From fc9fdd313bc08a4f290780dfa1cf9133eddf3bf3 Mon Sep 17 00:00:00 2001
From: Markus Teich <markus.teich@stusta.mhn.de>
Date: Fri, 14 Oct 2016 05:50:27 +0200
Subject: [PATCH] make test_brandt ready for M+1st price auctions

---
 test_brandt.c | 74 ++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 61 insertions(+), 13 deletions(-)

diff --git a/test_brandt.c b/test_brandt.c
index ee53a0d..8a27748 100644
--- a/test_brandt.c
+++ b/test_brandt.c
@@ -28,6 +28,7 @@
 #include "crypto.h"
 #include "util.h"
 
+#define MIN(A, B) ((A) < (B) ? (A) : (B))
 
 struct msg {
 	uint16_t sender;
@@ -55,26 +56,73 @@ static struct testcase tcase;
 static struct BRANDT_Result *
 expected_outcome (uint16_t i)
 {
+	struct BRANDT_Result *ret = NULL;
 	int32_t              highest_bidder = -1;
 	int32_t              highest_bid = -1;
-	struct BRANDT_Result *ret;
+	int32_t              mpf_highest_bidder;
+	int32_t              mpf_highest_bid;
+	int32_t              prev_mpf_highest_bidder = -1;
+	uint16_t             winners = MIN (tcase.m, tcase.n);
+	uint16_t             cur_winner = 0;
 
-	for (uint16_t h = 0; h < tcase.n; h++)
+	if (0 == tcase.m)
 	{
-		if (tcase.bids[h] > highest_bid)
-		{
-			highest_bid = tcase.bids[h];
-			highest_bidder = h;
-		}
+		for (uint16_t h = 0; h < tcase.n; h++)
+			if (tcase.bids[h] > highest_bid)
+				highest_bid = tcase.bids[highest_bidder = h];
+
+		if (!tcase.outcome_public && !(i == highest_bidder || i == tcase.n))
+			return NULL;
+
+		ret = GNUNET_new (struct BRANDT_Result);
+		ret->bidder = highest_bidder;
+		ret->price = highest_bid;
+		ret->status = BRANDT_bidder_won;
+		return ret;
 	}
 
-	if (!tcase.outcome_public && !(i == highest_bidder || i == tcase.n))
-		return NULL;
+	/* find M+1st highest bidder to determine selling price */
+	for (uint16_t m = 0; m <= MIN (tcase.m, tcase.n - 1); m++)
+	{
+		for (uint16_t h = 0; h < tcase.n; h++)
+		{
+			mpf_highest_bidder = -1;
+			mpf_highest_bid = -1;
+			if (tcase.bids[h] > mpf_highest_bid &&
+			    (-1 == prev_mpf_highest_bidder ||
+			     tcase.bids[h] < tcase.bids[prev_mpf_highest_bidder] ||
+			     h > prev_mpf_highest_bidder))
+				mpf_highest_bid = tcase.bids[mpf_highest_bidder = h];
+		}
+		prev_mpf_highest_bidder = mpf_highest_bidder;
+	}
 
-	ret = GNUNET_new (struct BRANDT_Result);
-	ret->bidder = highest_bidder;
-	ret->price = highest_bid;
-	ret->status = BRANDT_bidder_won;
+	/* for simplicity always locate the big block if we need to report at
+	 * least one winner. with private outcome for losing bidders or winners
+	 * only none or one element will be used respectively. */
+	if (tcase.outcome_public || i == tcase.n ||
+	    tcase.bids[i] > mpf_highest_bid ||
+	    (tcase.bids[i] == mpf_highest_bid && i < mpf_highest_bidder))
+		ret = GNUNET_new_array (winners, struct BRANDT_Result);
+
+	/* report winners */
+	for (uint16_t h = 0; h < tcase.n; h++)
+	{
+		if (((tcase.bids[h] == mpf_highest_bid && h < mpf_highest_bidder) ||
+		     tcase.bids[h] > mpf_highest_bid) &&              /* h is a winner */
+		    (tcase.outcome_public || i == h || i == tcase.n)) /* needs report */
+		{
+			if (cur_winner >= winners)
+			{
+				weprintf ("got too many winners");
+				_exit (1);
+			}
+			ret[cur_winner].bidder = h;
+			ret[cur_winner].price = mpf_highest_bid;
+			ret[cur_winner].status = BRANDT_bidder_won;
+			cur_winner++;
+		}
+	}
 	return ret;
 }