package service

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"strings"

	"schedule_converter/client"
	"schedule_converter/config"
	"schedule_converter/models"
	"schedule_converter/parser"
	apperr "schedule_converter/pkg/errors"

	pb "schedule_converter/proto/runner"
)

// GetEmptyClassrooms 获取空教室：登录 → GET 建立会话 → POST 查询 → 解析 → 转换为 pb 结果。
func (s *Service) GetEmptyClassrooms(ctx context.Context, req *pb.GetEmptyClassroomPayload) (*pb.EmptyClassroomResultData, error) {
	log := slog.With("username", req.Username, "semester", req.Semester)

	httpClient, err := s.newAuthenticatedClient(ctx, req.Username, req.Password, "")
	if err != nil {
		return nil, err
	}

	kjsURL := config.Get().BaseURL + "/kjscx/queryKjs"

	// 先 GET 建立会话（沿用原有行为：直接用 client.Get，仅取 cookie，丢弃 body）。
	sessionReq, err := http.NewRequestWithContext(ctx, "GET", kjsURL, nil)
	if err != nil {
		return nil, apperr.New("session_classroom", err, "建立空教室会话失败")
	}
	sessionReq.Header = client.GetHeaders()
	sessionResp, err := httpClient.Do(sessionReq)
	if err != nil {
		return nil, apperr.New("session_classroom", err, "访问空教室页面失败")
	}
	sessionResp.Body.Close()

	// POST 查询参数。
	data := fmt.Sprintf("pageXnxq=%s&pageZc1=%s&pageZc2=%s&pageXiaoqu=%s",
		req.Semester, req.WeekStart, req.WeekEnd, req.CampusCode)
	html, err := client.FetchHTML(ctx, httpClient, "POST", "/kjscx/queryKjs", strings.NewReader(data), "application/x-www-form-urlencoded", "/kjscx/queryKjs")
	if err != nil {
		return nil, apperr.New("fetch_empty_classrooms", err, "查询空教室失败")
	}

	entries, err := parser.ParseEmptyClassroomHTML(html, req.Semester, req.WeekStart, req.WeekEnd)
	if err != nil {
		return nil, apperr.New("parse_empty_classrooms", err, "解析空教室失败")
	}

	log.Info("空教室获取成功", "classroom_count", len(entries))

	return &pb.EmptyClassroomResultData{
		StudentId:  req.Username,
		Semester:   req.Semester,
		Classrooms: convertEmptyClassrooms(entries),
	}, nil
}

// convertEmptyClassrooms 将内部空教室模型转换为 pb.EmptyClassroomEntry 列表。
func convertEmptyClassrooms(entries []models.EmptyClassroomEntry) []*pb.EmptyClassroomEntry {
	result := make([]*pb.EmptyClassroomEntry, 0, len(entries))
	for _, e := range entries {
		result = append(result, &pb.EmptyClassroomEntry{
			Classroom: e.Classroom,
			Weekday:   e.Weekday,
			Periods:   e.Periods,
			Term:      e.Term,
			Weeks:     e.Weeks,
		})
	}
	return result
}