03. Persiapan ABI & Konfigurasi Kontrak RWA

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Pada modul sebelumnya, antarmuka visual RWA kita masih ditenagai oleh dummy data. Agar antarmuka React dapat berkomunikasi langsung dengan smart contract FractionalProperty.sol di Arbitrum Sepolia, kita memerlukan dua hal fundamental:

1. Alamat Kontrak (PROPERTY_CONTRACT_ADDRESS): Alamat unik smart contract properti Anda di jaringan Arbitrum Sepolia.
2. ABI (Application Binary Interface): "Buku petunjuk" berformat JSON yang mendeskripsikan fungsi, tipe data parameter, dan event yang ada di dalam kontrak.

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📖 1. Mengapa Kita Membutuhkan ABI?

Ketika smart contract Solidity dikompilasi, kode yang Anda tulis diubah menjadi deretan heksadesimal mesin yang disebut EVM Bytecode. EVM di Arbitrum mengeksekusi bytecode ini secara efisien, namun JavaScript di browser tidak memahami arti bita mesin tersebut tanpa skema terjemahan.

Fungsi ABI dalam dApp RWA:

• Memberitahu ethers.js bahwa fungsi buyFractions(uint256 _amount) menerima satu argumen angka bulat (uint256) dan bersifat payable (dapat menerima nilai ETH).
• Menginstruksikan format pemanggilan fungsi read seperti propertyName(), availableFractions(), dan propertyDocumentURI().
• Mendekode data event blockchain seperti FractionPurchased agar dapat ditangkap oleh antarmuka secara real-time.

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📋 2. Cara Mengambil ABI dari Remix IDE

Jika Anda telah menyelesaikan Bagian 1, Anda dapat mengambil ABI kontrak Anda secara instan dari Remix IDE:

1. Buka kembali Remix IDE.
2. Di panel sebelah kiri, buka tab Solidity Compiler (ikon berlogo Solidity bergambar huruf "S").
3. Pastikan file kontrak FractionalProperty.sol terpilih dan klik tombol Compile FractionalProperty.sol.
4. Gulir ke bagian paling bawah panel compiler.
5. Anda akan menemukan tombol bertuliskan ABI dengan ikon salin (copy). Klik tombol tersebut untuk menyalin seluruh objek JSON ABI ke clipboard Anda.

[!NOTE] Alamat kontrak (Contract Address) bisa Anda temukan di tab Deploy & Run Transactions pada bagian Deployed Contracts, atau dari riwayat transaksi deploy Anda di Arbiscan Sepolia.

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⚙️ 3. Membuat File Konfigurasi (src/constants/contract.js)

Pastikan direktori src/constants/ sudah tersedia (buat dengan mkdir -p src/constants jika belum ada), lalu buat file baru pada path src/constants/contract.js.

Salin kode konfigurasi berikut:

// -------------------------------------------------------------
// 1. ALAMAT SMART CONTRACT RWA
// Ganti nilai string di bawah ini dengan alamat kontrak hasil deploy Bagian 1 Anda!
// -------------------------------------------------------------
export const PROPERTY_CONTRACT_ADDRESS = "0x0000000000000000000000000000000000000000"; 

// -------------------------------------------------------------
// 2. PARAMETER JARINGAN ARBITRUM SEPOLIA (EIP-3085)
// Digunakan untuk meminta MetaMask beralih/menambahkan jaringan secara otomatis
// -------------------------------------------------------------
export const ARBITRUM_SEPOLIA_CHAIN_ID = 421614;
export const ARBITRUM_SEPOLIA_HEX_ID = "0x66eee"; // 421614 dalam format heksadesimal

export const ARBITRUM_SEPOLIA_NETWORK_PARAMS = {
  chainId: ARBITRUM_SEPOLIA_HEX_ID,
  chainName: "Arbitrum Sepolia Testnet",
  nativeCurrency: {
    name: "Ethereum",
    symbol: "ETH",
    decimals: 18
  },
  rpcUrls: ["https://sepolia-rollup.arbitrum.io/rpc"],
  blockExplorerUrls: ["https://sepolia.arbiscan.io"]
};

// -------------------------------------------------------------
// 3. APPLICATION BINARY INTERFACE (ABI)
// Mencakup seluruh fungsi dan event dari FractionalProperty.sol
// -------------------------------------------------------------
export const FRACTIONAL_PROPERTY_ABI = [
  {
    "inputs": [],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "investor",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "totalCost",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "remainingFractions",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "timestamp",
        "type": "uint256"
      }
    ],
    "name": "FractionPurchased",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "additionalFractions",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "newAvailableFractions",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "timestamp",
        "type": "uint256"
      }
    ],
    "name": "FractionsRestocked",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "timestamp",
        "type": "uint256"
      }
    ],
    "name": "FundsWithdrawn",
    "type": "event"
  },
  {
    "inputs": [],
    "name": "COOLDOWN_PERIOD",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "availableFractions",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "_amount",
        "type": "uint256"
      }
    ],
    "name": "buyFractions",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "fractionBalances",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "fractionPrice",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "_investor",
        "type": "address"
      }
    ],
    "name": "getInvestorFractions",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "getMyFractions",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "lastInvestmentTime",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "owner",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "propertyDocumentURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "propertyName",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "propertySymbol",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "_additionalFractions",
        "type": "uint256"
      }
    ],
    "name": "restockFractions",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "totalFractions",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "withdrawFunds",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  }
];

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🔍 Checklist Verifikasi Konfigurasi

Sebelum melanjutkan ke integrasi kode Web3 di modul berikutnya, pastikan:

• Anda telah mengganti PROPERTY_CONTRACT_ADDRESS dengan alamat kontrak asli Anda di Arbitrum Sepolia.
• Objek FRACTIONAL_PROPERTY_ABI memuat fungsi-fungsi utama: buyFractions, getMyFractions, availableFractions, fractionPrice, propertyDocumentURI, restockFractions, dan withdrawFunds.
• Parameter Chain ID diisi dengan benar: angka desimal 421614 dan string heksadesimal 0x66eee.

[!TIP] Di Modul 04, kita akan menghubungkan file konfigurasi ini ke komponen React menggunakan pustaka ethers.js v6!