package service

import (
	"context"
	"log/slog"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"time"

	"schedule_converter/auth"
	"schedule_converter/captcha"
	"schedule_converter/client"
	"schedule_converter/config"
	apperr "schedule_converter/pkg/errors"
)

const (
	maxLoginRetries    = 3
	loginRetryInterval = 3 * time.Second
)

// Service 封装教务系统的登录与数据抓取编排逻辑。
type Service struct{}

// NewService 创建 service。
func NewService() *Service {
	return &Service{}
}

// newAuthenticatedClient 创建带 cookie jar 的 HTTP 客户端，设置 TWFID cookie 并完成登录。
func (s *Service) newAuthenticatedClient(ctx context.Context, username, password, twfid string) (*http.Client, error) {
	jar, err := cookiejar.New(nil)
	if err != nil {
		return nil, apperr.New("create_jar", err, "创建 cookie jar 失败")
	}
	httpClient := &http.Client{Jar: jar}

	if twfid == "" {
		twfid = config.Get().TWFID
	}
	s.setTWFIDCookie(httpClient, config.Get().BaseURL, twfid)

	if err := s.login(ctx, httpClient, username, password); err != nil {
		return nil, err
	}
	return httpClient, nil
}

func (s *Service) setTWFIDCookie(httpClient *http.Client, baseURL, twfid string) {
	u, err := url.Parse(baseURL)
	if err != nil {
		slog.Warn("解析 baseURL 失败，无法设置 TWFID cookie", "base_url", baseURL, "error", err)
		return
	}
	httpClient.Jar.SetCookies(u, []*http.Cookie{
		{Name: "TWFID", Value: twfid},
	})
}

// login 执行登录流程，包含验证码识别与重试。
func (s *Service) login(ctx context.Context, httpClient *http.Client, username, password string) error {
	log := slog.With("username", username)

	if err := client.GetInitialCookiesWithClient(httpClient); err != nil {
		return apperr.New("get_cookies", err, "获取初始 Cookie 失败")
	}

	for attempt := 1; attempt <= maxLoginRetries; attempt++ {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		log.Info("尝试登录", "attempt", attempt, "max_retries", maxLoginRetries)

		captchaCode, err := captcha.GetAndRecognize(httpClient)
		if err != nil {
			log.Warn("验证码获取失败", "error", err, "attempt", attempt)
			time.Sleep(loginRetryInterval)
			continue
		}

		success, err := auth.LoginWithClient(ctx, httpClient, captchaCode, username, password)
		if err != nil {
			log.Warn("登录请求失败", "error", err, "attempt", attempt)
			time.Sleep(loginRetryInterval)
			continue
		}

		if success {
			return nil
		}

		log.Warn("登录验证失败", "attempt", attempt)
		time.Sleep(loginRetryInterval)
	}

	return apperr.ErrLoginFailed
}