package git

/*
#include <git2.h>

void _go_git_populate_credential_ssh_custom(git_cred_ssh_custom *cred);
*/
import "C"
import (
	"crypto/rand"
	"errors"
	"fmt"
	"unsafe"

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

type CredType uint

const (
	CredTypeUserpassPlaintext CredType = C.GIT_CREDTYPE_USERPASS_PLAINTEXT
	CredTypeSshKey            CredType = C.GIT_CREDTYPE_SSH_KEY
	CredTypeSshCustom         CredType = C.GIT_CREDTYPE_SSH_CUSTOM
	CredTypeDefault           CredType = C.GIT_CREDTYPE_DEFAULT
)

type Cred struct {
	doNotCompare
	ptr *C.git_cred
}

func (o *Cred) HasUsername() bool {
	if C.git_cred_has_username(o.ptr) == 1 {
		return true
	}
	return false
}

func (o *Cred) Type() CredType {
	return (CredType)(o.ptr.credtype)
}

func credFromC(ptr *C.git_cred) *Cred {
	return &Cred{ptr: ptr}
}

// GetUserpassPlaintext returns the plaintext username/password combination stored in the Cred.
func (o *Cred) GetUserpassPlaintext() (username, password string, err error) {
	if o.Type() != CredTypeUserpassPlaintext {
		err = errors.New("credential is not userpass plaintext")
		return
	}

	plaintextCredPtr := (*C.git_cred_userpass_plaintext)(unsafe.Pointer(o.ptr))
	username = C.GoString(plaintextCredPtr.username)
	password = C.GoString(plaintextCredPtr.password)
	return
}

// GetSSHKey returns the SSH-specific key information from the Cred object.
func (o *Cred) GetSSHKey() (username, publickey, privatekey, passphrase string, err error) {
	if o.Type() != CredTypeSshKey {
		err = fmt.Errorf("credential is not an SSH key: %v", o.Type())
		return
	}

	sshKeyCredPtr := (*C.git_cred_ssh_key)(unsafe.Pointer(o.ptr))
	username = C.GoString(sshKeyCredPtr.username)
	publickey = C.GoString(sshKeyCredPtr.publickey)
	privatekey = C.GoString(sshKeyCredPtr.privatekey)
	passphrase = C.GoString(sshKeyCredPtr.passphrase)
	return
}

func NewCredUsername(username string) (int, Cred) {
	cred := Cred{}
	cusername := C.CString(username)
	ret := C.git_cred_username_new(&cred.ptr, cusername)
	return int(ret), cred
}

func NewCredUserpassPlaintext(username string, password string) (int, Cred) {
	cred := Cred{}
	cusername := C.CString(username)
	defer C.free(unsafe.Pointer(cusername))
	cpassword := C.CString(password)
	defer C.free(unsafe.Pointer(cpassword))
	ret := C.git_cred_userpass_plaintext_new(&cred.ptr, cusername, cpassword)
	return int(ret), cred
}

// NewCredSshKey creates new ssh credentials reading the public and private keys
// from the file system.
func NewCredSshKey(username string, publicKeyPath string, privateKeyPath string, passphrase string) (int, Cred) {
	cred := Cred{}
	cusername := C.CString(username)
	defer C.free(unsafe.Pointer(cusername))
	cpublickey := C.CString(publicKeyPath)
	defer C.free(unsafe.Pointer(cpublickey))
	cprivatekey := C.CString(privateKeyPath)
	defer C.free(unsafe.Pointer(cprivatekey))
	cpassphrase := C.CString(passphrase)
	defer C.free(unsafe.Pointer(cpassphrase))
	ret := C.git_cred_ssh_key_new(&cred.ptr, cusername, cpublickey, cprivatekey, cpassphrase)
	return int(ret), cred
}

// NewCredSshKeyFromMemory creates new ssh credentials using the publicKey and privateKey
// arguments as the values for the public and private keys.
func NewCredSshKeyFromMemory(username string, publicKey string, privateKey string, passphrase string) (int, Cred) {
	cred := Cred{}
	cusername := C.CString(username)
	defer C.free(unsafe.Pointer(cusername))
	cpublickey := C.CString(publicKey)
	defer C.free(unsafe.Pointer(cpublickey))
	cprivatekey := C.CString(privateKey)
	defer C.free(unsafe.Pointer(cprivatekey))
	cpassphrase := C.CString(passphrase)
	defer C.free(unsafe.Pointer(cpassphrase))
	ret := C.git_cred_ssh_key_memory_new(&cred.ptr, cusername, cpublickey, cprivatekey, cpassphrase)
	return int(ret), cred
}

func NewCredSshKeyFromAgent(username string) (int, Cred) {
	cred := Cred{}
	cusername := C.CString(username)
	defer C.free(unsafe.Pointer(cusername))
	ret := C.git_cred_ssh_key_from_agent(&cred.ptr, cusername)
	return int(ret), cred
}

func NewCredDefault() (int, Cred) {
	cred := Cred{}
	ret := C.git_cred_default_new(&cred.ptr)
	return int(ret), cred
}

type credentialSSHCustomData struct {
	signer ssh.Signer
}

//export credentialSSHCustomFree
func credentialSSHCustomFree(cred *C.git_cred_ssh_custom) {
	if cred == nil {
		return
	}

	C.free(unsafe.Pointer(cred.username))
	C.free(unsafe.Pointer(cred.publickey))
	pointerHandles.Untrack(cred.payload)
	C.free(unsafe.Pointer(cred))
}

//export credentialSSHSignCallback
func credentialSSHSignCallback(
	errorMessage **C.char,
	sig **C.uchar,
	sig_len *C.size_t,
	data *C.uchar,
	data_len C.size_t,
	handle unsafe.Pointer,
) C.int {
	signer := pointerHandles.Get(handle).(*credentialSSHCustomData).signer
	signature, err := signer.Sign(rand.Reader, C.GoBytes(unsafe.Pointer(data), C.int(data_len)))
	if err != nil {
		return setCallbackError(errorMessage, err)
	}
	*sig = (*C.uchar)(C.CBytes(signature.Blob))
	*sig_len = C.size_t(len(signature.Blob))
	return C.int(ErrorCodeOK)
}

// NewCredentialSSHKeyFromSigner creates new SSH credentials using the provided signer.
func NewCredentialSSHKeyFromSigner(username string, signer ssh.Signer) (*Cred, error) {
	publicKey := signer.PublicKey().Marshal()

	ccred := (*C.git_cred_ssh_custom)(C.calloc(1, C.size_t(unsafe.Sizeof(C.git_cred_ssh_custom{}))))
	ccred.parent.credtype = C.GIT_CREDTYPE_SSH_CUSTOM
	ccred.username = C.CString(username)
	ccred.publickey = (*C.char)(C.CBytes(publicKey))
	ccred.publickey_len = C.size_t(len(publicKey))
	C._go_git_populate_credential_ssh_custom(ccred)

	data := credentialSSHCustomData{
		signer: signer,
	}
	ccred.payload = pointerHandles.Track(&data)

	cred := Cred{
		ptr: &ccred.parent,
	}

	return &cred, nil
}