computeNode

fn computeNode(
    buf: []u8,
    start_i: usize,
    start_nl_n: usize,
    serialized: Serialized,
    children: []const Children,
    node_index: Node.Index,
) struct { usize, usize } {
    var i = start_i;
    var nl_n = start_nl_n;

    i = computePrefix(buf, i, nl_n, serialized, children, node_index);

    if (i + lineUpperBoundLen(nl_n) > buf.len)
        return .{ start_i, start_nl_n };

    const storage = &serialized.storage[@backingInt(node_index)];
    const estimated_total = storage.estimated_total_count;
    const completed_items = storage.completed_count;
    const name = if (std.mem.findScalar(u8, &storage.name, 0)) |end| storage.name[0..end] else &storage.name;
    const parent = serialized.parents[@backingInt(node_index)];

    if (parent != .none) p: {
        if (@backingInt(parent) == 0 and serialized.storage[0].name[0] == 0) {
            break :p;
        }
        if (children[@backingInt(node_index)].sibling == .none) {
            i = appendTreeSymbol(.langle, buf, i);
        } else {
            i = appendTreeSymbol(.tee, buf, i);
        }
    }

    const is_empty_root = @backingInt(node_index) == 0 and serialized.storage[0].name[0] == 0;
    if (!is_empty_root) {
        if (name.len != 0 or estimated_total > 0) {
            if (estimated_total > 0) {
                if (std.mem.print(buf[i..], "[{d}/{d}] ", .{ completed_items, estimated_total })) |b| {
                    i += b.len;
                } else |_| {}
            } else if (completed_items != 0) {
                if (std.mem.print(buf[i..], "[{d}] ", .{completed_items})) |b| {
                    i += b.len;
                } else |_| {}
            }
            if (name.len != 0) {
                if (std.mem.print(buf[i..], "{s}", .{name})) |b| {
                    i += b.len;
                } else |_| {}
            }
        }

        i = @min(global_progress.cols + start_i, i);
        if (is_windows) {
            // \r\n on Windows is necessary for the old console with the
            // ENABLE_VIRTUAL_TERMINAL_PROCESSING | DISABLE_NEWLINE_AUTO_RETURN
            // console modes set to behave properly.
            buf[i] = '\r';
            i += 1;
        }
        buf[i] = '\n';
        i += 1;
        nl_n += 1;
    }

    if (global_progress.withinRowLimit(nl_n)) {
        if (children[@backingInt(node_index)].child.unwrap()) |child| {
            i, nl_n = computeNode(buf, i, nl_n, serialized, children, child);
        }
    }

    if (global_progress.withinRowLimit(nl_n)) {
        if (children[@backingInt(node_index)].sibling.unwrap()) |sibling| {
            i, nl_n = computeNode(buf, i, nl_n, serialized, children, sibling);
        }
    }

    return .{ i, nl_n };
}