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abis/ERC20.json

@@ -0,0 +1,222 @@
+[
+    {
+        "constant": true,
+        "inputs": [],
+        "name": "name",
+        "outputs": [
+            {
+                "name": "",
+                "type": "string"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "constant": false,
+        "inputs": [
+            {
+                "name": "_spender",
+                "type": "address"
+            },
+            {
+                "name": "_value",
+                "type": "uint256"
+            }
+        ],
+        "name": "approve",
+        "outputs": [
+            {
+                "name": "",
+                "type": "bool"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "nonpayable",
+        "type": "function"
+    },
+    {
+        "constant": true,
+        "inputs": [],
+        "name": "totalSupply",
+        "outputs": [
+            {
+                "name": "",
+                "type": "uint256"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "constant": false,
+        "inputs": [
+            {
+                "name": "_from",
+                "type": "address"
+            },
+            {
+                "name": "_to",
+                "type": "address"
+            },
+            {
+                "name": "_value",
+                "type": "uint256"
+            }
+        ],
+        "name": "transferFrom",
+        "outputs": [
+            {
+                "name": "",
+                "type": "bool"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "nonpayable",
+        "type": "function"
+    },
+    {
+        "constant": true,
+        "inputs": [],
+        "name": "decimals",
+        "outputs": [
+            {
+                "name": "",
+                "type": "uint8"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "constant": true,
+        "inputs": [
+            {
+                "name": "_owner",
+                "type": "address"
+            }
+        ],
+        "name": "balanceOf",
+        "outputs": [
+            {
+                "name": "balance",
+                "type": "uint256"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "constant": true,
+        "inputs": [],
+        "name": "symbol",
+        "outputs": [
+            {
+                "name": "",
+                "type": "string"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "constant": false,
+        "inputs": [
+            {
+                "name": "_to",
+                "type": "address"
+            },
+            {
+                "name": "_value",
+                "type": "uint256"
+            }
+        ],
+        "name": "transfer",
+        "outputs": [
+            {
+                "name": "",
+                "type": "bool"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "nonpayable",
+        "type": "function"
+    },
+    {
+        "constant": true,
+        "inputs": [
+            {
+                "name": "_owner",
+                "type": "address"
+            },
+            {
+                "name": "_spender",
+                "type": "address"
+            }
+        ],
+        "name": "allowance",
+        "outputs": [
+            {
+                "name": "",
+                "type": "uint256"
+            }
+        ],
+        "payable": false,
+        "stateMutability": "view",
+        "type": "function"
+    },
+    {
+        "payable": true,
+        "stateMutability": "payable",
+        "type": "fallback"
+    },
+    {
+        "anonymous": false,
+        "inputs": [
+            {
+                "indexed": true,
+                "name": "owner",
+                "type": "address"
+            },
+            {
+                "indexed": true,
+                "name": "spender",
+                "type": "address"
+            },
+            {
+                "indexed": false,
+                "name": "value",
+                "type": "uint256"
+            }
+        ],
+        "name": "Approval",
+        "type": "event"
+    },
+    {
+        "anonymous": false,
+        "inputs": [
+            {
+                "indexed": true,
+                "name": "from",
+                "type": "address"
+            },
+            {
+                "indexed": true,
+                "name": "to",
+                "type": "address"
+            },
+            {
+                "indexed": false,
+                "name": "value",
+                "type": "uint256"
+            }
+        ],
+        "name": "Transfer",
+        "type": "event"
+    }
+]

schema.graphql

@@ -15,3 +15,22 @@ type ProxyUpdated @entity(immutable: true) {
   blockTimestamp: BigInt!
   transactionHash: Bytes!
 }
+
+type Token @entity {
+  id: ID!
+  name: String!
+  symbol: String!
+  decimals: BigDecimal!
+}
+
+type Account @entity {
+  id: ID!
+  balances: [TokenBalance!]! @derivedFrom(field: "account")
+}
+
+type TokenBalance @entity {
+  id: ID!
+  token: Token!
+  account: Account!
+  amount: BigDecimal!
+}

