EIP-15 AgeUSD: build exchange transactions

ergoplatform · Apr 13, 2022 · 1abb7ab · 1abb7ab
1 parent 7b77aba
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Showing 10 changed files with 597 additions and 74 deletions.
diff --git a/appkit/src/test/resources/mockwebserver/explorer_responses/ageusd/bankboxbytoken.json b/appkit/src/test/resources/mockwebserver/explorer_responses/ageusd/bankboxbytoken.json
@@ -0,0 +1,58 @@
+{
+  "items": [
+    {
+      "boxId": "2342c916b272d8ede91da7e00bd3029f41beaa742bc75af3976916600de64f98",
+      "transactionId": "4bfb000123026edec42cf7252206a3aaf0b089af80d992f461322d1e1ec107d3",
+      "blockId": "15f39c5e65a0cdba80d4d01d925e12eaac01fabb58127423c0d5b7919a604833",
+      "value": 1458253206733705,
+      "index": 0,
+      "globalIndex": 15490910,
+      "creationHeight": 727025,
+      "settlementHeight": 727027,
+      "ergoTree": "102a0400040004000e20011d3364de07e5a26f0c4eef0852cddb387039a921b7154ef3cab22c6eda887f0400040204020400040004020500050005c8010500050005feffffffffffffffff0105000580897a05000580897a040405c80104c0933805c00c0580a8d6b907050005c8010580dac40905000500040404040500050005a0060101050005a0060100040004000e20239c170b7e82f94e6b05416f14b8a2a57e0bfff0e3c93f4abbcd160b6a5b271ad801d601db6501fed1ec9591b172017300d821d602b27201730100d603938cb2db63087202730200017303d604b2a5730400d605c17204d606db6308a7d607b27206730500d6088c720702d609db63087204d60ab27209730600d60b8c720a02d60c947208720bd60db27206730700d60e8c720d02d60fb27209730800d6108c720f02d61194720e7210d612e4c6a70505d613e4c672040505d614e4c6a70405d615e4c672040405d616b2a5730900d617e4c672160405d61895720c730a7217d61995720c7217730bd61ac1a7d61be4c672160505d61c9de4c672020405730cd61da2a1721a9c7214721c730dd61e9572119ca1721c95937214730e730f9d721d72147218d801d61e99721a721d9c9593721e7310731195937212731273139d721e72127219d61f9d9c721e7e7314057315d6209c7215721cd6219591a3731673177318d62295937220731972219d9c7205731a7220edededed7203ededededed927205731b93c27204c2a7edec720c7211efed720c7211ed939a720872129a720b7213939a720e72149a72107215edededed939a721472187215939a721272197213939a721a721b7205927215731c927213731deded938c720f018c720d01938c720a018c720701938cb27209731e00018cb27206731f000193721b9a721e958f721f7320f0721f721f957211959172187321927222732273239591721973249072227221927222732572037326938cb2db6308b2a4732700732800017329",
+      "address": "MUbV38YgqHy7XbsoXWF5z7EZm524Ybdwe5p9WDrbhruZRtehkRPT92imXer2eTkjwPDfboa1pR3zb3deVKVq3H7Xt98qcTqLuSBSbHb7izzo5jphEpcnqyKJ2xhmpNPVvmtbdJNdvdopPrHHDBbAGGeW7XYTQwEeoRfosXzcDtiGgw97b2aqjTsNFmZk7khBEQywjYfmoDc9nUCJMZ3vbSspnYo3LarLe55mh2Np8MNJqUN9APA6XkhZCrTTDRZb1B4krgFY1sVMswg2ceqguZRvC9pqt3tUUxmSnB24N6dowfVJKhLXwHPbrkHViBv1AKAJTmEaQW2DN1fRmD9ypXxZk8GXmYtxTtrj3BiunQ4qzUCu1eGzxSREjpkFSi2ATLSSDqUwxtRz639sHM6Lav4axoJNPCHbY8pvuBKUxgnGRex8LEGM8DeEJwaJCaoy8dBw9Lz49nq5mSsXLeoC4xpTUmp47Bh7GAZtwkaNreCu74m9rcZ8Di4w1cmdsiK1NWuDh9pJ2Bv7u3EfcurHFVqCkT3P86JUbKnXeNxCypfrWsFuYNKYqmjsix82g9vWcGMmAcu5nagxD4iET86iE2tMMfZZ5vqZNvntQswJyQqv2Wc6MTh4jQx1q2qJZCQe4QdEK63meTGbZNNKMctHQbp3gRkZYNrBtxQyVtNLR8xEY8zGp85GeQKbb37vqLXxRpGiigAdMe3XZA4hhYPmAAU5hpSMYaRAjtvvMT3bNiHRACGrfjvSsEG9G2zY5in2YWz5X9zXQLGTYRsQ4uNFkYoQRCBdjNxGv6R58Xq74zCgt19TxYZ87gPWxkXpWwTaHogG1eps8WXt8QzwJ9rVx6Vu9a5GjtcGsQxHovWmYixgBU8X9fPNJ9UQhYyAWbjtRSuVBtDAmoV1gCBEPwnYVP5GCGhCocbwoYhZkZjFZy6ws4uxVLid3FxuvhWvQrVEDYp7WRvGXbNdCbcSXnbeTrPMey1WPaXX",
