pub const ArgIteratorWasi = struct {
    allocator: Allocator,
    index: usize,
    args: [][:0]u8,

    pub const InitError = error{OutOfMemory} || posix.UnexpectedError;

    /// You must call deinit to free the internal buffer of the
    /// iterator after you are done.
    pub fn init(allocator: Allocator) InitError!ArgIteratorWasi {
        const fetched_args = try ArgIteratorWasi.internalInit(allocator);
        return ArgIteratorWasi{
            .allocator = allocator,
            .index = 0,
            .args = fetched_args,
        };
    }

    fn internalInit(allocator: Allocator) InitError![][:0]u8 {
        var count: usize = undefined;
        var buf_size: usize = undefined;

        switch (std.os.wasi.args_sizes_get(&count, &buf_size)) {
            .SUCCESS => {},
            else => |err| return posix.unexpectedErrno(err),
        }

        if (count == 0) {
            return &[_][:0]u8{};
        }

        const argv = try allocator.alloc([*:0]u8, count);
        defer allocator.free(argv);

        const argv_buf = try allocator.alloc(u8, buf_size);

        switch (std.os.wasi.args_get(argv.ptr, argv_buf.ptr)) {
            .SUCCESS => {},
            else => |err| return posix.unexpectedErrno(err),
        }

        var result_args = try allocator.alloc([:0]u8, count);
        var i: usize = 0;
        while (i < count) : (i += 1) {
            result_args[i] = mem.sliceTo(argv[i], 0);
        }

        return result_args;
    }

    pub fn next(self: *ArgIteratorWasi) ?[:0]const u8 {
        if (self.index == self.args.len) return null;

        const arg = self.args[self.index];
        self.index += 1;
        return arg;
    }

    pub fn skip(self: *ArgIteratorWasi) bool {
        if (self.index == self.args.len) return false;

        self.index += 1;
        return true;
    }

    /// Call to free the internal buffer of the iterator.
    pub fn deinit(self: *ArgIteratorWasi) void {
        const last_item = self.args[self.args.len - 1];
        const last_byte_addr = @intFromPtr(last_item.ptr) + last_item.len + 1; // null terminated
        const first_item_ptr = self.args[0].ptr;
        const len = last_byte_addr - @intFromPtr(first_item_ptr);
        self.allocator.free(first_item_ptr[0..len]);
        self.allocator.free(self.args);
    }
}