package index

import (
	"database/sql"
	"encoding/json"
	"strings"
)

// FTSResult 全文搜索结果
type FTSResult struct {
	ID      int64
	Path    string
	Title   string
	Section string
	Rank    float64
}

// CreateFTS 创建 FTS5 虚拟表
func (s *Store) CreateFTS() error {
	_, err := s.db.Exec(`
		CREATE VIRTUAL TABLE IF NOT EXISTS nodes_fts USING fts5(
			title,
			content,
			tags,
			entities,
			content='nodes',
			content_rowid='id'
		)
	`)
	return err
}

// PopulateFTS 填充 FTS 索引
func (s *Store) PopulateFTS() error {
	_, err := s.db.Exec(`
		INSERT INTO nodes_fts(rowid, title, content, tags, entities)
		SELECT id, title, content_fts, tags, entities FROM nodes
	`)
	return err
}

// FTSSearch 全文搜索
func (s *Store) FTSSearch(keywords []string, limit int) ([]FTSResult, error) {
	if len(keywords) == 0 {
		return nil, nil
	}

	// 构建 FTS5 查询
	query := strings.Join(keywords, " OR ")

	rows, err := s.db.Query(`
		SELECT n.id, n.path, n.title, n.section, fts.rank
		FROM nodes_fts fts
		JOIN nodes n ON n.id = fts.rowid
		WHERE nodes_fts MATCH ?
		ORDER BY fts.rank
		LIMIT ?
	`, query, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var results []FTSResult
	for rows.Next() {
		var r FTSResult
		if err := rows.Scan(&r.ID, &r.Path, &r.Title, &r.Section, &r.Rank); err != nil {
			return nil, err
		}
		results = append(results, r)
	}
	return results, nil
}

// GetNodeContent 获取节点内容
func (s *Store) GetNodeContent(id int64) (string, []string, []string, error) {
	var content, tagsJSON, entitiesJSON string
	err := s.db.QueryRow("SELECT content_fts, tags, entities FROM nodes WHERE id = ?", id).
		Scan(&content, &tagsJSON, &entitiesJSON)
	if err == sql.ErrNoRows {
		return "", nil, nil, nil
	}
	if err != nil {
		return "", nil, nil, err
	}

	// 解析 JSON 数组
	var tags, entities []string
	if tagsJSON != "" {
		if err := json.Unmarshal([]byte(tagsJSON), &tags); err != nil {
			tags = nil
		}
	}
	if entitiesJSON != "" {
		if err := json.Unmarshal([]byte(entitiesJSON), &entities); err != nil {
			entities = nil
		}
	}

	return content, tags, entities, nil
}