#!/usr/bin/env python3

import boto3
import datetime
import decimal
import json
import urllib.request
import sys

AGE_THRESHOLD = datetime.timedelta(hours=1)
D = decimal.Decimal

SLACK_URL = 'https://hooks.slack.com/services/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'

# Class to minimize network chaos when getting pricing information
# from the 'pricing' API. Basically, this caches price information
# in a dict so that we do not have to look up the price for the same
# instance type over and over in a single region.
class Prices:
    # The 'pricing' API uses these ridiculous descriptive names
    # instead of the ubiquitous short names, and I have no idea
    # where to look up the mapping between them, it's so silly.
    region_map = {
            'us-east-2': 'US East (Ohio)',
            'us-east-1': 'US East (N. Virginia)',
            'us-west-1': 'US West (N. California)',
            'us-west-2': 'US West (Oregon)',
            'af-south-1': 'Africa (Cape Town)',
            'ap-east-1': 'Asia Pacific (Hong Kong)',
            'ap-south-1': 'Asia Pacific (Mumbai)',
            'ap-northeast-3': 'Asia Pacific (Osaka)',
            'ap-northeast-2': 'Asia Pacific (Seoul)',
            'ap-southeast-1': 'Asia Pacific (Singapore)',
            'ap-southeast-2': 'Asia Pacific (Sydney)',
            'ap-northeast-1': 'Asia Pacific (Tokyo)',
            'ca-central-1': 'Canada (Central)',
            'eu-central-1': 'Europe (Frankfurt)',
            'eu-west-1': 'Europe (Ireland)',
            'eu-west-2': 'Europe (London)',
            'eu-south-1': 'Europe (Milan)',
            'eu-west-3': 'Europe (Paris)',
            'eu-north-1': 'Europe (Stockholm)',
            'me-south-1': 'Middle East (Bahrain)',
            'sa-east-1': 'South America (São Paulo)',
            }
    prices={}
    def __init__(self, region):
        self.region = region
        self.region_name = self.region_map[region]
        self.pricing = boto3.client('pricing', region_name='us-east-1')
    def price(self, instance_type):
        if not instance_type in self.prices:
            try:
                p = self.pricing.get_products(
                        ServiceCode='AmazonEC2',
                        FormatVersion='aws_v1',
                        Filters=[
                            { 'Type':'TERM_MATCH', 'Field':'operatingSystem', 'Value':'Linux'},
                            { 'Type':'TERM_MATCH', 'Field':'operation', 'Value':'RunInstances'},
                            { 'Type':'TERM_MATCH', 'Field':'capacitystatus', 'Value':'Used'},
                            { 'Type':'TERM_MATCH', 'Field':'tenancy', 'Value':'Shared'},
                            { 'Type':'TERM_MATCH', 'Field':'location', 'Value':self.region_name},
                            { 'Type':'TERM_MATCH', 'Field':'instanceType', 'Value':instance_type},
                            ]
                        )
                if len(p['PriceList']) > 1:
                    print('Price lookup matched more than one item!')
                price_details = json.loads(p['PriceList'][0])['terms']['OnDemand']
                if len(price_details) > 1:
                    print('Price lookup matched more than one item!')
                    print(price_details.keys())
                for px in price_details:
                    product = price_details[px]
                for px in product['priceDimensions']:
                    price = product['priceDimensions'][px]['pricePerUnit']['USD']
                self.prices[instance_type] = D(price)
            except KeyError as e:
                print('Could not find region: {}'.format(e.__traceback__))
        return(self.prices[instance_type])

def run():
    ec2 = boto3.client('ec2', region_name='us-east-1')
    regions = ec2.describe_regions()

    instances = {}
    # for region in ['us-east-1', 'us-east-2', 'us-west-1', 'us-west-2']:
    for region in [r['RegionName'] for r in regions['Regions']]:
        p = Prices(region=region)
        print(region)
        e = boto3.client('ec2', region_name=region)
        reservations = e.describe_instances(
                Filters=[{
                    'Name':'instance-state-name',
                    'Values':['running']
                    }])
        for r in reservations['Reservations']:
            for i in r['Instances']:
                # Skip instances younger than age_threshold
                if datetime.datetime.now(datetime.timezone.utc) - i['LaunchTime'] < AGE_THRESHOLD:
                    continue
                if region not in instances:
                    instances[region] = []
                inst={
                        'id': i['InstanceId'],
                        'az': i['Placement']['AvailabilityZone'],
                        'time': i['LaunchTime'],
                        'type': i['InstanceType'],
                        'key': i.get('KeyName'),
                        'cost': p.price(i['InstanceType']),
                        }
                instances[region].append(inst)

    total_cost = D()

    message = {'blocks': [
        {'type': 'section', 'text': {'type': 'mrkdwn',
            'text': 'Cost report for public cloud instances running longer than {}.'.format(AGE_THRESHOLD)}},
        {'type': 'divider'},
        ]}

    region_costs = []
    for r in instances:
        cost = sum([inst['cost'] for inst in instances[r]])
        total_cost += cost
        region_costs.append('*{}*: ${}\n'.format(r, cost.quantize(D('1.01'))))

    region_costs.append('total: ${}\n'.format(total_cost.quantize(D('1.01'))))

    message['blocks'] += [
            {'type': 'header', 'text': {'type': 'plain_text', 'text': 'AWS', 'emoji': True}},
            {'type': 'section', 'text': {'type': 'mrkdwn',
                'text': '\n'.join(region_costs)}}
            ]

    print(json.dumps(message))

    urllib.request.urlopen(SLACK_URL, json.dumps(message).encode() )

if __name__ == '__main__':
    run()