package yasrpc

import (
	"context"
	"errors"
	"fmt"
	"log"
	"net"
	"net/http/httptest"
	"reflect"
	"runtime"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

var (
	newServer                 *Server
	serverAddr, newServerAddr string
	httpServerAddr            string
	once, newOnce, httpOnce   sync.Once
)

const (
	newHttpPath = "/foo"
)

type Args struct {
	A, B int
}

type Reply struct {
	C int
}

type Arith int

// Some of Arith's methods have value args, some have pointer args. That's deliberate.

func (t *Arith) Add(args Args, reply *Reply) error {
	reply.C = args.A + args.B
	return nil
}

func (t *Arith) Mul(args *Args, reply *Reply) error {
	reply.C = args.A * args.B
	return nil
}

func (t *Arith) Div(args Args, reply *Reply) error {
	if args.B == 0 {
		return errors.New("divide by zero")
	}
	reply.C = args.A / args.B
	return nil
}

func (t *Arith) String(args *Args, reply *string) error {
	*reply = fmt.Sprintf("%d+%d=%d", args.A, args.B, args.A+args.B)
	return nil
}

func (t *Arith) Scan(args string, reply *Reply) (err error) {
	_, err = fmt.Sscan(args, &reply.C)
	return
}

func (t *Arith) Error(args *Args, reply *Reply) error {
	panic("ERROR")
}

func (t *Arith) SleepMilli(args *Args, reply *Reply) error {
	time.Sleep(time.Duration(args.A) * time.Millisecond)
	return nil
}

type hidden int

func (t *hidden) Exported(args Args, reply *Reply) error {
	reply.C = args.A + args.B
	return nil
}

type Embed struct {
	hidden
}

type BuiltinTypes struct{}

func (BuiltinTypes) Map(args *Args, reply *map[int]int) error {
	(*reply)[args.A] = args.B
	return nil
}

func (BuiltinTypes) Slice(args *Args, reply *[]int) error {
	*reply = append(*reply, args.A, args.B)
	return nil
}

func (BuiltinTypes) Array(args *Args, reply *[2]int) error {
	(*reply)[0] = args.A
	(*reply)[1] = args.B
	return nil
}

func listenTCP() (net.Listener, string) {
	l, e := net.Listen("tcp", "127.0.0.1:0")
	if e != nil {
		log.Fatalf("net.Listen tcp :0: %v", e)
	}
	return l, l.Addr().String()
}

func startDefaultServer() {
	Register(new(Arith))
	Register(new(Embed))
	Register(BuiltinTypes{})

	var l net.Listener
	l, serverAddr = listenTCP()
	log.Println("Test RPC server listening on", serverAddr)
	go Accept(l)

	HandleHTTP()
	httpOnce.Do(startHttpServer)
}

func startNewServer() {
	newServer = NewServer(nil)
	newServer.Register(new(Arith))
	newServer.Register(new(Embed))

	var l net.Listener
	l, newServerAddr = listenTCP()
	log.Println("NewServer test RPC server listening on", newServerAddr)
	go newServer.Accept(l)

	newServer.HandleHTTP(newHttpPath, "/bar")
	httpOnce.Do(startDefaultServer)
}

func startHttpServer() {
	server := httptest.NewServer(nil)
	httpServerAddr = server.Listener.Addr().String()
	log.Println("Test HTTP RPC server listening on ", httpServerAddr)
}

func TestRPC(t *testing.T) {
	once.Do(startDefaultServer)
	testRPC(t, serverAddr)
	newOnce.Do(startNewServer)
	testRPC(t, newServerAddr)
}

func testRPC(t *testing.T, addr string) {
	client, err := Dial("tcp", addr, nil, nil)
	if err != nil {
		t.Fatal("dialing: ", err)
	}
	defer client.Close()

	// Synchronous calls
	args := &Args{7, 8}
	reply := new(Reply)
	err = client.Call(context.Background(), "Arith.Add", args, reply)
	if err != nil {
		t.Errorf("Add: expected no error but got string %q", err.Error())
	}
	if reply.C != args.A+args.B {
		t.Errorf("Add: expected %d got %d", reply.C, args.A+args.B)
	}

	// Methods exported from unexported embedded structs
	args = &Args{7, 0}
	reply = new(Reply)
	err = client.Call(context.Background(), "Embed.Exported", args, reply)
	if err != nil {
		t.Errorf("Add: expected no error but got string %q", err.Error())
	}
	if reply.C != args.A+args.B {
		t.Errorf("Add: expected %d got %d", reply.C, args.A+args.B)
	}

