refactor: introduce service layer and migrate gRPC handlers to use it

Extract business logic from gRPC handlers into a dedicated service package.
Add context support throughout for cancellation and timeouts. Move models to
their own package, remove hardcoded credentials from config, and simplify
parsers to only handle HTML parsing.

parser/exam.go

@@ -1,107 +1,38 @@
 package parser
 
 import (
-	"fmt"
-	"log/slog"
-	"net/http"
 	"strings"
 
-	"schedule_converter/client"
-	"schedule_converter/config"
+	"schedule_converter/models"
 
 	"github.com/PuerkitoBio/goquery"
 )
 
-type ExamType string
-
-const (
-	ExamTypeFinal   ExamType = "final"
-	ExamTypeMidterm ExamType = "midterm"
-	ExamTypeMakeup  ExamType = "makeup"
-)
-
-type ExamEntry struct {
-	Course  string
-	Date    string
-	Time    string
-	Week    string
-	Weekday string
-	Type    ExamType
-}
-
-func examTypeToCode(t ExamType) string {
+// examTypeToCode 将考试类型映射为教务系统的请求码。
+func examTypeToCode(t models.ExamType) string {
 	switch t {
-	case ExamTypeMidterm:
+	case models.ExamTypeMidterm:
 		return "02"
-	case ExamTypeMakeup:
+	case models.ExamTypeMakeup:
 		return "03"
 	default:
 		return "01"
 	}
 }
 
-func FetchExams(httpClient *http.Client, examType ExamType) ([]ExamEntry, error) {
-	examURL := config.Get().BaseURL + "/kscx/queryKsForXs"
-	log := slog.With("exam_type", string(examType))
-	log.Info("获取考试时间数据")
-
-	data := fmt.Sprintf("xnxq=&kssjd=%s", examTypeToCode(examType))
-	req, err := http.NewRequest("POST", examURL, strings.NewReader(data))
-	if err != nil {
-		return nil, err
-	}
-
-	req.Header = client.GetHeadersWithContentType("application/x-www-form-urlencoded")
-
-	resp, err := httpClient.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("获取考试数据失败, 状态码: %d", resp.StatusCode)
-	}
-
-	html, err := decodeResponseBody(resp)
-	if err != nil {
-		return nil, err
-	}
-
-	exams, err := parseExamTimeHTML(html, examType)
-	if err != nil {
-		return nil, err
-	}
-
-	log.Info("考试数据获取完成", "exam_count", len(exams))
-	return exams, nil
+// ExamTypeCode 返回考试类型对应的请求码（供 client 层构造请求使用）。
+func ExamTypeCode(t models.ExamType) string {
+	return examTypeToCode(t)
 }
 
-func FetchAllExams(httpClient *http.Client) ([]ExamEntry, error) {
-	var allExams []ExamEntry
-	var lastErr error
-	for _, et := range []ExamType{ExamTypeFinal, ExamTypeMidterm, ExamTypeMakeup} {
-		exams, err := FetchExams(httpClient, et)
-		if err != nil {
-			slog.Warn("获取考试数据失败", "exam_type", string(et), "error", err)
-			lastErr = err
-			continue
-		}
-		allExams = append(allExams, exams...)
-	}
-	if len(allExams) == 0 && lastErr != nil {
-		return nil, fmt.Errorf("所有考试类型获取均失败: %w", lastErr)
-	}
-	return allExams, nil
-}
-
-func parseExamTimeHTML(html string, examType ExamType) ([]ExamEntry, error) {
+// ParseExamHTML 解析考试安排页面 HTML，返回考试条目列表。
+func ParseExamHTML(html string, examType models.ExamType) ([]models.ExamEntry, error) {
 	doc, err := goquery.NewDocumentFromReader(strings.NewReader(html))
 	if err != nil {
 		return nil, err
 	}
 
-	var exams []ExamEntry
+	var exams []models.ExamEntry
 
 	doc.Find("table.bot_line").Each(func(_ int, table *goquery.Selection) {
 		rows := table.Find("tr")
@@ -120,7 +51,7 @@ func parseExamTimeHTML(html string, examType ExamType) ([]ExamEntry, error) {
 
 			texts := getCellTexts(cells)
 
-			exam := ExamEntry{
+			exam := models.ExamEntry{
 				Course:  safeGet(texts, 1),
 				Date:    safeGet(texts, 2),
 				Time:    safeGet(texts, 3),
@@ -136,4 +67,4 @@ func parseExamTimeHTML(html string, examType ExamType) ([]ExamEntry, error) {
 	})
 
 	return exams, nil
-}
+}