+      "assets": [
+        {
+          "tokenId": "03faf2cb329f2e90d6d23b58d91bbb6c046aa143261cc21f52fbe2824bfcbf04",
+          "index": 0,
+          "amount": 9999844128263,
+          "name": "SigUSD",
+          "decimals": 2,
+          "type": "EIP-004"
+        },
+        {
+          "tokenId": "003bd19d0187117f130b62e1bcab0939929ff5c7709f843c5c4dd158949285d0",
+          "index": 1,
+          "amount": 9998636056232,
+          "name": "SigRSV",
+          "decimals": 0,
+          "type": "EIP-004"
+        },
+        {
+          "tokenId": "7d672d1def471720ca5782fd6473e47e796d9ac0c138d9911346f118b2f6d9d9",
+          "index": 2,
+          "amount": 1,
+          "name": "SUSD Bank V2 NFT",
+          "decimals": 0,
+          "type": "EIP-004"
+        }
+      ],
+      "additionalRegisters": {
+        "R4": {
+          "serializedValue": "05f4a7d39401",
+          "sigmaType": "SLong",
+          "renderedValue": "155871738"
+        },
+        "R5": {
+          "serializedValue": "05b285e1940a",
+          "sigmaType": "SLong",
+          "renderedValue": "1363943769"
+        }
+      },
+      "spentTransactionId": null,
+      "mainChain": true
+    }
+  ],
+  "total": 1
+
+}
diff --git a/appkit/src/test/resources/mockwebserver/explorer_responses/ageusd/rateboxtoken.json b/appkit/src/test/resources/mockwebserver/explorer_responses/ageusd/rateboxtoken.json
@@ -0,0 +1,48 @@
+{
+
+  "items": [
+    {
+      "boxId": "390a8fe7875910ba2fa7d836235afa10b81e878ccac9c5d61b3a3a5ab879560b",
+      "transactionId": "33ad33a0f81af1422ce784b10900cba682bbbffb4ff4fad3db76d3c9592490cb",
+      "blockId": "093ee04f0c8249963baa1c382787e9b8696cdfd5528d749722e5c78b47871c0d",
+      "value": 3471500000,
+      "index": 0,
+      "globalIndex": 15493690,
+      "creationHeight": 727095,
+      "settlementHeight": 727097,
+      "ergoTree": "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",
+      "address": "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",
+      "assets": [
+        {
+          "tokenId": "011d3364de07e5a26f0c4eef0852cddb387039a921b7154ef3cab22c6eda887f",
+          "index": 0,
+          "amount": 1,
+          "name": "ERGUSD-NFT",
+          "decimals": 0,
+          "type": "EIP-004"
+        }
+      ],
+      "additionalRegisters": {
+        "R4": {
+          "serializedValue": "0584e19fdc01",
+          "sigmaType": "SLong",
+          "renderedValue": "230946882"
+        },
+        "R5": {
+          "serializedValue": "04fee058",
+          "sigmaType": "SInt",
+          "renderedValue": "727103"
+        },
+        "R6": {
