package operator

import (
	"context"
	"errors"
	"fmt"
	"net"
	"sync"
	"testing"

	"nhooyr.io/websocket"

	altv1 "git.toki-labs.com/toki/alt/packages/contracts/gen/go/alt/v1"
	protoSocket "git.toki-labs.com/toki/proto-socket/go"
)

// fakeAPI configures the canned responses an in-process API server returns and
// captures the requests it received so tests can assert the client sent the
// right fields. A nil response slot makes the handler return an empty typed
// response.
type fakeAPI struct {
	helloCaps []string
	instResp  *altv1.ListInstrumentsResponse
	barsResp  *altv1.ListBarsResponse

	startBacktestResp        *altv1.StartBacktestResponse
	getBacktestRunResp       *altv1.GetBacktestRunResponse
	listBacktestRunsResp     *altv1.ListBacktestRunsResponse
	getBacktestRunDetailResp *altv1.GetBacktestRunDetailResponse
	getBacktestResultResp    *altv1.GetBacktestResultResponse
	compareBacktestRunsResp  *altv1.CompareBacktestRunsResponse

	getBacktestRunFunc func(req *altv1.GetBacktestRunRequest) (*altv1.GetBacktestRunResponse, error)

	mu                sync.Mutex
	instReq           *altv1.ListInstrumentsRequest
	barsReq           *altv1.ListBarsRequest
	startBacktestReq  *altv1.StartBacktestRequest
	getBacktestRunReq *altv1.GetBacktestRunRequest
}

func (f *fakeAPI) setInstReq(req *altv1.ListInstrumentsRequest) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.instReq = req
}

func (f *fakeAPI) setBarsReq(req *altv1.ListBarsRequest) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.barsReq = req
}

func (f *fakeAPI) setStartBacktestReq(req *altv1.StartBacktestRequest) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.startBacktestReq = req
}

func (f *fakeAPI) setGetBacktestRunReq(req *altv1.GetBacktestRunRequest) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.getBacktestRunReq = req
}

func (f *fakeAPI) lastInstReq() *altv1.ListInstrumentsRequest {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.instReq
}

func (f *fakeAPI) lastBarsReq() *altv1.ListBarsRequest {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.barsReq
}

func (f *fakeAPI) lastStartBacktestReq() *altv1.StartBacktestRequest {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.startBacktestReq
}

func (f *fakeAPI) lastGetBacktestRunReq() *altv1.GetBacktestRunRequest {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.getBacktestRunReq
}

// startFakeAPIServer starts a proto-socket server on a free localhost port that
// answers hello/list_instruments/list_bars with the supplied canned responses
// and records the received requests. It returns the ws:// URL and stops the
// server on test cleanup.
func startFakeAPIServer(t *testing.T, api *fakeAPI) string {
	t.Helper()

	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)

	host := "127.0.0.1"
	port := freePort(t)
	path := "/socket"