src/erc-20.ts

@@ -0,0 +1,41 @@
+import { Transfer } from "../generated/SEED-ERC20/ERC20"
+import { TokenBalance } from "../generated/schema"
+import {
+  fetchTokenDetails,
+  fetchAccount,
+  fetchBalance
+} from "./utils"
+import { BigDecimal } from "@graphprotocol/graph-ts"
+
+export function handleTransfer(event: Transfer): void {
+  let token = fetchTokenDetails(event)
+  if(!token) return
+
+  let fromAddress = event.params.from.toHex()
+  let toAddress = event.params.to.toHex()
+
+  let fromAccount = fetchAccount(fromAddress)
+  let toAccount = fetchAccount(toAddress)
+
+  let fromTokenBalance = TokenBalance.load(token.id + "-" + fromAccount.id)
+  if (!fromTokenBalance) {
+    fromTokenBalance = new TokenBalance(token.id + "-" + fromAccount.id)
+    fromTokenBalance.token = token.id
+    fromTokenBalance.account = fromAccount.id
+  }
+  fromTokenBalance.amount = fetchBalance(event.address, event.params.from)
+  if(fromTokenBalance.amount != BigDecimal.zero()) {
+    fromTokenBalance.save()
+  }
+
+  let toTokenBalance = TokenBalance.load(token.id + "-" + toAccount.id)
+  if (!toTokenBalance) {
+    toTokenBalance = new TokenBalance(token.id + "-" + toAccount.id)
+    toTokenBalance.token = token.id
+    toTokenBalance.account = toAccount.id
+  }
+  toTokenBalance.amount = fetchBalance(event.address, event.params.to)
+  if (toTokenBalance.amount != BigDecimal.zero()) {
+    toTokenBalance.save()
+  }
+}

src/utils.ts

@@ -0,0 +1,56 @@
+import { ERC20 } from "../generated/SEED-ERC20/ERC20"
+import { Account, Token } from "../generated/schema"
+import { BigDecimal, ethereum, Address } from "@graphprotocol/graph-ts"
+
+export function fetchTokenDetails(event: ethereum.Event): Token | null {
+  let token = Token.load(event.address.toHex())
+  if (!token) {
+    token = new Token(event.address.toHex())
+
+    token.name = "Uɴᴋɴᴏᴡɴ"
+    token.symbol = "𝑈𝑛𝑘𝑛𝑜𝑤𝑛"
+    token.decimals = BigDecimal.zero()
+
+    let erc20 = ERC20.bind(event.address)
+
+    let tokenName = erc20.try_name()
+    if (!tokenName.reverted) {
+      token.name = tokenName.value
+    }
+
+    let tokenSymbol = erc20.try_symbol()
+    if (!tokenSymbol.reverted) {
+      token.symbol = tokenSymbol.value
+    }
+
+    let tokenDecimal = erc20.try_decimals()
+    if (!tokenDecimal.reverted) {
+      token.decimals = BigDecimal.fromString(tokenDecimal.value.toString())
+    }
+
+    token.save()
+  }
+  return token
+}
+
+export function fetchAccount(address: string): Account {
+  let account = Account.load(address)
+  if (!account) {
+    account = new Account(address)
+    account.save()
+  }
+  if(!account) throw new Error(`Failed to fetch account: "${address}".`)
+  return account
+}
+
+export function fetchBalance(
+  tokenAddress: Address,
+  accountAddress: Address
+): BigDecimal {
+  let erc20 = ERC20.bind(tokenAddress)
+  let tokenBalance = erc20.try_balanceOf(accountAddress)
+  if(tokenBalance.reverted) {
+    throw new Error(`Failed to fetch balance: "${tokenBalance.reverted.toString()}".`)
+  }
+  return tokenBalance.value.toBigDecimal()
+}