package git

/*
#include <string.h>

#include <git2.h>
#include <git2/sys/cred.h>

extern void _go_git_populate_remote_callbacks(git_remote_callbacks *callbacks);
*/
import "C"
import (
	"crypto/x509"
	"errors"
	"reflect"
	"runtime"
	"strings"
	"sync"
	"unsafe"

	"golang.org/x/crypto/ssh"
)

// RemoteCreateOptionsFlag is Remote creation options flags
type RemoteCreateOptionsFlag uint

const (
	// Ignore the repository apply.insteadOf configuration
	RemoteCreateSkipInsteadof RemoteCreateOptionsFlag = C.GIT_REMOTE_CREATE_SKIP_INSTEADOF
	// Don't build a fetchspec from the name if none is set
	RemoteCreateSkipDefaultFetchspec RemoteCreateOptionsFlag = C.GIT_REMOTE_CREATE_SKIP_DEFAULT_FETCHSPEC
)

// RemoteCreateOptions contains options for creating a remote
type RemoteCreateOptions struct {
	Name      string
	FetchSpec string
	Flags     RemoteCreateOptionsFlag
}

type TransferProgress struct {
	TotalObjects    uint
	IndexedObjects  uint
	ReceivedObjects uint
	LocalObjects    uint
	TotalDeltas     uint
	ReceivedBytes   uint
}

func newTransferProgressFromC(c *C.git_transfer_progress) TransferProgress {
	return TransferProgress{
		TotalObjects:    uint(c.total_objects),
		IndexedObjects:  uint(c.indexed_objects),
		ReceivedObjects: uint(c.received_objects),
		LocalObjects:    uint(c.local_objects),
		TotalDeltas:     uint(c.total_deltas),
		ReceivedBytes:   uint(c.received_bytes)}
}

type RemoteCompletion uint
type ConnectDirection uint

const (
	RemoteCompletionDownload RemoteCompletion = C.GIT_REMOTE_COMPLETION_DOWNLOAD
	RemoteCompletionIndexing RemoteCompletion = C.GIT_REMOTE_COMPLETION_INDEXING
	RemoteCompletionError    RemoteCompletion = C.GIT_REMOTE_COMPLETION_ERROR

	ConnectDirectionFetch ConnectDirection = C.GIT_DIRECTION_FETCH
	ConnectDirectionPush  ConnectDirection = C.GIT_DIRECTION_PUSH
)

type TransportMessageCallback func(str string) error
type CompletionCallback func(RemoteCompletion) error
type CredentialsCallback func(url string, username_from_url string, allowed_types CredentialType) (*Credential, error)
type TransferProgressCallback func(stats TransferProgress) error
type UpdateTipsCallback func(refname string, a *Oid, b *Oid) error
type CertificateCheckCallback func(cert *Certificate, valid bool, hostname string) error
type PackbuilderProgressCallback func(stage int32, current, total uint32) error
type PushTransferProgressCallback func(current, total uint32, bytes uint) error
type PushUpdateReferenceCallback func(refname, status string) error

type RemoteCallbacks struct {
	SidebandProgressCallback TransportMessageCallback
	CompletionCallback
	CredentialsCallback
	TransferProgressCallback
	UpdateTipsCallback
	CertificateCheckCallback
	PackProgressCallback PackbuilderProgressCallback
	PushTransferProgressCallback
	PushUpdateReferenceCallback
}

type remoteCallbacksData struct {
	callbacks   *RemoteCallbacks
	errorTarget *error
}

type FetchPrune uint

const (
	// Use the setting from the configuration
	FetchPruneUnspecified FetchPrune = C.GIT_FETCH_PRUNE_UNSPECIFIED
	// Force pruning on
	FetchPruneOn FetchPrune = C.GIT_FETCH_PRUNE
	// Force pruning off
	FetchNoPrune FetchPrune = C.GIT_FETCH_NO_PRUNE
)

type DownloadTags uint

const (
	// Use the setting from the configuration.
	DownloadTagsUnspecified DownloadTags = C.GIT_REMOTE_DOWNLOAD_TAGS_UNSPECIFIED
	// Ask the server for tags pointing to objects we're already
	// downloading.
	DownloadTagsAuto DownloadTags = C.GIT_REMOTE_DOWNLOAD_TAGS_AUTO

