// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.

package stripecoinpayments

import (
	"context"
	"time"

	"github.com/shopspring/decimal"
	"github.com/zeebo/errs"
	"go.uber.org/zap"

	"storj.io/common/sync2"
	"storj.io/storj/satellite/payments/monetary"
)

// convertToCents convert amount to USD cents with given rate.
func convertToCents(rate decimal.Decimal, amount monetary.Amount) int64 {
	amountDecimal := amount.AsDecimal()
	usd := amountDecimal.Mul(rate)
	usdCents := usd.Shift(2)
	return usdCents.Round(0).IntPart()
}

// convertFromCents convert amount in cents to a StorjTokenAmount with given rate.
func convertFromCents(rate decimal.Decimal, usdCents int64) monetary.Amount {
	usd := decimal.NewFromInt(usdCents).Shift(-2)
	numStorj := usd.Div(rate)
	return monetary.AmountFromDecimal(numStorj, monetary.USDollars)
}

// ErrConversion defines version service error.
var ErrConversion = errs.Class("conversion service")

// ConversionService updates conversion rates in a loop.
//
// architecture: Service
type ConversionService struct {
	log     *zap.Logger
	service *Service
	Cycle   sync2.Cycle
}

// NewConversionService creates new instance of ConversionService.
func NewConversionService(log *zap.Logger, service *Service, interval time.Duration) *ConversionService {
	return &ConversionService{
		log:     log,
		service: service,
		Cycle:   *sync2.NewCycle(interval),
	}
}

// Run runs loop which updates conversion rates for service.
func (conversion *ConversionService) Run(ctx context.Context) (err error) {
	defer mon.Task()(&ctx)(&err)

	return ErrConversion.Wrap(conversion.Cycle.Run(ctx,
		func(ctx context.Context) error {
			conversion.log.Debug("running conversion rates update cycle")

			if err := conversion.service.UpdateRates(ctx); err != nil {
				conversion.log.Error("conversion rates update cycle failed", zap.Error(ErrChore.Wrap(err)))
			}

			return nil
		},
	))
}

// Close closes underlying cycle.
func (conversion *ConversionService) Close() (err error) {
	defer mon.Task()(nil)(&err)

	conversion.Cycle.Close()
	return nil
}