package dx

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"
)

// Config 网关鉴权与请求配置
type Config struct {
	BaseURL   string // 默认 https://cmp-api.ctwing.cn:20164
	AppKey    string
	AppSecret string
	Timeout   time.Duration
}

// Client API 客户端
type Client struct {
	baseURL   string
	appKey    string
	appSecret string
	http      *http.Client
}

// New 创建客户端
func NewClient(cfg Config) *Client {
	base := cfg.BaseURL
	if base == "" {
		base = DefaultBaseURL
	}
	timeout := cfg.Timeout
	if timeout == 0 {
		timeout = 10 * time.Second
	}
	return &Client{
		baseURL:   strings.TrimSuffix(base, "/"),
		appKey:    cfg.AppKey,
		appSecret: cfg.AppSecret,
		http: &http.Client{
			Timeout: timeout,
		},
	}
}

// DoGetRequest 通用GET请求（自动处理签名）
// endpoint: API路径，如 "/api/v1/openbill/queryTraffic"
// params: 查询参数，需调用方自行构建
func (c *Client) DoGetRequest(ctx context.Context, endpoint string, params url.Values) ([]byte, error) {
	req, err := c.doGetRequest(ctx, endpoint, params)
	if err != nil {
		return nil, err
	}
	return c.doRequest(req)
}

// doGetRequest 封装通用的 GET 请求构建逻辑
func (c *Client) doGetRequest(ctx context.Context, endpoint string, params url.Values) (*http.Request, error) {
	queryString := params.Encode()
	timestamp := GetTimestampGMT()
	signStr, err := BuildSign(queryString, "", c.appSecret, timestamp)
	if err != nil {
		return nil, err
	}
	reqURL := c.baseURL + endpoint + "?" + queryString
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("AppKey", c.appKey)
	req.Header.Set("Sign", signStr)
	req.Header.Set("Timestamp", timestamp)
	return req, nil
}

// doRequest 执行HTTP请求
func (c *Client) doRequest(req *http.Request) ([]byte, error) {
	resp, err := c.http.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("http status %d: %s", resp.StatusCode, string(body))
	}
	return body, nil
}