	// Don't ask for any tags beyond the refspecs.
	DownloadTagsNone DownloadTags = C.GIT_REMOTE_DOWNLOAD_TAGS_NONE

	// Ask for the all the tags.
	DownloadTagsAll DownloadTags = C.GIT_REMOTE_DOWNLOAD_TAGS_ALL
)

type FetchOptions struct {
	// Callbacks to use for this fetch operation
	RemoteCallbacks RemoteCallbacks
	// Whether to perform a prune after the fetch
	Prune FetchPrune
	// Whether to write the results to FETCH_HEAD. Defaults to
	// on. Leave this default in order to behave like git.
	UpdateFetchhead bool

	// Determines how to behave regarding tags on the remote, such
	// as auto-downloading tags for objects we're downloading or
	// downloading all of them.
	//
	// The default is to auto-follow tags.
	DownloadTags DownloadTags

	// Headers are extra headers for the fetch operation.
	Headers []string

	// Proxy options to use for this fetch operation
	ProxyOptions ProxyOptions
}

type ProxyType uint

const (
	// Do not attempt to connect through a proxy
	//
	// If built against lbicurl, it itself may attempt to connect
	// to a proxy if the environment variables specify it.
	ProxyTypeNone ProxyType = C.GIT_PROXY_NONE

	// Try to auto-detect the proxy from the git configuration.
	ProxyTypeAuto ProxyType = C.GIT_PROXY_AUTO

	// Connect via the URL given in the options
	ProxyTypeSpecified ProxyType = C.GIT_PROXY_SPECIFIED
)

type ProxyOptions struct {
	// The type of proxy to use (or none)
	Type ProxyType

	// The proxy's URL
	Url string
}

func proxyOptionsFromC(copts *C.git_proxy_options) *ProxyOptions {
	return &ProxyOptions{
		Type: ProxyType(copts._type),
		Url:  C.GoString(copts.url),
	}
}

type Remote struct {
	doNotCompare
	ptr       *C.git_remote
	callbacks RemoteCallbacks
	repo      *Repository
}

type remotePointerList struct {
	sync.RWMutex
	// stores the Go pointers
	pointers map[*C.git_remote]*Remote
}

func newRemotePointerList() *remotePointerList {
	return &remotePointerList{
		pointers: make(map[*C.git_remote]*Remote),
	}
}

// track adds the given pointer to the list of pointers to track and
// returns a pointer value which can be passed to C as an opaque
// pointer.
func (v *remotePointerList) track(remote *Remote) {
	v.Lock()
	v.pointers[remote.ptr] = remote
	v.Unlock()

	runtime.SetFinalizer(remote, (*Remote).Free)
}

// untrack stops tracking the git_remote pointer.
func (v *remotePointerList) untrack(remote *Remote) {
	v.Lock()
	delete(v.pointers, remote.ptr)
	v.Unlock()
}

// clear stops tracking all the git_remote pointers.
func (v *remotePointerList) clear() {
	v.Lock()
	var remotes []*Remote
	for remotePtr, remote := range v.pointers {
		remotes = append(remotes, remote)
		delete(v.pointers, remotePtr)
	}
	v.Unlock()

	for _, remote := range remotes {
		remote.free()
	}
}

// get retrieves the pointer from the given *git_remote.
func (v *remotePointerList) get(ptr *C.git_remote) (*Remote, bool) {
	v.RLock()
	defer v.RUnlock()

	r, ok := v.pointers[ptr]
	if !ok {
		return nil, false
	}

	return r, true
}

type CertificateKind uint

const (
	CertificateX509    CertificateKind = C.GIT_CERT_X509
	CertificateHostkey CertificateKind = C.GIT_CERT_HOSTKEY_LIBSSH2
)

// Certificate represents the two possible certificates which libgit2
// knows it might find. If Kind is CertficateX509 then the X509 field
// will be filled. If Kind is CertificateHostkey then the Hostkey
// field will be fille.d
type Certificate struct {
	Kind    CertificateKind
	X509    *x509.Certificate
	Hostkey HostkeyCertificate
}

