package peer

import (
	"net"
	"os"
	"path/filepath"
	"testing"
	"time"

	"omnisocketgo/cmd/internal/protocol"
	"omnisocketgo/cmd/internal/server"
	"omnisocketgo/cmd/internal/transport"
)

// TestUDPDialAndSendText 验证 UDP 客户端可以成功连接、注册并发送文本消息。
func TestUDPDialAndSendText(t *testing.T) {
	hubAddr := startUDPTestHub(t)

	clientA, err := DialUDP(hubAddr.String(), "peer-a")
	if err != nil {
		t.Fatalf("DialUDP(peer-a) error = %v", err)
	}
	defer clientA.Close()

	clientB, err := DialUDP(hubAddr.String(), "peer-b")
	if err != nil {
		t.Fatalf("DialUDP(peer-b) error = %v", err)
	}
	defer clientB.Close()

	// 等待注册被处理
	time.Sleep(50 * time.Millisecond)

	// peer-a 发送文本给 peer-b
	if err := clientA.SendText("peer-b", "hello from udp"); err != nil {
		t.Fatalf("SendText() error = %v", err)
	}

	// peer-b 接收
	msg := receiveUDPClientMessage(t, clientB)
	if msg.Type != protocol.MessageTypeText {
		t.Fatalf("message type = %s, want text", msg.Type)
	}
	if string(msg.Body) != "hello from udp" {
		t.Fatalf("message body = %q, want %q", string(msg.Body), "hello from udp")
	}
}

// TestUDPClientID 验证 ID() 返回正确的 peer 标识。
func TestUDPClientID(t *testing.T) {
	hubAddr := startUDPTestHub(t)

	client, err := DialUDP(hubAddr.String(), "my-peer-id")
	if err != nil {
		t.Fatalf("DialUDP() error = %v", err)
	}
	defer client.Close()

	if got := client.ID(); got != "my-peer-id" {
		t.Fatalf("ID() = %q, want %q", got, "my-peer-id")
	}
}

// TestUDPClientPersistMessage 验证 UDP 客户端可以将消息持久化到磁盘。
func TestUDPClientPersistMessage(t *testing.T) {
	hubAddr := startUDPTestHub(t)

	client, err := DialUDP(hubAddr.String(), "peer-persist")
	if err != nil {
		t.Fatalf("DialUDP() error = %v", err)
	}
	defer client.Close()

	inboxDir := t.TempDir()

	// 持久化文本消息
	textMsg := protocol.Message{
		Type: protocol.MessageTypeText,
		ID:   1,
		From: "sender",
		To:   "peer-persist",
		Body: []byte("persisted text"),
	}

	path, err := client.PersistMessage(textMsg, inboxDir)
	if err != nil {
		t.Fatalf("PersistMessage(text) error = %v", err)
	}
	if !filepath.IsAbs(path) && path == "" {
		t.Fatalf("PersistMessage(text) returned empty path")
	}

	// 持久化文件消息
	fileMsg := protocol.Message{
		Type:     protocol.MessageTypeFile,
		ID:       2,
		From:     "sender",
		To:       "peer-persist",
		FileName: "test.bin",
		Body:     []byte{0x01, 0x02, 0x03},
	}

	filePath, err := client.PersistMessage(fileMsg, inboxDir)
	if err != nil {
		t.Fatalf("PersistMessage(file) error = %v", err)
	}

	content, err := os.ReadFile(filePath)
	if err != nil {
		t.Fatalf("ReadFile(%s) error = %v", filePath, err)
	}
	if len(content) != 3 || content[0] != 0x01 {
		t.Fatalf("file content mismatch: got %v", content)
	}
}

// TestUDPClientSendFile 验证 UDP 客户端可以发送文件消息。
func TestUDPClientSendFile(t *testing.T) {
	hubAddr := startUDPTestHub(t)

	clientA, err := DialUDP(hubAddr.String(), "peer-a")
	if err != nil {
		t.Fatalf("DialUDP(peer-a) error = %v", err)
	}
	defer clientA.Close()

	clientB, err := DialUDP(hubAddr.String(), "peer-b")
	if err != nil {
		t.Fatalf("DialUDP(peer-b) error = %v", err)
	}
	defer clientB.Close()

	time.Sleep(50 * time.Millisecond)

	fileBody := []byte{0xDE, 0xAD, 0xBE, 0xEF}
	if err := clientA.SendFile("peer-b", "test.bin", fileBody); err != nil {
		t.Fatalf("SendFile() error = %v", err)
	}

	msg := receiveUDPClientMessage(t, clientB)
	if msg.Type != protocol.MessageTypeFile {
		t.Fatalf("message type = %s, want file", msg.Type)
	}
	if msg.FileName != "test.bin" {
		t.Fatalf("file name = %q, want %q", msg.FileName, "test.bin")
	}
	if len(msg.Body) != 4 {
		t.Fatalf("body length = %d, want 4", len(msg.Body))
	}
}

// startUDPTestHub 创建并启动一个测试用 UDPHub。
func startUDPTestHub(t *testing.T) *net.UDPAddr {
	t.Helper()

	addr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("ResolveUDPAddr() error = %v", err)
	}

	conn, err := net.ListenUDP("udp", addr)
	if err != nil {
		t.Fatalf("ListenUDP() error = %v", err)
	}

	hub, err := server.NewUDPHub(conn)
	if err != nil {
		_ = conn.Close()
		t.Fatalf("NewUDPHub() error = %v", err)
	}

	go func() {
		_ = hub.Serve()
	}()

	t.Cleanup(func() {
		_ = hub.Close()
	})

	return conn.LocalAddr().(*net.UDPAddr)
}

// receiveUDPClientMessage 从 UDP 客户端接收一条消息，带超时。
func receiveUDPClientMessage(t *testing.T, client *UDPClient) protocol.Message {
	t.Helper()

	type result struct {
		msg protocol.Message
		err error
	}

	ch := make(chan result, 1)
	go func() {
		msg, err := client.Receive()
		ch <- result{msg: msg, err: err}
	}()

	select {
	case r := <-ch:
		if r.err != nil {
			t.Fatalf("Receive() error = %v", r.err)
		}
		return r.msg
	case <-time.After(2 * time.Second):
		t.Fatal("Receive() timed out after 2s")
		return protocol.Message{}
	}
}

// Ensure transport package is used (needed for WithTXTimestampDebugLogger option).
var _ transport.TXTimestampDebugLogger = nil