package nixmsg

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
	"time"
)

func connectFake(t *testing.T, fake *FakeTransport) *Client {
	t.Helper()
	c := New()
	opts := Options{transport: fake, ConnectTimeout: 5 * time.Second}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := c.Connect(ctx, "ws://example.test/mqtt", "ep1", Credential{Password: "secret"}, opts); err != nil {
		t.Fatalf("connect: %v", err)
	}
	return c
}

func TestCleanStartEveryConnect(t *testing.T) {
	fake := NewFakeTransport()
	c := connectFake(t, fake)
	defer c.Close()

	if err := fake.SimulateReconnect(); err != nil {
		t.Fatal(err)
	}
	if err := fake.SimulateReconnect(); err != nil {
		t.Fatal(err)
	}
	cs := fake.Connects()
	if len(cs) < 3 {
		t.Fatalf("connects=%d want >=3", len(cs))
	}
	for i, c0 := range cs {
		if !c0.CleanStart {
			t.Fatalf("connect %d CleanStart=false", i)
		}
		if c0.SessionExpiry != 0 {
			t.Fatalf("connect %d SessionExpiry=%d", i, c0.SessionExpiry)
		}
	}
}

func TestSessionTokenCallback(t *testing.T) {
	fake := NewFakeTransport()
	fake.HelloToken = "nst_abc"
	c := New()
	var got string
	c.OnSession(func(tok string) { got = tok })
	opts := Options{transport: fake, ConnectTimeout: 5 * time.Second}
	ctx := context.Background()
	if err := c.Connect(ctx, "ws://example.test/mqtt", "ep1", Credential{Password: "p"}, opts); err != nil {
		t.Fatal(err)
	}
	defer c.Close()
	if got != "nst_abc" {
		t.Fatalf("token=%q", got)
	}
}

func TestDedupReack(t *testing.T) {
	fake := NewFakeTransport()
	c := connectFake(t, fake)
	defer c.Close()

	var calls int
	var mu sync.Mutex
	c.OnMessage(func(msg Message) error {
		mu.Lock()
		calls++
		mu.Unlock()
		return nil
	})

	// 自动回复 ack
	go func() {
		for i := 0; i < 50; i++ {
			for _, fr := range fake.FindUp("ack") {
				rid, _ := fr["rid"].(string)
				if rid != "" {
					fake.ReplyOK(rid, map[string]any{"result": "accepted"})
				}
			}
			time.Sleep(5 * time.Millisecond)
		}
	}()

	msg, _ := marshalJSON(map[string]any{
		"v": 1, "type": "msg", "id": "m1", "from": "a",
		"to": map[string]any{"kind": "endpoint", "id": "ep1"},
		"body": map[string]any{"enc": "utf8", "data": "hi"},
		"send_at_ms": 1,
	})
	fake.InjectDown(msg)
	fake.InjectDown(msg) // 已交给未确认：忽略
	time.Sleep(50 * time.Millisecond)

	// 等 ack 发出并标记已确认后再推一次
	deadline := time.Now().Add(2 * time.Second)
	for time.Now().Before(deadline) {
		if len(fake.FindUp("ack")) >= 1 {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
	time.Sleep(30 * time.Millisecond)
	fake.InjectDown(msg) // 已确认：再 ack，不回调
	time.Sleep(80 * time.Millisecond)

	mu.Lock()
	n := calls
	mu.Unlock()
	if n != 1 {
		t.Fatalf("callbacks=%d want 1", n)
	}
	acks := fake.FindUp("ack")
	if len(acks) < 2 {
		t.Fatalf("acks=%d want >=2 (re-ack)", len(acks))
	}
}

func TestBodyTooLargeLocal(t *testing.T) {
	fake := NewFakeTransport()
	fake.MaxBodyBytes = 16
	c := connectFake(t, fake)
	defer c.Close()