// HostkeyKind is a bitmask of the available hashes in HostkeyCertificate.
type HostkeyKind uint

const (
	HostkeyMD5    HostkeyKind = C.GIT_CERT_SSH_MD5
	HostkeySHA1   HostkeyKind = C.GIT_CERT_SSH_SHA1
	HostkeySHA256 HostkeyKind = C.GIT_CERT_SSH_SHA256
	HostkeyRaw    HostkeyKind = 1 << 3
)

// Server host key information. A bitmask containing the available fields.
// Check for combinations of: HostkeyMD5, HostkeySHA1, HostkeySHA256, HostkeyRaw.
type HostkeyCertificate struct {
	Kind         HostkeyKind
	HashMD5      [16]byte
	HashSHA1     [20]byte
	HashSHA256   [32]byte
	Hostkey      []byte
	SSHPublicKey ssh.PublicKey
}

type PushOptions struct {
	// Callbacks to use for this push operation
	RemoteCallbacks RemoteCallbacks

	PbParallelism uint

	// Headers are extra headers for the push operation.
	Headers []string
}

type RemoteHead struct {
	Id   *Oid
	Name string
}

func newRemoteHeadFromC(ptr *C.git_remote_head) RemoteHead {
	return RemoteHead{
		Id:   newOidFromC(&ptr.oid),
		Name: C.GoString(ptr.name),
	}
}

func untrackCallbacksPayload(callbacks *C.git_remote_callbacks) {
	if callbacks == nil || callbacks.payload == nil {
		return
	}
	pointerHandles.Untrack(callbacks.payload)
}

func populateRemoteCallbacks(ptr *C.git_remote_callbacks, callbacks *RemoteCallbacks, errorTarget *error) *C.git_remote_callbacks {
	C.git_remote_init_callbacks(ptr, C.GIT_REMOTE_CALLBACKS_VERSION)
	if callbacks == nil {
		return ptr
	}
	C._go_git_populate_remote_callbacks(ptr)
	data := &remoteCallbacksData{
		callbacks:   callbacks,
		errorTarget: errorTarget,
	}
	ptr.payload = pointerHandles.Track(data)
	return ptr
}

//export sidebandProgressCallback
func sidebandProgressCallback(errorMessage **C.char, _str *C.char, _len C.int, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.SidebandProgressCallback == nil {
		return C.int(ErrorCodeOK)
	}
	err := data.callbacks.SidebandProgressCallback(C.GoStringN(_str, _len))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export completionCallback
func completionCallback(errorMessage **C.char, completionType C.git_remote_completion_type, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.CompletionCallback == nil {
		return C.int(ErrorCodeOK)
	}
	err := data.callbacks.CompletionCallback(RemoteCompletion(completionType))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export credentialsCallback
func credentialsCallback(
	errorMessage **C.char,
	_cred **C.git_credential,
	_url *C.char,
	_username_from_url *C.char,
	allowed_types uint,
	handle unsafe.Pointer,
) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.CredentialsCallback == nil {
		return C.int(ErrorCodePassthrough)
	}
	url := C.GoString(_url)
	username_from_url := C.GoString(_username_from_url)
	cred, err := data.callbacks.CredentialsCallback(url, username_from_url, (CredentialType)(allowed_types))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	if cred != nil {
		*_cred = cred.ptr

		// have transferred ownership to libgit, 'forget' the native pointer
		cred.ptr = nil
		runtime.SetFinalizer(cred, nil)
	}
	return C.int(ErrorCodeOK)
}

//export transferProgressCallback
func transferProgressCallback(errorMessage **C.char, stats *C.git_transfer_progress, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.TransferProgressCallback == nil {
		return C.int(ErrorCodeOK)
	}
	err := data.callbacks.TransferProgressCallback(newTransferProgressFromC(stats))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export updateTipsCallback
func updateTipsCallback(
	errorMessage **C.char,
	_refname *C.char,
	_a *C.git_oid,
	_b *C.git_oid,
	handle unsafe.Pointer,
) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.UpdateTipsCallback == nil {
		return C.int(ErrorCodeOK)
	}
	refname := C.GoString(_refname)
	a := newOidFromC(_a)
	b := newOidFromC(_b)
	err := data.callbacks.UpdateTipsCallback(refname, a, b)
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export certificateCheckCallback
func certificateCheckCallback(
	errorMessage **C.char,
	_cert *C.git_cert,
	_valid C.int,
	_host *C.char,
	handle unsafe.Pointer,
) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	// if there's no callback set, we need to make sure we fail if the library didn't consider this cert valid
	if data.callbacks.CertificateCheckCallback == nil {
		if _valid == 0 {
			return C.int(ErrorCodeCertificate)
		}
		return C.int(ErrorCodeOK)
	}

