package seal

import (
	"bytes"
	"crypto/ed25519"
	"crypto/sha512"
	"encoding/base32"
	"encoding/json"
	"time"

	"kesim.org/seal/nizk/commit"
)

type Type int

const (
	TypHighest = iota
	TypSecondHighest
)

// Auction describes the asset of an auction and other
// relevant meta-data
type Description struct {
	Start           time.Time
	End             time.Time
	RoundTimeout    time.Duration // Timeout per round by which all responses must have arrived
	BitLength       uint8         // Length of the price encoding
	Currency        string
	Type            Type
	SellerPublicKey ed25519.PublicKey // Public key of the Seller
}

// The SignedAuction contains an Auction and the signature,
// signed by the seller's public key off the SHA512 hash of
// the normalized JSON-object.
type SignedDescription struct {
	Description
	SellerSignature []byte
}

// Auction is the simple interface for the engine
type Auction interface {
	Join(bidder Bidder)                   // A bidder calls this to join the auction
	Message(msg []byte, sig []byte) error // A bidder uses this method to publish a message
}

// Bidder is the interface that the Auction engine uses to communicate
type Bidder interface {
	Commitment() *commit.Commitment
	Start(map[string]*commit.Commitment)
	Result()
	Receive(msg []byte) error
}

func (sd *SignedDescription) Verify() (bool, error) {
	// TODO: need to normalize this encoding
	buf := &bytes.Buffer{}
	e := json.NewEncoder(buf).Encode(sd.Description)
	if e != nil {
		return false, e
	}
	r := ed25519.Verify(sd.SellerPublicKey, buf.Bytes(), sd.SellerSignature)
	return r, nil
}

func (d *Description) Hash() (hash string, e error) {
	buf := &bytes.Buffer{}
	e = json.NewEncoder(buf).Encode(d)
	if e != nil {
		return "", e
	}
	h := sha512.Sum512(buf.Bytes())
	return base32.StdEncoding.EncodeToString(h[:]), nil
}