/* fs example. Does it get any better ? */

#include <u.h>
#include <libc.h>
#include <mp.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>

typedef struct FibState {
	mpint *current;
	mpint *last;
}FibState;


Tree *fibtree;

static void freefibstate(FibState *state)
{
	mpfree(state->last);
	mpfree(state->current);
	free(state);
}

static FibState*
allocfibstate(void)
{
	FibState *new;
	
	new = emalloc9p(sizeof *new);
	new->current = itomp(1,nil);
	new->last = itomp(0,nil);
	if(new->current == nil || new->last == nil) {
		freefibstate(new);
		new = nil;
	}

	return new;
}

static u32int
nextfib(FibState *state,char *buf,u32int maxlen)
{
	int len;

	mpint* next = mpnew(96);
	if(next == nil)
		return 0;

	mptoa(state->current,10,buf,maxlen -1);

	mpadd(state->current,state->last,next);
	mpfree(state->last);
	state->last = state->current;
	state->current = next;
	len = strlen(buf);
	buf[len] = '\n';
	return len + 1;
}

static void 
fibread(Req *r)
{
	if(r->ifcall.count < 2) {
		respond(r,"Insufficient space");
		return;
	}

	if(r->fid->aux == nil)
		r->fid->aux = allocfibstate();

	if(r->fid->aux == nil) {
		respond(r,"Out of memory");
		return;
	}

	r->ofcall.count = nextfib(r->fid->aux,r->ofcall.data,r->ifcall.count);
	respond(r,nil);
}

static void
fibdestroyfid(Fid *f)
{
	FibState *state = f->aux;
	if(state) 
		freefibstate(state);
}

Srv fs = {
	.read = fibread,
	.destroyfid = fibdestroyfid
};

static void usage(void)
{
	fprint(2,"usage: fibfs [-D] [-m mntpt]\n");
	exits("usage");
}

void
main(int argc,char *argv[])
{
	char *mntpt = ".";

	ARGBEGIN{
	case 'D':
		chatty9p++;
		break;
	case 'm':
		mntpt = EARGF(usage());
		break;
	
	}ARGEND;

	fs.tree = fibtree = alloctree("none","none",DMDIR|0555,nil);
	closefile(createfile(fibtree->root,"fibs","none",0444,nil));
	postmountsrv(&fs,nil,mntpt,MAFTER);
	
	exits(nil);
}

/*yes.*/