	srv := protoSocket.NewWsServer(host, port, path, func(conn *websocket.Conn) *protoSocket.WsClient {
		return protoSocket.NewWsClient(conn, 0, 0, ParserMap())
	})
	srv.OnClientConnected = func(c *protoSocket.WsClient) {
		protoSocket.AddRequestListenerTyped[*altv1.HelloRequest, *altv1.HelloResponse](&c.Communicator, func(req *altv1.HelloRequest) (*altv1.HelloResponse, error) {
			return &altv1.HelloResponse{
				ServerName:         "alt-api-fake",
				ServerVersion:      "test",
				AltProtocolVersion: req.GetAltProtocolVersion(),
				Capabilities:       api.helloCaps,
			}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.ListInstrumentsRequest, *altv1.ListInstrumentsResponse](&c.Communicator, func(req *altv1.ListInstrumentsRequest) (*altv1.ListInstrumentsResponse, error) {
			api.setInstReq(req)
			if api.instResp != nil {
				return api.instResp, nil
			}
			return &altv1.ListInstrumentsResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.ListBarsRequest, *altv1.ListBarsResponse](&c.Communicator, func(req *altv1.ListBarsRequest) (*altv1.ListBarsResponse, error) {
			api.setBarsReq(req)
			if api.barsResp != nil {
				return api.barsResp, nil
			}
			return &altv1.ListBarsResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.StartBacktestRequest, *altv1.StartBacktestResponse](&c.Communicator, func(req *altv1.StartBacktestRequest) (*altv1.StartBacktestResponse, error) {
			api.setStartBacktestReq(req)
			if api.startBacktestResp != nil {
				return api.startBacktestResp, nil
			}
			return &altv1.StartBacktestResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.GetBacktestRunRequest, *altv1.GetBacktestRunResponse](&c.Communicator, func(req *altv1.GetBacktestRunRequest) (*altv1.GetBacktestRunResponse, error) {
			api.setGetBacktestRunReq(req)
			if api.getBacktestRunFunc != nil {
				return api.getBacktestRunFunc(req)
			}
			if api.getBacktestRunResp != nil {
				return api.getBacktestRunResp, nil
			}
			return &altv1.GetBacktestRunResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.ListBacktestRunsRequest, *altv1.ListBacktestRunsResponse](&c.Communicator, func(req *altv1.ListBacktestRunsRequest) (*altv1.ListBacktestRunsResponse, error) {
			if api.listBacktestRunsResp != nil {
				return api.listBacktestRunsResp, nil
			}
			return &altv1.ListBacktestRunsResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.GetBacktestRunDetailRequest, *altv1.GetBacktestRunDetailResponse](&c.Communicator, func(req *altv1.GetBacktestRunDetailRequest) (*altv1.GetBacktestRunDetailResponse, error) {
			if api.getBacktestRunDetailResp != nil {
				return api.getBacktestRunDetailResp, nil
			}
			return &altv1.GetBacktestRunDetailResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.GetBacktestResultRequest, *altv1.GetBacktestResultResponse](&c.Communicator, func(req *altv1.GetBacktestResultRequest) (*altv1.GetBacktestResultResponse, error) {
			if api.getBacktestResultResp != nil {
				return api.getBacktestResultResp, nil
			}
			return &altv1.GetBacktestResultResponse{}, nil
		})
		protoSocket.AddRequestListenerTyped[*altv1.CompareBacktestRunsRequest, *altv1.CompareBacktestRunsResponse](&c.Communicator, func(req *altv1.CompareBacktestRunsRequest) (*altv1.CompareBacktestRunsResponse, error) {
			if api.compareBacktestRunsResp != nil {
				return api.compareBacktestRunsResp, nil
			}
			return &altv1.CompareBacktestRunsResponse{}, nil
		})
	}

	if err := srv.Start(ctx); err != nil {
		t.Fatalf("start fake API server: %v", err)
	}
	t.Cleanup(func() { _ = srv.Stop() })

	return fmt.Sprintf("ws://%s:%d%s", host, port, path)
}

func freePort(t *testing.T) int {
	t.Helper()
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("reserve TCP port: %v", err)
	}
	defer listener.Close()
	addr, ok := listener.Addr().(*net.TCPAddr)
	if !ok {
		t.Fatalf("unexpected listener address type %T", listener.Addr())
	}
	return addr.Port
}

func dialTestClient(t *testing.T, url string) *APIClient {
	t.Helper()
	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)
	client, err := Dial(ctx, url)
	if err != nil {
		t.Fatalf("dial fake API: %v", err)
	}
	t.Cleanup(func() { _ = client.Close() })
	return client
}

func TestAPIClientHello(t *testing.T) {
	url := startFakeAPIServer(t, &fakeAPI{helloCaps: []string{"hello", "market-read"}})
	client := dialTestClient(t, url)

