// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package jrpc

import (
	"context"
	"strconv"
	"strings"

	"github.com/ethereum/go-ethereum/common/hexutil"
)

// ServerCodec implements reading, parsing and writing RPC messages for the server side of
// a RPC session. Implementations must be go-routine safe since the codec can be called in
// multiple go-routines concurrently.
type ServerCodec interface {
	peerInfo() PeerInfo
	readBatch() (msgs []*jsonrpcMessage, isBatch bool, err error)
	close()

	jsonWriter
}

// jsonWriter can write JSON messages to its underlying connection.
// Implementations must be safe for concurrent use.
type jsonWriter interface {
	writeJSON(context.Context, any) error
	// Closed returns a channel which is closed when the connection is closed.
	closed() <-chan any
	// RemoteAddr returns the peer address of the connection.
	remoteAddr() string
}

// DecimalOrHex unmarshals a non-negative decimal or hex parameter into a uint64.
type DecimalOrHex uint64

// UnmarshalJSON implements json.Unmarshaler.
func (dh *DecimalOrHex) UnmarshalJSON(data []byte) error {
	input := strings.TrimSpace(string(data))
	if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
		input = input[1 : len(input)-1]
	}

	value, err := strconv.ParseUint(input, 10, 64)
	if err != nil {
		value, err = hexutil.DecodeUint64(input)
	}
	if err != nil {
		return err
	}
	*dh = DecimalOrHex(value)
	return nil
}