package utils

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"math/rand"
	"net/http"
	"time"
)

// LocationResponse represents the response from IP location API
type LocationResponse struct {
	IP          string `json:"ip"`
	Pro         string `json:"pro"`
	ProCode     string `json:"proCode"`
	City        string `json:"city"`
	CityCode    string `json:"cityCode"`
	Region      string `json:"region"`
	RegionCode  string `json:"regionCode"`
	Addr        string `json:"addr"`
	RegionNames string `json:"regionNames"`
	Err         string `json:"err"`
}

// userAgents is a list of common browser user agents for random selection
var userAgents = []string{
	"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
	"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36",
	"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
	"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Safari/605.1.15",
	"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0",
	"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0",
	"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
	"Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1",
	"Mozilla/5.0 (iPad; CPU OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1",
	"Mozilla/5.0 (Linux; Android 14; SM-S918B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36",
}

// randomUserAgent returns a random user agent string
func randomUserAgent() string {
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	return userAgents[r.Intn(len(userAgents))]
}

// GetLocation 获取IP的地理位置信息
// 调用太平洋网络IP地址查询API，返回省份和城市
func GetLocation(ctx context.Context, ip string) (province string, city string, err error) {
	url := fmt.Sprintf("https://whois.pconline.com.cn/ipJson.jsp?ip=%s&json=true", ip)

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return "", "", fmt.Errorf("create request failed: %w", err)
	}

	// Set random user agent to simulate browser
	req.Header.Set("User-Agent", randomUserAgent())
	req.Header.Set("Accept", "application/json, text/plain, */*")
	req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9,en;q=0.8")
	req.Header.Set("Referer", "https://whois.pconline.com.cn/")

	client := &http.Client{
		Timeout: 5 * time.Second,
	}

	resp, err := client.Do(req)
	if err != nil {
		return "", "", fmt.Errorf("request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", "", fmt.Errorf("request failed with status: %d", resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", "", fmt.Errorf("read response failed: %w", err)
	}

	var location LocationResponse
	if err := json.Unmarshal(body, &location); err != nil {
		return "", "", fmt.Errorf("parse response failed: %w", err)
	}

	// Check for error in response
	if location.Err != "" {
		return "", "", fmt.Errorf("API error: %s", location.Err)
	}

	return location.Pro, location.City, nil
}

// GetLocationWithCache 获取IP的地理位置信息（带缓存）
// 如果缓存中有则直接返回，否则调用API并缓存结果
func GetLocationWithCache(ctx context.Context, ip string, cache func(key string, fetch func() (string, string, error)) (string, string, error)) (province string, city string, err error) {
	return cache(ip, func() (string, string, error) {
		return GetLocation(ctx, ip)
	})
}