// bytes — slice operations over []u8.

export fn equal(a: []u8, b: []u8) bool = {
	let i: i32 = 0;
	for (i < a.len) {
		if (i >= b.len) { return false; };
		if (a[i] != b[i]) { return false; };
		i += 1;
	};
	return i == b.len;
};

// indexbyte — first index of byte `c` in `s`. Hare-shaped optional:
// (i32 | void). void variant indicates "not found".
export fn indexbyte(s: []u8, c: u8) (i32 | void) = {
	let i: i32 = 0;
	for (i < s.len) {
		if (s[i] == c) { return i; };
		i += 1;
	};
	return;
};

export fn copy(dst: []u8, src: []u8) i32 = {
	let n: i32 = dst.len;
	if (src.len < n) { n = src.len; };
	let i: i32 = 0;
	for (i < n) {
		dst[i] = src[i];
		i += 1;
	};
	return n;
};

// index — first index of `sub` in `s`. Mirrors Hare's bytes::index
// (the []u8 needle variant; the u8 needle stays as indexbyte until we
// have union-arg dispatch). Empty `sub` matches at 0.
export fn index(s: []u8, sub: []u8) (i32 | void) = {
	if (sub.len == 0) { return 0; };
	if (sub.len > s.len) { return; };
	let last: i32 = s.len - sub.len;
	let i: i32 = 0;
	for (i <= last) {
		let j: i32 = 0;
		let ok: bool = true;
		for (j < sub.len) {
			if (s[i + j] != sub[j]) { ok = false; j = sub.len; }
			else { j += 1; };
		};
		if (ok) { return i; };
		i += 1;
	};
	return;
};