+          "serializedValue": "0e20f7ef73c4a4ab91b84bb0a2905108d534114472ec057be3a57a9dfc9b1fbd85c1",
+          "sigmaType": "Coll[SByte]",
+          "renderedValue": "f7ef73c4a4ab91b84bb0a2905108d534114472ec057be3a57a9dfc9b1fbd85c1"
+        }
+      },
+      "spentTransactionId": null,
+      "mainChain": true
+    }
+  ],
+  "total": 1
+
+}
diff --git a/...est/resources/mockwebserver/explorer_responses/ageusd/response_boxesByAddressUnspent.json b/...est/resources/mockwebserver/explorer_responses/ageusd/response_boxesByAddressUnspent.json
@@ -0,0 +1,36 @@
+{
+  "items": [
+    {
+      "boxId": "976c21fbd859cca4113a0711706c33b3d1f1052958a0196d61480f4b950fdf91",
+      "transactionId": "093eb4a9a963d52a304cb0f8f8150775854a55bd59db8b797fc2ae4d525dba65",
+      "blockId": "54406fd13168c6be1f4306e5d7b896783c12223e043e7ef2cc189bc72e6ee39e",
+      "value": 40981000000,
+      "creationHeight": 130509,
+      "settlementHeight": 505913,
+      "ergoTree": "0008cd02472963123ce32c057907c7a7268bc09f45d9ca57819d3327b9e7497d7b1cc347",
+      "address": "9hHDQb26AjnJUXxcqriqY1mnhpLuUeC81C4pggtK7tupr92Ea1K",
+      "assets": [
+        {
+          "tokenId": "03faf2cb329f2e90d6d23b58d91bbb6c046aa143261cc21f52fbe2824bfcbf04",
+          "index": 0,
+          "amount": 1000,
+          "name": "SigUSD",
+          "decimals": 2,
+          "type": "EIP-004"
+        },
+        {
+          "tokenId": "003bd19d0187117f130b62e1bcab0939929ff5c7709f843c5c4dd158949285d0",
+          "index": 1,
+          "amount": 1000,
+          "name": "SigRSV",
+          "decimals": 0,
+          "type": "EIP-004"
+        }
+      ],
+      "additionalRegisters": {},
+      "spentTransactionId": null,
+      "mainChain": true
+    }
+  ],
+  "total": 1
+}
diff --git a/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_Box1.json b/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_Box1.json
@@ -0,0 +1,19 @@
+{
+  "boxId": "976c21fbd859cca4113a0711706c33b3d1f1052958a0196d61480f4b950fdf91",
+  "value": 40981000000,
+  "ergoTree": "0008cd036ba5cfbc03ea2471fdf02737f64dbcd58c34461a7ec1e586dcd713dacbf89a12",
+  "creationHeight": 130509,
+  "assets": [
+    {
+      "tokenId": "03faf2cb329f2e90d6d23b58d91bbb6c046aa143261cc21f52fbe2824bfcbf04",
+      "amount": 1000
+    },
+    {
+      "tokenId": "003bd19d0187117f130b62e1bcab0939929ff5c7709f843c5c4dd158949285d0",
+      "amount": 1000
+    }
+  ],
+  "additionalRegisters": {},
+  "transactionId": "c5710af17f5124a232a5ef731fdf94a493025334c2a7d5a79e9923210972b962",
+  "index": 2
+}
diff --git a/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_bankbox.json b/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_bankbox.json
@@ -0,0 +1,28 @@
+{
+
+  "boxId": "2342c916b272d8ede91da7e00bd3029f41beaa742bc75af3976916600de64f98",
+  "value": 1458253206733705,
+  "ergoTree": "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",
+  "assets": [
+    {
+      "tokenId": "03faf2cb329f2e90d6d23b58d91bbb6c046aa143261cc21f52fbe2824bfcbf04",
