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.

grpc/handler.go

@@ -2,21 +2,28 @@ package grpc
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"log/slog"
 	"sync"
 	"time"
 
+	"schedule_converter/service"
+
 	pb "schedule_converter/proto/runner"
 )
 
 type TaskHandler struct {
-	cancelledTasks sync.Map
+	service      *service.Service
+	cancels      sync.Map // taskID -> context.CancelFunc（运行中的任务）
+	preCancelled sync.Map // taskID -> struct{}（任务开始前就已取消）
 }
 
 func NewTaskHandler() *TaskHandler {
-	return &TaskHandler{}
+	return &TaskHandler{
+		service: service.NewService(),
+	}
 }
 
 func (h *TaskHandler) Execute(task *pb.Task) *pb.TaskResult {
@@ -28,14 +35,17 @@ func (h *TaskHandler) Execute(task *pb.Task) *pb.TaskResult {
 		CompletedAt: time.Now().UnixMilli(),
 	}
 
-	if h.IsCancelled(task.TaskId) {
+	// 任务开始前检查是否已被预取消。
+	if _, cancelled := h.preCancelled.LoadAndDelete(task.TaskId); cancelled {
 		result.Status = pb.TaskStatus_TASK_STATUS_CANCELLED
 		result.ErrorMessage = "任务已取消"
 		log.Info("任务已取消")
 		return result
 	}
 
-	ctx := context.Background()
+	ctx, cancel := h.buildTaskContext(task)
+	defer cancel()
+
 	data, err := h.dispatch(ctx, task)
 
 	if err != nil {
@@ -57,31 +67,68 @@ func (h *TaskHandler) Execute(task *pb.Task) *pb.TaskResult {
 	return result
 }
 
-var errUnknownTaskType = fmt.Errorf("unknown task type")
-
-func (h *TaskHandler) dispatch(ctx context.Context, task *pb.Task) ([]byte, error) {
-	switch task.Type {
-	case pb.TaskType_TASK_TYPE_GET_SCHEDULE:
-		return h.getSchedule(ctx, task.Payload)
-	case pb.TaskType_TASK_TYPE_GET_GRADES:
-		return h.getGrades(ctx, task.Payload)
-	case pb.TaskType_TASK_TYPE_GET_EXAMS:
-		return h.getExams(ctx, task.Payload)
-	case pb.TaskType_TASK_TYPE_LOGIN:
-		return h.login(ctx, task.Payload)
-	case pb.TaskType_TASK_TYPE_GET_EMPTY_CLASSROOM:
-		return h.getEmptyClassrooms(ctx, task.Payload)
-	default:
-		return nil, fmt.Errorf("%w: %v", errUnknownTaskType, task.Type)
+// buildTaskContext 构造任务执行 context：根据 TimeoutSeconds 设置截止时间，
+// 并注册 cancel 函数，使 CancelTask 能够中断正在执行的任务。
+func (h *TaskHandler) buildTaskContext(task *pb.Task) (context.Context, context.CancelFunc) {
+	ctx := context.Background()
+	if task.TimeoutSeconds > 0 {
+		ctx, cancel := context.WithTimeout(ctx, time.Duration(task.TimeoutSeconds)*time.Second)
+		h.cancels.Store(task.TaskId, context.CancelFunc(cancel))
+		return ctx, func() {
+			h.cancels.Delete(task.TaskId)
+			cancel()
+		}
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	h.cancels.Store(task.TaskId, context.CancelFunc(cancel))
+	return ctx, func() {
+		h.cancels.Delete(task.TaskId)
+		cancel()
 	}
 }
 
+var errUnknownTaskType = fmt.Errorf("unknown task type")
+
+// taskHandlers 将任务类型映射到处理方法。
+var taskHandlers = map[pb.TaskType]func(h *TaskHandler, ctx context.Context, payload []byte) ([]byte, error){
+	pb.TaskType_TASK_TYPE_GET_SCHEDULE:        (*TaskHandler).getSchedule,
+	pb.TaskType_TASK_TYPE_GET_GRADES:          (*TaskHandler).getGrades,
+	pb.TaskType_TASK_TYPE_GET_EXAMS:           (*TaskHandler).getExams,
+	pb.TaskType_TASK_TYPE_LOGIN:               (*TaskHandler).login,
+	pb.TaskType_TASK_TYPE_GET_EMPTY_CLASSROOM: (*TaskHandler).getEmptyClassrooms,
+}
+
+// supportedTaskTypes 返回当前支持的任务类型列表，供注册 capabilities 使用。
+func supportedTaskTypes() []pb.TaskType {
+	types := make([]pb.TaskType, 0, len(taskHandlers))
+	for t := range taskHandlers {
+		types = append(types, t)
+	}
+	return types
+}
+
+func (h *TaskHandler) dispatch(ctx context.Context, task *pb.Task) ([]byte, error) {
+	handler, ok := taskHandlers[task.Type]
+	if !ok {
+		return nil, fmt.Errorf("%w: %v", errUnknownTaskType, task.Type)
+	}
+	return handler(h, ctx, task.Payload)
+}
+
+// CancelTask 取消任务：若任务正在执行则中断其 context；若尚未开始则记为预取消。
 func (h *TaskHandler) CancelTask(taskID string) {
-	h.cancelledTasks.Store(taskID, true)
+	if v, ok := h.cancels.LoadAndDelete(taskID); ok {
+		if cancel, ok := v.(context.CancelFunc); ok {
+			cancel()
+		}
+		return
+	}
+	// 任务尚未开始执行，标记为预取消，待 Execute 时直接返回取消。
+	h.preCancelled.Store(taskID, struct{}{})
 	slog.Info("任务已标记为取消", "task_id", taskID)
 }
 
-func (h *TaskHandler) IsCancelled(taskID string) bool {
-	v, ok := h.cancelledTasks.Load(taskID)
-	return ok && v.(bool)
+// unmarshalPayload 解码任务载荷。
+func unmarshalPayload(payload []byte, v any) error {
+	return json.Unmarshal(payload, v)
 }