	// Nonexistent method
	args = &Args{7, 0}
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.BadOperation", args, reply)
	// expect an error
	if err == nil {
		t.Error("BadOperation: expected error")
	} else if !strings.HasPrefix(err.Error(), "rpc server: can't find method") {
		t.Errorf("BadOperation: expected can't find method error; got %q", err)
	}

	// Unknown service
	args = &Args{7, 8}
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.Unknown", args, reply)
	if err == nil {
		t.Error("expected error calling unknown service")
	} else if !strings.Contains(err.Error(), "method") {
		t.Error("expected error about method; got", err)
	}

	// Out of order.
	args = &Args{7, 8}
	mulReply := new(Reply)
	mulCall := client.Go("Arith.Mul", args, mulReply, nil, nil)
	addReply := new(Reply)
	addCall := client.Go("Arith.Add", args, addReply, nil, nil)

	addCall = <-addCall.Done
	if addCall.Error != nil {
		t.Errorf("Add: expected no error but got string %q", addCall.Error.Error())
	}
	if addReply.C != args.A+args.B {
		t.Errorf("Add: expected %d got %d", addReply.C, args.A+args.B)
	}

	mulCall = <-mulCall.Done
	if mulCall.Error != nil {
		t.Errorf("Mul: expected no error but got string %q", mulCall.Error.Error())
	}
	if mulReply.C != args.A*args.B {
		t.Errorf("Mul: expected %d got %d", mulReply.C, args.A*args.B)
	}

	// Error test
	args = &Args{7, 0}
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.Div", args, reply)
	// expect an error: zero divide
	if err == nil {
		t.Error("Div: expected error")
	} else if err.Error() != "divide by zero" {
		t.Error("Div: expected divide by zero error; got", err)
	}

	// Bad type.
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.Add", reply, reply) // args, reply would be the correct thing to use
	if err == nil {
		t.Error("expected error calling Arith.Add with wrong arg type")
	} else if !strings.Contains(err.Error(), "type") {
		t.Error("expected error about type; got", err)
	}

	// Non-struct argument
	const Val = 12345
	str := fmt.Sprint(Val)
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.Scan", &str, reply)
	if err != nil {
		t.Errorf("Scan: expected no error but got string %q", err.Error())
	} else if reply.C != Val {
		t.Errorf("Scan: expected %d got %d", Val, reply.C)
	}

	// Non-struct reply
	args = &Args{27, 35}
	str = ""
	err = client.Call(context.Background(), "Arith.String", args, &str)
	if err != nil {
		t.Errorf("String: expected no error but got string %q", err.Error())
	}
	expect := fmt.Sprintf("%d+%d=%d", args.A, args.B, args.A+args.B)
	if str != expect {
		t.Errorf("String: expected %s got %s", expect, str)
	}

	args = &Args{7, 8}
	reply = new(Reply)
	err = client.Call(context.Background(), "Arith.Mul", args, reply)
	if err != nil {
		t.Errorf("Mul: expected no error but got string %q", err.Error())
	}
	if reply.C != args.A*args.B {
		t.Errorf("Mul: expected %d got %d", reply.C, args.A*args.B)
	}
}

func TestHTTP(t *testing.T) {
	once.Do(startDefaultServer)
	testHTTPRPC(t)
}

func testHTTPRPC(t *testing.T) {
	client, err := DialHTTP("tcp", httpServerAddr, nil, nil)
	if err != nil {
		t.Fatal("dialing", err)
	}
	defer client.Close()

	// Synchronous calls
	args := &Args{7, 8}
	reply := new(Reply)
	err = client.Call(context.Background(), "Arith.Add", args, reply)
	if err != nil {
		t.Errorf("Add: expected no error but got string %q", err.Error())
	}
	if reply.C != args.A+args.B {
		t.Errorf("Add: expected %d got %d", reply.C, args.A+args.B)
	}
}

func TestBuiltinTypes(t *testing.T) {
	once.Do(startDefaultServer)

	client, err := DialHTTP("tcp", httpServerAddr, nil, nil)
	if err != nil {
		t.Fatal("dialing", err)
	}
	defer client.Close()

	// Map
	args := &Args{7, 8}
	replyMap := map[int]int{}
	err = client.Call(context.Background(), "BuiltinTypes.Map", args, &replyMap)
	if err != nil {
		t.Errorf("Map: expected no error but got string %q", err.Error())
	}
	if replyMap[args.A] != args.B {
		t.Errorf("Map: expected %d got %d", args.B, replyMap[args.A])
	}