	body := Body{Enc: "utf8", Data: strings.Repeat("x", 64)}
	_, err := c.Send(context.Background(), Target{Kind: "endpoint", ID: "b"}, body, SendOptions{})
	var ae *APIError
	if !errors.As(err, &ae) || ae.Code != CodeBodyTooLarge {
		t.Fatalf("err=%v", err)
	}
}

func TestFrameTooLargeLocal(t *testing.T) {
	fake := NewFakeTransport()
	fake.MaxBodyBytes = 1 << 20
	fake.MaxFrameBytes = 200
	c := connectFake(t, fake)
	defer c.Close()

	body := Body{Enc: "utf8", Data: strings.Repeat("y", 180)}
	_, err := c.Send(context.Background(), Target{Kind: "endpoint", ID: "b"}, body, SendOptions{})
	var ae *APIError
	if !errors.As(err, &ae) || ae.Code != CodeFrameTooLarge {
		t.Fatalf("err=%v", err)
	}
}

func TestResendKeepsIDAndSendAt(t *testing.T) {
	fake := NewFakeTransport()
	c := connectFake(t, fake)
	defer c.Close()

	at := time.UnixMilli(1_700_000_000_000)
	var firstID string
	var firstSendAt any
	var once sync.Once
	done := make(chan struct{})

	go func() {
		for {
			select {
			case <-done:
				return
			default:
			}
			sends := fake.FindUp("send")
			if len(sends) == 0 {
				time.Sleep(5 * time.Millisecond)
				continue
			}
			last := sends[len(sends)-1]
			rid, _ := last["rid"].(string)
			once.Do(func() {
				firstID, _ = last["id"].(string)
				firstSendAt = last["send_at_ms"]
				fake.ReplyErr(rid, CodeRateLimited, "slow")
			})
			if len(sends) >= 2 {
				second := sends[1]
				if second["id"] != firstID {
					t.Errorf("id changed %v -> %v", firstID, second["id"])
				}
				if second["send_at_ms"] != firstSendAt {
					t.Errorf("send_at_ms changed %v -> %v", firstSendAt, second["send_at_ms"])
				}
				fake.ReplyOK(second["rid"].(string), map[string]any{
					"id": firstID, "send_at_ms": firstSendAt, "state": "scheduled",
				})
				return
			}
			time.Sleep(5 * time.Millisecond)
		}
	}()

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	res, err := c.Send(ctx, Target{Kind: "endpoint", ID: "b"}, Body{Enc: "utf8", Data: "hi"}, SendOptions{SendAt: &at})
	close(done)
	if err != nil {
		t.Fatal(err)
	}
	if res.ID == "" || res.ID != firstID {
		t.Fatalf("result id=%q first=%q", res.ID, firstID)
	}
}

func TestRegisterHTTP(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/client/register" {
			t.Fatalf("path %s", r.URL.Path)
		}
		_ = json.NewEncoder(w).Encode(map[string]any{
			"ok": true, "data": map[string]any{"id": "e_1", "login_password": "genpass"},
		})
	}))
	defer srv.Close()

	// 从 ws 地址推出
	ws := "ws" + strings.TrimPrefix(srv.URL, "http") + "/mqtt"
	res, err := Register(context.Background(), ws, "code", RegisterOptions{Name: "n"})
	if err != nil {
		t.Fatal(err)
	}
	if res.ID != "e_1" || res.LoginPassword != "genpass" {
		t.Fatalf("%+v", res)
	}
}

func TestBuildCleanConnectFlags(t *testing.T) {
	clean, exp := buildCleanConnectFlags()
	if !clean || exp != 0 {
		t.Fatalf("clean=%v exp=%d", clean, exp)
	}
}

func TestBackoffNominal(t *testing.T) {
	if d := computeBackoffDelay(time.Second, 1); d != time.Second {
		t.Fatal(d)
	}
	if d := computeBackoffDelay(time.Second, 6); d != 30*time.Second {
		t.Fatal(d)
	}
}