	host := C.GoString(_host)
	valid := _valid != 0

	var cert Certificate
	if _cert.cert_type == C.GIT_CERT_X509 {
		cert.Kind = CertificateX509
		ccert := (*C.git_cert_x509)(unsafe.Pointer(_cert))
		x509_certs, err := x509.ParseCertificates(C.GoBytes(ccert.data, C.int(ccert.len)))
		if err != nil {
			if data.errorTarget != nil {
				*data.errorTarget = err
			}
			return setCallbackError(errorMessage, err)
		}
		if len(x509_certs) < 1 {
			err := errors.New("empty certificate list")
			if data.errorTarget != nil {
				*data.errorTarget = err
			}
			return setCallbackError(errorMessage, err)
		}

		// we assume there's only one, which should hold true for any web server we want to talk to
		cert.X509 = x509_certs[0]
	} else if _cert.cert_type == C.GIT_CERT_HOSTKEY_LIBSSH2 {
		cert.Kind = CertificateHostkey
		ccert := (*C.git_cert_hostkey)(unsafe.Pointer(_cert))
		cert.Hostkey.Kind = HostkeyKind(ccert._type)
		C.memcpy(unsafe.Pointer(&cert.Hostkey.HashMD5[0]), unsafe.Pointer(&ccert.hash_md5[0]), C.size_t(len(cert.Hostkey.HashMD5)))
		C.memcpy(unsafe.Pointer(&cert.Hostkey.HashSHA1[0]), unsafe.Pointer(&ccert.hash_sha1[0]), C.size_t(len(cert.Hostkey.HashSHA1)))
		C.memcpy(unsafe.Pointer(&cert.Hostkey.HashSHA256[0]), unsafe.Pointer(&ccert.hash_sha256[0]), C.size_t(len(cert.Hostkey.HashSHA256)))
	} else {
		err := errors.New("unsupported certificate type")
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}

	err := data.callbacks.CertificateCheckCallback(&cert, valid, host)
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export packProgressCallback
func packProgressCallback(errorMessage **C.char, stage C.int, current, total C.uint, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.PackProgressCallback == nil {
		return C.int(ErrorCodeOK)
	}

	err := data.callbacks.PackProgressCallback(int32(stage), uint32(current), uint32(total))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export pushTransferProgressCallback
func pushTransferProgressCallback(errorMessage **C.char, current, total C.uint, bytes C.size_t, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.PushTransferProgressCallback == nil {
		return C.int(ErrorCodeOK)
	}

	err := data.callbacks.PushTransferProgressCallback(uint32(current), uint32(total), uint(bytes))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

//export pushUpdateReferenceCallback
func pushUpdateReferenceCallback(errorMessage **C.char, refname, status *C.char, handle unsafe.Pointer) C.int {
	data := pointerHandles.Get(handle).(*remoteCallbacksData)
	if data.callbacks.PushUpdateReferenceCallback == nil {
		return C.int(ErrorCodeOK)
	}

	err := data.callbacks.PushUpdateReferenceCallback(C.GoString(refname), C.GoString(status))
	if err != nil {
		if data.errorTarget != nil {
			*data.errorTarget = err
		}
		return setCallbackError(errorMessage, err)
	}
	return C.int(ErrorCodeOK)
}

func populateProxyOptions(copts *C.git_proxy_options, opts *ProxyOptions) *C.git_proxy_options {
	C.git_proxy_options_init(copts, C.GIT_PROXY_OPTIONS_VERSION)
	if opts == nil {
		return nil
	}

	copts._type = C.git_proxy_t(opts.Type)
	copts.url = C.CString(opts.Url)
	return copts
}

func freeProxyOptions(copts *C.git_proxy_options) {
	if copts == nil {
		return
	}