	resp, err := client.Hello(context.Background(), &altv1.HelloRequest{AltProtocolVersion: "alt.v1"})
	if err != nil {
		t.Fatalf("hello: %v", err)
	}
	if resp.GetServerName() != "alt-api-fake" {
		t.Errorf("server name = %q, want alt-api-fake", resp.GetServerName())
	}
	if resp.GetAltProtocolVersion() != "alt.v1" {
		t.Errorf("protocol version = %q, want alt.v1", resp.GetAltProtocolVersion())
	}
}

func TestAPIClientListInstruments(t *testing.T) {
	api := &fakeAPI{instResp: &altv1.ListInstrumentsResponse{
		Instruments: []*altv1.Instrument{{Id: "KRX:005930", Symbol: "005930"}},
	}}
	url := startFakeAPIServer(t, api)
	client := dialTestClient(t, url)

	resp, err := client.ListInstruments(context.Background(), &altv1.ListInstrumentsRequest{Market: altv1.Market_MARKET_KR})
	if err != nil {
		t.Fatalf("list instruments: %v", err)
	}
	if resp.GetError() != nil {
		t.Fatalf("unexpected typed error: %+v", resp.GetError())
	}
	if len(resp.GetInstruments()) != 1 {
		t.Fatalf("instruments = %d, want 1", len(resp.GetInstruments()))
	}
	if resp.GetInstruments()[0].GetId() != "KRX:005930" {
		t.Errorf("instrument id = %q, want KRX:005930", resp.GetInstruments()[0].GetId())
	}

	got := api.lastInstReq()
	if got == nil {
		t.Fatal("server did not receive a list instruments request")
	}
	if got.GetMarket() != altv1.Market_MARKET_KR {
		t.Errorf("server received market = %v, want MARKET_KR", got.GetMarket())
	}
}

func TestAPIClientListBars(t *testing.T) {
	api := &fakeAPI{barsResp: &altv1.ListBarsResponse{
		Bars: []*altv1.Bar{{InstrumentId: "KRX:005930", Timeframe: altv1.Timeframe_TIMEFRAME_DAILY}},
	}}
	url := startFakeAPIServer(t, api)
	client := dialTestClient(t, url)

	req := &altv1.ListBarsRequest{
		InstrumentId: "KRX:005930",
		Timeframe:    altv1.Timeframe_TIMEFRAME_DAILY,
		FromUnixMs:   1746057600000,
		ToUnixMs:     1747267200000,
	}
	resp, err := client.ListBars(context.Background(), req)
	if err != nil {
		t.Fatalf("list bars: %v", err)
	}
	if resp.GetError() != nil {
		t.Fatalf("unexpected typed error: %+v", resp.GetError())
	}
	if len(resp.GetBars()) != 1 {
		t.Fatalf("bars = %d, want 1", len(resp.GetBars()))
	}

	got := api.lastBarsReq()
	if got == nil {
		t.Fatal("server did not receive a list bars request")
	}
	if got.GetInstrumentId() != "KRX:005930" {
		t.Errorf("server received instrument_id = %q, want KRX:005930", got.GetInstrumentId())
	}
	if got.GetTimeframe() != altv1.Timeframe_TIMEFRAME_DAILY {
		t.Errorf("server received timeframe = %v, want TIMEFRAME_DAILY", got.GetTimeframe())
	}
	if got.GetFromUnixMs() != 1746057600000 || got.GetToUnixMs() != 1747267200000 {
		t.Errorf("server received window = [%d,%d], want [1746057600000,1747267200000]", got.GetFromUnixMs(), got.GetToUnixMs())
	}
}

func TestAPIClientConnectUnavailable(t *testing.T) {
	// Reserve then release a port so the dial target is almost certainly closed.
	port := freePort(t)
	url := fmt.Sprintf("ws://127.0.0.1:%d/socket", port)

	_, err := Dial(context.Background(), url)
	if err == nil {
		t.Fatal("expected dial to a closed port to fail")
	}
	if !errors.Is(err, ErrTransport) {
		t.Errorf("error = %v, want it to wrap ErrTransport", err)
	}
}