package okx

import (
	"encoding/json"
	"fmt"
	"github.com/google/go-querystring/query" // 用于将 struct 转为 URL 参数，需要安装：go get github.com/google/go-querystring
	"net/http"
	"net/url"
)

type OkxPublicDataService struct {
	BaseURL string
}

// NewOkxPublicDataService 创建服务实例
func NewOkxPublicDataService() *OkxPublicDataService {
	return &OkxPublicDataService{
		BaseURL: "https://www.okx.com/api/v5",
	}
}

// GetInstruments 获取交易对信息
func (s *OkxPublicDataService) GetInstruments(params InstrumentsRequest) ([]Instrument, error) {
	u, err := url.Parse(s.BaseURL + "/public/instruments")
	if err != nil {
		return nil, err
	}

	// 将 struct 转为查询参数
	q, err := query.Values(params)
	if err != nil {
		return nil, err
	}
	u.RawQuery = q.Encode()

	resp, err := http.Get(u.String())
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var apiResp ApiResponse
	apiResp.Data = new([]Instrument) // 预分配 Data 字段为 Instrument 切片
	if err := json.NewDecoder(resp.Body).Decode(&apiResp); err != nil {
		return nil, err
	}

	if apiResp.Code != "0" {
		return nil, fmt.Errorf("API error: %s", apiResp.Msg)
	}

	return *apiResp.Data.(*[]Instrument), nil
}

// GetCandles 获取K线数据
func (s *OkxPublicDataService) GetCandles(params CandlesRequest) ([]Candle, error) {
	u, err := url.Parse(s.BaseURL + "/market/candles")
	if err != nil {
		return nil, err
	}

	// 将 struct 转为查询参数
	q, err := query.Values(params)
	if err != nil {
		return nil, err
	}
	u.RawQuery = q.Encode()

	resp, err := http.Get(u.String())
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var apiResp struct {
		Code string     `json:"code"`
		Msg  string     `json:"msg"`
		Data [][]string `json:"data"` // K线数据是二维数组
	}
	if err := json.NewDecoder(resp.Body).Decode(&apiResp); err != nil {
		return nil, err
	}

	if apiResp.Code != "0" {
		return nil, fmt.Errorf("API error: %s", apiResp.Msg)
	}

	// 将二维数组转为 Candle 切片
	candles := make([]Candle, len(apiResp.Data))
	for i, item := range apiResp.Data {
		candles[i] = Candle{
			Timestamp: item[0],
			Open:      item[1],
			High:      item[2],
			Low:       item[3],
			Close:     item[4],
			Volume:    item[5],
			VolumeCcy: item[6],
		}
	}

	return candles, nil
} // GetTicker 获取单个交易对的 ticker 数据
func (s *OkxPublicDataService) GetTicker(params TickerRequest) (*Ticker, error) {
	u, err := url.Parse(s.BaseURL + "/market/ticker")
	if err != nil {
		return nil, err
	}

	// 将 struct 转为查询参数
	q, err := query.Values(params)
	if err != nil {
		return nil, err
	}
	u.RawQuery = q.Encode()

	resp, err := http.Get(u.String())
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var apiResp struct {
		Code string   `json:"code"`
		Msg  string   `json:"msg"`
		Data []Ticker `json:"data"` // 返回的是数组
	}
	if err := json.NewDecoder(resp.Body).Decode(&apiResp); err != nil {
		return nil, err
	}

	if apiResp.Code != "0" {
		return nil, fmt.Errorf("API error: %s", apiResp.Msg)
	}

	if len(apiResp.Data) == 0 {
		return nil, fmt.Errorf("no ticker data returned")
	}

	// 返回第一个 ticker（通常只返回一个）
	return &apiResp.Data[0], nil
}