package socket

import (
	"context"
	"errors"

	protoSocket "git.toki-labs.com/toki/proto-socket/go"

	altv1 "git.toki-labs.com/toki/alt/packages/contracts/gen/go/alt/v1"
	"git.toki-labs.com/toki/alt/services/api/internal/workerclient"
)

const (
	marketErrorInvalidRequest = "invalid_request"
	marketErrorUnavailable    = "unavailable"
	marketErrorTimeout        = "timeout"
	marketErrorInternal       = "internal"
)

// marketHandlers returns the API session handlers for market data reads. The
// API validates query shape and forwards the request unchanged to the worker.
func marketHandlers(worker workerclient.WorkerClient) []sessionHandler {
	return []sessionHandler{
		{
			requestType: protoSocket.TypeNameOf(&altv1.ListInstrumentsRequest{}),
			register: func(client *protoSocket.WsClient) {
				protoSocket.AddRequestListenerTyped[*altv1.ListInstrumentsRequest, *altv1.ListInstrumentsResponse](&client.Communicator, func(req *altv1.ListInstrumentsRequest) (*altv1.ListInstrumentsResponse, error) {
					return handleListInstruments(worker, req)
				})
			},
		},
		{
			requestType: protoSocket.TypeNameOf(&altv1.ListBarsRequest{}),
			register: func(client *protoSocket.WsClient) {
				protoSocket.AddRequestListenerTyped[*altv1.ListBarsRequest, *altv1.ListBarsResponse](&client.Communicator, func(req *altv1.ListBarsRequest) (*altv1.ListBarsResponse, error) {
					return handleListBars(worker, req)
				})
			},
		},
	}
}

func handleListInstruments(worker workerclient.WorkerClient, req *altv1.ListInstrumentsRequest) (*altv1.ListInstrumentsResponse, error) {
	if !isValidMarketFilter(req.GetMarket()) {
		return &altv1.ListInstrumentsResponse{Error: marketInvalidRequest("market filter is unsupported")}, nil
	}
	if worker == nil {
		return &altv1.ListInstrumentsResponse{Error: marketWorkerUnavailable()}, nil
	}

	ctx, cancel := context.WithTimeout(context.Background(), workerRequestTimeout)
	defer cancel()

	if err := worker.Connect(ctx); err != nil {
		return &altv1.ListInstrumentsResponse{Error: marketWorkerErrorInfo(err)}, nil
	}

	res, err := worker.ListInstruments(ctx, req)
	if err != nil {
		return &altv1.ListInstrumentsResponse{Error: marketWorkerErrorInfo(err)}, nil
	}
	if res == nil {
		return &altv1.ListInstrumentsResponse{Error: marketInternalError("worker returned no list instruments response")}, nil
	}
	return res, nil
}

func handleListBars(worker workerclient.WorkerClient, req *altv1.ListBarsRequest) (*altv1.ListBarsResponse, error) {
	if req.GetInstrumentId() == "" {
		return &altv1.ListBarsResponse{Error: marketInvalidRequest("instrument_id is required")}, nil
	}
	if !isValidTimeframe(req.GetTimeframe()) {
		return &altv1.ListBarsResponse{Error: marketInvalidRequest("timeframe is unsupported")}, nil
	}
	if req.GetFromUnixMs() == 0 {
		return &altv1.ListBarsResponse{Error: marketInvalidRequest("from_unix_ms is required")}, nil
	}
	if req.GetToUnixMs() == 0 {
		return &altv1.ListBarsResponse{Error: marketInvalidRequest("to_unix_ms is required")}, nil
	}
	if req.GetFromUnixMs() > req.GetToUnixMs() {
		return &altv1.ListBarsResponse{Error: marketInvalidRequest("from_unix_ms cannot be after to_unix_ms")}, nil
	}
	if worker == nil {
		return &altv1.ListBarsResponse{Error: marketWorkerUnavailable()}, nil
	}

	ctx, cancel := context.WithTimeout(context.Background(), workerRequestTimeout)
	defer cancel()

	if err := worker.Connect(ctx); err != nil {
		return &altv1.ListBarsResponse{Error: marketWorkerErrorInfo(err)}, nil
	}

	res, err := worker.ListBars(ctx, req)
	if err != nil {
		return &altv1.ListBarsResponse{Error: marketWorkerErrorInfo(err)}, nil
	}
	if res == nil {
		return &altv1.ListBarsResponse{Error: marketInternalError("worker returned no list bars response")}, nil
	}
	return res, nil
}

func isValidMarketFilter(m altv1.Market) bool {
	switch m {
	case altv1.Market_MARKET_UNSPECIFIED, altv1.Market_MARKET_KR, altv1.Market_MARKET_US:
		return true
	default:
		return false
	}
}

func isValidTimeframe(t altv1.Timeframe) bool {
	switch t {
	case altv1.Timeframe_TIMEFRAME_DAILY, altv1.Timeframe_TIMEFRAME_MINUTE_1, altv1.Timeframe_TIMEFRAME_MINUTE_5:
		return true
	default:
		return false
	}
}

func marketInvalidRequest(reason string) *altv1.ErrorInfo {
	return errorInfo(marketErrorInvalidRequest, "invalid market request: "+reason)
}

func marketWorkerUnavailable() *altv1.ErrorInfo {
	return errorInfo(marketErrorUnavailable, "market worker unavailable")
}

func marketInternalError(message string) *altv1.ErrorInfo {
	return errorInfo(marketErrorInternal, message)
}

func marketWorkerErrorInfo(err error) *altv1.ErrorInfo {
	if err == nil {
		return nil
	}
	switch {
	case errors.Is(err, workerclient.ErrUnavailable):
		return errorInfo(marketErrorUnavailable, "market worker unavailable")
	case errors.Is(err, workerclient.ErrTimeout):
		return errorInfo(marketErrorTimeout, "market worker timeout")
	default:
		return errorInfo(marketErrorInternal, err.Error())
	}
}