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

#include "iso9660.h"

/*
 * Add the requisite path tables to the CD image.
 * They get put on the end once everything else is done.
 * We use the path table itself as a queue in the breadth-first
 * traversal of the tree.  
 *
 * The only problem with this is that the path table does not
 * store the lengths of the directories.  So we keep an explicit
 * map in an array in memory.
 */

enum {
	Big,
	Little
};

static void
Crdpath(Cdimg *cd, Cpath *p)
{
	p->namelen = Cgetc(cd);
	if(p->namelen == 0) {
		Crseek(cd, (Croffset(cd)+Blocksize-1)/Blocksize * Blocksize);
		p->namelen = Cgetc(cd);
		assert(p->namelen != 0);
	}

	p->xlen = Cgetc(cd);
	assert(p->xlen == 0);	/* sanity, might not be true if we start using the extended fields */

	Cread(cd, p->dloc, 4);
	Cread(cd, p->parent, 2);
	p->name[0] = '\0';
	Crseek(cd, Croffset(cd)+p->namelen+p->xlen+(p->namelen&1));	/* skip name, ext data */
}

static void
writepath(Cdimg *cd, Cdir *c, int parent, int size)
{
	int l;

	l = 1+1+4+2+c->namelen;
	if(Cwoffset(cd)/Blocksize != (Cwoffset(cd)+l)/Blocksize)
		Cpadblock(cd);

	Cputc(cd, c->namelen);
	Cputc(cd, 0);
	Cwrite(cd, c->dloc + (size==Little ? 0 : 4), 4);
	(size==Little ? Cputnl : Cputnm)(cd, parent, 2);
	Cwrite(cd, c->name, c->namelen);
	if(c->namelen & 1)
		Cputc(cd, 0);
}

static ulong*
addlength(ulong *a, ulong x, int n)
{
	if(n%128==0)
		a = erealloc(a, (n+128)*sizeof a[0]);
	a[n] = x;
	return a;
}

static ulong
writepathtable(Cdimg *cd, ulong vdblock, int size)
{
	int rp, wp;
	uchar buf[Blocksize];
	ulong bk, end, i, *len, n, rdoff, start;
	Cdir *c;
	Cpath p;

	Creadblock(cd, buf, vdblock, Blocksize);
	c = (Cdir*)(buf+offsetof(Cvoldesc, rootdir[0]));

	rp = 0;
	wp = 0;
	len = nil;
	start = cd->nextblock*Blocksize;
	Cwseek(cd, start);
	Crseek(cd, start);
	writepath(cd, c, 1, size);
	len = addlength(len, little(c->dlen, 4), wp);
	wp++;

	while(rp < wp) {
		Crdpath(cd, &p);
		n = (len[rp]+Blocksize-1)/Blocksize;
		rp++;
		bk = (size==Big ? big : little)(p.dloc, 4);
		rdoff = Croffset(cd);
		for(i=0; i<n; i++) {
			Creadblock(cd, buf, bk+i, Blocksize);
			c = (Cdir*)buf;
			if(i != 0 && c->namelen == 1 && c->name[0] == '\0')	/* hit another directory; stop */
				break;
			while(c->len && c->namelen && (uchar*)c+c->len < buf+Blocksize) {
				if((c->flags & 0x02) && (c->namelen > 1 || c->name[0] > '\001')) {	/* directory */
					writepath(cd, c, rp, size);
					len = addlength(len, little(c->dlen, 4), wp);
					wp++;
				}
				c = (Cdir*)((uchar*)c+c->len);
			}
		}
		Crseek(cd, rdoff);
	}
	end = Cwoffset(cd);
	Cpadblock(cd);
	return end-start;
}


static void
writepathtablepair(Cdimg *cd, ulong vdblock)
{
	ulong bloc, lloc, sz, sz2;

	lloc = cd->nextblock;
	sz = writepathtable(cd, vdblock, Little);
	bloc = cd->nextblock;
	sz2 = writepathtable(cd, vdblock, Big);
	assert(sz == sz2);
	setpathtable(cd, vdblock, sz, lloc, bloc);
}

void
writepathtables(Cdimg *cd)
{
	cd->pathblock = cd->nextblock;

	writepathtablepair(cd, cd->iso9660pvd);
	if(cd->flags & CDjoliet)
		writepathtablepair(cd, cd->jolietsvd);
}