package kb

import (
	"context"
	"fmt"
	"strings"

	"github.com/jackc/pgx/v5/pgxpool"
)

// Store PostgreSQL 知识库存储访问层
type Store struct {
	Pool *pgxpool.Pool
}

// NewStore 创建 Store 实例
func NewStore(pool *pgxpool.Pool) *Store {
	return &Store{Pool: pool}
}

// OpenPool 建立 PostgreSQL pgx 连接池
func OpenPool(ctx context.Context, dsn string) (*pgxpool.Pool, error) {
	if strings.TrimSpace(dsn) == "" {
		return nil, fmt.Errorf("empty postgres dsn")
	}
	cfg, err := pgxpool.ParseConfig(dsn)
	if err != nil {
		return nil, err
	}
	cfg.MaxConns = 8
	cfg.MinConns = 1
	pool, err := pgxpool.NewWithConfig(ctx, cfg)
	if err != nil {
		return nil, err
	}
	if err := pool.Ping(ctx); err != nil {
		pool.Close()
		return nil, err
	}
	return pool, nil
}

// Stats 查询各知识领域的数据行数与切片规模
func (s *Store) Stats(ctx context.Context) (map[KnowledgeDomain]Stats, error) {
	out := make(map[KnowledgeDomain]Stats)
	if s == nil || s.Pool == nil {
		return out, fmt.Errorf("store not connected")
	}

	// 1. 法规领域统计
	var regStats Stats
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM reg_documents`).Scan(&regStats.DocumentCount)
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM reg_nodes`).Scan(&regStats.NodeCount)
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM reg_chunks`).Scan(&regStats.ChunkCount)
	out[DomainRegulatory] = regStats

	// 2. 项目数字资产领域统计
	var assetStats Stats
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM asset_projects`).Scan(&assetStats.DocumentCount)
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM asset_chunks`).Scan(&assetStats.ChunkCount)
	out[DomainProjectAsset] = assetStats

	// 3. 员工能力领域统计
	var staffStats Stats
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM staff_profiles`).Scan(&staffStats.DocumentCount)
	_ = s.Pool.QueryRow(ctx, `SELECT count(*) FROM staff_experience_records`).Scan(&staffStats.ChunkCount)
	out[DomainStaffCapability] = staffStats

	return out, nil
}

// VectorLiteral 将 float32 向量序列化为 pgvector 接受的字面量字符串 [0.1,0.2,...]
func VectorLiteral(vec []float32) string {
	if len(vec) == 0 {
		return ""
	}
	var sb strings.Builder
	sb.WriteByte('[')
	for i, f := range vec {
		if i > 0 {
			sb.WriteByte(',')
		}
		sb.WriteString(fmt.Sprintf("%g", f))
	}
	sb.WriteByte(']')
	return sb.String()
}