multilingual support
	indexMapping := bleve.NewIndexMapping()

	// Register CJK analyzer
	err := indexMapping.AddCustomAnalyzer("multilingual", map[string]interface{}{
		"type":      custom.Name,
		"tokenizer": unicode.Name,
		"token_filters": []string{
			cjk.BigramName,
			lowercase.Name,
			porter.Name,
		},
	})
	if err != nil {
		b.logger.Warn("Failed to add multilingual analyzer", mlog.Err(err))
	}

	postMapping := bleve.NewDocumentMapping()

	// ID field - keyword
	idField := bleve.NewTextFieldMapping()
	idField.Analyzer = keyword.Name
	postMapping.AddFieldMappingsAt("id", idField)

	// Team ID - keyword
	teamField := bleve.NewTextFieldMapping()
	teamField.Analyzer = keyword.Name
	postMapping.AddFieldMappingsAt("team_id", teamField)

	// Channel ID - keyword
	channelField := bleve.NewTextFieldMapping()
	channelField.Analyzer = keyword.Name
	postMapping.AddFieldMappingsAt("channel_id", channelField)

	// User ID - keyword
	userField := bleve.NewTextFieldMapping()
	userField.Analyzer = keyword.Name
	postMapping.AddFieldMappingsAt("user_id", userField)

	// Message - full text with multilingual support
	messageField := bleve.NewTextFieldMapping()
	messageField.Analyzer = standard.Name
	messageField.Store = true
	messageField.IncludeTermVectors = true
	postMapping.AddFieldMappingsAt("message", messageField)

	// Hashtags
	hashtagField := bleve.NewTextFieldMapping()
	hashtagField.Analyzer = keyword.Name
	postMapping.AddFieldMappingsAt("hashtags", hashtagField)

	// Create time - date
	createField := bleve.NewDateTimeFieldMapping()
	postMapping.AddFieldMappingsAt("create_at", createField)

	indexMapping.AddDocumentMapping("post", postMapping)
	indexMapping.DefaultMapping = postMapping

	return indexMapping
}

func (b *BleveEngine) createChannelMapping() mapping.IndexMapping {
	indexMapping := bleve.NewIndexMapping()

	channelMapping := bleve.NewDocumentMapping()

	// ID field
	idField := bleve.NewTextFieldMapping()
	idField.Analyzer = keyword.Name
	channelMapping.AddFieldMappingsAt("id", idField)

	// Team ID
	teamField := bleve.NewTextFieldMapping()
	teamField.Analyzer = keyword.Name
	channelMapping.AddFieldMappingsAt("team_id", teamField)

	// Type
	typeField := bleve.NewTextFieldMapping()
	typeField.Analyzer = keyword.Name
	channelMapping.AddFieldMappingsAt("type", typeField)

	// Name - text search
	nameField := bleve.NewTextFieldMapping()
	nameField.Analyzer = standard.Name
	channelMapping.AddFieldMappingsAt("name", nameField)

	// Display name - text search
	displayField := bleve.NewTextFieldMapping()
	displayField.Analyzer = standard.Name
	channelMapping.AddFieldMappingsAt("display_name", displayField)

	// User IDs - for private channel access
	userIDsField := bleve.NewTextFieldMapping()
	userIDsField.Analyzer = keyword.Name
	channelMapping.AddFieldMappingsAt("user_ids", userIDsField)

	indexMapping.AddDocumentMapping("channel", channelMapping)
	indexMapping.DefaultMapping = channelMapping

	return indexMapping
}

func (b *BleveEngine) createUserMapping() mapping.IndexMapping {
	indexMapping := bleve.NewIndexMapping()

	userMapping := bleve.NewDocumentMapping()

	// ID
	idField := bleve.NewTextFieldMapping()
	idField.Analyzer = keyword.Name
	userMapping.AddFieldMappingsAt("id", idField)

	// Username - both keyword and prefix search
	usernameField := bleve.NewTextFieldMapping()
	usernameField.Analyzer = standard.Name
	userMapping.AddFieldMappingsAt("username", usernameField)

	// Nickname
	nicknameField := bleve.NewTextFieldMapping()
	nicknameField.Analyzer = standard.Name
	userMapping.AddFieldMappingsAt("nickname", nicknameField)

	// First name
	firstField := bleve.NewTextFieldMapping()
	firstField.Analyzer = standard.Name
	userMapping.AddFieldMappingsAt("first_name", firstField)

	// Last name
	lastField := bleve.NewTextFieldMapping()
	lastField.Analyzer = standard.Name
	userMapping.AddFieldMappingsAt("last_name", lastField)

	// Team IDs
	teamField := bleve.NewTextFieldMapping()
	teamField.Analyzer = keyword.Name
	userMapping.AddFieldMappingsAt("team_ids", teamField)

	// Channel IDs
	channelField := bleve.NewTextFieldMapping()
	channelField.Analyzer = keyword.Name
	userMapping.AddFieldMappingsAt("channel_ids", channelField)

	// Delete at - numeric for filtering active users
	deleteField := bleve.NewNumericFieldMapping()
	userMapping.AddFieldMappingsAt("delete_at", deleteField)

	indexMapping.AddDocumentMapping("user", userMapping)
	indexMapping.DefaultMapping = userMapping

	return indexMapping
}

func (b *BleveEngine) createFileMapping() mapping.IndexMapping {
	indexMapping := bleve.NewIndexMapping()

	fileMapping := bleve.NewDocumentMapping()

	// ID
	idField := bleve.NewTextFieldMapping()
	idField.Analyzer = keyword.Name
	fileMapping.AddFieldMappingsAt("id", idField)

	// Channel ID
	channelField := bleve.NewTextFieldMapping()
	channelField.Analyzer = keyword.Name
	fileMapping.AddFieldMappingsAt("channel_id", channelField)

	// Post ID
	postField := bleve.NewTextFieldMapping()
	postField.Analyzer = keyword.Name
	fileMapping.AddFieldMappingsAt("post_id", postField)

	// User ID
	userField := bleve.NewTextFieldMapping()
	userField.Analyzer = keyword.Name
	fileMapping.AddFieldMappingsAt("user_id", userField)

	// Name - text search
	nameField := bleve.NewTextFieldMapping()
	nameField.Analyzer = standard.Name
	fileMapping.AddFieldMappingsAt("name", nameField)

	// Extension
	extField := bleve.NewTextFieldMapping()
	extField.Analyzer = keyword.Name
	fileMapping.AddFieldMappingsAt("extension", extField)

	// Content - full text
	contentField := bleve.NewTextFieldMapping()
	contentField.Analyzer = standard.Name
	fileMapping.AddFieldMappingsAt("content", contentField)

	// Create time
	createField := bleve.NewDateTimeFieldMapping()
	fileMapping.AddFieldMappingsAt("create_at", createField)

	indexMapping.AddDocumentMapping("file", fileMapping)
	indexMapping.DefaultMapping = fileMapping

	return indexMapping
}

func floatPtr(f float64) *float64 {
	return &f
}