+      "amount": 9999844128263
+    },
+    {
+      "tokenId": "003bd19d0187117f130b62e1bcab0939929ff5c7709f843c5c4dd158949285d0",
+      "amount": 9998636056232
+    },
+    {
+      "tokenId": "7d672d1def471720ca5782fd6473e47e796d9ac0c138d9911346f118b2f6d9d9",
+      "amount": 1
+    }
+  ],
+  "creationHeight": 727025,
+  "additionalRegisters": {
+    "R4": "05f4a7d39401",
+    "R5": "05b285e1940a"
+  },
+  "transactionId": "4bfb000123026edec42cf7252206a3aaf0b089af80d992f461322d1e1ec107d3",
+  "index": 0
+
+}
diff --git a/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_ratebox.json b/appkit/src/test/resources/mockwebserver/node_responses/ageusd/response_ratebox.json
@@ -0,0 +1,21 @@
+{
+
+  "boxId": "390a8fe7875910ba2fa7d836235afa10b81e878ccac9c5d61b3a3a5ab879560b",
+  "value": 3471500000,
+  "ergoTree": "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",
+  "assets": [
+    {
+      "tokenId": "011d3364de07e5a26f0c4eef0852cddb387039a921b7154ef3cab22c6eda887f",
+      "amount": 1
+    }
+  ],
+  "creationHeight": 727095,
+  "additionalRegisters": {
+    "R4": "0584e19fdc01",
+    "R5": "04fee058",
+    "R6": "0e20f7ef73c4a4ab91b84bb0a2905108d534114472ec057be3a57a9dfc9b1fbd85c1"
+  },
+  "transactionId": "33ad33a0f81af1422ce784b10900cba682bbbffb4ff4fad3db76d3c9592490cb",
+  "index": 0
+
+}
diff --git a/appkit/src/test/scala/org/ergoplatform/appkit/AgeUsdBankSpec.scala b/appkit/src/test/scala/org/ergoplatform/appkit/AgeUsdBankSpec.scala
@@ -0,0 +1,180 @@
+package org.ergoplatform.appkit
+
+import org.ergoplatform.appkit.impl.{AgeUsdBank, AgeUsdExchangeTransactionBuilder}
+import org.ergoplatform.appkit.testing.AppkitTesting
+import org.scalatest.{Matchers, PropSpec}
+
+class AgeUsdBankSpec extends PropSpec with Matchers
+  with AppkitTesting
+  with HttpClientTesting {
+
+  property("Age USD calculation tests") {
+    val ageUsdBank = new AgeUsdBank(210526315, 160402193, 1375438973, 1477201069508651L)
+
+    ageUsdBank.getStableCoinPrice shouldBe 2105263
+    ageUsdBank.getReserveCoinPrice shouldBe 828471
+    ageUsdBank.getCurrentReserveRatio shouldBe 437
+  }
+
+  property("Age USD exchange tx tests") {
+    // Withdraw from bank
+    val ageUsdBank = new AgeUsdBank(230946882, 155871738, 1363943769, 1458253206733705L)
+    ageUsdBank.getCurrentReserveRatio shouldBe 405
+    ageUsdBank.getStableCoinPrice shouldBe 2309468
+
+    // redeem stable coin
+    testAgeUsdTransaction(ageUsdBank, { txBuilder: AgeUsdExchangeTransactionBuilder =>
+      txBuilder.buildStableCoinExchangeTransaction(100)
+    })
+
+    // mint stable coin
+    testAgeUsdTransaction(ageUsdBank, { txBuilder: AgeUsdExchangeTransactionBuilder =>
+      txBuilder.buildStableCoinExchangeTransaction(-100)
+    })
+
+    // redeem reserve coin
+    testAgeUsdTransaction(ageUsdBank, { txBuilder: AgeUsdExchangeTransactionBuilder =>
+      txBuilder.buildReserveCoinExchangeTransaction(1000)
+    })
+
+    // mint reserve coin
