// cancellation 演示运行中取消、处理器确认停止、结果查询和有界排空。
package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"time"

	orbit "git.yuntuo.hk/k2safe/orbit/sdk/go"
)

func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}
func run() error {
	token, queue := os.Getenv("ORBIT_TOKEN"), os.Getenv("ORBIT_QUEUE_ID")
	if path := os.Getenv("ORBIT_CREDENTIALS_FILE"); path != "" {
		raw, err := os.ReadFile(path)
		if err != nil {
			return fmt.Errorf("read private credentials: %w", err)
		}
		var c struct {
			Token   string `json:"token"`
			QueueID string `json:"queue_id"`
		}
		if json.Unmarshal(raw, &c) != nil {
			return errors.New("invalid credentials file")
		}
		if token == "" {
			token = c.Token
		}
		if queue == "" {
			queue = c.QueueID
		}
	}
	client, err := orbit.NewClient(os.Getenv("ORBIT_URL"), orbit.Options{Token: token})
	if err != nil {
		return err
	}
	operation, err := orbit.NewWorkerMessageID()
	if err != nil {
		return err
	}
	name := "object.cancel." + operation
	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
	defer cancel()
	entered := make(chan struct{})
	w, err := orbit.NewWorker(client, orbit.WorkerOptions{QueueID: queue, Capacity: 1, ShutdownTimeout: 5 * time.Second, Handlers: []orbit.WorkerHandler{{Capability: orbit.WorkerCapability{Handler: name, HandlerVersion: "v1", PayloadVersion: "v1"}, Handle: func(work context.Context, e orbit.WorkerExecution) (json.RawMessage, error) {
		close(entered)
		<-work.Done()
		if !errors.Is(context.Cause(work), orbit.ErrTaskCancellationRequested) {
			return nil, work.Err()
		}
		// 此示例没有外部副作用，因此可以确认安全停止；真实接入需完成自己的核实。
		return nil, &orbit.WorkerCancellationConfirmed{Details: json.RawMessage(`{"evidence_ref":"objects/no-external-work"}`)}
	}}}})
	if err != nil {
		return err
	}
	task, err := client.SubmitTask(ctx, "submit-"+operation, orbit.SubmitTaskRequest{QueueID: queue, Handler: name, HandlerVersion: "v1", PayloadVersion: "v1", Payload: json.RawMessage(`{"object_ref":"objects/example"}`), TaskTimeoutMS: 20000, Retry: orbit.RetryPolicy{MaxAttempts: 1, AttemptTimeoutMS: 15000}})
	if err != nil {
		return err
	}
	run, stop := context.WithCancel(ctx)
	done := make(chan error, 1)
	go func() { done <- w.Run(run) }()
	waited := false
	defer func() {
		stop()
		if !waited {
			<-done
		}
	}()
	select {
	case <-entered:
	case err := <-done:
		waited = true
		return fmt.Errorf("Worker stopped before handler: %v", err)
	case <-ctx.Done():
		return ctx.Err()
	}
	for {
		current, err := client.GetTask(ctx, task.Task.ID)
		if err != nil {
			return err
		}
		key, err := orbit.NewWorkerMessageID()
		if err != nil {
			return err
		}
		out, err := client.CancelTask(ctx, current.ID, key, orbit.CancelTaskRequest{ExpectedRevision: current.Revision, Reason: "finish cancellation example"})
		if err == nil {
			fmt.Printf("task=%s cancel_requested=%t accepted_state=%s\n", out.Task.ID, out.Task.CancelRequestedAt != nil, out.Task.State)
			break
		}
		var api *orbit.APIError
		if !errors.As(err, &api) || api.Code != "STATE_CONFLICT" {
			return err
		}
	}
	for {
		current, err := client.GetTask(ctx, task.Task.ID)
		if err != nil {
			return err
		}
		if current.State == orbit.TaskCancelled {
			fmt.Printf("final_state=%s attempts=%d\n", current.State, current.AttemptCount)
			break
		}
		if current.State == orbit.TaskNeedsReview || current.State == orbit.TaskFailed || current.State == orbit.TaskSucceeded {
			return fmt.Errorf("unexpected result: %s", current.State)
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(100 * time.Millisecond):
		}
	}
	stop()
	err = <-done
	waited = true
	if err != nil {
		return err
	}
	fmt.Printf("worker_drained=true running=%d\n", w.Stats().Running)
	return nil
}