package gateway

import (
	"context"
	"net/http"
	"strings"

	"github.com/tech/sendico/gateway/aurora/internal/appversion"
	"github.com/tech/sendico/gateway/aurora/internal/service/provider"
	"github.com/tech/sendico/gateway/aurora/storage"
	gatewayoutbox "github.com/tech/sendico/gateway/common/outbox"
	"github.com/tech/sendico/pkg/api/routers"
	"github.com/tech/sendico/pkg/api/routers/gsresponse"
	clockpkg "github.com/tech/sendico/pkg/clock"
	"github.com/tech/sendico/pkg/discovery"
	msg "github.com/tech/sendico/pkg/messaging"
	"github.com/tech/sendico/pkg/mlogger"
	pmodel "github.com/tech/sendico/pkg/model"
	"github.com/tech/sendico/pkg/mservice"
	gatewayv1 "github.com/tech/sendico/pkg/proto/common/gateway/v1"
	connectorv1 "github.com/tech/sendico/pkg/proto/connector/v1"
	"go.uber.org/zap"
	"google.golang.org/grpc"
)

type Service struct {
	logger            mlogger.Logger
	clock             clockpkg.Clock
	producer          msg.Producer
	msgCfg            pmodel.SettingsT
	storage           storage.Repository
	config            provider.Config
	httpClient        *http.Client
	card              *cardPayoutProcessor
	outbox            gatewayoutbox.ReliableRuntime
	gatewayDescriptor *gatewayv1.GatewayInstanceDescriptor
	announcer         *discovery.Announcer
	invokeURI         string
	strictIsolation   bool

	connectorv1.UnimplementedConnectorServiceServer
}

type payoutFailure interface {
	error
	Reason() string
}

type reasonedError struct {
	reason string
	err    error
}

func (r reasonedError) Error() string {
	return r.err.Error()
}

func (r reasonedError) Unwrap() error {
	return r.err
}

func (r reasonedError) Reason() string {
	return r.reason
}

// NewService constructs the Aurora gateway service skeleton.
func NewService(logger mlogger.Logger, opts ...Option) *Service {
	svc := &Service{
		logger: logger.Named("service"),
		clock:  clockpkg.NewSystem(),
		config: provider.DefaultConfig(),
		msgCfg: map[string]any{},
	}

	initMetrics()

	for _, opt := range opts {
		if opt != nil {
			opt(svc)
		}
	}

	if svc.clock == nil {
		svc.clock = clockpkg.NewSystem()
	}

	if svc.httpClient == nil {
		svc.httpClient = &http.Client{Timeout: svc.config.Timeout()}
	} else if svc.httpClient.Timeout <= 0 {
		svc.httpClient.Timeout = svc.config.Timeout()
	}

	svc.card = newCardPayoutProcessor(svc.logger, svc.config, svc.clock, svc.storage, svc.httpClient, svc.producer)
	if svc.strictIsolation {
		svc.card.setExecutionMode(newStrictIsolatedPayoutExecutionMode())
	}
	svc.card.outbox = &svc.outbox
	svc.card.msgCfg = svc.msgCfg
	if err := svc.card.startOutboxReliableProducer(); err != nil {
		svc.logger.Warn("Failed to initialise outbox reliable producer", zap.Error(err))
	}
	svc.card.applyGatewayDescriptor(svc.gatewayDescriptor)
	svc.startDiscoveryAnnouncer()

	return svc
}

// Register wires the service onto the provided gRPC router.
func (s *Service) Register(router routers.GRPC) error {
	return router.Register(func(reg grpc.ServiceRegistrar) {
		connectorv1.RegisterConnectorServiceServer(reg, s)
	})
}

func (s *Service) Shutdown() {
	if s == nil {
		return
	}
	if s.card != nil {
		s.card.stopRetries()
	}
	s.outbox.Stop()
	if s.announcer != nil {
		s.announcer.Stop()
	}
}

func executeUnary[TReq any, TResp any](ctx context.Context, svc *Service, method string, handler func(context.Context, *TReq) gsresponse.Responder[TResp], req *TReq) (*TResp, error) {
	log := svc.logger.Named("rpc")
	log.Info("RPC request started", zap.String("method", method))

	start := svc.clock.Now()
	resp, err := gsresponse.Unary(svc.logger, mservice.MntxGateway, handler)(ctx, req)
	duration := svc.clock.Now().Sub(start)
	observeRPC(method, err, duration)

	if err != nil {
		log.Warn("RPC request failed", zap.String("method", method), zap.Duration("duration", duration), zap.Error(err))
	} else {
		log.Info("RPC request completed", zap.String("method", method), zap.Duration("duration", duration))
	}
	return resp, err
}

func normalizeReason(reason string) string {
	return strings.ToLower(strings.TrimSpace(reason))
}

func newPayoutError(reason string, err error) error {
	return reasonedError{
		reason: normalizeReason(reason),
		err:    err,
	}
}

