/*
 * Copyright 2018-present Open Networking Foundation

 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at

 * http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package core

import (
	"crypto/rand"
	"encoding/hex"
	"errors"
	"fmt"
	m "math/rand"
	"strconv"
)

func randomHex(n int) (string, error) {
	bytes := make([]byte, n)
	if _, err := rand.Read(bytes); err != nil {
		return "", err
	}
	return hex.EncodeToString(bytes), nil
}

// CreateDeviceID produces a device ID. DeviceId is 16 hex long - lower 12 hex is the device id.
// TODO:  A cluster unique ID may be required
func CreateDeviceID() string {
	val, _ := randomHex(12)
	return val
}

// CreateLogicalDeviceID is not used for now as the logical device ID is derived from the
// OLT MAC address
func CreateLogicalDeviceID() string {
	// logical device id is 16 hex long - lower 12 hex is the logical device id.  For now just generate the 12 hex
	val, _ := randomHex(12)
	return val
}

// CreateLogicalPortID produces a random port ID for a logical device.
func CreateLogicalPortID() uint32 {
	//	A logical port is a uint32
	return m.Uint32()
}

// CreateDataPathID creates uint64 pathid from string pathid
func CreateDataPathID(idInHexString string) (uint64, error) {
	if idInHexString == "" {
		return 0, errors.New("id-empty")
	}
	// First prepend 0x to the string
	newID := fmt.Sprintf("0x%s", idInHexString)
	d, err := strconv.ParseUint(newID, 0, 64)
	if err != nil {
		return 0, err
	}
	return d, nil
}