package grpc

import (
	"context"
	"fmt"
	"log"
	"sync"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/keepalive"
)

var (
	userClientOnce sync.Once
	userClient     *UserClient
)

// AdminSimpleInfo 临时结构，等 proto 生成后会被替换
type AdminSimpleInfo struct {
	Id       int32
	Username string
	Realname string
}

// SimpleListAllUserResp 临时结构，等 proto 生成后会被替换
type SimpleListAllUserResp struct {
	List []*AdminSimpleInfo
}

type UserClient struct {
	conn   *grpc.ClientConn
	addr   string
	client interface{} // 临时使用 interface{}，等 proto 生成后改为 userv1.UserClient
}

// NewUserClient 创建用户服务 gRPC 客户端
func NewUserClient(addr string) (*UserClient, error) {
	if addr == "" {
		return nil, fmt.Errorf("gRPC server address is empty")
	}

	var err error
	userClientOnce.Do(func() {
		opts := []grpc.DialOption{
			grpc.WithTransportCredentials(insecure.NewCredentials()),
			grpc.WithKeepaliveParams(keepalive.ClientParameters{
				Time:                10 * time.Second,
				Timeout:             3 * time.Second,
				PermitWithoutStream: true,
			}),
		}

		conn, dialErr := grpc.Dial(addr, opts...)
		if dialErr != nil {
			err = fmt.Errorf("failed to connect to gRPC server %s: %w", addr, dialErr)
			return
		}

		// TODO: 等 proto 文件生成后，取消注释下面的代码
		// client := userv1.NewUserClient(conn)
		userClient = &UserClient{
			conn:   conn,
			addr:   addr,
			client: nil, // 临时设为 nil，等 proto 生成后使用 userv1.NewUserClient(conn)
		}
		log.Printf("gRPC user client connected to %s (proto code not generated yet)", addr)
	})

	if err != nil {
		return nil, err
	}

	return userClient, nil
}

// SimpleListAllUser 调用 SimpleListAllUser gRPC 方法
// 注意：此方法需要 proto 生成的代码才能正常工作
// 请先运行: cd grpc && make generate
func (c *UserClient) SimpleListAllUser(ctx context.Context, keyword string) (*SimpleListAllUserResp, error) {
	// TODO: 等 proto 文件生成后，取消注释下面的代码并删除临时实现
	// req := &userv1.SimpleListAllUserReq{
	//     Keyword: keyword,
	// }
	// resp, err := c.client.SimpleListAllUser(ctx, req)
	// if err != nil {
	//     return nil, fmt.Errorf("gRPC SimpleListAllUser failed: %w", err)
	// }
	// return resp, nil

	// 临时实现：返回错误提示需要生成 proto
	return nil, fmt.Errorf("proto code not generated, please run 'cd grpc && make generate' first, then rebuild with -tags proto_generated")
}

// Close 关闭连接
func (c *UserClient) Close() error {
	if c.conn != nil {
		return c.conn.Close()
	}
	return nil
}

// GetConn 获取 gRPC 连接（用于直接调用生成的客户端）
func (c *UserClient) GetConn() *grpc.ClientConn {
	return c.conn
}