package repository

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"strings"
	"time"

	"github.com/Wei-Shaw/sub2api/internal/config"
	"github.com/Wei-Shaw/sub2api/internal/pkg/httpclient"
	"github.com/Wei-Shaw/sub2api/internal/service"
)

func NewProxyExitInfoProber(cfg *config.Config) service.ProxyExitInfoProber {
	insecure := false
	allowPrivate := false
	validateResolvedIP := true
	if cfg != nil {
		insecure = cfg.Security.ProxyProbe.InsecureSkipVerify
		allowPrivate = cfg.Security.URLAllowlist.AllowPrivateHosts
		validateResolvedIP = cfg.Security.URLAllowlist.Enabled
	}
	if insecure {
		log.Printf("[ProxyProbe] Warning: insecure_skip_verify is not allowed and will cause probe failure.")
	}
	return &proxyProbeService{
		ipInfoURL:          defaultIPInfoURL,
		insecureSkipVerify: insecure,
		allowPrivateHosts:  allowPrivate,
		validateResolvedIP: validateResolvedIP,
	}
}

const (
	defaultIPInfoURL         = "http://ip-api.com/json/?lang=zh-CN"
	defaultProxyProbeTimeout = 30 * time.Second
)

type proxyProbeService struct {
	ipInfoURL          string
	insecureSkipVerify bool
	allowPrivateHosts  bool
	validateResolvedIP bool
}

func (s *proxyProbeService) ProbeProxy(ctx context.Context, proxyURL string) (*service.ProxyExitInfo, int64, error) {
	client, err := httpclient.GetClient(httpclient.Options{
		ProxyURL:           proxyURL,
		Timeout:            defaultProxyProbeTimeout,
		InsecureSkipVerify: s.insecureSkipVerify,
		ProxyStrict:        true,
		ValidateResolvedIP: s.validateResolvedIP,
		AllowPrivateHosts:  s.allowPrivateHosts,
	})
	if err != nil {
		return nil, 0, fmt.Errorf("failed to create proxy client: %w", err)
	}

	startTime := time.Now()
	req, err := http.NewRequestWithContext(ctx, "GET", s.ipInfoURL, nil)
	if err != nil {
		return nil, 0, fmt.Errorf("failed to create request: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, 0, fmt.Errorf("proxy connection failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	latencyMs := time.Since(startTime).Milliseconds()

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

	var ipInfo struct {
		Status      string `json:"status"`
		Message     string `json:"message"`
		Query       string `json:"query"`
		City        string `json:"city"`
		Region      string `json:"region"`
		RegionName  string `json:"regionName"`
		Country     string `json:"country"`
		CountryCode string `json:"countryCode"`
	}

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

	if err := json.Unmarshal(body, &ipInfo); err != nil {
		return nil, latencyMs, fmt.Errorf("failed to parse response: %w", err)
	}
	if strings.ToLower(ipInfo.Status) != "success" {
		if ipInfo.Message == "" {
			ipInfo.Message = "ip-api request failed"
		}
		return nil, latencyMs, fmt.Errorf("ip-api request failed: %s", ipInfo.Message)
	}

	region := ipInfo.RegionName
	if region == "" {
		region = ipInfo.Region
	}
	return &service.ProxyExitInfo{
		IP:          ipInfo.Query,
		City:        ipInfo.City,
		Region:      region,
		Country:     ipInfo.Country,
		CountryCode: ipInfo.CountryCode,
	}, latencyMs, nil
}