Get Number of Occurrences Based on Date Range and Set Days of Week - date

Question

I am trying to calculate the total number of events that would occur based on the following known parameters
start date
end date
Days of the week
frequency of weeks (every week, every 2 weeks, etc)
For example, based on the following example data:
05/01/2017
05/31/2017
1,4 (Sunday, Wednesday)
Every 2 weeks
I would have to calculate that this event would run four times (5/7, 5/10, 5/21, 5/24)
Below is the skeleton I have set up. I'm fully stumped on how to increment the current day in the loop based on the number of weeks have passed.
<cfset local.totalRuns = 0 />
<cfset local.startDate = '2017-05-01' />
<cfset local.endDate = '2017-05-31' />
<cfset local.totalDays = DateDiff("d", local.startDate, local.endDate) />
<cfset local.daysPerWeek = '1,4' />
<cfset local.recurrence = 2 />
<cfset local.currentLoop = 0 />
<cfset local.weeksToCount = local.recurrence * 2 />
<!--- Loop a day at a time --->
<cfloop from="#local.startDate#" to="#local.endDate#" index="local.thisDay" step="#createTimespan(1, 0, 0, 0)#">
<cfset local.currentDate = local.thisDay />
<!--- Loop over each allowed day of the current week and determine actual date --->
<cfloop list="#local.daysPerWeek#" index="local.currentDay">
<!--- if current date does not exceed the end date add increment (this current is incorrect) --->
<cfif DateDiff("d", local.currentDate, local.endDate) LTE 0>
<cfset local.totalRuns++ />
</cfif>
</cfloop>
<cfset local.currentLoop++ />
</cfloop>

Answer 1

This is a formatted comment. It shows the approach I would take.
set the recurrence count to 0
start looping through the list of valid days of the week (1,4) in this case
set the control date to the start date.
do something to set the control date to the earliest
date that matches the day of the week in this loop.
if the control date is greater than the end date, break out of the loop.
otherwise
add 1 to the recurrence count
set up a while loop that adds the specified number of weeks
to the control date, and repeats the check I just described
end looping through the list of valid days of the week (1,4) in this case