def get_environment(self):
        """
        Get environment facts.

        power and fan are currently not implemented
        cpu is using 1-minute average
        cpu hard-coded to cpu0 (i.e. only a single CPU)
        """
        environment = {}
        cpu_cmd = "show proc cpu"
        mem_cmd = "show memory statistics"
        temp_cmd = "show env temperature status"

        output = self._send_command(cpu_cmd)
        environment.setdefault("cpu", {})
        environment["cpu"][0] = {}
        environment["cpu"][0]["%usage"] = 0.0
        for line in output.splitlines():
            if "CPU utilization" in line:
                # CPU utilization for five seconds: 2%/0%; one minute: 2%; five minutes: 1%
                cpu_regex = r"^.*one minute: (\d+)%; five.*$"
                match = re.search(cpu_regex, line)
                environment["cpu"][0]["%usage"] = float(match.group(1))
                break

        output = self._send_command(mem_cmd)
        for line in output.splitlines():
            if "Processor" in line:
                _, _, proc_total_mem, proc_used_mem, _ = line.split()[:5]
            elif "I/O" in line or "io" in line:
                _, _, io_total_mem, io_used_mem, _ = line.split()[:5]
        total_mem = int(proc_total_mem) + int(io_total_mem)
        used_mem = int(proc_used_mem) + int(io_used_mem)
        environment.setdefault("memory", {})
        environment["memory"]["used_ram"] = used_mem
        environment["memory"]["available_ram"] = total_mem

        environment.setdefault("temperature", {})
        re_temp_value = re.compile("(.*) Temperature Value")
        # The 'show env temperature status' is not ubiquitous in Cisco IOS
        output = self._send_command(temp_cmd)
        if "% Invalid" not in output:
            for line in output.splitlines():
                m = re_temp_value.match(line)
                if m is not None:
                    temp_name = m.group(1).lower()
                    temp_value = float(line.split(":")[1].split()[0])
                    env_value = {
                        "is_alert": False,
                        "is_critical": False,
                        "temperature": temp_value,
                    }
                    environment["temperature"][temp_name] = env_value
                elif "Yellow Threshold" in line:
                    system_temp_alert = float(line.split(":")[1].split()[0])
                    if temp_value > system_temp_alert:
                        env_value["is_alert"] = True
                elif "Red Threshold" in line:
                    system_temp_crit = float(line.split(":")[1].split()[0])
                    if temp_value > system_temp_crit:
                        env_value["is_critical"] = True
        else:
            env_value = {"is_alert": False, "is_critical": False, "temperature": -1.0}
            environment["temperature"]["invalid"] = env_value

        # Initialize 'power' and 'fan' to default values (not implemented)
        environment.setdefault("power", {})
        environment["power"]["invalid"] = {
            "status": True,
            "output": -1.0,
            "capacity": -1.0,
        }
        environment.setdefault("fans", {})
        environment["fans"]["invalid"] = {"status": True}

        return environment