	C.free(unsafe.Pointer(copts.url))
}

// RemoteIsValidName returns whether the remote name is well-formed.
func RemoteIsValidName(name string) bool {
	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))

	return C.git_remote_is_valid_name(cname) == 1
}

// free releases the resources of the Remote.
func (r *Remote) free() {
	runtime.SetFinalizer(r, nil)
	C.git_remote_free(r.ptr)
	r.ptr = nil
	r.repo = nil
}

// Free releases the resources of the Remote.
func (r *Remote) Free() {
	r.repo.Remotes.untrackRemote(r)
	r.free()
}

type RemoteCollection struct {
	doNotCompare
	repo *Repository

	sync.RWMutex
	remotes map[*C.git_remote]*Remote
}

func (c *RemoteCollection) trackRemote(r *Remote) {
	c.Lock()
	c.remotes[r.ptr] = r
	c.Unlock()

	remotePointers.track(r)
}

func (c *RemoteCollection) untrackRemote(r *Remote) {
	c.Lock()
	delete(c.remotes, r.ptr)
	c.Unlock()

	remotePointers.untrack(r)
}

func (c *RemoteCollection) List() ([]string, error) {
	var r C.git_strarray

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ecode := C.git_remote_list(&r, c.repo.ptr)
	runtime.KeepAlive(c.repo)
	if ecode < 0 {
		return nil, MakeGitError(ecode)
	}
	defer C.git_strarray_dispose(&r)

	remotes := makeStringsFromCStrings(r.strings, int(r.count))
	return remotes, nil
}

func (c *RemoteCollection) Create(name string, url string) (*Remote, error) {
	remote := &Remote{repo: c.repo}

	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))
	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_create(&remote.ptr, c.repo.ptr, cname, curl)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	c.trackRemote(remote)
	return remote, nil
}

//CreateWithOptions Creates a repository object with extended options.
func (c *RemoteCollection) CreateWithOptions(url string, option *RemoteCreateOptions) (*Remote, error) {
	remote := &Remote{repo: c.repo}

	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	copts := populateRemoteCreateOptions(&C.git_remote_create_options{}, option, c.repo)
	defer freeRemoteCreateOptions(copts)

	ret := C.git_remote_create_with_opts(&remote.ptr, curl, copts)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	c.trackRemote(remote)
	return remote, nil
}

func (c *RemoteCollection) Delete(name string) error {
	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_delete(c.repo.ptr, cname)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (c *RemoteCollection) CreateWithFetchspec(name string, url string, fetch string) (*Remote, error) {
	remote := &Remote{repo: c.repo}

	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))
	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))
	cfetch := C.CString(fetch)
	defer C.free(unsafe.Pointer(cfetch))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_create_with_fetchspec(&remote.ptr, c.repo.ptr, cname, curl, cfetch)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	c.trackRemote(remote)
	return remote, nil
}

func (c *RemoteCollection) CreateAnonymous(url string) (*Remote, error) {
	remote := &Remote{repo: c.repo}

	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_create_anonymous(&remote.ptr, c.repo.ptr, curl)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	c.trackRemote(remote)
	return remote, nil
}

func (c *RemoteCollection) Lookup(name string) (*Remote, error) {
	remote := &Remote{repo: c.repo}

	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_lookup(&remote.ptr, c.repo.ptr, cname)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	c.trackRemote(remote)
	return remote, nil
}

func (c *RemoteCollection) Free() {
	var remotes []*Remote
	c.Lock()
	for remotePtr, remote := range c.remotes {
		remotes = append(remotes, remote)
		delete(c.remotes, remotePtr)
	}
	c.Unlock()

	for _, remote := range remotes {
		remotePointers.untrack(remote)
	}
}

func (o *Remote) Name() string {
	s := C.git_remote_name(o.ptr)
	runtime.KeepAlive(o)
	return C.GoString(s)
}

func (o *Remote) Url() string {
	s := C.git_remote_url(o.ptr)
	runtime.KeepAlive(o)
	return C.GoString(s)
}

func (o *Remote) PushUrl() string {
	s := C.git_remote_pushurl(o.ptr)
	runtime.KeepAlive(o)
	return C.GoString(s)
}

