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

package rewards

import (
	"context"
	"time"

	"github.com/zeebo/errs"

	"storj.io/storj/internal/currency"
)

var (
	// MaxRedemptionErr is the error class used when an offer has reached its redemption capacity
	MaxRedemptionErr = errs.Class("offer redemption has reached its capacity")
	// NoCurrentOfferErr is the error class used when no current offer is set
	NoCurrentOfferErr = errs.Class("no current offer")
)

// DB holds information about offer
type DB interface {
	ListAll(ctx context.Context) (Offers, error)
	GetActiveOffersByType(ctx context.Context, offerType OfferType) (Offers, error)
	Create(ctx context.Context, offer *NewOffer) (*Offer, error)
	Finish(ctx context.Context, offerID int) error
}

// NewOffer holds information that's needed for creating a new offer
type NewOffer struct {
	Name        string
	Description string

	AwardCredit   currency.USD
	InviteeCredit currency.USD

	RedeemableCap int

	AwardCreditDurationDays   int
	InviteeCreditDurationDays int

	ExpiresAt time.Time

	Status OfferStatus
	Type   OfferType
}

// UpdateOffer holds fields needed for update an offer
type UpdateOffer struct {
	ID        int
	Status    OfferStatus
	ExpiresAt time.Time
}

// OfferType indicates the type of an offer
type OfferType int

const (
	// Invalid is a default value for offers that don't have correct type associated with it
	Invalid = OfferType(0)
	// FreeCredit is a type of offers used for Free Credit Program
	FreeCredit = OfferType(1)
	// Referral is a type of offers used for Referral Program
	Referral = OfferType(2)
	// Partner is an OfferType used be the Open Source Partner Program
	Partner = OfferType(3)
)

// OfferStatus represents the different stage an offer can have in its life-cycle.
type OfferStatus int

const (

	// Done is the status of an offer that is no longer in use.
	Done = OfferStatus(iota)

	// Active is the status of an offer that is currently in use.
	Active

	// Default is the status of an offer when there is no active offer.
	Default
)

// Offer contains info needed for giving users free credits through different offer programs
type Offer struct {
	ID          int
	Name        string
	Description string

	AwardCredit   currency.USD
	InviteeCredit currency.USD

	AwardCreditDurationDays   int
	InviteeCreditDurationDays int

	RedeemableCap int

	ExpiresAt time.Time
	CreatedAt time.Time

	Status OfferStatus
	Type   OfferType
}

// IsEmpty evaluates whether or not an on offer is empty
func (o Offer) IsEmpty() bool {
	return o.Name == ""
}

// GetActiveOffer returns an offer that is active based on its type
func (offers Offers) GetActiveOffer(offerType OfferType, partnerID string) (offer *Offer, err error) {
	if len(offers) < 1 {
		return nil, NoCurrentOfferErr.New("no active offers")
	}
	switch offerType {
	case Partner:
		if partnerID == "" {
			return nil, errs.New("partner ID is empty")
		}
		partnerInfo, ok := LoadPartnerInfos()[partnerID]
		if !ok {
			return nil, NoMatchPartnerIDErr.New("no partnerInfo found")
		}
		for i := range offers {
			if offers[i].Name == partnerInfo.Name {
				offer = &offers[i]
			}
		}
	default:
		if len(offers) > 1 {
			return nil, errs.New("multiple active offers found")
		}
		offer = &offers[0]
	}

	return offer, nil
}

// Offers contains a slice of offers.
type Offers []Offer