From f40338c277925ca80a007466336592e57380e962 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Magiera?= <magik6k@gmail.com>
Date: Thu, 6 Jan 2022 18:02:34 +0100
Subject: [PATCH] paych: Better off-chain errors

---
 markets/retrievaladapter/client.go |  1 +
 paychmgr/simple.go                 | 13 ++++++++-----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/markets/retrievaladapter/client.go b/markets/retrievaladapter/client.go
index 60f41ca296d..97a157b19cd 100644
--- a/markets/retrievaladapter/client.go
+++ b/markets/retrievaladapter/client.go
@@ -70,6 +70,7 @@ func (rcn *retrievalClientNode) GetOrCreatePaymentChannel(ctx context.Context, c
 		OffChain: rcn.forceOffChain,
 	})
 	if err != nil {
+		log.Errorw("paych get failed", "error", err)
 		return address.Undef, cid.Undef, err
 	}
 	if ci.WaitSentinel == cid.Undef {
diff --git a/paychmgr/simple.go b/paychmgr/simple.go
index ffb13b6c233..ef0f81b8748 100644
--- a/paychmgr/simple.go
+++ b/paychmgr/simple.go
@@ -186,7 +186,10 @@ func (m *mergedFundsReq) completeAmount(avail types.BigInt, channelInfo *Channel
 				// can't fill, so OffChain want an error
 				if r.isActive() {
 					failed = types.BigAdd(failed, r.amt)
-					r.onComplete(&paychFundsRes{channel: *channelInfo.Channel, err: xerrors.Errorf("not enough available funds in the payment channel")})
+					r.onComplete(&paychFundsRes{
+						channel: *channelInfo.Channel,
+						err:     xerrors.Errorf("not enough funds available in the payment channel %s; add funds with 'lotus paych add-funds %s %s %s'", channelInfo.Channel, channelInfo.from(), channelInfo.to(), types.FIL(r.amt).Unitless()),
+					})
 				}
 				next = i + 1
 				continue
@@ -212,7 +215,7 @@ func (m *mergedFundsReq) completeAmount(avail types.BigInt, channelInfo *Channel
 	return nil, used, failed
 }
 
-func (m *mergedFundsReq) failOffChain(msg string) (*paychFundsRes, types.BigInt) {
+func (m *mergedFundsReq) failOffChainNoChannel(from, to address.Address) (*paychFundsRes, types.BigInt) {
 	next := 0
 	freed := types.NewInt(0)
 
@@ -225,13 +228,13 @@ func (m *mergedFundsReq) failOffChain(msg string) (*paychFundsRes, types.BigInt)
 		if !r.isActive() {
 			continue
 		}
-		r.onComplete(&paychFundsRes{err: xerrors.New(msg)})
+		r.onComplete(&paychFundsRes{err: xerrors.Errorf("payment channel doesn't exist, create with 'lotus paych add-funds %s %s %s'", from, to, types.FIL(r.amt).Unitless())})
 		next = i + 1
 	}
 
 	m.reqs = m.reqs[next:]
 	if len(m.reqs) == 0 {
-		return &paychFundsRes{err: xerrors.New(msg)}, freed
+		return &paychFundsRes{err: xerrors.Errorf("payment channel doesn't exist, create with 'lotus paych add-funds %s %s 0'", from, to)}, freed
 	}
 
 	return nil, freed
@@ -440,7 +443,7 @@ func (ca *channelAccessor) processTask(merged *mergedFundsReq, amt, avail types.
 
 	// If a channel has not yet been created, create one.
 	if channelInfo == nil {
-		res, freed := merged.failOffChain("payment channel doesn't exist")
+		res, freed := merged.failOffChainNoChannel(ca.from, ca.to)
 		if res != nil {
 			return res
 		}