#!/usr/bin/env python3

import os
import re
import sys
import boto3
import subprocess
from datetime import datetime


def main(sample_count=5):
    try:
        _, from_location, to_location, hostname = sys.argv
    except ValueError:
        print("usage: {} <this_location> <to_location> <hostname>".format(
            os.path.basename(sys.argv[0])))
        sys.exit(1)

    client = boto3.client("cloudwatch")
    now = datetime.now()

    patt = re.compile(
        "round-trip min/avg/max = "
        "(?P<min>[0-9]+\.[0-9]+)/(?P<avg>[0-9]+\.[0-9]+)/"
        "(?P<max>[0-9]+\.[0-9]+) (?P<unit>.*)")

    out = subprocess.run(
        ["ping", "-c", str(sample_count), hostname],
        stdout=subprocess.PIPE, stderr=subprocess.PIPE)

    # Prevent failing with an error if the ping fails
    match = patt.search(out.stdout.decode("us-ascii"))
    if not match:
        return 1

    val = match.groupdict()

    client.put_metric_data(
        Namespace="VPNLatency",
        MetricData=[
            {
                "MetricName": "PingRTT",
                "Dimensions": [
                    {
                        "Name": "From Location",
                        "Value": from_location,
                    },
                    {
                        "Name": "To Location",
                        "Value": to_location,
                    }
                ],
                "Timestamp": now,
                "StatisticValues": {
                    "SampleCount": sample_count,
                    "Sum": float(val["avg"]) * sample_count,
                    "Minimum": float(val["min"]),
                    "Maximum": float(val["max"]),
                },
                "Unit": "Milliseconds"
            },
            {
                "MetricName": "PingRTT",
                "Dimensions": [
                    {
                        "Name": "From Location",
                        "Value": from_location,
                    },
                ],
                "Timestamp": now,
                "StatisticValues": {
                    "SampleCount": sample_count,
                    "Sum": float(val["avg"]) * sample_count,
                    "Minimum": float(val["min"]),
                    "Maximum": float(val["max"]),
                },
                "Unit": "Milliseconds"
            },
            {
                "MetricName": "PingRTT",
                "Dimensions": [
                    {
                        "Name": "To Location",
                        "Value": to_location,
                    }
                ],
                "Timestamp": now,
                "StatisticValues": {
                    "SampleCount": sample_count,
                    "Sum": float(val["avg"]) * sample_count,
                    "Minimum": float(val["min"]),
                    "Maximum": float(val["max"]),
                },
                "Unit": "Milliseconds"
            },
        ]
    )

    return 0


if __name__ == "__main__":
    sys.exit(main())