#include "fileutil.h"
#include <gint/defs/util.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

int __fp_open(FILE *fp, int fd, bool use_buffering)
{
	/* We initialize fdpos to 0 even in append mode (7.19.3§1) */
	fp->fd = fd;
	fp->fdpos = 0;

	/* We assume all files in the filesystem are non-interactive in order
	   to conform to (7.19.5.3§7)
	   TODO: Vhex might want something more elaborate here */
	if(use_buffering && setvbuf(fp, NULL, _IOFBF, BUFSIZ))
		return -1;

	return 0;
}

void __fp_close(FILE *fp, bool free_fp)
{
	if(!fp)
		return;

	if(fp->fd >= 0) {
		fflush(fp);
		close(fp->fd);
	}
	if(fp->bufowned)
		free(fp->buf);
	if(free_fp)
		free(fp);
}

void __fp_remove_buffer(FILE *fp)
{
	if(fp->bufowned)
		free(fp->buf);

	fp->buf = NULL;
	fp->bufowned = false;
	fp->bufsize = 0;
}

bool __fp_set_buffer(FILE *fp, void *buf, size_t size)
{
	bool owned = false;

	if(!buf) {
		owned = true;
		buf = malloc(size);
		if(!buf)
			return false;
	}

	fp->buf = buf;
	fp->bufowned = owned;
	fp->bufsize = size;
	return true;
}

void __fp_buffer_mode_read(FILE *fp)
{
	if(__fp_hasbuf_write(fp)) {
		fflush(fp);
	}
	if(fp->buf)
		fp->bufdir = __FILE_BUF_READ;
}

void __fp_buffer_mode_write(FILE *fp)
{
	if(__fp_hasbuf_read(fp))
		fflush(fp);
	if(fp->buf)
		fp->bufdir = __FILE_BUF_WRITE;
}

ssize_t __fp_buffered_read(FILE *fp, void *data, size_t request_size)
{
	if(!fp->buf || __fp_hasbuf_write(fp))
		return -1;

	int read_size = min((int)request_size, fp->bufread - fp->bufpos);
	if(read_size <= 0)
		return 0;

	memcpy(data, fp->buf + fp->bufpos, read_size);
	fp->bufpos += read_size;
	fp->bufungetc = max(fp->bufungetc - read_size, 0);

	/* Rewind the buffer if we read it fully */
	if(fp->bufpos >= fp->bufread) {
		fp->bufread = 0;
		fp->bufpos = 0;

		/* Clear temporary ungetc() buffers of _IONBF streams */
		if(fp->bufmode == _IONBF)
			__fp_remove_buffer(fp);
	}

	return read_size;
}

ssize_t __fp_read(FILE *fp, void *data, size_t size)
{
	size_t read_ = 0;

	while(read_ < size) {
		ssize_t rc = read(fp->fd, data + read_, size - read_);

		if(rc < 0) {
			fp->error = 1;
			return EOF;
		}
		if(rc == 0) {
			fp->eof = 1;
			break;
		}

		fp->fdpos += rc;
		read_ += rc;
	}

	return read_;
}

ssize_t __fp_write(FILE *fp, void const *data, size_t size)
{
	size_t written = 0;

	while(written < size) {
		ssize_t rc = write(fp->fd, data + written, size - written);

		if(rc < 0) {
			fp->error = 1;
			return EOF;
		}
		if(rc == 0)
			break;

		fp->fdpos += rc;
		written += rc;
	}

	return written;
}

int __fp_parse_mode(char const *mode, FILE *fp)
{
	int base = 0;
	bool binary = false;
	bool update = false;

	for(int i = 0; mode[i]; i++) {
		if(mode[i] == 'r' || mode[i] == 'w' || mode[i] == 'a') {
			if(base) goto err;
			base = mode[i];
		}
		else if(mode[i] == 'b')
			binary = true;
		else if(mode[i] == '+')
			update = true;
	}
	if(!base) goto err;

	if(fp) {
		fp->readable = (base == 'r' || update);
		fp->writable = (base == 'w' || base == 'a' || update);
		fp->append = (base == 'a');
		fp->text = !binary;
	}

	if(base == 'r')
		return (update ? O_RDWR : O_RDONLY);
	if(base == 'w')
		return (update ? O_RDWR : O_WRONLY) | O_CREAT | O_TRUNC;
	if(base == 'a')
		return (update ? O_RDWR : O_WRONLY) | O_CREAT;
	/* Fallthrough */

err:
	errno = EINVAL;
	return -1;
}