func (c *RemoteCollection) Rename(remote, newname string) ([]string, error) {
	cproblems := C.git_strarray{}
	defer freeStrarray(&cproblems)
	cnewname := C.CString(newname)
	defer C.free(unsafe.Pointer(cnewname))
	cremote := C.CString(remote)
	defer C.free(unsafe.Pointer(cremote))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_rename(&cproblems, c.repo.ptr, cremote, cnewname)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return []string{}, MakeGitError(ret)
	}

	problems := makeStringsFromCStrings(cproblems.strings, int(cproblems.count))
	return problems, nil
}

func (c *RemoteCollection) SetUrl(remote, url string) error {
	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))
	cremote := C.CString(remote)
	defer C.free(unsafe.Pointer(cremote))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_set_url(c.repo.ptr, cremote, curl)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (c *RemoteCollection) SetPushUrl(remote, url string) error {
	curl := C.CString(url)
	defer C.free(unsafe.Pointer(curl))
	cremote := C.CString(remote)
	defer C.free(unsafe.Pointer(cremote))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_set_pushurl(c.repo.ptr, cremote, curl)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (c *RemoteCollection) AddFetch(remote, refspec string) error {
	crefspec := C.CString(refspec)
	defer C.free(unsafe.Pointer(crefspec))
	cremote := C.CString(remote)
	defer C.free(unsafe.Pointer(cremote))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_add_fetch(c.repo.ptr, cremote, crefspec)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func sptr(p uintptr) *C.char {
	return *(**C.char)(unsafe.Pointer(p))
}

func makeStringsFromCStrings(x **C.char, l int) []string {
	s := make([]string, l)
	i := 0
	for p := uintptr(unsafe.Pointer(x)); i < l; p += unsafe.Sizeof(uintptr(0)) {
		s[i] = C.GoString(sptr(p))
		i++
	}
	return s
}

func makeCStringsFromStrings(s []string) **C.char {
	l := len(s)
	x := (**C.char)(C.malloc(C.size_t(unsafe.Sizeof(unsafe.Pointer(nil)) * uintptr(l))))
	i := 0
	for p := uintptr(unsafe.Pointer(x)); i < l; p += unsafe.Sizeof(uintptr(0)) {
		*(**C.char)(unsafe.Pointer(p)) = C.CString(s[i])
		i++
	}
	return x
}

func freeStrarray(arr *C.git_strarray) {
	count := int(arr.count)
	size := unsafe.Sizeof(unsafe.Pointer(nil))

	i := 0
	for p := uintptr(unsafe.Pointer(arr.strings)); i < count; p += size {
		C.free(unsafe.Pointer(sptr(p)))
		i++
	}

	C.free(unsafe.Pointer(arr.strings))
}

func (o *Remote) FetchRefspecs() ([]string, error) {
	crefspecs := C.git_strarray{}

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_get_fetch_refspecs(&crefspecs, o.ptr)
	runtime.KeepAlive(o)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	defer C.git_strarray_dispose(&crefspecs)

	refspecs := makeStringsFromCStrings(crefspecs.strings, int(crefspecs.count))
	return refspecs, nil
}

func (c *RemoteCollection) AddPush(remote, refspec string) error {
	crefspec := C.CString(refspec)
	defer C.free(unsafe.Pointer(crefspec))
	cremote := C.CString(remote)
	defer C.free(unsafe.Pointer(cremote))

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_add_push(c.repo.ptr, cremote, crefspec)
	runtime.KeepAlive(c.repo)
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (o *Remote) PushRefspecs() ([]string, error) {
	crefspecs := C.git_strarray{}