+    testAgeUsdTransaction(ageUsdBank, { txBuilder: AgeUsdExchangeTransactionBuilder =>
+      txBuilder.buildReserveCoinExchangeTransaction(-1000)
+    })
+  }
+
+  private def testAgeUsdTransaction(ageUsdBank: AgeUsdBank, action: AgeUsdExchangeTransactionBuilder => UnsignedTransaction) = {
+    val data = MockData(
+      Seq(
+        loadNodeResponse("ageusd/response_Box1.json"),
+        loadNodeResponse("ageusd/response_bankbox.json"),
+        loadNodeResponse("ageusd/response_ratebox.json")
+      ),
+      Seq(
+        loadExplorerResponse("ageusd/response_boxesByAddressUnspent.json"),
+        loadExplorerResponse("ageusd/bankboxbytoken.json"),
+        loadExplorerResponse("ageusd/rateboxtoken.json")
+      ))
+
+    val ergoClient = createMockedErgoClient(data)
+    val storage = SecretStorage.loadFrom("storage/E2.json")
+    storage.unlock("abc")
+
+    val unsignedTransaction = ergoClient.execute { ctx: BlockchainContext =>
+      action(ageUsdBank.getExchangeTransactionBuilder(BoxOperations.createForSender(storage.getAddressFor(NetworkType.MAINNET), ctx)))
+    }
+
+    unsignedTransaction.getDataInputs.size() shouldBe 1
+    unsignedTransaction.getOutputs.size() shouldBe 4
+    checkSmartContractRun(unsignedTransaction) shouldBe true
+    ergoClient.execute { ctx: BlockchainContext =>
+      ctx.newProverBuilder().withSecretStorage(storage).build().sign(unsignedTransaction)
+    }
+  }
+
+  def checkSmartContractRun(unsignedTransaction: UnsignedTransaction): Boolean = {
+    // this is the code for EIP-15, see https://github.com/ergoplatform/eips/blob/master/eip-0015.md
+    // it is not necessary to have this here as script signing above will reduce the ErgoTree
+    // and test. However, with having this here debugging is possible
+
+    val rateBox = unsignedTransaction.getDataInputs.get(0)
+    val bankBoxIn = unsignedTransaction.getInputs.get(0)
+    val bankBoxOut = unsignedTransaction.getOutputs.get(0)
+    val receiptBox = unsignedTransaction.getOutputs.get(1)
+    val rate = rateBox.getRegisters.get(0).getValue.asInstanceOf[Long] / 100
+
+    val scCircIn = bankBoxIn.getRegisters.get(0).getValue.asInstanceOf[Long]
+    val rcCircIn = bankBoxIn.getRegisters.get(1).getValue.asInstanceOf[Long]
+    val bcReserveIn = bankBoxIn.getValue
+
+    val scTokensIn = bankBoxIn.getTokens.get(0).getValue
+    val rcTokensIn = bankBoxIn.getTokens.get(1).getValue
+
+    val scCircOut = bankBoxOut.getRegisters.get(0).getValue.asInstanceOf[Long]
+    val rcCircOut = bankBoxOut.getRegisters.get(1).getValue.asInstanceOf[Long]
+    val bcReserveOut = bankBoxOut.getValue
+
+    val scTokensOut = bankBoxOut.getTokens.get(0).getValue
+    val rcTokensOut = bankBoxOut.getTokens.get(1).getValue
+
+    val totalScIn = scTokensIn + scCircIn
+    val totalScOut = scTokensOut + scCircOut
+
+    val totalRcIn = rcTokensIn + rcCircIn
+    val totalRcOut = rcTokensOut + rcCircOut
+
+    val rcExchange = rcTokensIn != rcTokensOut