	// Slice
	args = &Args{7, 8}
	replySlice := new([]int)
	err = client.Call(context.Background(), "BuiltinTypes.Slice", args, replySlice)
	if err != nil {
		t.Errorf("Slice: expected no error but got string %q", err.Error())
	}
	if e := []int{args.A, args.B}; !reflect.DeepEqual(*replySlice, e) {
		t.Errorf("Slice: expected %v got %v", e, replySlice)
	}

	// Array
	args = &Args{7, 8}
	replyArray := [2]int{}
	err = client.Call(context.Background(), "BuiltinTypes.Array", args, &replyArray)
	if err != nil {
		t.Errorf("Array: expected no error but got string %q", err.Error())
	}
	if e := [2]int{args.A, args.B}; !reflect.DeepEqual(replyArray, e) {
		t.Errorf("Array: expected %v got %v", e, replyArray)
	}
}

type ReplyNotPointer int
type ArgNotPublic int
type ReplyNotPublic int
type NeedsPtrType int
type local struct{}

func (t *ReplyNotPointer) ReplyNotPointer(args *Args, reply Reply) error {
	return nil
}

func (t *ArgNotPublic) ArgNotPublic(args *local, reply *Reply) error {
	return nil
}

func (t *ReplyNotPublic) ReplyNotPublic(args *Args, reply *local) error {
	return nil
}

func (t *NeedsPtrType) NeedsPtrType(args *Args, reply *Reply) error {
	return nil
}

// Check that registration handles lots of bad methods and a type with no suitable methods.
func TestRegistrationError(t *testing.T) {
	err := Register(new(ReplyNotPointer))
	if err == nil {
		t.Error("expected error registering ReplyNotPointer")
	}
	err = Register(new(ArgNotPublic))
	if err == nil {
		t.Error("expected error registering ArgNotPublic")
	}
	err = Register(new(ReplyNotPublic))
	if err == nil {
		t.Error("expected error registering ReplyNotPublic")
	}
	err = Register(NeedsPtrType(0))
	if err == nil {
		t.Error("expected error registering NeedsPtrType")
	} else if !strings.Contains(err.Error(), "suitable type") {
		t.Error("expected hint when registering NeedsPtrType")
	}
}

type WriteFailCodec int

func (WriteFailCodec) Write(*Header, interface{}) error {
	// the panic caused by this error used to not unlock a lock.
	return errors.New("fail")
}

func (WriteFailCodec) ReadHeader(*Header) error {
	select {}
}

func (WriteFailCodec) ReadBody(interface{}) error {
	select {}
}

func (WriteFailCodec) Close() error {
	return nil
}

func (WriteFailCodec) ClientIp() string {
	return ""
}

func TestSendDeadlock(t *testing.T) {
	client := newClientCodec(WriteFailCodec(0), nil, nil)
	defer client.Close()

	done := make(chan bool)
	go func() {
		testSendDeadlock(client)
		testSendDeadlock(client)
		done <- true
	}()
	select {
	case <-done:
		return
	case <-time.After(5 * time.Second):
		t.Fatal("deadlock")
	}
}

func testSendDeadlock(client *Client) {
	defer func() {
		recover()
	}()
	args := &Args{7, 8}
	reply := new(Reply)
	client.Call(context.Background(), "Arith.Add", args, reply)
}

func dialDirect() (*Client, error) {
	return Dial("tcp", serverAddr, nil, nil)
}

func dialHTTP() (*Client, error) {
	return DialHTTP("tcp", httpServerAddr, nil, nil)
}

func countMallocs(dial func() (*Client, error), t *testing.T) float64 {
	once.Do(startDefaultServer)
	client, err := dial()
	if err != nil {
		t.Fatal("error dialing", err)
	}
	defer client.Close()

	args := &Args{7, 8}
	reply := new(Reply)
	return testing.AllocsPerRun(100, func() {
		err := client.Call(context.Background(), "Arith.Add", args, reply)
		if err != nil {
			t.Errorf("Add: expected no error but got string %q", err.Error())
		}
		if reply.C != args.A+args.B {
			t.Errorf("Add: expected %d got %d", reply.C, args.A+args.B)
		}
	})
}

