From 4a5d71cca2297cfd98b5dd907df2fc355d0da297 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Sun, 22 May 2022 16:18:09 +0200
Subject: -implement reserve history DB logic

---
 src/exchangedb/exchange-0001-part.sql       | 58 ++++++++++++++++++++++++++++-
 src/exchangedb/plugin_exchangedb_postgres.c | 35 ++++++++++++++---
 2 files changed, 86 insertions(+), 7 deletions(-)

(limited to 'src/exchangedb')

diff --git a/src/exchangedb/exchange-0001-part.sql b/src/exchangedb/exchange-0001-part.sql
index d8855b011..a47a2aede 100644
--- a/src/exchangedb/exchange-0001-part.sql
+++ b/src/exchangedb/exchange-0001-part.sql
@@ -3429,11 +3429,65 @@ CREATE OR REPLACE FUNCTION exchange_do_history_request(
   IN in_history_fee_val INT8,
   IN in_history_fee_frac INT4,
   OUT out_balance_ok BOOLEAN,
-  OUT out_conflict BOOLEAN)
+  OUT out_idempotent BOOLEAN)
 LANGUAGE plpgsql
 AS $$
 BEGIN
-  -- FIXME
+
+  -- Insert and check for idempotency.
+  INSERT INTO history_requests
+  (reserve_pub
+  ,request_timestamp
+  ,reserve_sig
+  ,history_fee_val
+  ,history_fee_frac)
+  VALUES
+  (in_reserve_pub
+  ,in_request_timestamp
+  ,in_reserve_sig
+  ,in_history_fee_val
+  ,in_history_fee_frac)
+  ON CONFLICT DO NOTHING;
+
+  IF NOT FOUND
+  THEN
+    out_balance_ok=TRUE;
+    out_conflict=TRUE;
+    RETURN;
+  END IF;
+
+  out_conflict=FALSE;
+
+  -- Update reserve balance.
+  UPDATE reserves
+   SET
+    current_balance_frac=current_balance_frac-in_history_fee_frac
+       + CASE
+         WHEN reserve_frac < in_history_fee_frac
+         THEN 100000000
+         ELSE 0
+         END,
+    current_balance_val=current_balance_val-in_history_fee_val
+       - CASE
+         WHEN current_balance_frac < in_history_fee_frac
+         THEN 1
+         ELSE 0
+         END
+  WHERE
+    reserve_pub=in_reserve_pub
+    AND ( (current_balance_val > in_history_fee_val) OR
+          ( (current_balance_frac >= in_history_fee_frac) AND
+            (current_balance_val >= in_history_fee_val) ) );
+
+  IF NOT FOUND
+  THEN
+    -- Either reserve does not exist, or balance insufficient.
+    -- Both we treat the same here as balance insufficient.
+    out_balance_ok=FALSE;
+    RETURN;
+  END IF;
+
+  out_balance_ok=TRUE;
 END $$;
 
 
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c
index 7a908398d..5d84a2af4 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -3641,7 +3641,9 @@ prepare_statements (struct PostgresClosure *pg)
     /* Used in #postgres_insert_history_request() */
     GNUNET_PQ_make_prepare (
       "call_history_request",
-      "SELECT 1"
+      "SELECT"
+      "  out_balance_ok AS balance_ok"
+      " ,out_idempotent AS idempotent"
       " FROM exchange_do_history_request"
       "  ($1, $2, $3, $4, $5)",
       5),
@@ -14014,6 +14016,9 @@ postgres_do_account_merge (
  * @param reserve_sig signature affirming the request
  * @param request_timestamp when was the request made
  * @param history_fee how much should the @a reserve_pub be charged for the request
+ * @param[out] balance_ok set to TRUE if the reserve balance
+ *         was sufficient
+ * @param[out] idempotent set to TRUE if the request is already in the DB
  * @return transaction status code
  */
 static enum GNUNET_DB_QueryStatus
@@ -14021,11 +14026,31 @@ postgres_insert_history_request (
   void *cls,
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const struct TALER_ReserveSignatureP *reserve_sig,
-  struct GNUNET_TIME_Absolute request_timestamp,
-  const struct TALER_Amount *history)
+  struct GNUNET_TIME_Timestamp request_timestamp,
+  const struct TALER_Amount *history,
+  bool *balance_ok,
+  bool *idempotent)
 {
-  GNUNET_break (0); // FIXME
-  return GNUNET_DB_STATUS_HARD_ERROR;
+  struct PostgresClosure *pg = cls;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (reserve_pub),
+    GNUNET_PQ_query_param_auto_from_type (reserve_sig),
+    GNUNET_PQ_query_param_timestamp (&request_timestamp),
+    TALER_PQ_query_param_amount (history),
+    GNUNET_PQ_query_param_end
+  };
+  struct GNUNET_PQ_ResultSpec rs[] = {
+    GNUNET_PQ_result_spec_bool ("balance_ok",
+                                balance_ok),
+    GNUNET_PQ_result_spec_bool ("idempotent",
+                                idempotent),
+    GNUNET_PQ_result_spec_end
+  };
+
+  return GNUNET_PQ_eval_prepared_singleton_select (pg->conn,
+                                                   "call_history_request",
+                                                   params,
+                                                   rs);
 }
 
 
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