package plan

import (
	"context"
	"github.com/tech/sendico/pkg/discovery"
	"sort"
	"strings"

	"github.com/shopspring/decimal"
	"github.com/tech/sendico/payments/storage/model"
	"github.com/tech/sendico/pkg/merrors"
	"github.com/tech/sendico/pkg/mlogger"
	paymenttypes "github.com/tech/sendico/pkg/payments/types"
	"go.uber.org/zap"
)

func ensureGatewayForAction(ctx context.Context, logger mlogger.Logger, registry GatewayRegistry, cache map[model.Rail]*model.GatewayInstanceDescriptor, rail model.Rail, network string, amount *paymenttypes.Money, action model.RailOperation, instanceID string, dir sendDirection) (*model.GatewayInstanceDescriptor, error) {
	if registry == nil {
		return nil, merrors.InvalidArgument("plan builder: gateway registry is required")
	}
	if gw, ok := cache[rail]; ok && gw != nil {
		if instanceID == "" || strings.EqualFold(gw.InstanceID, instanceID) {
			if err := validateGatewayAction(gw, network, amount, action, dir); err != nil {
				logger.Warn("Failed to validate gateway", zap.Error(err),
					zap.String("instance_id", instanceID), zap.String("rail", string(rail)),
					zap.String("network", network), zap.String("action", string(action)),
					zap.String("direction", sendDirectionLabel(dir)), zap.Int("rails_qty", len(cache)),
				)
				return nil, err
			}
			return gw, nil
		}
	}
	gw, err := selectGateway(ctx, registry, rail, network, amount, action, instanceID, dir)
	if err != nil {
		logger.Warn("Failed to select gateway", zap.Error(err),
			zap.String("instance_id", instanceID), zap.String("rail", string(rail)),
			zap.String("network", network), zap.String("action", string(action)),
			zap.String("direction", sendDirectionLabel(dir)), zap.Int("rails_qty", len(cache)),
		)
		return nil, err
	}
	cache[rail] = gw
	return gw, nil
}

func validateGatewayAction(gw *model.GatewayInstanceDescriptor, network string, amount *paymenttypes.Money, action model.RailOperation, dir sendDirection) error {
	if gw == nil {
		return merrors.InvalidArgument("plan builder: gateway instance is required")
	}
	currency := ""
	amt := decimal.Zero
	if amount != nil && strings.TrimSpace(amount.GetAmount()) != "" {
		value, err := decimalFromMoney(amount)
		if err != nil {
			return err
		}
		amt = value
		currency = strings.ToUpper(strings.TrimSpace(amount.GetCurrency()))
	}
	if err := model.IsGatewayEligible(gw, gw.Rail, network, currency, action, toGatewayDirection(dir), amt); err != nil {
		return merrors.NoData(model.NoEligibleGatewayMessage(network, currency, action, toGatewayDirection(dir)))
	}
	return nil
}

type sendDirection int

const (
	sendDirectionAny sendDirection = iota
	sendDirectionOut
	sendDirectionIn
)

func sendDirectionForRail(rail model.Rail) sendDirection {
	switch rail {
	case discovery.RailFiatOnRamp:
		return sendDirectionIn
	default:
		return sendDirectionOut
	}
}

func selectGateway(ctx context.Context, registry GatewayRegistry, rail model.Rail, network string, amount *paymenttypes.Money, action model.RailOperation, instanceID string, dir sendDirection) (*model.GatewayInstanceDescriptor, error) {
	if registry == nil {
		return nil, merrors.InvalidArgument("plan builder: gateway registry is required")
	}
	all, err := registry.List(ctx)
	if err != nil {
		return nil, err
	}
	if len(all) == 0 {
		return nil, merrors.InvalidArgument("plan builder: no gateway instances available")
	}

	currency := ""
	amt := decimal.Zero
	if amount != nil && strings.TrimSpace(amount.GetAmount()) != "" {
		amt, err = decimalFromMoney(amount)
		if err != nil {
			return nil, err
		}
		currency = strings.ToUpper(strings.TrimSpace(amount.GetCurrency()))
	}
	network = strings.ToUpper(strings.TrimSpace(network))

	eligible := make([]*model.GatewayInstanceDescriptor, 0)
	for _, gw := range all {
		if err := model.IsGatewayEligible(gw, rail, network, currency, action, toGatewayDirection(dir), amt); err != nil {
			continue
		}
		eligible = append(eligible, gw)
	}
	if len(eligible) == 0 {
		return nil, merrors.NoData(model.NoEligibleGatewayMessage(network, currency, action, toGatewayDirection(dir)))
	}
	sort.Slice(eligible, func(i, j int) bool {
		return eligible[i].ID < eligible[j].ID
	})
	if instanceID != "" {
		for _, gw := range eligible {
			if strings.EqualFold(strings.TrimSpace(gw.InstanceID), instanceID) {
				return gw, nil
			}
		}
	}
	return eligible[0], nil
}

func sendDirectionLabel(dir sendDirection) string {
	return toGatewayDirection(dir).String()
}

func toGatewayDirection(dir sendDirection) model.GatewayDirection {
	switch dir {
	case sendDirectionOut:
		return model.GatewayDirectionOut
	case sendDirectionIn:
		return model.GatewayDirectionIn
	default:
		return model.GatewayDirectionAny
	}
}