func TestCountMallocs(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping malloc count in short mode")
	}
	runtime.GOMAXPROCS(1)
	fmt.Printf("mallocs per rpc round trip: %v\n", countMallocs(dialDirect, t))
}

func TestCountMallocsOverHTTP(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping malloc count in short mode")
	}
	runtime.GOMAXPROCS(1)
	fmt.Printf("mallocs per HTTP rpc round trip: %v\n", countMallocs(dialHTTP, t))
}

func TestTCPClose(t *testing.T) {
	once.Do(startDefaultServer)

	client, err := dialHTTP()
	if err != nil {
		t.Fatalf("dialing: %v", err)
	}
	defer client.Close()

	args := Args{17, 8}
	var reply Reply
	err = client.Call(context.Background(), "Arith.Mul", args, &reply)
	if err != nil {
		t.Fatal("arith error:", err)
	}
	t.Logf("Arith: %d*%d=%d\n", args.A, args.B, reply)
	if reply.C != args.A*args.B {
		t.Errorf("Add: expected %d got %d", reply.C, args.A*args.B)
	}
}

func TestErrorAfterClientClose(t *testing.T) {
	once.Do(startDefaultServer)

	client, err := dialHTTP()
	if err != nil {
		t.Fatalf("dialing: %v", err)
	}
	err = client.Close()
	if err != nil {
		t.Fatal("close error:", err)
	}
	err = client.Call(context.Background(), "Arith.Add", &Args{7, 9}, new(Reply))
	if err != ErrShutdown {
		t.Errorf("Forever: expected ErrShutdown got %v", err)
	}
}

func TestAcceptExitAfterListenerClose(t *testing.T) {
	newServer := NewServer(nil)
	newServer.Register(new(Arith))

	var l net.Listener
	l, _ = listenTCP()
	l.Close()
	newServer.Accept(l)
}

func benchmarkEndToEnd(dial func() (*Client, error), b *testing.B) {
	once.Do(startDefaultServer)
	client, err := dial()
	if err != nil {
		b.Fatal("error dialing:", err)
	}
	defer client.Close()

	// Synchronous calls
	args := &Args{7, 8}
	b.ResetTimer()

	b.RunParallel(func(pb *testing.PB) {
		reply := new(Reply)
		for pb.Next() {
			err := client.Call(context.Background(), "Arith.Add", args, reply)
			if err != nil {
				b.Fatalf("rpc error: Add: expected no error but got string %q", err.Error())
			}
			if reply.C != args.A+args.B {
				b.Fatalf("rpc error: Add: expected %d got %d", reply.C, args.A+args.B)
			}
		}
	})
}

func benchmarkEndToEndAsync(dial func() (*Client, error), b *testing.B) {
	if b.N == 0 {
		return
	}
	const MaxConcurrentCalls = 100
	once.Do(startDefaultServer)
	client, err := dial()
	if err != nil {
		b.Fatal("error dialing:", err)
	}
	defer client.Close()

	// Asynchronous calls
	args := &Args{7, 8}
	procs := 4 * runtime.GOMAXPROCS(-1)
	send := int32(b.N)
	recv := int32(b.N)
	var wg sync.WaitGroup
	wg.Add(procs)
	gate := make(chan bool, MaxConcurrentCalls)
	res := make(chan *Call, MaxConcurrentCalls)
	b.ResetTimer()

	for p := 0; p < procs; p++ {
		go func() {
			for atomic.AddInt32(&send, -1) >= 0 {
				gate <- true
				reply := new(Reply)
				client.Go("Arith.Add", args, reply, res, nil)
			}
		}()
		go func() {
			for call := range res {
				A := call.Args.(*Args).A
				B := call.Args.(*Args).B
				C := call.Reply.(*Reply).C
				if A+B != C {
					b.Errorf("incorrect reply: Add: expected %d got %d", A+B, C)
					return
				}
				<-gate
				if atomic.AddInt32(&recv, -1) == 0 {
					close(res)
				}
			}
			wg.Done()
		}()
	}
	wg.Wait()
}

func BenchmarkEndToEnd(b *testing.B) {
	benchmarkEndToEnd(dialDirect, b)
}

func BenchmarkEndToEndHTTP(b *testing.B) {
	benchmarkEndToEnd(dialHTTP, b)
}

func BenchmarkEndToEndAsync(b *testing.B) {
	benchmarkEndToEndAsync(dialDirect, b)
}

func BenchmarkEndToEndAsyncHTTP(b *testing.B) {
	benchmarkEndToEndAsync(dialHTTP, b)
}