#include <u.h>
#include <libc.h>

void	split(char *, char **, char **);
int	samefile(char *, char *);
int	mv(char *from, char *todir, char *toelem);
int	copy1(int fdf, int fdt, char *from, char *to);
void	hardremove(char *);

void
main(int argc, char *argv[])
{
	int i;
	int failed;
	Dir *dirto, *dirfrom;
	char *todir, *toelem;

	if(argc<3){
		fprint(2, "usage: mv fromfile tofile\n");
		fprint(2, "	  mv fromfile ... todir\n");
		exits("bad usage");
	}
	if((dirto = dirstat(argv[argc-1])) != nil && (dirto->mode&DMDIR)){
		if(argc == 3
		&& (dirfrom = dirstat(argv[1])) !=nil
		&& (dirfrom->mode & DMDIR))
			split(argv[argc-1], &todir, &toelem);
		else{
			todir = argv[argc-1];
			toelem = 0;	/* toelem will be fromelem */
		}
	}else
		split(argv[argc-1], &todir, &toelem);
	if(argc>3 && toelem != 0){
		fprint(2, "mv: %s not a directory\n", argv[argc-1]);
		exits("bad usage");
	}
	failed = 0;
	for(i=1; i < argc-1; i++)
		if (mv(argv[i], todir, toelem) < 0)
			failed++;
	if(failed)
		exits("failure");
	exits(0);
}

int
mv(char *from, char *todir, char *toelem)
{
	Dir *dirb, *dirt, null;
	char toname[4096], fromname[4096];
	int fdf, fdt, i, j;
	int stat;
	char *fromdir, *fromelem;

	dirb = dirstat(from);
	if(dirb == nil){
		fprint(2, "mv: can't stat %s: %r\n", from);
		return -1;
	}
	strncpy(fromname, from, sizeof fromname);
	split(from, &fromdir, &fromelem);
	if(toelem == 0)
		toelem = fromelem;
	i = strlen(toelem);
	if(i==0){
		fprint(2, "mv: null last name element moving %s\n", fromname);
		return -1;
	}
	j = strlen(todir);
	if(i + j + 2 > sizeof toname){
		fprint(2, "mv: path too big (max %d): %s/%s\n", sizeof toname, todir, toelem);
		return -1;
	}
	memmove(toname, todir, j);
	toname[j] = '/';
	memmove(toname+j+1, toelem, i);
	toname[i+j+1] = 0;
	if(samefile(fromdir, todir)){
		if(samefile(fromname, toname)){
			fprint(2, "mv: %s and %s are the same\n", fromname, toname);
			return -1;
		}
		dirt = dirstat(toname);
		if(dirt != nil){
			free(dirt);
			hardremove(toname);
		}
		nulldir(&null);
		null.name = toelem;
		if(dirwstat(fromname, &null) >= 0)
			return 0;
		if(dirb->mode & DMDIR){
			fprint(2, "mv: can't rename directory %s: %r\n", fromname);
			return -1;
		}
	}
	/*
	 * Renaming won't work --- must copy
	 */
	if(dirb->mode & DMDIR){
		fprint(2, "mv: %s is a directory, not copied to %s\n", fromname, toname);
		return -1;
	}
	fdf = open(fromname, OREAD);
	if(fdf < 0){
		fprint(2, "mv: can't open %s: %r\n", fromname);
		return -1;
	}
	dirt = dirstat(toname);
	if(dirt != nil && (dirt->mode & DMAPPEND))
		hardremove(toname);	/* because create() won't truncate file */
	free(dirt);
	fdt = create(toname, OWRITE, dirb->mode);
	if(fdt < 0){
		fprint(2, "mv: can't create %s: %r\n", toname);
		close(fdf);
		return -1;
	}
	if ((stat = copy1(fdf, fdt, fromname, toname)) != -1) {
		nulldir(&null);
		null.mtime = dirb->mtime;
		null.mode = dirb->mode;
		dirfwstat(fdt, &null);	/* ignore errors; e.g. user none always fails */
		if (remove(fromname) < 0) {
			fprint(2, "mv: can't remove %s: %r\n", fromname);
			close(fdf);
			close(fdt);
			return -1;
		}
	}
	close(fdf);
	close(fdt);
	return stat;
}

int
copy1(int fdf, int fdt, char *from, char *to)
{
	char buf[8192];
	long n, n1;

	for(;;) {
		n = read(fdf, buf, sizeof buf);
		if(n >= 0) {
			if(n == 0)
				break;
			n1 = write(fdt, buf, n);
			if(n1 != n) {
				fprint(2, "mv: error writing %s: %r\n", to);
				return -1;
			}
		}
	}
	if(n < 0) {
		fprint(2, "mv: error reading %s: %r\n", from);
		return -1;
	}
	return 0;
}

void
split(char *name, char **pdir, char **pelem)
{
	char *s;

	s = utfrrune(name, '/');
	if(s){
		*s = 0;
		*pelem = s+1;
		*pdir = name;
	}else if(strcmp(name, "..") == 0){
		*pdir = "..";
		*pelem = ".";
	}else{
		*pdir = ".";
		*pelem = name;
	}
}

int
samefile(char *a, char *b)
{
	Dir *da, *db;
	int ret;

	if(strcmp(a, b) == 0)
		return 1;
	da = dirstat(a);
	db = dirstat(b);
	ret = (da !=nil ) &&
		(db != nil) &&
		(da->qid.type==db->qid.type) &&
		(da->qid.path==db->qid.path) &&
		(da->qid.vers==db->qid.vers) &&
		(da->dev==db->dev) &&
		da->type==db->type;
	free(da);
	free(db);
	return ret;
}

void
hardremove(char *a)
{
	if(remove(a) == -1){
		fprint(2, "mv: can't remove %s: %r\n", a);
		exits("mv");
	}
	do; while(remove(a) != -1);
}