rework discount calculation, #20613, #19173, #19354

1 files changed, 115 insertions, 81 deletions

diff --git a/FS/FS/part_pkg/discount_Mixin.pm b/FS/FS/part_pkg/discount_Mixin.pm
index abde93f8f..5de7d8ea5 100644
--- a/FS/FS/part_pkg/discount_Mixin.pm
+++ b/FS/FS/part_pkg/discount_Mixin.pm
@@ -28,11 +28,15 @@ sub calc_recur {
 
 =head METHODS
 
-=item calc_discount
+=item calc_discount CUST_PKG, SDATE, DETAILS_ARRAYREF, PARAM_HASHREF
 
-Takes all the arguments of calc_recur.  Calculates and returns  the amount 
-by which to reduce the recurring fee; also increments months used on the 
-discount.
+Takes all the arguments of calc_recur.  Calculates and returns the amount 
+by which to reduce the charge; also increments months used on the discount.
+
+If there is a setup fee, this will be called once with 'setup_charge' => the
+setup fee amount (and should return the discount to be applied to the setup
+charge, if any), and again without it (for the recurring fee discount). 
+PARAM_HASHREF carries over between the two invocations.
 
 =cut
 
@@ -40,9 +44,6 @@ sub calc_discount {
   my($self, $cust_pkg, $sdate, $details, $param ) = @_;
   my $conf = new FS::Conf;
 
-  my $br_permonth = $self->base_recur_permonth($cust_pkg, $sdate);
-  $br_permonth += $param->{'override_charges'} if $param->{'override_charges'};
-
   my $br = $self->base_recur($cust_pkg, $sdate);
   $br += $param->{'override_charges'} * ($cust_pkg->part_pkg->freq || 0) if $param->{'override_charges'};
 
@@ -83,52 +84,125 @@ sub calc_discount {
     my $discount_left;
     my $discount = $cust_pkg_discount->discount;
     #UI enforces one or the other (for now?  probably for good)
+    # $chg_months: the number of months we are charging recur for
+    # $months: $chg_months or the months left on the discount, whchever is less
+
+    my $chg_months = $cust_pkg->part_pkg->freq || 1;
+    if ( defined($param->{'months'}) ) { # then override
+      $chg_months = $param->{'months'};
+    }
+
+    my $months = $chg_months;
+    if ( $discount->months ) {
+      $months = min( $chg_months,
+                     $discount->months - $cust_pkg_discount->months_used );
+    }
+
+    # $amount is now the (estimated) discount amount on the recurring charge.
+    # if it's a percent discount, that's base recur * percentage.
+
     my $amount = 0;
-    $amount += $discount->amount
-        if $cust_pkg->pkgpart == $param->{'real_pkgpart'};
-    $amount += sprintf('%.2f', $discount->percent * $br_permonth / 100 ); # FIXME: should this use $br / $freq to avoid rounding errors?
-    my $chg_months = defined($param->{'months'}) ?
-                      $param->{'months'} :
-                      $cust_pkg->part_pkg->freq;
-
-    my $months = $discount->months
-    ? min( $chg_months,
-      $discount->months - $cust_pkg_discount->months_used )
-    : $chg_months;
 
     if (defined $param->{'setup_charge'}) {
+
+        # we are calculating the setup discount.
+        # if this discount doesn't apply to setup fees, skip it.
+        # if it's a percent discount, set $amount = percent * setup_charge.
+        # if it's a flat amount discount for one month:
+        # - if the discount amount > setup_charge, then set it to setup_charge,
+        #   and set 'discount_left_recur' to the difference.
+        # - otherwise set it to just the discount amount.
+        # if it's a flat amount discount for other than one month:
+        # - skip the discount. unsure, leaving it alone for now.
+
         next unless $discount->setup;
 
