Calculate Date and Time difference considering the weekends and workhours

Really appreciate the work y'all put in to get a working DAX solution. I turned it into a custom M function so that you can easily apply it to multiple columns without having a ton of duplication. Also fixed a couple of small bugs that were in the original DAX.

To use, just copy this into a new blank query and should work out of the box.

Of course you're free to change the start/end times (currently at 8am and 5pm) etc

(from, to) => let
    // utility functions
    dateWithSetTime = (dt, t) => DateTime.From(Date.ToText(Date.From(dt)) & " " & Time.ToText(t)),
    max2 = (first, second) => if first > second then first else second,
    min2 = (first, second) => if first < second then first else second,
    isBetween = (t, first, last) => t >= first and t <= last,
    isWeekend = (day) => Date.DayOfWeek(day) = 5 or Date.DayOfWeek(day) = 6,
    isWorkday = (day) => not isWeekend(day),
    numDaysBetween = (f, t) =>
        let
            start = Date.AddDays(Date.From(from), 1),
            length = Duration.Days(Date.From(to) - Date.From(from)) - 1,
            dates = List.Dates(start, length, #duration(1, 0, 0, 0)),
            workdays = List.Select(dates, each isWorkday(_))
        in
            List.Count(workdays),
    dur = (days) => Duration.From(days),
    
    // variables and initial setup 
    startTime = #time(8,0,0),
    endTime = #time(17,0,0),
    firstDayStartTime = dateWithSetTime(from, startTime),
    firstDayEndTime = dateWithSetTime(from, endTime),
    lastDayStartTime = dateWithSetTime(to, startTime),
    lastDayEndTime = dateWithSetTime(to, endTime),
    endsOnStartDay = Date.From(from) = Date.From(to),
    
    // get seconds for first, middle, and last days
    firstDaySeconds =
        // make sure that end date is after start date 
        if from > to then error "The start date is greater than the end date. Make sure that you passed the arguments in the right order." else
        // record 0 time if weekend, starts after day ends, or ends before day starts
        if isWeekend(Date.From(from)) or from > firstDayEndTime or to < firstDayStartTime
        then dur(0)
        else min2( to, firstDayEndTime ) - max2( from, firstDayStartTime ),
        
    middleDaysSeconds =
        if endsOnStartDay
        then dur(0)
        else (endTime - startTime) * numDaysBetween(from, to),
    
    lastDaysSeconds =
        // record 0 time if holiday, weekend, already counted, or ends before day starts 
        if isWeekend(Date.From(to)) or endsOnStartDay or to < lastDayStartTime 
        then dur(0)
        else min2(to, lastDayEndTime) - lastDayStartTime,
    
    totalSeconds = Duration.TotalSeconds(firstDaySeconds + middleDaysSeconds + lastDaysSeconds) 
in
    totalSeconds / 3600