func (s *Service) startDiscoveryAnnouncer() {
	if s == nil || s.producer == nil {
		return
	}
	announce := discovery.Announcement{
		Service:    mservice.MntxGateway,
		Rail:       discovery.RailCardPayout,
		Operations: discovery.CardPayoutRailGatewayOperations(),
		InvokeURI:  s.invokeURI,
		Version:    appversion.Create().Short(),
		InstanceID: discovery.InstanceID(),
	}
	if s.gatewayDescriptor != nil {
		if id := strings.TrimSpace(s.gatewayDescriptor.GetId()); id != "" {
			announce.ID = id
		}
		announce.Currencies = currenciesFromDescriptor(s.gatewayDescriptor)
	}
	if strings.TrimSpace(announce.ID) == "" {
		announce.ID = discovery.StablePaymentGatewayID(discovery.RailCardPayout)
	}
	s.announcer = discovery.NewAnnouncer(s.logger, s.producer, string(mservice.MntxGateway), announce)
	s.announcer.Start()
}

func currenciesFromDescriptor(src *gatewayv1.GatewayInstanceDescriptor) []discovery.CurrencyAnnouncement {
	if src == nil {
		return nil
	}
	network := strings.TrimSpace(src.GetNetwork())
	limitsCfg := src.GetLimits()
	values := src.GetCurrencies()
	if len(values) == 0 {
		return nil
	}
	seen := map[string]bool{}
	result := make([]discovery.CurrencyAnnouncement, 0, len(values))
	for _, value := range values {
		currency := strings.ToUpper(strings.TrimSpace(value))
		if currency == "" || seen[currency] {
			continue
		}
		seen[currency] = true
		result = append(result, discovery.CurrencyAnnouncement{
			Currency: currency,
			Network:  network,
			Limits:   currencyLimitsFromDescriptor(limitsCfg, currency),
		})
	}
	if len(result) == 0 {
		return nil
	}
	return result
}

func currencyLimitsFromDescriptor(src *gatewayv1.Limits, currency string) *discovery.CurrencyLimits {
	if src == nil {
		return nil
	}
	amountMin := firstNonEmpty(src.GetPerTxMinAmount(), src.GetMinAmount())
	amountMax := firstNonEmpty(src.GetPerTxMaxAmount(), src.GetMaxAmount())

	limits := &discovery.CurrencyLimits{}
	if amountMin != "" || amountMax != "" {
		limits.Amount = &discovery.CurrencyAmount{
			Min: amountMin,
			Max: amountMax,
		}
	}

	running := &discovery.CurrencyRunningLimits{}
	for bucket, max := range src.GetVolumeLimit() {
		bucket = strings.TrimSpace(bucket)
		max = strings.TrimSpace(max)
		if bucket == "" || max == "" {
			continue
		}
		running.Volume = append(running.Volume, discovery.VolumeLimit{
			Window: discovery.Window{
				Raw:   bucket,
				Named: bucket,
			},
			Max: max,
		})
	}
	for bucket, max := range src.GetVelocityLimit() {
		bucket = strings.TrimSpace(bucket)
		if bucket == "" || max <= 0 {
			continue
		}
		running.Velocity = append(running.Velocity, discovery.VelocityLimit{
			Window: discovery.Window{
				Raw:   bucket,
				Named: bucket,
			},
			Max: int(max),
		})
	}
	if override := src.GetCurrencyLimits()[strings.ToUpper(strings.TrimSpace(currency))]; override != nil {
		if min := strings.TrimSpace(override.GetMinAmount()); min != "" {
			if limits.Amount == nil {
				limits.Amount = &discovery.CurrencyAmount{}
			}
			limits.Amount.Min = min
		}
		if max := strings.TrimSpace(override.GetMaxAmount()); max != "" {
			if limits.Amount == nil {
				limits.Amount = &discovery.CurrencyAmount{}
			}
			limits.Amount.Max = max
		}
		if maxVolume := strings.TrimSpace(override.GetMaxVolume()); maxVolume != "" {
			running.Volume = append(running.Volume, discovery.VolumeLimit{
				Window: discovery.Window{
					Raw:   "default",
					Named: "default",
				},
				Max: maxVolume,
			})
		}
		if maxOps := int(override.GetMaxOps()); maxOps > 0 {
			running.Velocity = append(running.Velocity, discovery.VelocityLimit{
				Window: discovery.Window{
					Raw:   "default",
					Named: "default",
				},
				Max: maxOps,
			})
		}
	}
	if len(running.Volume) > 0 || len(running.Velocity) > 0 {
		limits.Running = running
	}
	if limits.Amount == nil && limits.Running == nil {
		return nil
	}
	return limits
}

func firstNonEmpty(values ...string) string {
	for _, value := range values {
		clean := strings.TrimSpace(value)
		if clean != "" {
			return clean
		}
	}
	return ""
}