From 4cfe3ac7beb8fa8de59156e9ff97730b396c66ab Mon Sep 17 00:00:00 2001
From: Florian Dold <florian.dold@gmail.com>
Date: Sun, 27 Aug 2017 02:01:12 +0200
Subject: fix refund generation (hopefully)

---
 src/backenddb/plugin_merchantdb_postgres.c | 125 +++++++++++++++--------------
 1 file changed, 64 insertions(+), 61 deletions(-)

(limited to 'src/backenddb/plugin_merchantdb_postgres.c')

diff --git a/src/backenddb/plugin_merchantdb_postgres.c b/src/backenddb/plugin_merchantdb_postgres.c
index 443d5276..c19602a5 100644
--- a/src/backenddb/plugin_merchantdb_postgres.c
+++ b/src/backenddb/plugin_merchantdb_postgres.c
@@ -2104,22 +2104,23 @@ process_deposits_for_refund_cb (void *cls,
 				unsigned int num_results)
 {
   struct InsertRefundContext *ctx = cls;
-  struct TALER_Amount previous_refund;
+  struct TALER_Amount current_refund;
+  struct TALER_Amount deposit_refund[num_results];
+  struct TALER_CoinSpendPublicKeyP deposit_coin_pubs[num_results];
+  struct TALER_Amount deposit_amount_with_fee[num_results];
+  struct TALER_Amount deposit_refund_fee[num_results];
 
   TALER_amount_get_zero (ctx->refund->currency,
-                         &previous_refund);
+                         &current_refund);
 
-  for (unsigned int i=0;i<num_results;i++)
+  /* Pass 1:  Collect amount of existing refunds into current_refund.
+   * Also store existing refunded amount for each deposit in deposit_refund. */
+
+  for (unsigned int i=0; i<num_results; i++)
   {
     struct TALER_CoinSpendPublicKeyP coin_pub;
     struct TALER_Amount amount_with_fee;
     struct TALER_Amount refund_fee;
-    struct FindRefundContext ictx;
-    enum GNUNET_DB_QueryStatus ires;
-    struct GNUNET_PQ_QueryParam params[] = {
-      GNUNET_PQ_query_param_auto_from_type (&coin_pub),
-      GNUNET_PQ_query_param_end
-    };
     struct GNUNET_PQ_ResultSpec rs[] = {
       GNUNET_PQ_result_spec_auto_from_type ("coin_pub",
                                             &coin_pub),
@@ -2129,9 +2130,6 @@ process_deposits_for_refund_cb (void *cls,
                                    &refund_fee),
       GNUNET_PQ_result_spec_end
     };
-    struct TALER_Amount left;
-    struct TALER_Amount remaining_refund;
-    const struct TALER_Amount *increment;
 
     if (GNUNET_OK !=
         GNUNET_PQ_extract_result (result,
@@ -2143,11 +2141,14 @@ process_deposits_for_refund_cb (void *cls,
       return;
     }
 
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                "Processing refund for coin %s, deposit value was %s\n",
-                TALER_B2S (&coin_pub),
-                TALER_amount2s (&amount_with_fee));
-    TALER_amount_get_zero (amount_with_fee.currency,
+    struct FindRefundContext ictx;
+    enum GNUNET_DB_QueryStatus ires;
+    struct GNUNET_PQ_QueryParam params[] = {
+      GNUNET_PQ_query_param_auto_from_type (&coin_pub),
+      GNUNET_PQ_query_param_end
+    };
+
+    TALER_amount_get_zero (ctx->refund->currency,
                            &ictx.refunded_amount);
     ictx.err = GNUNET_OK; /* no error so far */
     ires = GNUNET_PQ_eval_prepared_multi_select (ctx->pg->conn,
@@ -2167,39 +2168,47 @@ process_deposits_for_refund_cb (void *cls,
       ctx->qs = GNUNET_DB_STATUS_SOFT_ERROR;
       return;
     }
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                "Processing refund for coin %s total up to %s\n",
-                TALER_B2S (&coin_pub),
-                TALER_amount2s (&ictx.refunded_amount));
-    
-    /**
-     * Sum coin's contribution for refunding to the total (previously
-     * awarded) refund.  If this value will exceed the current awarded
-     * refund, we'll return #GNUNET_DB_STATUS_SUCCESS_NO_RESULTS.
-     */
+    deposit_refund[i] = ictx.refunded_amount;
+    deposit_amount_with_fee[i] = amount_with_fee;
+    deposit_coin_pubs[i] = coin_pub;
+    deposit_refund_fee[i] = refund_fee;
     if (GNUNET_SYSERR ==
-	TALER_amount_add (&previous_refund,
-			  &previous_refund,
+	TALER_amount_add (&current_refund,
+			  &current_refund,
 			  &ictx.refunded_amount))
     {
       GNUNET_break (0);
       ctx->qs = GNUNET_DB_STATUS_HARD_ERROR;
       return;
     }
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Existing refund for coin %s is %s\n",
+                TALER_B2S (&coin_pub),
+                TALER_amount2s (&ictx.refunded_amount));
+  }
 
