package bus_test

import (
	"context"
	"encoding/json"
	"testing"
	"time"

	natsserver "github.com/nats-io/nats-server/v2/server"
	natstest "github.com/nats-io/nats-server/v2/test"

	"github.com/sundynix/sundynix-shared/bus"
	"github.com/sundynix/sundynix-shared/contract"
)

// startEmbeddedNATS 启动一个内嵌、开启 JetStream 的 NATS 服务器，免 Docker。
func startEmbeddedNATS(t *testing.T) string {
	t.Helper()
	opts := natstest.DefaultTestOptions
	opts.Port = -1 // 随机端口
	opts.JetStream = true
	opts.StoreDir = t.TempDir()
	srv := natstest.RunServer(&opts)
	if !srv.ReadyForConnections(5 * time.Second) {
		t.Fatal("embedded NATS not ready")
	}
	t.Cleanup(srv.Shutdown)
	_ = natsserver.Server{} // 触发包引用
	return srv.ClientURL()
}

// TestTaskRoundTrip 模拟 Gateway 发布 → NATS → Dispatcher 消费 的完整任务流。
func TestTaskRoundTrip(t *testing.T) {
	url := startEmbeddedNATS(t)

	// --- Gateway 侧：连接并声明任务流 ---
	gw, err := bus.Connect(url)
	if err != nil {
		t.Fatalf("gateway connect: %v", err)
	}
	defer gw.Close()

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := gw.EnsureTaskStream(ctx); err != nil {
		t.Fatalf("ensure stream: %v", err)
	}

	// --- Dispatcher 侧：连接并开始消费 ---
	dp, err := bus.Connect(url)
	if err != nil {
		t.Fatalf("dispatcher connect: %v", err)
	}
	defer dp.Close()

	got := make(chan *contract.Task, 1)
	stop, err := dp.ConsumeTasks(ctx, func(_ context.Context, task *contract.Task) error {
		got <- task
		return nil
	})
	if err != nil {
		t.Fatalf("consume: %v", err)
	}
	defer stop()

	// --- Gateway 发布一个任务 ---
	want := &contract.Task{
		ID:    "task_demo_001",
		Graph: json.RawMessage(`{"nodes":[{"id":"n1","type":"agent"}],"edges":[]}`),
		Meta:  map[string]any{"user": "wt"},
	}
	seq, err := gw.PublishTask(ctx, want)
	if err != nil {
		t.Fatalf("publish: %v", err)
	}
	if seq == 0 {
		t.Fatal("expected non-zero stream sequence")
	}

	// --- 断言 Dispatcher 收到同一个任务 ---
	select {
	case task := <-got:
		if task.ID != want.ID {
			t.Fatalf("task id = %q, want %q", task.ID, want.ID)
		}
		if task.Meta["user"] != "wt" {
			t.Fatalf("task meta lost: %+v", task.Meta)
		}
		t.Logf("✓ 任务流打通：Gateway publish (seq=%d) → NATS → Dispatcher consume，task_id=%s", seq, task.ID)
	case <-time.After(5 * time.Second):
		t.Fatal("timeout: dispatcher 未收到任务")
	}
}

// TestTokenStreamRoundTrip 模拟 Dispatcher 回流 Token → Gateway 订阅 的流式闭环。
func TestTokenStreamRoundTrip(t *testing.T) {
	url := startEmbeddedNATS(t)

	// Gateway 侧：先订阅（core NATS 无持久化，须先连）。
	gw, err := bus.Connect(url)
	if err != nil {
		t.Fatalf("gateway connect: %v", err)
	}
	defer gw.Close()

	const taskID = "task_stream_001"
	var got []string
	done := make(chan struct{})
	unsub, err := gw.SubscribeTokens(taskID,
		func(tok []byte) { got = append(got, string(tok)) },
		func() { close(done) },
	)
	if err != nil {
		t.Fatalf("subscribe tokens: %v", err)
	}
	defer func() { _ = unsub() }()

	// Dispatcher 侧：逐 Token 回流后发结束信号。
	dp, err := bus.Connect(url)
	if err != nil {
		t.Fatalf("dispatcher connect: %v", err)
	}
	defer dp.Close()

	want := []string{"Hello", " ", "Agent", "!"}
	for _, tok := range want {
		if err := dp.PublishToken(taskID, []byte(tok)); err != nil {
			t.Fatalf("publish token: %v", err)
		}
	}
	if err := dp.CompleteStream(taskID); err != nil {
		t.Fatalf("complete stream: %v", err)
	}

	select {
	case <-done:
		joined := ""
		for _, s := range got {
			joined += s
		}
		if joined != "Hello Agent!" {
			t.Fatalf("token stream = %q, want %q", joined, "Hello Agent!")
		}
		t.Logf("✓ Token 流闭环：Dispatcher 回流 %d 个 token → Gateway 拼回 %q", len(got), joined)
	case <-time.After(5 * time.Second):
		t.Fatal("timeout: 未收到流结束信号")
	}
}