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_get_push_refspecs(&crefspecs, o.ptr)
	if ret < 0 {
		return nil, MakeGitError(ret)
	}
	defer C.git_strarray_dispose(&crefspecs)
	runtime.KeepAlive(o)

	refspecs := makeStringsFromCStrings(crefspecs.strings, int(crefspecs.count))
	return refspecs, nil
}

func (o *Remote) RefspecCount() uint {
	count := C.git_remote_refspec_count(o.ptr)
	runtime.KeepAlive(o)
	return uint(count)
}

func populateFetchOptions(copts *C.git_fetch_options, opts *FetchOptions, errorTarget *error) *C.git_fetch_options {
	C.git_fetch_options_init(copts, C.GIT_FETCH_OPTIONS_VERSION)
	if opts == nil {
		return nil
	}
	populateRemoteCallbacks(&copts.callbacks, &opts.RemoteCallbacks, errorTarget)
	copts.prune = C.git_fetch_prune_t(opts.Prune)
	copts.update_fetchhead = cbool(opts.UpdateFetchhead)
	copts.download_tags = C.git_remote_autotag_option_t(opts.DownloadTags)

	copts.custom_headers = C.git_strarray{
		count:   C.size_t(len(opts.Headers)),
		strings: makeCStringsFromStrings(opts.Headers),
	}
	populateProxyOptions(&copts.proxy_opts, &opts.ProxyOptions)
	return copts
}

func freeFetchOptions(copts *C.git_fetch_options) {
	if copts == nil {
		return
	}
	freeStrarray(&copts.custom_headers)
	untrackCallbacksPayload(&copts.callbacks)
	freeProxyOptions(&copts.proxy_opts)
}

func populatePushOptions(copts *C.git_push_options, opts *PushOptions, errorTarget *error) *C.git_push_options {
	C.git_push_options_init(copts, C.GIT_PUSH_OPTIONS_VERSION)
	if opts == nil {
		return nil
	}

	copts.pb_parallelism = C.uint(opts.PbParallelism)
	copts.custom_headers = C.git_strarray{
		count:   C.size_t(len(opts.Headers)),
		strings: makeCStringsFromStrings(opts.Headers),
	}
	populateRemoteCallbacks(&copts.callbacks, &opts.RemoteCallbacks, errorTarget)
	return copts
}

func freePushOptions(copts *C.git_push_options) {
	if copts == nil {
		return
	}
	untrackCallbacksPayload(&copts.callbacks)
	freeStrarray(&copts.custom_headers)
}

// Fetch performs a fetch operation. refspecs specifies which refspecs
// to use for this fetch, use an empty list to use the refspecs from
// the configuration; msg specifies what to use for the reflog
// entries. Leave "" to use defaults.
func (o *Remote) Fetch(refspecs []string, opts *FetchOptions, msg string) error {
	var cmsg *C.char = nil
	if msg != "" {
		cmsg = C.CString(msg)
		defer C.free(unsafe.Pointer(cmsg))
	}

	var err error
	crefspecs := C.git_strarray{
		count:   C.size_t(len(refspecs)),
		strings: makeCStringsFromStrings(refspecs),
	}
	defer freeStrarray(&crefspecs)

	coptions := populateFetchOptions(&C.git_fetch_options{}, opts, &err)
	defer freeFetchOptions(coptions)

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_fetch(o.ptr, &crefspecs, coptions, cmsg)
	runtime.KeepAlive(o)

	if ret == C.int(ErrorCodeUser) && err != nil {
		return err
	}
	if ret < 0 {
		return MakeGitError(ret)
	}

	return nil
}

func (o *Remote) ConnectFetch(callbacks *RemoteCallbacks, proxyOpts *ProxyOptions, headers []string) error {
	return o.Connect(ConnectDirectionFetch, callbacks, proxyOpts, headers)
}

func (o *Remote) ConnectPush(callbacks *RemoteCallbacks, proxyOpts *ProxyOptions, headers []string) error {
	return o.Connect(ConnectDirectionPush, callbacks, proxyOpts, headers)
}

// Connect opens a connection to a remote.
//
// The transport is selected based on the URL. The direction argument
// is due to a limitation of the git protocol (over TCP or SSH) which
// starts up a specific binary which can only do the one or the other.
//
// 'headers' are extra HTTP headers to use in this connection.
func (o *Remote) Connect(direction ConnectDirection, callbacks *RemoteCallbacks, proxyOpts *ProxyOptions, headers []string) error {
	var err error
	ccallbacks := populateRemoteCallbacks(&C.git_remote_callbacks{}, callbacks, &err)
	defer untrackCallbacksPayload(ccallbacks)

	cproxy := populateProxyOptions(&C.git_proxy_options{}, proxyOpts)
	defer freeProxyOptions(cproxy)

	cheaders := C.git_strarray{
		count:   C.size_t(len(headers)),
		strings: makeCStringsFromStrings(headers),
	}
	defer freeStrarray(&cheaders)