-    if (0 >= TALER_amount_cmp (ctx->refund,
-			       &previous_refund))
-    {
-      /* refund <= refunded_amount; nothing to do! */ 
-      ctx->qs = GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
-      return;
-    }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Total existing refund is %s\n",
+              TALER_amount2s (&current_refund));
+
+  /* stop immediately if we are done */
+  if (0 == TALER_amount_cmp (ctx->refund,
+                             &current_refund))
+    return;
+
+
+  /* Phase 2:  Try to increase current refund until it matches desired refund */
+
+  for (unsigned int i=0; i<num_results; i++)
+  {
+    const struct TALER_Amount *increment;
+    struct TALER_Amount left;
 
     /* How much of the coin is left after the existing refunds? */
     if (GNUNET_SYSERR ==
 	TALER_amount_subtract (&left, 
-			       &amount_with_fee,
-			       &ictx.refunded_amount))
+			       &deposit_amount_with_fee[i],
+			       &deposit_refund[i]))
     {
       GNUNET_break (0);
       ctx->qs = GNUNET_DB_STATUS_HARD_ERROR;
@@ -2212,15 +2221,17 @@ process_deposits_for_refund_cb (void *cls,
       /* coin was fully refunded, move to next coin */
       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 		  "Coin %s fully refunded, moving to next coin\n",
-		  TALER_B2S (&coin_pub));
+		  TALER_B2S (&deposit_coin_pubs[i]));
       continue;
     }
 
+    struct TALER_Amount remaining_refund;
+
     /* How much of the refund is left? */
     if (GNUNET_SYSERR ==
 	TALER_amount_subtract (&remaining_refund, 
 			       ctx->refund,
-			       &previous_refund))
+			       &current_refund))
     {
       GNUNET_break (0);
       ctx->qs = GNUNET_DB_STATUS_HARD_ERROR;
@@ -2240,8 +2251,8 @@ process_deposits_for_refund_cb (void *cls,
     }
     
     if (GNUNET_SYSERR ==
-	TALER_amount_add (&previous_refund,
-			  &previous_refund,
+	TALER_amount_add (&current_refund,
+			  &current_refund,
 			  increment))
     {
       GNUNET_break (0);
@@ -2249,21 +2260,14 @@ process_deposits_for_refund_cb (void *cls,
       return;
     }
     
-    /* Subtract from refund what has already been awarded */
-    if (GNUNET_SYSERR ==
-	TALER_amount_subtract (&remaining_refund,
-			       ctx->refund,
-			       &ictx.refunded_amount))
-    {
-      GNUNET_break (0);
-      ctx->qs = GNUNET_DB_STATUS_HARD_ERROR;
-      return;
-    }
-
     /* actually run the refund */
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+		"Coin %s deposit amount is %s\n",
+		TALER_B2S (&deposit_coin_pubs[i]),
+		TALER_amount2s (&deposit_amount_with_fee[i]));
     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 		"Coin %s refund will be incremented by %s\n",
-		TALER_B2S (&coin_pub),
+		TALER_B2S (&deposit_coin_pubs[i]),
 		TALER_amount2s (increment));
     {
       enum GNUNET_DB_QueryStatus qs;
@@ -2272,21 +2276,20 @@ process_deposits_for_refund_cb (void *cls,
 	  (qs = insert_refund (ctx->pg,
 			       ctx->merchant_pub,
 			       ctx->h_contract_terms,
-			       &coin_pub,
+			       &deposit_coin_pubs[i],
 			       ctx->reason,
 			       increment,
-			       &refund_fee)))
+			       &deposit_refund_fee[i])))
       {
 	GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
 	ctx->qs = qs;
 	return;    
       }
-      
-      /* stop immediately if we are done */
-      if (0 == TALER_amount_cmp (ctx->refund,
-				 &previous_refund))
-	return;
     }
+    /* stop immediately if we are done */
+    if (0 == TALER_amount_cmp (ctx->refund,
+                               &current_refund))
+      return;
   }
 
   /**
-- 
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