#!/usr/bin/env python

import BaseHTTPServer
import SocketServer
import errno
import os
import signal
import socket
import json

PLUGIN_ID="prometheus"
PLUGIN_UNIX_SOCK = "/var/run/scope/plugins/" + PLUGIN_ID + ".sock"
METRIC_NAME="http_requests_per_second"
METRIC_LABEL="HTTP req/sec"

class Handler(BaseHTTPServer.BaseHTTPRequestHandler):
    def do_GET(self):
        # The logger requires a client_address, but unix sockets don't have
        # one, so we fake it.
        self.client_address = "-"

        # Get current timestamp in RFC3339
        date = datetime.datetime.utcnow()
        date = date.isoformat('T') + 'Z'

        # Generate our json body
        body = json.dumps({
            'Plugins': [
                {
                    'id': PLUGIN_ID,
                    'label': 'Prometheus data translator',
                    'description': 'Takes data from prometheus and puts it into scope',
                    'interfaces': ['reporter'],
                    'api_version': '1',
                }
            ],
            'Container': {
                'nodes': {
                    'abcd1234;<container>': {
                        'metrics': {
                            METRIC_NAME: {
                                'samples': [{
                                    'date': date,
                                    'value': float(1.0),
                                }]
                            }
                        }
                    }
                },
                'metric_templates': {
                    METRIC_NAME: {
                        'id':       METRIC_NAME,
                        'label':    METRIC_LABEL,
                        'priority': 0.1,
                    }
                }
            },
        })

        # Send the headers
        self.send_response(200)
        self.send_header('Content-type', 'application/json')
        self.send_header('Content-length', len(body))
        self.end_headers()

        # Send the body
        self.wfile.write(body)

def mkdir_p(path):
    try:
        os.makedirs(path)
    except OSError as exc:
        if exc.errno == errno.EEXIST and os.path.isdir(path):
            pass
        else:
            raise

def delete_socket_file():
    if os.path.exists(PLUGIN_UNIX_SOCK):
        os.remove(PLUGIN_UNIX_SOCK)

def sig_handler(b, a):
    delete_socket_file()
    exit(0)

def main():
    signal.signal(signal.SIGTERM, sig_handler)
    signal.signal(signal.SIGINT, sig_handler)

    mkdir_p(os.path.dirname(PLUGIN_UNIX_SOCK))
    delete_socket_file()
    server = SocketServer.UnixStreamServer(PLUGIN_UNIX_SOCK, Handler)
    try:
        server.serve_forever()
    except:
        delete_socket_file()
        raise

main()