// event-protocol 验证冻结结果、连接切换与ACK重报；不执行业务写入。
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 err
		}
		var credential struct {
			Token   string `json:"token"`
			QueueID string `json:"queue_id"`
		}
		if json.Unmarshal(raw, &credential) != nil {
			return errors.New("invalid credential file")
		}
		if token == "" {
			token = credential.Token
		}
		if queue == "" {
			queue = credential.QueueID
		}
	}
	if token == "" || queue == "" {
		return errors.New("event-enabled token and isolated example queue are required")
	}
	api, err := orbit.NewClient(os.Getenv("ORBIT_URL"), orbit.Options{Token: token})
	if err != nil {
		return err
	}
	ctx, stop := context.WithTimeout(context.Background(), 15*time.Second)
	defer stop()
	id, err := orbit.NewEventMessageID()
	if err != nil {
		return err
	}
	created, err := api.CreateSubscription(ctx, "sub-"+id, orbit.CreateSubscriptionRequest{Name: "protocol-" + id, QueueID: queue, Types: []string{"task.cancelled"}, MaxPending: 10, MaxAttempts: 3})
	if err != nil {
		return err
	}
	sub := created.Subscription
	task, err := api.SubmitTask(ctx, "task-"+id, orbit.SubmitTaskRequest{QueueID: queue, Handler: "object.prepare", HandlerVersion: "v1", PayloadVersion: "v1", Payload: json.RawMessage(`{}`)})
	if err != nil {
		return err
	}
	if _, err = api.CancelTask(ctx, task.Task.ID, "cancel-"+id, orbit.CancelTaskRequest{ExpectedRevision: task.Task.Revision, Reason: "event protocol example"}); err != nil {
		return err
	}
	first, err := api.DialEvents(ctx, orbit.EventRegistration{SubscriptionID: sub.ID, Capacity: 1})
	if err != nil {
		return err
	}
	defer first.Close()
	grant, err := first.Next(ctx)
	if err != nil {
		return err
	}
	if grant.Event.Snapshot.TaskID != task.Task.ID || grant.Event.Snapshot.State != orbit.TaskCancelled {
		return errors.New("unexpected example queue event")
	}
	// 本例只读取并验证结果，没有业务数据库写入；业务处理必须先提交Inbox事务再ACK。
	ackID, err := orbit.NewEventMessageID()
	if err != nil {
		return err
	}
	confirmed, err := first.Ack(ctx, ackID, grant.Proof())
	if err != nil {
		return err
	}
	first.Close()
	second, err := api.DialEvents(ctx, orbit.EventRegistration{SubscriptionID: sub.ID, Capacity: 1})
	if err != nil {
		return err
	}
	defer second.Close()
	replayID, err := orbit.NewEventMessageID()
	if err != nil {
		return err
	}
	replayed, err := second.Ack(ctx, replayID, grant.Proof())
	if err != nil {
		return err
	}
	if !replayed.Deduplicated || !replayed.AcknowledgedAt.Equal(confirmed.AcknowledgedAt) {
		return errors.New("acknowledgement receipt changed across connections")
	}
	paused, err := api.ConfigureSubscription(ctx, sub.ID, "pause-"+id, orbit.ConfigureSubscriptionRequest{ExpectedRevision: sub.Revision, Enabled: false, Reason: "protocol example completed"})
	if err != nil {
		return err
	}
	fmt.Printf("event=%s task=%s state=%s\n", grant.Event.ID, task.Task.ID, grant.Event.Snapshot.State)
	fmt.Printf("ack_replayed=%t same_receipt=true pending=%d subscription_enabled=%t\n", replayed.Deduplicated, paused.Subscription.PendingCount, paused.Subscription.Enabled)
	return nil
}