get-leaders.py

from __future__ import print_function

import boto3
from boto3.dynamodb.conditions import Key, Attr
from decimal import *


# Helper for quering DynamoDB table
def dynamo_request(table_obj, request_dict):
    resp = table_obj.get_item(Key=request_dict)
    if resp.has_key('Item') and resp['Item']:
        return resp['Item']
    else:
        return None


# Helper for quering DynamoDB table
def dynamo_query(table_obj, key, value):
    resp = table_obj.query(KeyConditionExpression=Key(key).eq(value))
    if resp.has_key('Items') and resp['Items']:
        return resp['Items']
    else:
        return None


# Helper for put new item to DynamoDB table
def dynamo_put(table_obj, item_dict):
    try:
        resp = table_obj.put_item(Item=item_dict)
        if resp:
            if resp['ResponseMetadata']['HTTPStatusCode'] != 200:
                return None
    except:
        return None
    return True


# Helper for updating item in DynamoDB table
def dynamo_update(table_obj, request_dict, value_dict):
    resp = table_obj.get_item(Key=request_dict)
    if resp.has_key('Item') and resp['Item']:
        item = resp['Item']
        for key in value_dict.keys():
            item[key] = value_dict[key]
        try:
            resp = table_obj.put_item(Item=item)
            if resp:
                if resp['ResponseMetadata']['HTTPStatusCode'] != 200:
                    return None
        except:
            return None

    else:
        return None

    return True

# Constance for gamification
NEW_SQUARE = 10
NEW_POI = 20

# Constance for calculating of grid
LAT_SHIFT = Decimal("0.001")
LON_SHIFT = Decimal("0.0015")

NUM_LAT = 180 / LAT_SHIFT
NUM_LON = 360 / LON_SHIFT


# Function for calculating lower left corner of sqare as a Decimal
def calculate_sqare(lat, lon):
    grid_lat = ((Decimal(str(lat)) + 90) // LAT_SHIFT) * LAT_SHIFT - 90
    grid_lon = ((Decimal(str(lon)) + 180) // LON_SHIFT) * LON_SHIFT - 180
    return (grid_lat, grid_lon)


# Function for calculating id of the square
def calculate_id(grid_lat, grid_lon):
    return (grid_lat + 90) / LAT_SHIFT * NUM_LON + (grid_lon + 180) / LON_SHIFT


# Function for getting lat lon from square id
def calculate_grid(id):
    lat = (id // NUM_LON) * LAT_SHIFT - 90
    lon = (id % NUM_LON) * LON_SHIFT - 180
    return (lat, lon)


# Dummy function, in future filtration of abuse usage
def filter(user, square_id):
    return True


def lambda_handler(event, context):
    '''Provide an event that contains the following keys:

      - token: user token
      - id: user id
      - self: return user own data inside
    '''

    dyn_users = boto3.resource('dynamodb').Table('mapexplorer-users')

    user = dynamo_request(dyn_users, {'id': event['id']})
    if user:
        if user['token'] == event['token']:
            answer = []
            resp = dyn_users.query(
                IndexName='lastLocation-xp-index',
                ScanIndexForward=False,
                KeyConditionExpression=Key('lastLocation').eq(0) & Key('xp').gte(0))
            if resp.has_key('Items'):
                for i in resp['Items']:
                    rec = {'id': i['id'], 'name': i['name'], 'color': i['color'], 'xp': i['xp']}
                    answer.append(rec)
                return answer
            else:
                raise Exception("Bad Request: Error quering users data")
        else:
            raise Exception("Unauthorized: Wrong token")
    else:
        raise Exception("Not Found: User not found")