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_connect(o.ptr, C.git_direction(direction), ccallbacks, cproxy, &cheaders)
	runtime.KeepAlive(o)
	if ret == C.int(ErrorCodeUser) && err != nil {
		return err
	}
	if ret != 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (o *Remote) Disconnect() {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	C.git_remote_disconnect(o.ptr)
	runtime.KeepAlive(o)
}

func (o *Remote) Ls(filterRefs ...string) ([]RemoteHead, error) {

	var refs **C.git_remote_head
	var length C.size_t

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_ls(&refs, &length, o.ptr)
	runtime.KeepAlive(o)
	if ret != 0 {
		return nil, MakeGitError(ret)
	}

	size := int(length)

	if size == 0 {
		return make([]RemoteHead, 0), nil
	}

	hdr := reflect.SliceHeader{
		Data: uintptr(unsafe.Pointer(refs)),
		Len:  size,
		Cap:  size,
	}

	goSlice := *(*[]*C.git_remote_head)(unsafe.Pointer(&hdr))

	var heads []RemoteHead

	for _, s := range goSlice {
		head := newRemoteHeadFromC(s)

		if len(filterRefs) > 0 {
			for _, r := range filterRefs {
				if strings.Contains(head.Name, r) {
					heads = append(heads, head)
					break
				}
			}
		} else {
			heads = append(heads, head)
		}
	}

	return heads, nil
}

func (o *Remote) Push(refspecs []string, opts *PushOptions) error {
	crefspecs := C.git_strarray{
		count:   C.size_t(len(refspecs)),
		strings: makeCStringsFromStrings(refspecs),
	}
	defer freeStrarray(&crefspecs)

	var err error
	coptions := populatePushOptions(&C.git_push_options{}, opts, &err)
	defer freePushOptions(coptions)

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_push(o.ptr, &crefspecs, coptions)
	runtime.KeepAlive(o)
	if ret == C.int(ErrorCodeUser) && err != nil {
		return err
	}
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

func (o *Remote) PruneRefs() bool {
	return C.git_remote_prune_refs(o.ptr) > 0
}

func (o *Remote) Prune(callbacks *RemoteCallbacks) error {
	var err error
	ccallbacks := populateRemoteCallbacks(&C.git_remote_callbacks{}, callbacks, &err)
	defer untrackCallbacksPayload(ccallbacks)

	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	ret := C.git_remote_prune(o.ptr, ccallbacks)
	runtime.KeepAlive(o)
	if ret == C.int(ErrorCodeUser) && err != nil {
		return err
	}
	if ret < 0 {
		return MakeGitError(ret)
	}
	return nil
}

// DefaultApplyOptions returns default options for remote create
func DefaultRemoteCreateOptions() (*RemoteCreateOptions, error) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	opts := C.git_remote_create_options{}
	ecode := C.git_remote_create_options_init(&opts, C.GIT_REMOTE_CREATE_OPTIONS_VERSION)
	if ecode < 0 {
		return nil, MakeGitError(ecode)
	}

	return &RemoteCreateOptions{
		Flags: RemoteCreateOptionsFlag(opts.flags),
	}, nil
}

func populateRemoteCreateOptions(copts *C.git_remote_create_options, opts *RemoteCreateOptions, repo *Repository) *C.git_remote_create_options {
	C.git_remote_create_options_init(copts, C.GIT_REMOTE_CREATE_OPTIONS_VERSION)
	if opts == nil {
		return nil
	}

	var cRepository *C.git_repository
	if repo != nil {
		cRepository = repo.ptr
	}
	copts.repository = cRepository
	copts.name = C.CString(opts.Name)
	copts.fetchspec = C.CString(opts.FetchSpec)
	copts.flags = C.uint(opts.Flags)

	return copts
}

func freeRemoteCreateOptions(ptr *C.git_remote_create_options) {
	if ptr == nil {
		return
	}
	C.free(unsafe.Pointer(ptr.name))
	C.free(unsafe.Pointer(ptr.fetchspec))
}