package xy_sh

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

// Client 供应商接口客户端
type Client struct {
	httpClient  *http.Client
	sm4Key      []byte // SM4加密密钥，16字节
	sm3Salt     []byte // SM3签名盐值
	orderURL    string // 下单接口地址
	queryURL    string // 查询接口地址
	rechargeURL string // 微信立减金充值接口地址
}

// NewClient 创建新的客户端
//   - sm4Key: SM4加密密钥，必须为16字节
//   - sm3Salt: SM3签名盐值
//   - orderURL: 下单接口地址
//   - queryURL: 查询接口地址
//   - rechargeURL: 微信立减金充值接口地址
func NewClient(sm4Key []byte, sm3Salt []byte, orderURL, queryURL, rechargeURL string) (*Client, error) {
	if len(sm4Key) != 16 {
		return nil, fmt.Errorf("SM4密钥长度必须为16字节")
	}
	if len(sm3Salt) == 0 {
		return nil, fmt.Errorf("SM3盐值不能为空")
	}
	return &Client{
		httpClient:  &http.Client{},
		sm4Key:      sm4Key,
		sm3Salt:     sm3Salt,
		orderURL:    orderURL,
		queryURL:    queryURL,
		rechargeURL: rechargeURL,
	}, nil
}

// SetHTTPClient 设置自定义HTTP客户端
func (c *Client) SetHTTPClient(httpClient *http.Client) {
	c.httpClient = httpClient
}

// doRequest 执行加密请求并解密响应
func (c *Client) doRequest(ctx context.Context, url string, bizReq interface{}) (*RawResponse, error) {
	// 1. 序列化业务参数为JSON
	bizBody, err := json.Marshal(bizReq)
	if err != nil {
		return nil, fmt.Errorf("序列化业务参数失败: %v", err)
	}

	// 2. SM4加密业务参数
	encryptedData, err := SM4Encrypt(bizBody, c.sm4Key)
	if err != nil {
		return nil, fmt.Errorf("SM4加密失败: %v", err)
	}

	// 3. 生成时间戳和签名
	timestamp := GenerateTimestampMillis()
	sign := GenerateSign(timestamp, encryptedData, c.sm3Salt)

	// 4. 构建加密请求体
	reqBody := EncryptedRequest{EncryptedData: encryptedData}
	reqBytes, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("序列化请求体失败: %v", err)
	}

	// 5. 创建HTTP请求
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(reqBytes))
	if err != nil {
		return nil, fmt.Errorf("创建HTTP请求失败: %v", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("timestamp", timestamp)
	req.Header.Set("sign", sign)

	// 6. 发送请求
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("发送HTTP请求失败: %v", err)
	}
	defer resp.Body.Close()

	// 7. 读取响应体
	respBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("读取响应体失败: %v", err)
	}

	// 8. 解析原始响应
	var rawResp RawResponse
	if err := json.Unmarshal(respBytes, &rawResp); err != nil {
		return nil, fmt.Errorf("解析响应JSON失败: %v", err)
	}

	return &rawResp, nil
}

// decryptData 解密响应中的data字段
func (c *Client) decryptData(encryptedData string, target interface{}) error {
	if encryptedData == "" {
		return nil
	}
	plaintext, err := SM4Decrypt(encryptedData, c.sm4Key)
	if err != nil {
		return fmt.Errorf("SM4解密失败: %v", err)
	}
	if err := json.Unmarshal(plaintext, target); err != nil {
		return fmt.Errorf("解析解密后数据失败: %v", err)
	}
	return nil
}

// Order 卡券/直充权益下单
// 适用于卡密、直充商品下单
func (c *Client) Order(ctx context.Context, req *OrderRequest) (*OrderResponse, error) {
	rawResp, err := c.doRequest(ctx, c.orderURL, req)
	if err != nil {
		return nil, err
	}

	resp := &OrderResponse{
		Code: rawResp.Code,
		Msg:  rawResp.Msg,
	}

	if rawResp.Data != "" {
		var data OrderData
		if err := c.decryptData(rawResp.Data, &data); err != nil {
			return nil, err
		}
		resp.Data = &data
	}

	return resp, nil
}

// QueryOrder 卡券/直充/微信立减金订单查询
// 通过供应商订单号查询订单状态
func (c *Client) QueryOrder(ctx context.Context, req *QueryRequest) (*QueryResponse, error) {
	rawResp, err := c.doRequest(ctx, c.queryURL, req)
	if err != nil {
		return nil, err
	}

	resp := &QueryResponse{
		Code: rawResp.Code,
		Msg:  rawResp.Msg,
	}

	if rawResp.Data != "" {
		var data QueryData
		if err := c.decryptData(rawResp.Data, &data); err != nil {
			return nil, err
		}
		resp.Data = &data
	}

	return resp, nil
}

// WechatRecharge 微信立减金订单充值
func (c *Client) WechatRecharge(ctx context.Context, req *WechatRechargeRequest) (*WechatRechargeResponse, error) {
	rawResp, err := c.doRequest(ctx, c.rechargeURL, req)
	if err != nil {
		return nil, err
	}

	resp := &WechatRechargeResponse{
		Code: rawResp.Code,
		Msg:  rawResp.Msg,
	}

	if rawResp.Data != "" {
		var data WechatRechargeData
		if err := c.decryptData(rawResp.Data, &data); err != nil {
			return nil, err
		}
		resp.Data = &data
	}

	return resp, nil
}

// SendCallback 发送回调通知（供应商调用行方回调接口）
// 返回的 CallbackResponse 中 StatusCode 为 HTTP 状态码，Body 为响应体内容
func (c *Client) SendCallback(ctx context.Context, callbackURL string, req *CallbackRequest) (*CallbackResponse, error) {
	// 1. 序列化业务参数
	bizBody, err := json.Marshal(req)
	if err != nil {
		return nil, fmt.Errorf("序列化回调参数失败: %v", err)
	}

	// 2. SM4加密
	encryptedData, err := SM4Encrypt(bizBody, c.sm4Key)
	if err != nil {
		return nil, fmt.Errorf("SM4加密失败: %v", err)
	}

	// 3. 生成时间戳和签名
	timestamp := GenerateTimestampMillis()
	sign := GenerateSign(timestamp, encryptedData, c.sm3Salt)

	// 4. 构建请求体
	reqBody := EncryptedRequest{EncryptedData: encryptedData}
	reqBytes, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("序列化请求体失败: %v", err)
	}

	// 5. 创建HTTP请求
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, callbackURL, bytes.NewReader(reqBytes))
	if err != nil {
		return nil, fmt.Errorf("创建HTTP请求失败: %v", err)
	}
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("timestamp", timestamp)
	httpReq.Header.Set("sign", sign)

	// 6. 发送请求
	resp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return nil, fmt.Errorf("发送回调请求失败: %v", err)
	}
	defer resp.Body.Close()

	// 7. 读取响应体
	respBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("读取回调响应失败: %v", err)
	}

	return &CallbackResponse{
		StatusCode: resp.StatusCode,
		Body:       string(respBytes),
	}, nil
}