+        $months = 0; # never count a setup discount as a month of discount
+                     # (the recur discount in the same month should do it)
+
         if ( $discount->percent > 0 ) {
-            $amount = sprintf('%.2f', $discount->percent * $param->{'setup_charge'} / 100 );
-            $months = 1;
-        } elsif ( $discount->amount > 0 && $discount->months == 1) {
-            $discount_left = $param->{'setup_charge'} - $discount->amount;
-            $amount = $param->{'setup_charge'} if $discount_left < 0;
-            $amount = $discount->amount if $discount_left >= 0;
-            $months = 1;
-                
+            $amount = $discount->percent * $param->{'setup_charge'} / 100;
+        } elsif ( $discount->amount > 0 && ($discount->months || 0) == 1) {
+            # apply the discount amount, up to a maximum of the setup charge
+            $amount = min($discount->amount, $param->{'setup_charge'});
+            $discount_left = sprintf('%.2f', $discount->amount - $amount);
             # transfer remainder of discount, if any, to recur
-            $param->{'discount_left_recur'}{$discount->discountnum} = 
-                0 - $discount_left if $discount_left < 0;
+            $param->{'discount_left_recur'}{$discount->discountnum} = $discount_left;
         } else {
+          # I guess we don't allow multiple-month flat amount discounts to
+          # apply to setup?
             next; 
         }
-    } elsif ( defined $param->{'discount_left_recur'}{$discount->discountnum}
-              && $param->{'discount_left_recur'}{$discount->discountnum} > 0
-            ) {
-        # use up transferred remainder of discount from setup
+
+    } else {
+      
+      # we are calculating a recurring fee discount. estimate the recurring
+      # fee:
+      # XXX it would be more accurate for calc_recur to just _tell us_ what
+      # it's going to charge
+
+      my $recur_charge = $br * ($cust_pkg->quantity || 1) * $chg_months / $self->freq;
+      # round this, because the real recur charge is rounded
+      $recur_charge = sprintf('%.2f', $recur_charge);
+
+      # if it's a percentage discount, calculate it based on that estimate.
+      # otherwise use the flat amount.
+      
+      if ( $discount->percent > 0 ) {
+        $amount = $recur_charge * $discount->percent / 100;
+      } elsif ( $discount->amount > 0
+                and $cust_pkg->pkgpart == $param->{'real_pkgpart'} ) {
+        $amount = $discount->amount * $months;
+      }
+
+      if ( exists $param->{'discount_left_recur'}{$discount->discountnum} ) {
+        # there is a discount_left_recur entry for this discountnum, so this
+        # is the second (recur) pass on the discount.  use up transferred
+        # remainder of discount from setup.
+        #
+        # note that discount_left_recur can now be zero.
         $amount = $param->{'discount_left_recur'}{$discount->discountnum};
         $param->{'discount_left_recur'}{$discount->discountnum} = 0;
-        $months = 1;
-    } elsif (    $discount->setup
-              && $discount->months == 1
-              && $discount->amount > 0
-            ) {
-        next;
-    }
+        $months = 1; # XXX really? not $chg_months?
+      }
+      #elsif (    $discount->setup
+      #          && ($discount->months || 0) == 1
+      #          && $discount->amount > 0
+      #        ) {
+      #    next;
+      #
+      #    RT #11512: bugfix to prevent applying flat discount to both setup
+      #    and recur. The original implementation ignored discount_left_recur
+      #    if it was zero, so if the setup fee used up the entire flat 
+      #    discount, the recurring charge would get to use the entire flat
+      #    discount also. This bugfix was a kludge. Instead, we now allow
+      #    discount_left_recur to be zero in that case, and then the available
+      #    recur discount is zero. 
+      #}
+
+      # transfer remainder of discount, if any, to setup
+      # this is used when the recur phase wants to add a setup fee
+      # (prorate_defer_bill): the "discount_left_setup" amount will
+      # be subtracted in _make_lines.
+      if ( $discount->setup && $discount->amount > 0
+          && ($discount->months || 0) != 1
+         )
+      {
+        # $amount is no longer permonth at this point! correct. very good.
+        $discount_left = $amount - $recur_charge; # backward, as above
+        if ( $discount_left > 0 ) {
+          $amount = $recur_charge;
+          $param->{'discount_left_setup'}{$discount->discountnum} = 
+            0 - $discount_left;
+        }
+      }
 
-    if ( ! defined $param->{'setup_charge'} ) {
+      # cap the discount amount at the recur charge
+      $amount = min($amount, $recur_charge);
+
+      # if this is the base pkgpart, schedule increment_months_used to run at
+      # the end of billing. (addon packages haven't been calculated yet, so
+      # don't let the discount expire during the billing process. RT#17045.)
       if ( $cust_pkg->pkgpart == $param->{'real_pkgpart'} ) {
         push @{ $param->{precommit_hooks} }, sub {
           my $error = $cust_pkg_discount->increment_months_used($months);
@@ -136,62 +210,22 @@ sub calc_discount {
         };
       }
 
-      $amount = min($amount * $months, $br);
     }
 
     $amount = sprintf('%.2f', $amount + 0.00000001 ); #so 1.005 rounds to 1.01
 
     next unless $amount > 0;
 
-    # transfer remainder of discount, if any, to setup
-    if ( $discount->setup && $discount->amount > 0
-        && (!$discount->months || $discount->months != 1)
-        && !defined $param->{'setup_charge'}
-       )
-    {
-      $discount_left = $br_permonth - $amount; # FIXME: $amount is no longer permonth at this point!
-      if ( $discount_left < 0 ) {
-        $amount = $br_permonth; # FIXME: seems like this should *= $months
-        $param->{'discount_left_setup'}{$discount->discountnum} = 
-          0 - $discount_left;
-      }
-    }
-
     #record details in cust_bill_pkg_discount
     my $cust_bill_pkg_discount = new FS::cust_bill_pkg_discount {
       'pkgdiscountnum' => $cust_pkg_discount->pkgdiscountnum,
       'amount'         => $amount,
       'months'         => $months,
+      # XXX should have a 'setuprecur'
     };
     push @{ $param->{'discounts'} }, $cust_bill_pkg_discount;
     $tot_discount += $amount;
 
-    #add details on discount to invoice
-    # no longer! this is now done during rendering based on the existence
-    # of the cust_bill_pkg_discount record
-    #
-    #my $money_char = $conf->config('money_char') || '$';
-    #$months = sprintf('%.2f', $months) if $months =~ /\./;
-
-    #my $d = 'Includes ';
-    #my $format;
-
-    #if ( $months eq '1' ) {
-    #  $d .= "discount of $money_char$amount";
-    #  $d .= " each" if $cust_pkg->quantity > 1;
-    #  $format = 'Undiscounted amount: %s%.2f';
-    #} else {
-    #  $d .= 'setup ' if defined $param->{'setup_charge'};
-    #  $d .= 'discount of '. $discount->description_short;
-    #  $d .= " for $months months"
-    #    unless defined $param->{'setup_charge'};
-    #  $d .= ": $money_char$amount" if $discount->percent;
-    #  $format = 'Undiscounted monthly amount: %s%.2f';
-    #}
-
-    #push @$details, $d;
-    #push @$details, sprintf( $format, $money_char, $br_permonth );
-
   }
 
   sprintf('%.2f', $tot_discount);