package service

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"time"
)

const qweatherAPIBase = "https://devapi.qweather.com"

// WeatherNow 实时天气
type WeatherNow struct {
	Temp     float64 `json:"temp"`
	Humidity float64 `json:"humidity"`
	Text     string  `json:"text"`
}

// DailyForecast 逐日预报
type DailyForecast struct {
	Date      string  `json:"date"`
	TextDay   string  `json:"textDay"`
	TextNight string  `json:"textNight"`
	TempMax   float64 `json:"tempMax"`
	TempMin   float64 `json:"tempMin"`
	Humidity  float64 `json:"humidity"`
}

// WeatherService 和风天气客户端（未配置时 Configured()=false，调用返回明确错误）
type WeatherService struct {
	key      string
	location string
	baseURL  string
	client   *http.Client
}

// NewWeatherService 创建和风天气客户端
func NewWeatherService(key, location string) *WeatherService {
	return &WeatherService{
		key:      key,
		location: location,
		baseURL:  qweatherAPIBase,
		client:   &http.Client{Timeout: 15 * time.Second},
	}
}

// Configured 是否已配置 API Key 与位置
func (s *WeatherService) Configured() bool {
	return s.key != "" && s.location != ""
}

// FetchNow 实时天气
func (s *WeatherService) FetchNow(ctx context.Context) (*WeatherNow, error) {
	var out struct {
		Code string `json:"code"`
		Now  struct {
			Temp     string `json:"temp"`
			Text     string `json:"text"`
			Humidity string `json:"humidity"`
		} `json:"now"`
	}
	if err := s.get(ctx, "/v7/weather/now", &out); err != nil {
		return nil, err
	}
	temp, _ := strconv.ParseFloat(out.Now.Temp, 64)
	hum, _ := strconv.ParseFloat(out.Now.Humidity, 64)
	return &WeatherNow{Temp: temp, Humidity: hum, Text: out.Now.Text}, nil
}

// FetchDaily 未来 3 天预报
func (s *WeatherService) FetchDaily(ctx context.Context) ([]DailyForecast, error) {
	var out struct {
		Code  string `json:"code"`
		Daily []struct {
			FxDate    string `json:"fxDate"`
			TextDay   string `json:"textDay"`
			TextNight string `json:"textNight"`
			TempMax   string `json:"tempMax"`
			TempMin   string `json:"tempMin"`
			Humidity  string `json:"humidity"`
		} `json:"daily"`
	}
	if err := s.get(ctx, "/v7/weather/3d", &out); err != nil {
		return nil, err
	}
	list := make([]DailyForecast, 0, len(out.Daily))
	for _, d := range out.Daily {
		max, _ := strconv.ParseFloat(d.TempMax, 64)
		min, _ := strconv.ParseFloat(d.TempMin, 64)
		hum, _ := strconv.ParseFloat(d.Humidity, 64)
		list = append(list, DailyForecast{
			Date: d.FxDate, TextDay: d.TextDay, TextNight: d.TextNight,
			TempMax: max, TempMin: min, Humidity: hum,
		})
	}
	return list, nil
}

// get 发起 GET 并校验 code=200
func (s *WeatherService) get(ctx context.Context, path string, out any) error {
	if !s.Configured() {
		return fmt.Errorf("天气服务未配置（QWEATHER_API_KEY/QWEATHER_LOCATION）")
	}
	u := s.baseURL + path + "?location=" + url.QueryEscape(s.location) + "&key=" + url.QueryEscape(s.key)
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
	if err != nil {
		return err
	}
	resp, err := s.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if err := json.Unmarshal(body, out); err != nil {
		return err
	}
	var head struct {
		Code string `json:"code"`
	}
	_ = json.Unmarshal(body, &head)
	if head.Code != "200" {
		return fmt.Errorf("和风天气返回错误 code=%s", head.Code)
	}
	return nil
}