#include <u.h>
#include <libc.h>
#include <bio.h>
#include "diff.h"

#define	DIRECTORY(s)		((s).qid.path&CHDIR)
#define	REGULAR_FILE(s)		((s).type == 'M' && !DIRECTORY(s))

Biobuf	stdout;

static char *tmp[] = {"/tmp/diff1", "/tmp/diff2"};
static int whichtmp;
static char *progname;
static char usage[] = "diff [ -efbwr ] file1 ... file2\n";

static void
rmtmpfiles(void)
{
	while (whichtmp > 0) {
		whichtmp--;
		remove(tmp[whichtmp]);
	}
}

void	
done(int status)
{
	rmtmpfiles();
	switch(status)
	{
	case 0:
		exits("");
	case 1:
		exits("some");
	default:
		exits("error");
	}
	/*NOTREACHED*/
}

void
panic(int status, char *format, ...)
{
	char buf[1024], *out;

	Bflush(&stdout);
	out = doprint(buf, buf+sizeof(buf), "%s: ", &progname);
	out = doprint(out, buf+sizeof(buf), format, ((long*)&format)+1);
	write(2, buf, out-buf);
	if (status)
		done(status);
		/*NOTREACHED*/
}

static int
catch(void *a, char *msg)
{
	USED(a);
	panic(2, msg);
	return 1;
}

int
mkpathname(char *pathname, char *path, char *name)
{
	if (strlen(path) + strlen(name) > MAXPATHLEN) {
		panic(0, "pathname %s/%s too long\n", path, name);
		return 1;
	}
	sprint(pathname, "%s/%s", path, name);
	return 0;
}
	
static char *
mktmpfile(int input, Dir *sb)
{
	int fd, i;
	char *p;
	char buf[8192];

	atnotify(catch, 1);
	p = tmp[whichtmp++];
	fd = create(p, OWRITE, 0600);
	if (fd < 0) {
		panic(mflag ? 0: 2, "cannot create %s\n", p);
		return 0;
	}
	while ((i = read(input, buf, sizeof(buf))) > 0) {
		if ((i = write(fd, buf, i)) < 0)
			break;
	}
	dirfstat(fd, sb);
	close(fd);
	if (i < 0) {
		panic(mflag ? 0: 2, "cannot read/write %s\n", p);
		return 0;
	}
	return p;
}

static char *
statfile(char *file, Dir *sb)
{
	int input;

	if (dirstat(file, sb) == -1) {
		if (strcmp(file, "-") || dirfstat(0, sb) == -1) {
			panic(mflag ? 0: 2, "cannot stat %s\n", file);
			return 0;
		}
		file = mktmpfile(0, sb);
	}
	else if (!REGULAR_FILE(*sb) && !DIRECTORY(*sb)) {
		if ((input = open(file, OREAD)) == -1) {
			panic(mflag ? 0: 2, "cannot open %s\n", file);
			return 0;
		}
		file = mktmpfile(input, sb);
		close(input);
	}
	return file;
}

void
diff(char *f, char *t, int level)
{
	char *fp, *tp, *p, fb[MAXPATHLEN+1], tb[MAXPATHLEN+1];
	Dir fsb, tsb;

	if ((fp = statfile(f, &fsb)) == 0)
		return;
	if ((tp = statfile(t, &tsb)) == 0)
		return;
	if (DIRECTORY(fsb) && DIRECTORY(tsb)) {
		if (rflag || level == 0)
			diffdir(fp, tp, level);
		else
			Bprint(&stdout, "Common subdirectories: %s and %s\n",
				fp, tp);
	}
	else if (REGULAR_FILE(fsb) && REGULAR_FILE(tsb))
		diffreg(fp, tp);
	else {
		if (REGULAR_FILE(fsb)) {
			if ((p = utfrrune(f, '/')) == 0)
				p = f;
			else
				p++;
			if (mkpathname(tb, tp, p))
				return;
			diffreg(fp, tb);
		}
		else {
			if ((p = utfrrune(t, '/')) == 0)
				p = t;
			else
				p++;
			if (mkpathname(fb, fp, p))
				return;
			diffreg(fb, tp);
		}
	}
}

void
main(int argc, char *argv[])
{
	char *p;
	int i;
	Dir fsb, tsb;

	Binit(&stdout, 1, OWRITE);
	progname = *argv;
	while (--argc && (*++argv)[0] == '-' && (*argv)[1]) {
		for (p = *argv+1; *p; p++) {
			switch (*p) {

			case 'e':
			case 'f':
				mode = *p;
				break;

			case 'w':
				bflag = 2;
				break;

			case 'b':
				bflag = 1;
				break;

			case 'r':
				rflag = 1;
				break;

			case 'h':
			default:
				progname = "Usage";
				panic(2, usage);
			}
		}
	}
	if (argc < 2)
		panic(2, usage, progname);
	if (dirstat(argv[argc-1], &tsb) == -1)
		panic(2, "can't stat %s\n", argv[argc-1]);
	if (argc > 2) {
		if (!DIRECTORY(tsb))
			panic(2, usage, progname);
		mflag = 1;
	}
	else {
		if (dirstat(argv[0], &fsb) == -1)
			panic(2, "can't stat %s\n", argv[0]);
		if (DIRECTORY(fsb) && DIRECTORY(tsb))
			mflag = 1;
	}
	for (i = 0; i < argc-1; i++) {
		diff(argv[i], argv[argc-1], 0);
		rmtmpfiles();
	}
	done(anychange);
	/*NOTREACHED*/
}

static char noroom[] = "out of memory - try diff -h\n";

void *
emalloc(unsigned n)
{
	register void *p;

	if ((p = malloc(n)) == 0)
		panic(2, noroom);
	return p;
}

void *
erealloc(void *p, unsigned n)
{
	register void *rp;

	if ((rp = realloc(p, n)) == 0)
		panic(2, noroom);
	return rp;
}