// Copyright (c) 2014-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package wire

import (
	"fmt"
	"io"

	"github.com/kaspanet/kaspad/util/daghash"
)

// RejectCode represents a numeric value by which a remote peer indicates
// why a message was rejected.
type RejectCode uint8

// These constants define the various supported reject codes.
const (
	RejectMalformed       RejectCode = 0x01
	RejectInvalid         RejectCode = 0x10
	RejectObsolete        RejectCode = 0x11
	RejectDuplicate       RejectCode = 0x12
	RejectNotRequested    RejectCode = 0x13
	RejectNonstandard     RejectCode = 0x40
	RejectDust            RejectCode = 0x41
	RejectInsufficientFee RejectCode = 0x42
	RejectFinality        RejectCode = 0x43
	RejectDifficulty      RejectCode = 0x44
)

// Map of reject codes back strings for pretty printing.
var rejectCodeStrings = map[RejectCode]string{
	RejectMalformed:       "REJECT_MALFORMED",
	RejectInvalid:         "REJECT_INVALID",
	RejectObsolete:        "REJECT_OBSOLETE",
	RejectDuplicate:       "REJECT_DUPLICATE",
	RejectNonstandard:     "REJECT_NONSTANDARD",
	RejectDust:            "REJECT_DUST",
	RejectInsufficientFee: "REJECT_INSUFFICIENTFEE",
	RejectFinality:        "REJECT_FINALITY",
	RejectDifficulty:      "REJECT_DIFFICULTY",
	RejectNotRequested:    "REJECT_NOTREQUESTED",
}

// String returns the RejectCode in human-readable form.
func (code RejectCode) String() string {
	if s, ok := rejectCodeStrings[code]; ok {
		return s
	}

	return fmt.Sprintf("Unknown RejectCode (%d)", uint8(code))
}

// MsgReject implements the Message interface and represents a kaspa reject
// message.
//
// This message was not added until protocol version RejectVersion.
type MsgReject struct {
	// Cmd is the command for the message which was rejected such as
	// as CmdBlock or CmdTx. This can be obtained from the Command function
	// of a Message.
	Cmd MessageCommand

	// RejectCode is a code indicating why the command was rejected. It
	// is encoded as a uint8 on the wire.
	Code RejectCode

	// Reason is a human-readable string with specific details (over and
	// above the reject code) about why the command was rejected.
	Reason string

	// Hash identifies a specific block or transaction that was rejected
	// and therefore only applies the MsgBlock and MsgTx messages.
	Hash *daghash.Hash
}

// KaspaDecode decodes r using the kaspa protocol encoding into the receiver.
// This is part of the Message interface implementation.
func (msg *MsgReject) KaspaDecode(r io.Reader, pver uint32) error {
	// Command that was rejected.
	err := ReadElement(r, &msg.Cmd)
	if err != nil {
		return err
	}

	// Code indicating why the command was rejected.
	err = ReadElement(r, &msg.Code)
	if err != nil {
		return err
	}

	// Human readable string with specific details (over and above the
	// reject code above) about why the command was rejected.
	reason, err := ReadVarString(r, pver)
	if err != nil {
		return err
	}
	msg.Reason = reason

	// CmdBlock and CmdTx messages have an additional hash field that
	// identifies the specific block or transaction.
	if msg.Cmd == CmdBlock || msg.Cmd == CmdTx {
		msg.Hash = &daghash.Hash{}
		err := ReadElement(r, msg.Hash)
		if err != nil {
			return err
		}
	}

	return nil
}

// KaspaEncode encodes the receiver to w using the kaspa protocol encoding.
// This is part of the Message interface implementation.
func (msg *MsgReject) KaspaEncode(w io.Writer, pver uint32) error {
	// Command that was rejected.
	err := WriteElement(w, msg.Cmd)
	if err != nil {
		return err
	}

	// Code indicating why the command was rejected.
	err = WriteElement(w, msg.Code)
	if err != nil {
		return err
	}

	// Human readable string with specific details (over and above the
	// reject code above) about why the command was rejected.
	err = WriteVarString(w, msg.Reason)
	if err != nil {
		return err
	}

	// CmdBlock and CmdTx messages have an additional hash field that
	// identifies the specific block or transaction.
	if msg.Cmd == CmdBlock || msg.Cmd == CmdTx {
		err := WriteElement(w, msg.Hash)
		if err != nil {
			return err
		}
	}

	return nil
}

// Command returns the protocol command string for the message. This is part
// of the Message interface implementation.
func (msg *MsgReject) Command() MessageCommand {
	return CmdReject
}

// MaxPayloadLength returns the maximum length the payload can be for the
// receiver. This is part of the Message interface implementation.
func (msg *MsgReject) MaxPayloadLength(pver uint32) uint32 {
	// Unfortunately the kaspa protocol does not enforce a sane
	// limit on the length of the reason, so the max payload is the
	// overall maximum message payload.
	return uint32(MaxMessagePayload)
}

// NewMsgReject returns a new kaspa reject message that conforms to the
// Message interface. See MsgReject for details.
func NewMsgReject(command MessageCommand, code RejectCode, reason string) *MsgReject {
	return &MsgReject{
		Cmd:    command,
		Code:   code,
		Reason: reason,
		Hash:   &daghash.ZeroHash,
	}
}