From 6b68fa6771b5b854638dd5c66026ec3c30273313 Mon Sep 17 00:00:00 2001
From: Nitesh Balusu <niteshbalusu@icloud.com>
Date: Mon, 5 Aug 2024 11:35:35 -0400
Subject: [PATCH] add inbound fees support to getFeeRates

---
 lnd_methods/offchain/get_fee_rates.d.ts             | 12 ++++++++++++
 lnd_methods/offchain/get_fee_rates.js               |  2 ++
 lnd_responses/channel_edge_as_channel.js            |  2 ++
 lnd_responses/rpc_fees_as_channel_fees.js           |  4 ++++
 test/lnd_methods/offchain/test_get_fee_rates.js     |  2 ++
 test/lnd_responses/test_rpc_fees_as_channel_fees.js |  2 ++
 6 files changed, 24 insertions(+)

diff --git a/lnd_methods/offchain/get_fee_rates.d.ts b/lnd_methods/offchain/get_fee_rates.d.ts
index ae05c9c3..fa6755b4 100644
--- a/lnd_methods/offchain/get_fee_rates.d.ts
+++ b/lnd_methods/offchain/get_fee_rates.d.ts
@@ -11,6 +11,18 @@ export type GetFeeRatesResult = {
     fee_rate: number;
     /** Standard Format Channel Id */
     id: string;
+    /**
+    * Source Based Base Fee Reduction String
+    *
+    * Not supported on LND 0.17.5 and below
+    */
+    inbound_base_discount_mtokens: string;
+    /**
+    * Source Based Per Million Rate Reduction Number
+    *
+    * Not supported on LND 0.17.5 and below
+    */
+    inbound_rate_discount: number;
     /** Channel Funding Transaction Id Hex */
     transaction_id: string;
     /** Funding Outpoint Output Index */
diff --git a/lnd_methods/offchain/get_fee_rates.js b/lnd_methods/offchain/get_fee_rates.js
index a44f99da..8a854758 100644
--- a/lnd_methods/offchain/get_fee_rates.js
+++ b/lnd_methods/offchain/get_fee_rates.js
@@ -23,6 +23,8 @@ const type = 'default';
       base_fee_mtokens: <Base Flat Fee Millitokens String>
       fee_rate: <Fee Rate in Millitokens Per Million Number>
       id: <Standard Format Channel Id String>
+      inbound_base_discount_mtokens: <Source Based Base Fee Reduction String>
+      inbound_rate_discount: <Source Based Per Million Rate Reduction Number>
       transaction_id: <Channel Funding Transaction Id Hex String>
       transaction_vout: <Funding Outpoint Output Index Number>
     }]
diff --git a/lnd_responses/channel_edge_as_channel.js b/lnd_responses/channel_edge_as_channel.js
index ab0e9d04..7ef35e37 100644
--- a/lnd_responses/channel_edge_as_channel.js
+++ b/lnd_responses/channel_edge_as_channel.js
@@ -43,6 +43,8 @@ const separatorChar = ':';
       [base_fee_mtokens]: <Base Fee Millitokens String>
       [cltv_delta]: <Locktime Delta Number>
       [fee_rate]: <Fees Charged in Millitokens Per Million Number>
+      inbound_base_discount_mtokens: <Source Specific Base Fee Reduction String>
+      inbound_rate_discount: <Source Specific Per Million Rate Reduction Number>
       [is_disabled]: <Channel Is Disabled Bool>
       [max_htlc_mtokens]: <Maximum HTLC Millitokens Value String>
       [min_htlc_mtokens]: <Minimum HTLC Millitokens Value String>
diff --git a/lnd_responses/rpc_fees_as_channel_fees.js b/lnd_responses/rpc_fees_as_channel_fees.js
index 06f71cf1..c0391612 100644
--- a/lnd_responses/rpc_fees_as_channel_fees.js
+++ b/lnd_responses/rpc_fees_as_channel_fees.js
@@ -2,6 +2,8 @@ const {chanFormat} = require('bolt07');
 
 const {safeTokens} = require('./../bolt00');
 
+const discount = fee => (!fee ? 0 : -fee).toString();
+const inverse = rate => !rate ? 0 : -rate;
 const isHash = n => /^[0-9A-F]{64}$/i.test(n);
 const notFound = -1;
 const outpointDivider = ':';
@@ -61,6 +63,8 @@ module.exports = channel => {
     base_fee_mtokens: channel.base_fee_msat,
     fee_rate: Number(channel.fee_per_mil),
     id: chanFormat({number: channel.chan_id}).channel,
+    inbound_base_discount_mtokens: discount(channel.inbound_base_fee_msat),
+    inbound_rate_discount: inverse(channel.inbound_fee_per_mil),
     transaction_id: txId,
     transaction_vout: Number(index),
   };
diff --git a/test/lnd_methods/offchain/test_get_fee_rates.js b/test/lnd_methods/offchain/test_get_fee_rates.js
index dba5f3e0..55866273 100644
--- a/test/lnd_methods/offchain/test_get_fee_rates.js
+++ b/test/lnd_methods/offchain/test_get_fee_rates.js
@@ -56,6 +56,8 @@ const tests = [
         base_fee_mtokens: '0',
         fee_rate: 0,
         id: '0x0x1',
+        inbound_base_discount_mtokens: '0',
+        inbound_rate_discount: 0,
         transaction_id: Buffer.alloc(32).toString('hex'),
         transaction_vout: 0,
       }],
diff --git a/test/lnd_responses/test_rpc_fees_as_channel_fees.js b/test/lnd_responses/test_rpc_fees_as_channel_fees.js
index a0a0e7e2..385742d8 100644
--- a/test/lnd_responses/test_rpc_fees_as_channel_fees.js
+++ b/test/lnd_responses/test_rpc_fees_as_channel_fees.js
@@ -66,6 +66,8 @@ const tests = [
       base_fee_mtokens: '1',
       fee_rate: 0,
       id: '0x0x1',
+      inbound_base_discount_mtokens: '0',
+      inbound_rate_discount: 0,
       transaction_id: Buffer.alloc(32).toString('hex'),
       transaction_vout: 0,
     },