Xdai/minimal base fee (#3576)

* Add Eip1559BaseFeeMinValue logic

* update int256

* update xdai chainspec

* chuck testa

* add min base fee test

* Revert "update xdai chainspec"

This reverts commit 842d958.

* Revert "chuck testa"

This reverts commit 69e1269.

# Conflicts:
#	src/Nethermind/Nethermind.Specs.Test/ChainSpecStyle/ChainSpecLoaderTests.cs

src/Nethermind/Nethermind.Core.Test/BlockHeaderTests.cs

@@ -114,10 +114,14 @@ public void Eip_1559_CalculateBaseFee_should_returns_zero_when_eip1559_not_enabl
         [TestCase(500, 0, 0, 200)]
         [TestCase(21, 23, 23, 21)]
         [TestCase(21, 23, 61, 300)]
-        public void Eip_1559_CalculateBaseFee(long gasTarget, long baseFee, long expectedBaseFee, long gasUsed)
+        [TestCase(500, 0, 10, 200, 10)]
+        [TestCase(100, 100, 88, 0, 80)]
+        [TestCase(100, 100, 110, 0, 110)]
+        public void Eip_1559_CalculateBaseFee(long gasTarget, long baseFee, long expectedBaseFee, long gasUsed, long? minimalBaseFee = null)
         {
             IReleaseSpec releaseSpec = Substitute.For<IReleaseSpec>();
             releaseSpec.IsEip1559Enabled.Returns(true);
+            releaseSpec.Eip1559BaseFeeMinValue.Returns((UInt256?)minimalBaseFee);
 
             BlockHeader blockHeader = Build.A.BlockHeader.TestObject;
             blockHeader.Number = 2001;

src/Nethermind/Nethermind.Core/BaseFeeCalculator.cs

@@ -15,6 +15,7 @@
 //  along with the Nethermind. If not, see <http://www.gnu.org/licenses/>.
 // 
 
+using System;
 using Nethermind.Core.Specs;
 using Nethermind.Int256;
 
@@ -59,6 +60,11 @@ public static UInt256 Calculate(BlockHeader parent, IReleaseSpec spec)
                 {
                     expectedBaseFee = Eip1559Constants.ForkBaseFee;
                 }
+
+                if (spec.Eip1559BaseFeeMinValue.HasValue)
+                {
+                    expectedBaseFee = UInt256.Max(expectedBaseFee, spec.Eip1559BaseFeeMinValue.Value);
+                }
             }
 
             return expectedBaseFee;

src/Nethermind/Nethermind.Core/Specs/IReleaseSpec.cs

@@ -330,5 +330,7 @@ public interface IReleaseSpec
         public bool BaseFeeEnabled => IsEip3198Enabled;
 
         public Address? Eip1559FeeCollector => null;
+
+        public UInt256? Eip1559BaseFeeMinValue => null;
     }
 }

src/Nethermind/Nethermind.Specs.Test/ChainSpecStyle/ChainSpecBasedSpecProviderTests.cs

@@ -22,6 +22,7 @@
 using FluentAssertions;
 using Nethermind.Core;
 using Nethermind.Core.Specs;
+using Nethermind.Int256;
 using Nethermind.Serialization.Json;
 using Nethermind.Specs.ChainSpecStyle;
 using Nethermind.Specs.Forks;
@@ -398,6 +399,8 @@ public void Eip_transitions_loaded_correctly()
                     Eip1559Transition = 15590L,
                     Eip1559FeeCollectorTransition = 15591L,
                     Eip1559FeeCollector = Address.SystemUser,
+                    Eip1559BaseFeeMinValueTransition = 15592L,
+                    Eip1559BaseFeeMinValue = UInt256.UInt128MaxValue,
                     Eip3198Transition = 31980L,
                     Eip3529Transition = 35290L,
                     Eip3541Transition = 35410L,
@@ -455,6 +458,7 @@ void TestTransitions(long blockNumber, Action<ReleaseSpec> changes)
             TestTransitions(13440L, r => { r.IsEip1344Enabled = true; });
             TestTransitions(15590L, r => { r.IsEip1559Enabled = true; });
             TestTransitions(15591L, r => { r.Eip1559FeeCollector = Address.SystemUser; });
+            TestTransitions(15592L, r => { r.Eip1559BaseFeeMinValue = UInt256.UInt128MaxValue; });
             TestTransitions(18840L, r => { r.IsEip1884Enabled = true; });
             TestTransitions(20280L, r => { r.IsEip2028Enabled = true; });
             TestTransitions(22000L, r => { r.IsEip2200Enabled = true; });

