Refactored crawler to use task dispatcher

internal/task.go

@@ -0,0 +1,47 @@
+package internal
+
+import "fmt"
+
+type TaskState int
+
+const (
+	TaskStatePending TaskState = iota
+	TaskStateRunning
+	TaskStateComplete
+	TaskStateFailed
+)
+
+func (t TaskState) String() string {
+	switch t {
+	case TaskStatePending:
+		return "pending"
+	case TaskStateRunning:
+		return "running"
+	case TaskStateComplete:
+		return "complete"
+	case TaskStateFailed:
+		return "failed"
+	default:
+		return "unknown"
+	}
+}
+
+type TaskData map[string]string
+
+type TaskResult struct {
+	State string   `json:"state"`
+	Error string   `json:"error"`
+	Data  TaskData `json:"data"`
+}
+
+// Task is an interface that represents a single task to be executed by a
+// worker. Any object can implement a `Task` if it implements the interface.
+type Task interface {
+	fmt.Stringer
+
+	ID() string
+	State() TaskState
+	Result() TaskResult
+	Error() error
+	Run() error
+}