package dashboard

import (
	"bytes"
	"crypto/ed25519"
	"encoding/base32"
	"encoding/json"

	"kesim.org/seal"
)

type Dashboard interface {
	NewAuction(description *seal.SignedDescription) (auctionId string, e error)
	Auctions(state AuctionState) map[string]*seal.SignedDescription
	Join(auctionId string, commitment SignedCommitment, bidderId ed25519.PublicKey) error
	Commitments(auctionId string) (bidders map[string]SignedCommitment, e error)
	Publish(auctionId string, round uint8, message SignedMessage, bidderId ed25519.PublicKey) error
	Messages(auctionId string, round uint8) (messages map[string]SignedMessage, e error)
	Cancel(auctionId string, reason SignedMessage, bidderId ed25519.PublicKey) error
	Result(auctionId string) (price uint64, winner ed25519.PublicKey, e error)
}

type SignedMessage struct {
	Message   []byte
	Signature []byte
}

type SignedCommitment struct {
	*seal.Commitment
	Signature []byte
}

type Error int

const (
	ErrUnknownError Error = iota

	ErrSellerIncorrectSignature
	ErrSellerAuctionExists

	ErrAuctionUnknown
	ErrAuctionNotStarted
	ErrAuctionNotReady
	ErrAuctionNotRunning
	ErrAuctionFinished
	ErrAuctionCanceled
	ErrAuctionTimeout
	ErrAuctionInvalidRound

	ErrBidderUnknown
	ErrBidderTimeout
	ErrBidderEmptyMessage
	ErrBidderIncorrectSignature
	ErrBidderWrongRound
	ErrBidderVerificationFailed
)

func (d Error) Error() string {
	switch d {
	case ErrUnknownError:
		return "unknown error"

	case ErrSellerIncorrectSignature:
		return "incorrect seller signature"
	case ErrSellerAuctionExists:
		return "auction with that id already exists"

	case ErrAuctionUnknown:
		return "unknown auction"
	case ErrAuctionNotStarted:
		return "auction not started yet"
	case ErrAuctionNotReady:
		return "auction not ready"
	case ErrAuctionNotRunning:
		return "auction is not running"
	case ErrAuctionFinished:
		return "auction is finished"
	case ErrAuctionTimeout:
		return "action has timed out"
	case ErrAuctionCanceled:
		return "auction has been canceled"
	case ErrAuctionInvalidRound:
		return "invalid round"

	case ErrBidderUnknown:
		return "bidder is unknown"
	case ErrBidderTimeout:
		return "bidder has timed out"
	case ErrBidderEmptyMessage:
		return "empty message"
	case ErrBidderIncorrectSignature:
		return "incorrect signature from bidder"
	case ErrBidderWrongRound:
		return "wrong round"
	case ErrBidderVerificationFailed:
		return "round data couldn't be verified"

	default:
		panic("should not happen")
	}
}

type AuctionState int

const (
	AuctionStateUnknown AuctionState = iota

	AuctionStateReady
	AuctionStateRunning
	AuctionStateFinished
	AuctionStateCanceled
	AuctionStateTimeout

	AuctionStateLAST
)

func (s *SignedMessage) Verify(pubkey ed25519.PublicKey) bool {
	return ed25519.Verify(pubkey, s.Message, s.Signature)
}

func (s *SignedCommitment) Verify(pubkey ed25519.PublicKey) bool {
	buf := &bytes.Buffer{}
	e := json.NewEncoder(buf).Encode(s.Commitment)
	if e != nil {
		return false
	}

	return ed25519.Verify(pubkey, buf.Bytes(), s.Signature)
}

func Pub2String(pubkey ed25519.PublicKey) string {
	return base32.StdEncoding.EncodeToString(pubkey)
}