/******************************************************************************
 *
 *                Copyright (c) 2017-2019 by Löwenware Ltd
 *             Please, refer LICENSE file for legal information
 *
 ******************************************************************************/

/**
 * @file file.c
 * @author Ilja Kartašov <ik@lowenware.com>
 * @brief 
 *
 * @see https://lowenware.com/
 */
#include <stdio.h>
#include <sys/sendfile.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

#include <sys/stat.h>
#include "file.h"


bool
cstuff_file_exists(const char *file)
{
	return ( access( file, F_OK ) != -1 ) ? true : false;
}


CStuffRetcode
cstuff_file_copy(const char *src, const char *dest)
{
	CStuffRetcode rc = CSTUFF_SYSCALL_ERROR;
	int fd_src = open(src, O_RDWR), fd_dest, len;
	struct stat src_stat;

	if (!(fd_src < 0)) {
		if (lockf(fd_src, F_LOCK, 0) != -1) {
			if (!stat(src, &src_stat)) {
				fd_dest = open(dest, O_CREAT | O_WRONLY | O_TRUNC);
				if (!(fd_dest < 0)) {
					len = sendfile(fd_dest, fd_src, NULL, src_stat.st_size);
					if (len == src_stat.st_size) {
						rc = CSTUFF_SUCCESS;
					} else {
						fprintf(stderr, "sendfile error (%d != %d): %s\n", len,
								(int)src_stat.st_size, strerror(errno));
					}
					close(fd_dest);
				} else {
					fprintf(stderr, "dest open() error\n");
				}
			} else {
				fprintf(stderr, "src stat() error\n");
			}
			if (lockf(fd_src, F_TEST, 0) == 0){
				lockf(fd_src, F_ULOCK, 0);
			}
		} else {
			fprintf(stderr, "src lockf() error\n");
		}
		close(fd_src);
	} else {
		fprintf(stderr, "src open() error\n");
	}
	return rc;
}


CStuffRetcode
cstuff_file_move(const char *src, const char *dest)
{
	CStuffRetcode rc;

	if (!(rc = cstuff_file_copy(src, dest))) {
		if (unlink(src) != 0)
			return CSTUFF_SYSCALL_ERROR;
	}

	return rc;
}


CStuffRetcode
cstuff_file_get_lines(const char *src, CStuffFileGetLine get_line, void *ctx)
{
	FILE *f = NULL;
	size_t sz = 256;
	char *line;
	ssize_t rs;
	CStuffRetcode result = CSTUFF_SUCCESS;

	if (!(line = malloc(sz)))
		goto e_malloc;

	if (!(f = fopen(src, "r")))
		goto e_syscall;

	while ((rs = getdelim(&line, &sz, '\n', f)) != -1) {
		if (!get_line(line, rs, ctx)) {
			continue;
		} else {
			goto e_input;
		}
	}

	switch(errno) {
	case 0:
		break;

	case ENOMEM:
		goto e_malloc;

	default:
		goto e_syscall;
	}
	goto finally;

e_input:
	result = CSTUFF_INPUT_ERROR;
	goto finally;

e_malloc:
	result = CSTUFF_MALLOC_ERROR;
	goto finally;

e_syscall:
	result = CSTUFF_SYSCALL_ERROR;
	goto finally;

finally:
	if (line)
		free(line);
	if (f)
		fclose(f);
	return result;
}