import "../mod/libfwdio.so"
import "../mod/libfwdmem.so"
import "../mod/libfwdutil.so"

vec {
	u64 n;
	u64 s;
	*i64 buf;
}

init_vec(u64 n, (vec) ok)
{
	ok([n => n, 0 as u64 => s, * => buf] vec);
}

next_s_vec(u64 s, (u64) ok)
{
	if s == 0 as u64 {
		ok(1 as u64);
	} else {
		ok(2 as u64 * s);
	}
}

reserve_vec(vec v, u64 c, (vec) ok)
{
	v => [n => n, s => s, buf => buf];
	n + c => nn;

	/* expand if we run out of space */
	if nn > s {
		next_s_vec(s) => s;

		/* note that fwdrealloc creates a new closure, meaning that it
		 * takes ownership of v.buf, so we can't back out and do a
		 * single ok(v) at the end of the function */
		fwdrealloc(buf, s * sizeof(i64)) => nbuf;
		ok([nn => n, s => s, nbuf => buf] vec);
	} else {
		ok([nn => n, s => s, buf => buf] vec);
	}
}

set_vec(vec v, i64 i, i64 e, (vec) ok)
{
	v => [n => n, s => s, buf => buf];
	buf + (n - 1 as u64) => nbuf;
	nil nbuf {fwdpanic("should never happen");} => dst;
	e => dst*;
	ok([n => n, s => s, nbuf => buf] vec);
}

n_vec(vec v, (vec, u64) ok)
{
	v => [n => n, s => s, buf => buf];
	ok([n => n, s => s, buf => buf] vec, n);
}

append_vec(vec v, i64 e, (vec) ok)
{
	n_vec(v) => v, n;
	reserve_vec(v, n + 1 as u64) => v;
	set_vec(v, n as i64 - 1, e) => v;
	ok(v);
}

at_vec(vec v, u64 i, (vec, &i64) ok)
{
	v => [n => n, s => s, buf => buf];
	if i >= n {fwdpanic("bounds error");}
	fwdptradd(buf, (i * sizeof(i64)) as i64) => *i64 buf;
	nil buf {fwdpanic("should never happen");} => &i64 bufr;
	ok([n => n, s => s, buf => buf] vec, bufr);
}

destroy_vec(vec v)
{
	v => [n => n, s => s, buf => buf];
	fwdfree(buf);
	nil n;
	nil s;
}

populate_vec(i64 i, i64 n, vec v, (vec) ok)
{
	if i < n {
		append_vec(v, i) => vec v;
		populate_vec(i + 1, n, v, ok);
	} else {
		ok(v);
	}
}

guard(bool c, () err | () ok)
{
	if c {
		err();
	} else {
		ok();
	}
}

check_vec(i64 i, i64 n, vec v, (vec) ok)
{
	if i < n {
		at_vec(v, i as u64) => v, elem;

		guard(elem* != i) =>  {
			destroy_vec(v);
			fwdpanic("vec built wrong");
		} => ;

		check_vec(i + 1, n, v, ok);
	} else {
		ok(v);
	}
}

main()
{
	init_vec(0 as u64) => vec v;
	populate_vec(0, 1000000, v) => vec v;
	check_vec(0, 1000000, v) => vec v;
	destroy_vec(v);
}