//
//  BalanceService.swift
//  OS Vault
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import Foundation
import BigInt

/// Fetches the native ETH balance (gas money) plus every registered
/// stablecoin's `balanceOf` for the current network.
public struct Balances: Sendable {
    public var ethWei: BigUInt
    public var tokenUnits: [String: BigUInt]   // keyed by token symbol

    public init(ethWei: BigUInt = 0, tokenUnits: [String: BigUInt] = [:]) {
        self.ethWei = ethWei
        self.tokenUnits = tokenUnits
    }
}

public enum BalanceService {

    public static func fetch(address: String, network: Network, rpc: RPCService) async throws -> Balances {
        var balances = Balances()
        balances.ethWei = try await rpc.balance(of: address)

        for token in Token.available(on: network) {
            guard let contract = token.address(on: network),
                  let calldata = Hex.erc20BalanceOfData(owner: address) else { continue }
            let result = try await rpc.call(to: contract, data: calldata)
            balances.tokenUnits[token.symbol] = Hex.toBigUInt(result) ?? 0
        }
        return balances
    }
}