From f7b6471b13b73df43740347d1cd49ca55aec5acf Mon Sep 17 00:00:00 2001
From: DanB <danb@cgrates.org>
Date: Mon, 25 Jan 2021 18:02:55 +0100
Subject: [PATCH] AccountS - skel of abstractBalance.debitUsage

---
 accounts/abstractbalance.go | 40 +++++++++++++++++++++++++------------
 accounts/libaccounts.go     | 10 ++++++++++
 2 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/accounts/abstractbalance.go b/accounts/abstractbalance.go
index aaf799306..5aeadc8e1 100644
--- a/accounts/abstractbalance.go
+++ b/accounts/abstractbalance.go
@@ -234,28 +234,42 @@ func (aB *abstractBalance) debitUsage(usage *utils.Decimal, startTime time.Time,
 
 	// balance smaller than usage, correct usage
 	if aB.blnCfg.Units.Compare(usage) == -1 {
+		// decrease the usage to match the maximum increments
 		// will use special rounding to 0 since otherwise we go negative (ie: 0.05 as increment)
-		maxIncrm := decimal.WithContext(
-			decimal.Context{RoundingMode: decimal.ToZero}).Quo(aB.blnCfg.Units.Big,
-			costIcrm.Increment.Big).RoundToInt()
-		usage.Big = utils.MultiplyBig(maxIncrm, costIcrm.Increment.Big) // decrease the usage to match the maximum increments
+		usage.Big = roundedUsageWithIncrements(aB.blnCfg.Units.Big, costIcrm.Increment.Big)
 	}
 
 	// attempt to debit usage with cost
 	// fix the maximum number of iterations
+	usagePaid, usageDenied := new(decimal.Big), new(decimal.Big)
+	clnedUnts := cloneUnitsFromConcretes(aB.cncrtBlncs) // so we can revert during usage checks
 	for i := 0; i < 10000; i++ {
 		if err = aB.debitUsageFromConcrete(usage, costIcrm, cgrEv); err != nil {
-			if err == utils.ErrInsufficientCredit {
-				continue
+			if err != utils.ErrInsufficientCredit {
+				aB.blnCfg.Units.Big = origBlclVal
+				return
 			}
-			aB.blnCfg.Units.Big = origBlclVal
+			usageDenied = new(decimal.Big).Copy(usage.Big)
+			usage.Big = utils.DivideBig( // divide by 2
+				utils.SubstractBig(usageDenied, usagePaid),
+				decimal.New(2, 0)).RoundToInt()
+			usage.Big = roundedUsageWithIncrements(usage.Big, costIcrm.Increment.Big) // make sure usage is multiple of increments
+		}
+		if i == 0 { // no estimation done, covering full
+			return
+		}
+		usagePaid = new(decimal.Big).Copy(usage.Big)
+		usage.Big = utils.DivideBig( // divide by 2
+			utils.SubstractBig(usageDenied, usagePaid),
+			decimal.New(2, 0)).RoundToInt()
+		usage.Big = roundedUsageWithIncrements(usage.Big, costIcrm.Increment.Big)
+		if usage.Big.Cmp(usagePaid) <= 0 ||
+			usage.Big.Cmp(usageDenied) >= 0 {
 			return
 		}
-		continue
 	}
-
-	fmt.Printf("costIcrm: %+v, blncLmt: %+v, hasLmt: %+v, uF: %+v, origBlclVal: %s, hasUF: %v",
-		costIcrm, blncLmt, hasLmt, uF, origBlclVal, hasUF)
-
-	return
+	fmt.Printf("hasLmt: %v, hasUF: %v", hasLmt, hasUF)
+	restoreUnitsFromClones(aB.cncrtBlncs, clnedUnts) // since we are erroring, we restore the concerete balances
+	aB.blnCfg.Units.Big = origBlclVal
+	return nil, utils.ErrMaxIncrementsExceeded
 }
diff --git a/accounts/libaccounts.go b/accounts/libaccounts.go
index 5aff13618..ed3125f99 100644
--- a/accounts/libaccounts.go
+++ b/accounts/libaccounts.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/cgrates/cgrates/engine"
 	"github.com/cgrates/cgrates/utils"
+	"github.com/ericlagergren/decimal"
 )
 
 // newAccountBalances constructs accountBalances
@@ -93,3 +94,12 @@ type balanceOperator interface {
 	debitUsage(usage *utils.Decimal, startTime time.Time,
 		cgrEv *utils.CGREvent) (ec *utils.EventCharges, err error)
 }
+
+// roundUsageWithIncrements rounds the usage based on increments
+func roundedUsageWithIncrements(usage, incrm *decimal.Big) (rndedUsage *decimal.Big) {
+	usgMaxIncrm := decimal.WithContext(
+		decimal.Context{RoundingMode: decimal.ToZero}).Quo(usage,
+		incrm).RoundToInt()
+	rndedUsage = utils.MultiplyBig(usgMaxIncrm, incrm)
+	return
+}