/* Common parts for printing diff output */
/*
 * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <unistd.h>

#include <diff/diff_output.h>

static char
get_atom_byte(struct diff_atom *atom, off_t off)
{
	char ch;
	off_t cur;

	if (atom->at != NULL)
		return atom->at[off];

	cur = lseek(atom->d->root->fd, 0, SEEK_CUR);
	if (cur == -1)
		abort(); /* XXX cannot return error */

	if (cur != atom->pos + off &&
	    lseek(atom->d->root->fd, atom->pos + off, SEEK_SET) == -1)
		abort(); /* XXX cannot return error */

	if (read(atom->d->root->fd, &ch, sizeof(ch)) == -1)
		abort(); /* XXX cannot return error */

	return ch;
}

void
diff_output_lines(FILE *dest, const char *prefix, struct diff_atom *start_atom,
		  unsigned int count)
{
	struct diff_atom *atom;
	foreach_diff_atom(atom, start_atom, count) {
		fprintf(dest, "%s", prefix);
		int i;
		unsigned int len = atom->len;
		if (len) {
			char ch;
			ch = get_atom_byte(atom, len - 1);
			if (ch == '\n')
				len--;
			if (len) {
				ch = get_atom_byte(atom, len - 1);
				if (ch == '\r')
					len--;
			}
		}

		for (i = 0; i < len; i++) {
			char c = get_atom_byte(atom, i);
			if ((c < 0x20 || c >= 0x7f) && c != '\t')
				fprintf(dest, "\\x%02x", (unsigned char)c);
			else
				fprintf(dest, "%c", c);
		}
		fprintf(dest, "\n");
	}
}