// keyed-concurrency 演示跨队列资源互斥及资源端单调序号校验。
package main

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

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

var errStale = errors.New("stale resource token")

// resource 仅用于本地示范。生产必须在资源存储事务内持久化最高序号和操作身份，
// 并与实际写入原子提交；Go mutex 无法保护其他进程或外部服务。
type resource struct {
	mu             sync.Mutex
	namespace, key string
	highest        uint64
	operations     map[string]bool
}

func (r *resource) apply(namespace, key string, token uint64, operation string) error {
	r.mu.Lock()
	defer r.mu.Unlock()
	if namespace != r.namespace || key != r.key || token == 0 || token < r.highest {
		return errStale
	}
	r.highest = token
	// 同一操作的重报不产生第二次模拟写入。
	r.operations[operation] = true
	return nil
}
func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}
func run() error {
	token := os.Getenv("ORBIT_TOKEN")
	if path := os.Getenv("ORBIT_CREDENTIALS_FILE"); path != "" && token == "" {
		raw, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		var c struct {
			Token string `json:"token"`
		}
		if err = json.Unmarshal(raw, &c); err != nil {
			return err
		}
		token = c.Token
	}
	api, err := orbit.NewClient(os.Getenv("ORBIT_URL"), orbit.Options{Token: token})
	if err != nil {
		return err
	}
	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
	defer cancel()
	op, err := orbit.NewWorkerMessageID()
	if err != nil {
		return err
	}
	name := "keyed." + op
	var queues []string
	var tasks []orbit.Task
	for i := 0; i < 2; i++ {
		q, err := api.CreateQueue(ctx, fmt.Sprintf("queue-%s-%d", op, i), orbit.CreateQueueRequest{Name: fmt.Sprintf("%s.%d", name, i), MaxConcurrency: 4, RatePerSecond: 100})
		if err != nil {
			return err
		}
		queues = append(queues, q.Queue.ID)
		in := orbit.SubmitTaskRequest{QueueID: q.Queue.ID, Handler: name, HandlerVersion: "v1", PayloadVersion: "v1", Payload: json.RawMessage(`{"object_ref":"objects/shared"}`), ConcurrencyKey: "object/" + op, TaskTimeoutMS: 20000, Retry: orbit.RetryPolicy{MaxAttempts: 1, AttemptTimeoutMS: 10000}}
		out, err := api.SubmitTask(ctx, fmt.Sprintf("operation-%s-%d", op, i), in)
		if err != nil {
			return err
		}
		tasks = append(tasks, out.Task)
	}
	r := &resource{namespace: tasks[0].NamespaceID, key: tasks[0].ConcurrencyKey, operations: map[string]bool{}}
	handler := orbit.WorkerHandler{Capability: orbit.WorkerCapability{Handler: name, HandlerVersion: "v1", PayloadVersion: "v1"}, Handle: func(ctx context.Context, e orbit.WorkerExecution) (json.RawMessage, error) {
		if err := ctx.Err(); err != nil {
			return nil, err
		}
		// 本示例每条任务表示一个独立操作，Task.ID 在安全重试期间保持不变。
		if err := r.apply(e.Task.NamespaceID, e.Task.ConcurrencyKey, e.ConcurrencyToken, e.Task.ID); err != nil {
			return nil, &orbit.WorkerFailure{Code: "STALE_RESOURCE_TOKEN"}
		}
		return json.RawMessage(`{"updated":true}`), nil
	}}
	run, stop := context.WithCancel(ctx)
	done := make(chan error, 2)
	started := 0
	defer func() {
		stop()
		for i := 0; i < started; i++ {
			<-done
		}
	}()
	for _, queue := range queues {
		w, err := orbit.NewWorker(api, orbit.WorkerOptions{QueueID: queue, Capacity: 4, ShutdownTimeout: 5 * time.Second, Handlers: []orbit.WorkerHandler{handler}})
		if err != nil {
			return err
		}
		started++
		go func() { done <- w.Run(run) }()
	}
	var low, high uint64
	for _, task := range tasks {
		for {
			current, err := api.GetTask(ctx, task.ID)
			if err != nil {
				return err
			}
			if current.State == orbit.TaskSucceeded {
				break
			}
			if current.State == orbit.TaskFailed || current.State == orbit.TaskCancelled || current.State == orbit.TaskNeedsReview {
				return fmt.Errorf("unexpected task state: %s", current.State)
			}
			select {
			case <-ctx.Done():
				return ctx.Err()
			case <-time.After(80 * time.Millisecond):
			}
		}
		history, err := api.ListTaskAttempts(ctx, task.ID, orbit.HistoryPageRequest{})
		if err != nil {
			return err
		}
		if len(history.Items) != 1 || history.Items[0].ConcurrencyToken == 0 {
			return errors.New("missing resource token")
		}
		v := history.Items[0].ConcurrencyToken
		if low == 0 || v < low {
			low = v
		}
		if v > high {
			high = v
		}
	}
	if low == high {
		return errors.New("resource token reused")
	}
	if !errors.Is(r.apply(r.namespace, r.key, low, "late-write"), errStale) {
		return errors.New("old resource token accepted")
	}
	r.mu.Lock()
	count := len(r.operations)
	r.mu.Unlock()
	if count != 2 {
		return errors.New("unexpected resource writes")
	}
	stop()
	for started > 0 {
		err := <-done
		started--
		if err != nil {
			return err
		}
	}
	fmt.Printf("queues=2 completed=2 tokens_increasing=true\nresource_writes=%d stale_write_rejected=true worker_drained=true\n", count)
	return nil
}