package bidder

import (
	"fmt"

	. "kesim.org/seal/nizk"

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

type bid struct {
	// TODO: These should probably become ed25519.(Private|Public)Key's
	id *Scalar
	Id *Point

	price uint64 // bigendian encoding of the bid
	n     uint8  // number of bits encoded in zbid.

	// bits are derived from zbid and the zero element in
	// the slice corresponds to the highest bit in zbid
	bits []*commit.Statement
}

// NewBid creates a new Bidder for the given price, using the lower bits up to bitlength
func NewBid(price uint64, bitlength uint8) (*bid, error) {
	if bitlength > 63 {
		return nil, fmt.Errorf("bitlength too large, maximum is 63")
	} else if 0 != (price >> bitlength) {
		return nil, fmt.Errorf("price %d too large for given bitlength %d", price, bitlength)
	}

	bid := &bid{
		price: price,
		n:     bitlength,
	}

	bid.id = Curve.RandomScalar()
	bid.Id = G.Exp(bid.id)

	bid.bits = make([]*commit.Statement, bitlength)
	for i := bitlength; i > 0; i-- {
		set := (price>>(i-1)&1 != 0)
		a, b := Curve.RandomScalar(), Curve.RandomScalar()
		bid.bits[i-1] = commit.NewStatement(a, b, set)
	}

	return bid, nil
}

// Commit returns the public commitment to the bits and a signature
// TODO: return signature over bid
func (bid *bid) Commit() (c []*commit.Commitment) {
	c = make([]*commit.Commitment, len(bid.bits))
	for i := range bid.bits {
		c[i] = bid.bits[i].Commit(bid.Id)
	}
	return c
}

func (bid *bid) Result() {
}

func (bid *bid) Send(msg []byte, sig []byte) error {
	return fmt.Errorf("bidder.Send not implemented")
}