src/Nethermind/Nethermind.Specs/ChainSpecStyle/ChainParameters.cs

@@ -103,6 +103,16 @@ public class ChainParameters
         /// <summary>
         /// Optional, address where burnt EIP-1559 fees will go
         /// </summary>
-        public Address Eip1559FeeCollector { get; set; } 
+        public Address Eip1559FeeCollector { get; set; }
+
+        /// <summary>
+        /// Block from which EIP1559 base fee cannot drop below <see cref="Eip1559BaseFeeMinValue"/>
+        /// </summary>
+        public long? Eip1559BaseFeeMinValueTransition { get; set; }
+
+        /// <summary>
+        /// Optional, minimal value of EIP1559 base fee
+        /// </summary>
+        public UInt256? Eip1559BaseFeeMinValue { get; set; }
     }
 }

src/Nethermind/Nethermind.Specs/ChainSpecStyle/ChainSpecBasedSpecProvider.cs

@@ -141,7 +141,8 @@ private void BuildTransitions()
                 releaseSpec.IsEip3675Enabled = (_chainSpec.Parameters.Eip3675Transition ?? long.MaxValue) <= releaseStartBlock;
                 releaseSpec.ValidateChainId = (_chainSpec.Parameters.ValidateChainIdTransition ?? 0) <= releaseStartBlock; 
                 releaseSpec.ValidateReceipts = ((_chainSpec.Parameters.ValidateReceiptsTransition > 0) ? Math.Max(_chainSpec.Parameters.ValidateReceiptsTransition ?? 0, _chainSpec.Parameters.Eip658Transition ?? 0) : 0) <= releaseStartBlock;
-                releaseSpec.Eip1559FeeCollector = releaseSpec.IsEip1559Enabled && (_chainSpec.Parameters.Eip1559FeeCollectorTransition ?? long.MaxValue) <= releaseStartBlock ? _chainSpec.Parameters.Eip1559FeeCollector : null; 
+                releaseSpec.Eip1559FeeCollector = releaseSpec.IsEip1559Enabled && (_chainSpec.Parameters.Eip1559FeeCollectorTransition ?? long.MaxValue) <= releaseStartBlock ? _chainSpec.Parameters.Eip1559FeeCollector : null;
+                releaseSpec.Eip1559BaseFeeMinValue = releaseSpec.IsEip1559Enabled && (_chainSpec.Parameters.Eip1559BaseFeeMinValueTransition ?? long.MaxValue) <= releaseStartBlock ? _chainSpec.Parameters.Eip1559BaseFeeMinValue : null;
 
                 if (_chainSpec.Ethash != null)
                 {

src/Nethermind/Nethermind.Specs/ChainSpecStyle/ChainSpecLoader.cs

@@ -155,8 +155,9 @@ private void LoadParameters(ChainSpecJson chainSpecJson, ChainSpec chainSpec)
                 Eip1559BaseFeeMaxChangeDenominator = chainSpecJson.Params.Eip1559BaseFeeMaxChangeDenominator ??
                                                      Eip1559Constants.BaseFeeMaxChangeDenominator,
                 Eip1559FeeCollector = chainSpecJson.Params.Eip1559FeeCollector,
-                Eip1559FeeCollectorTransition = chainSpecJson.Params.Eip1559FeeCollectorTransition
-
+                Eip1559FeeCollectorTransition = chainSpecJson.Params.Eip1559FeeCollectorTransition,
+                Eip1559BaseFeeMinValueTransition = chainSpecJson.Params.Eip1559BaseFeeMinValueTransition,
+                Eip1559BaseFeeMinValue = chainSpecJson.Params.Eip1559BaseFeeMinValue,
             };
 
             chainSpec.Parameters.Eip152Transition ??= GetTransitionForExpectedPricing("blake2_f", "price.blake2_f.gas_per_round", 1);

src/Nethermind/Nethermind.Specs/ChainSpecStyle/Json/ChainSpecParamsJson.cs

@@ -134,5 +134,9 @@ internal class ChainSpecParamsJson
         public long? Eip1559FeeCollectorTransition { get; set; }
 
         public Address Eip1559FeeCollector { get; set; } 
+
+        public long? Eip1559BaseFeeMinValueTransition { get; set; }
+
+        public UInt256? Eip1559BaseFeeMinValue  { get; set; }
     }
 }

src/Nethermind/Nethermind.Specs/ReleaseSpec.cs

@@ -75,7 +75,7 @@ public class ReleaseSpec : IReleaseSpec
         public bool ValidateChainId { get; set; }
         public bool ValidateReceipts { get; set; }
         public long Eip1559TransitionBlock { get; set; }
-
         public Address Eip1559FeeCollector { get; set; }
+        public UInt256? Eip1559BaseFeeMinValue { get; set; }
     }
 }