import copy
import json

def process_template(template, parameters):
    new_template = copy.deepcopy(template)
    status = 'success'

    for name, resource in template['Resources'].items():
        if 'Count' in resource:
            #Get the number of times to multiply the resource
            count = new_template['Resources'][name].pop('Count')
            print("Found 'Count' property with value {} in '{}' resource....multiplying!".format(count,name))
            if isinstance(count, dict) and 'Ref' in count:
                count = int(parameters[count['Ref']])
                print('Count from ref: %i' % count)
            #Remove the original resource from the template but take a local copy of it
            resourceToMultiply = new_template['Resources'].pop(name)
            #Create a new block of the resource multiplied with names ending in the iterator and the placeholders substituted
            resourcesAfterMultiplication = multiply(name, resourceToMultiply, count)
            if not set(resourcesAfterMultiplication.keys()) & set(new_template['Resources'].keys()):
                new_template['Resources'].update(resourcesAfterMultiplication)
            else:
                status = 'failed'
                return status, template
        else:
            print("Did not find 'Count' property in '{}' resource....Nothing to do!".format(name))
    return status, new_template

def update_placeholder(resource_structure, iteration):
    #Convert the json into a string
    resourceString = json.dumps(resource_structure)
    #Count the number of times the placeholder is found in the string
    placeHolderCount = resourceString.count('%d')

    #If the placeholder is found then replace it
    if placeHolderCount > 0:
        print("Found {} occurrences of decimal placeholder in JSON, replacing with iterator value {}".format(placeHolderCount, iteration))
        #Make a list of the values that we will use to replace the decimal placeholders - the values will all be the same
        placeHolderReplacementValues = [iteration] * placeHolderCount
        #Replace the decimal placeholders using the list - the syntax below expands the list
        resourceString = resourceString % (*placeHolderReplacementValues,)
        #Convert the string back to json and return it
        return json.loads(resourceString)
    else:
        print("No occurences of decimal placeholder found in JSON, therefore nothing will be replaced")
        return resource_structure

def multiply(resource_name, resource_structure, count):
    resources = {}
    #Loop according to the number of times we want to multiply, creating a new resource each time
    for iteration in range(1, (count + 1)):
        print("Multiplying '{}', iteration count {}".format(resource_name,iteration))
        multipliedResourceStructure = update_placeholder(resource_structure,iteration)
        resources[resource_name+str(iteration)] = multipliedResourceStructure
    return resources


def handler(event, context):
    result = process_template(event['fragment'], event['templateParameterValues'])
    return {
        'requestId': event['requestId'],
        'status': result[0],
        'fragment': result[1],
    }