/*
 * Copyright (c)2019 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2023-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

package zerotier

//#cgo CFLAGS: -O3
//#include "../../native/GoGlue.h"
import "C"

import (
	"encoding/json"
	"unsafe"
)

// LocatorDNSSigningKey is the public (as a secure DNS name) and private keys for entering locators into DNS
type LocatorDNSSigningKey struct {
	SecureDNSName string
	PrivateKey    []byte
}

// NewLocatorDNSSigningKey creates a new signing key and secure DNS name for storing locators in DNS
func NewLocatorDNSSigningKey() (*LocatorDNSSigningKey, error) {
	var nameBuf [256]C.char
	var keyBuf [64]byte
	keySize := int(C.ZT_GoLocator_makeSecureDNSName(&nameBuf[0], 256, (*C.uint8_t)(unsafe.Pointer(&keyBuf[0])), 128))
	if keySize <= 0 {
		return nil, ErrInternal
	}
	var sk LocatorDNSSigningKey
	sk.SecureDNSName = C.GoString(&nameBuf[0])
	sk.PrivateKey = keyBuf[0:keySize]
	return &sk, nil
}

// Locator is a binary serialized record containing information about where a ZeroTier node is located on the network.
// Note that for JSON objects only Bytes needs to be specified. When JSON is deserialized only this field is used
// and the others are always reconstructed from it.
type Locator struct {
	// Identity is the full identity of the node being located
	Identity *Identity

	// Physical is a list of static physical network addresses for this node
	Physical []*InetAddress

	// Virtual is a list of ZeroTier nodes that can relay to this node
	Virtual []*Identity

	// Bytes is the raw serialized Locator
	Bytes []byte
}

// NewLocator creates a new locator with the given identity and addresses and the current time as timestamp.
// The identity must include its secret key so that it can sign the final locator.
func NewLocator(id *Identity, virtualAddresses []*Identity, physicalAddresses []*InetAddress) (*Locator, error) {
	if !id.HasPrivate() {
		return nil, ErrSecretKeyRequired
	}

	idstr := id.PrivateKeyString()
	phy := make([]C.struct_sockaddr_storage, len(physicalAddresses))
	virt := make([]*C.char, len(virtualAddresses))
	idCstr := C.CString(idstr)

	defer func() {
		C.free(unsafe.Pointer(idCstr))
		for _, v := range virt {
			if uintptr(unsafe.Pointer(v)) != 0 {
				C.free(unsafe.Pointer(v))
			}
		}
	}()

	for i := 0; i < len(physicalAddresses); i++ {
		if !makeSockaddrStorage(physicalAddresses[i].IP, physicalAddresses[i].Port, &phy[i]) {
			return nil, ErrInvalidParameter
		}
	}

	for i := 0; i < len(virtualAddresses); i++ {
		idstr := virtualAddresses[i].String()
		virt[i] = C.CString(idstr)
	}

	var buf [65536]byte
	var pPhy *C.struct_sockaddr_storage
	var pVirt **C.char
	if len(phy) > 0 {
		pPhy = &phy[0]
	}
	if len(virt) > 0 {
		pVirt = &virt[0]
	}
	locSize := C.ZT_GoLocator_makeLocator((*C.uint8_t)(unsafe.Pointer(&buf[0])), 65536, C.int64_t(TimeMs()), idCstr, pPhy, C.uint(len(phy)), pVirt, C.uint(len(virt)))
	if locSize <= 0 {
		return nil, ErrInvalidParameter
	}

	r := make([]byte, int(locSize))
	copy(r[:], buf[0:int(locSize)])
	return &Locator{
		Identity: id,
		Physical: physicalAddresses,
		Virtual:  virtualAddresses,
		Bytes:    r,
	}, nil
}

// NewLocatorFromBytes decodes a locator from its serialized byte array form
func NewLocatorFromBytes(b []byte) (*Locator, error) {
	if len(b) == 0 {
		return nil, ErrInvalidParameter
	}
	var info C.struct_ZT_GoLocator_Info
	res := C.ZT_GoLocator_decodeLocator((*C.uint8_t)(unsafe.Pointer(&b[0])), C.uint(len(b)), &info)
	if res == -2 {
		return nil, ErrInvalidSignature
	} else if res <= 0 {
		return nil, ErrInvalidParameter
	}

	var loc Locator

	var err error
	loc.Identity, err = NewIdentityFromString(C.GoString(&info.id[0]))
	if err != nil {
		return nil, err
	}
	for i := 0; i < int(info.phyCount); i++ {
		ua := sockaddrStorageToUDPAddr(&info.phy[i])
		if ua != nil {
			loc.Physical = append(loc.Physical, &InetAddress{IP: ua.IP, Port: ua.Port})
		}
	}
	for i := 0; i < int(info.virtCount); i++ {
		id, err := NewIdentityFromString(C.GoString(&info.virt[i][0]))
		if err == nil {
			loc.Virtual = append(loc.Virtual, id)
		}
	}

	return &loc, nil
}

// MakeTXTRecords creates secure DNS TXT records for this locator
func (l *Locator) MakeTXTRecords(key *LocatorDNSSigningKey) ([]string, error) {
	if key == nil || len(l.Bytes) == 0 || len(key.PrivateKey) == 0 {
		return nil, ErrInvalidParameter
	}
	var results [256][256]C.char
	cName := C.CString(key.SecureDNSName)
	defer C.free(unsafe.Pointer(cName))
	count := int(C.ZT_GoLocator_makeSignedTxtRecords((*C.uint8_t)(&l.Bytes[0]), C.uint(len(l.Bytes)), cName, (*C.uint8_t)(&key.PrivateKey[0]), C.uint(len(key.PrivateKey)), &results[0]))
	if count > 0 {
		var t []string
		for i := 0; i < int(count); i++ {
			t = append(t, C.GoString(&results[i][0]))
		}
		return t, nil
	}
	return nil, ErrInternal
}

// MarshalJSON marshals this Locator as its byte encoding
func (l *Locator) MarshalJSON() ([]byte, error) {
	return json.Marshal(l)
}

// UnmarshalJSON unmarshals this Locator from a byte array in JSON.
func (l *Locator) UnmarshalJSON(j []byte) error {
	err := json.Unmarshal(j, l)
	if err != nil {
		return err
	}
	tmp, err := NewLocatorFromBytes(l.Bytes)
	if err != nil {
		return err
	}
	l.Identity = tmp.Identity
	l.Physical = tmp.Physical
	l.Virtual = tmp.Virtual
	return nil
}