def utf8_uri_encode(utf8_string, length=0):
    unicode = ''
    values = []
    num_octets = 1
    unicode_length = 0

    string_length = len(utf8_string)

    for i in range(0, string_length):

        value = ord(utf8_string[i])

        if value < 128:
            if length and (unicode_length >= length):
                break
            unicode += chr(value)
            unicode_length += 1
        else:
            if len(values) == 0:
                if value < 224:
                    num_octets = 2
                elif value < 240:
                    num_octets = 3
                else:
                    num_octets = 4

            values.append(value)

            if length and ((unicode_length + (num_octets * 3)) > length):
                break
            if len(values) == num_octets:
                for j in range(0, num_octets):
                    unicode += '%' + hex(values[j])

                unicode_length += num_octets * 3

                values = []
                num_octets = 1

    return unicode