package util

/*
#include <stdlib.h>
#define Error const char*
#define RustDataPtr void*

typedef struct {
	unsigned int len;
	Error err;
} ExecRustWriteResult_t;

typedef ExecRustWriteResult_t (*RustWriteFunc) (RustDataPtr RustData, void* buff, unsigned int len);
typedef void (*RustWritterDropFunc) (RustDataPtr RustData);

static ExecRustWriteResult_t _exec_rust_write_func (RustWriteFunc funcptr, RustDataPtr RustData, void* buff, unsigned int len) {
	return (funcptr)(RustData, buff, len);
}

static void _exec_rust_writter_drop_func (RustWritterDropFunc funcptr, RustDataPtr RustData) {
    (funcptr)(RustData);
}

*/
import (
	"C"
)
import (
	"errors"
	"nosql_db_sdk_ffi/util/ptrproxy"
	"runtime"
	"unsafe"
)

type RustIOWritter struct {
	wrapperPtr  C.RustWriteFunc
	writterPtr  RustWritterPtrGo
	dropFuncPtr C.RustWritterDropFunc
}

//export ffi_rust_IO_writter_new
func ffi_rust_IO_writter_new(wrapperFuncPtr C.RustWriteFunc, writterPtr unsafe.Pointer, dropFuncPtr C.RustWritterDropFunc) unsafe.Pointer {
	rustIOWritter := RustIOWritter{
		wrapperFuncPtr,
		RustWritterPtrGo(writterPtr),
		dropFuncPtr,
	}
	runtime.SetFinalizer(&rustIOWritter, RustIOWritterClose)
	return ptrproxy.Ref(unsafe.Pointer(&rustIOWritter))
}

//export ffi_rust_IO_writter_drop
func ffi_rust_IO_writter_drop(unsafe_writter_ptr unsafe.Pointer) {
	ptrproxy.Free(unsafe.Pointer(unsafe_writter_ptr))
}

func RustIOWritterClose(obj *RustIOWritter) {
	C._exec_rust_writter_drop_func(obj.dropFuncPtr, unsafe.Pointer(obj.writterPtr))
}

func (cw RustIOWritter) Write(p []byte) (n int, err error) {
	len := len(p)
	buff := C.CBytes(p)
	result := C._exec_rust_write_func(cw.wrapperPtr, unsafe.Pointer(cw.writterPtr), buff, C.uint(len))
	C.free(buff)
	if result.err != nil {
		return int(result.len), nil
	}
	return 0, errors.New(C.GoString(result.err))
}