package util

/*
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int encfile(char *in_filename, char *pwd, char *out_filename) {
	if (in_filename ==NULL || pwd == NULL || out_filename ==NULL) {
		printf("invalid argument!\n");
		return -3;
	}
	if (strlen(pwd)<6) {
		printf("pwd lenth must >=6\n");
		return -3;
	}

	FILE *fp1, *fp2;
	register char ch;
	int j =0;
	int j0=0;
	fp1 = fopen(in_filename, "r");
	if(fp1==NULL) {
		printf("cannot open in-file\n");
		return -1;
	}
	fp2=fopen(out_filename, "w");
	if(fp2==NULL) {
		printf("cannot open or create out-file\n");
		return -2;
	}
	while(pwd[++j0]);
	ch = fgetc(fp1);
	while(!feof(fp1)) {
		if(j0>6) {
			j0=0;
		}
		ch +=pwd[j0++];
		fputc(ch, fp2);
		ch = fgetc(fp1);
	}
	fclose(fp1);
	fclose(fp2);
	return 0;
}

int decfile(char *in_filename, char *pwd, char *out_filename) {
	if(in_filename == NULL || pwd == NULL || out_filename == NULL) {
		printf("invalid argument!\n");
		return -3;
	}
	if (strlen(pwd) <6) {
		printf("pwd lenth must >=6\n");
		return -3;
	}

	FILE *fp1, *fp2;
	register char ch;
	int j =0;
	int j0=0;
	fp1 = fopen(in_filename, "r");
	if(fp1==NULL) {
		printf("cannot open in-file\n");
		return -1;
	}
	fp2=fopen(out_filename, "w");
	if(fp2==NULL) {
		printf("cannot open or create out-file\n");
		return -2;
	}
	while(pwd[++j0]);
	ch = fgetc(fp1);
	while(!feof(fp1)) {
		if(j0>6) {
			j0=0;
		}
		ch -=pwd[j0++];
		fputc(ch, fp2);
		ch = fgetc(fp1);
	}
	fclose(fp1);
	fclose(fp2);
	return 0;
}

//将明文加密后写入到文件中
int writeContent2EncFile(char *in_data, char *pwd, char *in_filename) {
	if (in_data == NULL || pwd == NULL || in_filename == NULL) {
		printf("invalid argument!\n");
		return -3;
	}
	if (strlen(pwd) <6) {
		printf("pwd lenth must >=6\n");
		return -3;
	}
	FILE *fp = fopen(in_filename, "w");
	if(fp == NULL) {
		printf("cannot open file %s \n", in_filename);
		return -1;
	}
	int j =0;
	while(pwd[++j]);
	int i=0;
	int len = strlen(in_data);
	register char ch;
	for(i=0;i<len;i++) {
		ch = in_data[i];
		if(j>6) {
			j=0;
		}
		ch +=pwd[j++];
		fputc(ch, fp);
	}
	fclose(fp);
	return 0;
}

//获取加密文件的内容
int readEncryptFile(char *in_filename, char *pwd, void **outData, int *len) {
	if (in_filename ==NULL || pwd == NULL || outData == NULL || len == NULL) {
		printf("invalid argument!\n");
		return -3;
	}
	if (strlen(pwd) <6) {
		printf("pwd lenth must >=6\n");
		return -3;
	}

	FILE *fp = fopen(in_filename, "r");
	if(fp == NULL) {
		printf("cannot open file %s \n", in_filename);
		return -1;
	}
	fseek(fp, 0, SEEK_END);
	int size = ftell(fp);
	char *content = (char*)malloc(sizeof(char)*size);
	if(content == NULL) {
		printf("malloc file size:%d err!!!\n", size);
		fclose(fp);
		return -2;
	}
	memset(content, 0, size);
	fseek(fp, 0, SEEK_SET);
	int j = 0;
	while(pwd[++j]);
	char ch;
	int n = 0;
	while(!feof(fp)) {
		ch = fgetc(fp);
		if(j>6) {
			j=0;
		}
		ch -=pwd[j++];
		content[n++] = ch;
	}

	*outData = content;
	*len = size;
	fclose(fp);
	return 0;
}

*/
import "C"

import (
	"strconv"
	"unsafe"
	"errors"
)

const pwd = "123456"
func CallEncFile(srcAbsFileName string, outAbsPath string) error {
	inPath := C.CString(srcAbsFileName)
	cpwd := C.CString(pwd)
	outPath := C.CString(outAbsPath)
	defer func() {
		C.free(unsafe.Pointer(inPath))
		C.free(unsafe.Pointer(outPath))
		C.free(unsafe.Pointer(cpwd))
	}()
	cret := C.encfile(inPath, cpwd, outPath)
	if cret!=0 {
		if cret == -1 {
			return errors.New("cannot open original file")
		} else if cret == -2 {
			return errors.New("cannot open or create output file")
		} else {
			return errors.New("unknown enc file err")
		}
	}
	return nil
}

func CallDecFile(srcAbsFileName string, outAbsPath string) error {
	inPath := C.CString(srcAbsFileName)
	cpwd := C.CString(pwd)
	outPath := C.CString(outAbsPath)
	defer func() {
		C.free(unsafe.Pointer(inPath))
		C.free(unsafe.Pointer(outPath))
		C.free(unsafe.Pointer(cpwd))
	}()
	cret := C.decfile(inPath, cpwd, outPath)
	if cret!=0 {
		if cret == -1 {
			return errors.New("cannot open original file")
		} else if cret == -2 {
			return errors.New("cannot open or create output file")
		} else {
			return errors.New("unknown enc file err")
		}
	}
	return nil
}

func CallEncContent2File(data string, fpath string) error {
	cpath := C.CString(fpath)
	cpwd := C.CString(pwd)
	cdata := C.CString(data)
	defer func() {
		C.free(unsafe.Pointer(cpath))
		C.free(unsafe.Pointer(cpwd))
		C.free(unsafe.Pointer(cdata))
	}()
	cRet := C.writeContent2EncFile(cdata, cpwd, cpath)
	if cRet != 0 {
		return errors.New("C.writeContent2EncFile ret:"+strconv.Itoa(int(cRet)))
	}
	return nil
}

//解密获取文件内容
func CallDecFileContent(fpath string) ([]byte, error) {
	inPath := C.CString(fpath)
	cpwd := C.CString(pwd)
	cData := unsafe.Pointer(nil)
	cLen := C.int(0)
	defer func() {
		C.free(unsafe.Pointer(inPath))
		C.free(unsafe.Pointer(cpwd))
		C.free(unsafe.Pointer(cData))
	}()
	cRet := C.readEncryptFile(inPath, cpwd, &cData, &cLen)
	if cRet != 0 {
		return nil, errors.New("cgo call ret:"+ strconv.Itoa(int(cRet)))
	}

	fileData := C.GoBytes(cData, cLen)

	return fileData, nil
}