XL 2016 MFC Planning de Gant

Function Avancement(datecalcul As Range, deb As Date, fin As Date, horaire As Range, feries As Range) As Date
Dim t1 As Date, t2 As Date, t3 As Date, t4 As Date, jour1 As Date, jour2 As Date, dat&, t As Date
fin = IIf(datecalcul < fin, datecalcul, fin)
If fin < deb Then Exit Function
t1 = horaire(1): t2 = horaire(1, 2): jour1 = t2 - t1
t3 = horaire(2, 1): t4 = horaire(2, 2): jour2 = t4 - t3
If Int(deb) = Int(fin) Then
  If t1 < TimeValue(deb) Then t1 = TimeValue(deb)
  If t2 < t1 Then t2 = t1
  If t3 < TimeValue(deb) Then t3 = TimeValue(deb)
  If t4 < t3 Then t4 = t3
End If
For dat = Int(deb) To Int(fin)
  If Application.CountIf(feries, dat) = 0 And Weekday(dat, 2) < 6 Then
    If dat = Int(deb) And dat <> Int(fin) Then
      t = TimeValue(deb)
      If Weekday(dat, 2) < 5 Then
        If t <= t1 Then Avancement = Avancement + jour1
        If t > t1 And t < t2 Then Avancement = Avancement + t2 - t
      ElseIf Weekday(dat, 2) = 5 Then
        If t <= t3 Then Avancement = Avancement + jour2
        If t > t3 And t < t4 Then Avancement = Avancement + t4 - t
      End If
    ElseIf dat = Int(fin) Then
      t = TimeValue(fin)
      If Weekday(dat, 2) < 5 Then
        If t >= t2 Then Avancement = Avancement + t2 - t1
        If t > t1 And t < t2 Then Avancement = Avancement + t - t1
      ElseIf Weekday(dat, 2) = 5 Then
        If t >= t4 Then Avancement = Avancement + t4 - t3
        If t > t3 And t < t4 Then Avancement = Avancement + t - t3
      End If
    Else
      Avancement = Avancement + IIf(Weekday(dat, 2) < 5, jour1, jour2)
    End If
  End If
Next
End Function