+    val scExchange = scTokensIn != scTokensOut
+
+    val rcExchangeXorScExchange = (rcExchange || scExchange) && !(rcExchange && scExchange)
+
+    val circDelta = receiptBox.getRegisters.get(0).getValue.asInstanceOf[Long]
+    val bcReserveDelta = receiptBox.getRegisters.get(1).getValue.asInstanceOf[Long]
+
+    val rcCircDelta = if (rcExchange) circDelta else 0L
+    val scCircDelta = if (rcExchange) 0L else circDelta
+
+    val validDeltas = (scCircIn + scCircDelta == scCircOut) &&
+      (rcCircIn + rcCircDelta == rcCircOut) &&
+      (bcReserveIn + bcReserveDelta == bcReserveOut) &&
+      scCircOut >= 0 && rcCircOut >= 0
+
+    val coinsConserved = totalRcIn == totalRcOut && totalScIn == totalScOut
+
+    val tokenIdsConserved = bankBoxOut.getTokens.get(0).getId == bankBoxIn.getTokens.get(0).getId &&
+      bankBoxOut.getTokens.get(1).getId == bankBoxIn.getTokens.get(1).getId &&
+      bankBoxOut.getTokens.get(2).getId == bankBoxIn.getTokens.get(2).getId
+
+    val mandatoryRateConditions = true // simplified
+    val mandatoryBankConditions = bankBoxOut.getValue >= 0 &&
+      bankBoxOut.getErgoTree == bankBoxIn.getErgoTree &&
+      rcExchangeXorScExchange &&
+      coinsConserved &&
+      validDeltas &&
+      tokenIdsConserved
+
+    // exchange equations
+    val bcReserveNeededOut = scCircOut * rate
+    val bcReserveNeededIn = scCircIn * rate
+    val liabilitiesIn = Math.max(Math.min(bcReserveIn, bcReserveNeededIn), 0)
+    val maxReserveRatioPercent = AgeUsdBank.MAX_RESERVE_RATIO_PERCENT
+
+    val reserveRatioPercentOut = if (bcReserveNeededOut == 0) maxReserveRatioPercent else bcReserveOut * 100 / bcReserveNeededOut
+
+    val validReserveRatio = if (scExchange) {
+      if (scCircDelta > 0) {
+        reserveRatioPercentOut >= AgeUsdBank.MIN_RESERVE_RATIO_PERCENT
+      } else true
+    } else {
+      if (rcCircDelta > 0) {
+        reserveRatioPercentOut <= maxReserveRatioPercent
+      } else {
+        reserveRatioPercentOut >= AgeUsdBank.MIN_RESERVE_RATIO_PERCENT
+      }
+    }
+
+    val brDeltaExpected = if (scExchange) { // sc
+      val liableRate = if (scCircIn == 0) Long.MaxValue else liabilitiesIn / scCircIn
+      val scNominalPrice = Math.min(rate, liableRate)
+      scNominalPrice * scCircDelta
+    } else { // rc
+      val equityIn = bcReserveIn - liabilitiesIn
+      val equityRate = if (rcCircIn == 0) AgeUsdBank.RC_DEFAULT_PRICE else equityIn / rcCircIn
+      val rcNominalPrice = if (equityIn == 0) AgeUsdBank.RC_DEFAULT_PRICE else equityRate
+      rcNominalPrice * rcCircDelta
+    }
+
+    val fee = brDeltaExpected * AgeUsdBank.FEE_PERCENT / 100
+    val actualFee = if (fee < 0) {
+      -fee
+    } else fee
+
+    // actualFee is always positive, irrespective of brDeltaExpected
+    val brDeltaExpectedWithFee = brDeltaExpected + actualFee
+
+    mandatoryRateConditions &&
+      mandatoryBankConditions &&
+      bcReserveDelta == brDeltaExpectedWithFee &&
+      validReserveRatio
+  }
+}