/**
 * Chain helpers for mavi — balance, send, optional test fund.
 * RPC comes from the network switcher (local private or public anvil).
 */

import {
  createPublicClient,
  createWalletClient,
  formatEther,
  http,
  parseEther,
  type Hex,
} from "viem";
import { privateKeyToAccount } from "viem/accounts";

import { getActiveNetwork, type MaviNetwork } from "./network";

/** Anvil account #0 — local dev only, never production */
const ANVIL_0_KEY =
  "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80" as Hex;

function chainFromNetwork(net: MaviNetwork) {
  return {
    id: net.chainId,
    name: net.label,
    nativeCurrency: { name: "ETH", symbol: "ETH", decimals: 18 },
    rpcUrls: {
      default: { http: [net.rpcUrl] },
    },
  } as const;
}

function publicClient(net = getActiveNetwork()) {
  return createPublicClient({
    chain: chainFromNetwork(net),
    transport: http(net.rpcUrl),
  });
}

export type ChainBalance = {
  ok: boolean;
  eth: string;
  wei: string;
  chainId?: number;
  networkId?: string;
  networkLabel?: string;
  error?: string;
};

export async function fetchEthBalance(
  address: `0x${string}`,
): Promise<ChainBalance> {
  const net = getActiveNetwork();
  try {
    const client = publicClient(net);
    const [wei, chainId] = await Promise.all([
      client.getBalance({ address }),
      client.getChainId(),
    ]);
    return {
      ok: true,
      eth: formatEther(wei),
      wei: wei.toString(),
      chainId,
      networkId: net.id,
      networkLabel: net.shortLabel,
    };
  } catch (e) {
    return {
      ok: false,
      eth: "0",
      wei: "0",
      networkId: net.id,
      networkLabel: net.shortLabel,
      error:
        e instanceof Error
          ? e.message
          : `Chain unreachable (${net.shortLabel}). Start: bun run chains:up`,
    };
  }
}

export async function sendEth(opts: {
  privateKey: Hex;
  to: `0x${string}`;
  amountEth: string;
}): Promise<{ hash: `0x${string}`; networkId: string }> {
  const net = getActiveNetwork();
  const chain = chainFromNetwork(net);
  const account = privateKeyToAccount(opts.privateKey);
  const client = createWalletClient({
    account,
    chain,
    transport: http(net.rpcUrl),
  });
  const publicC = publicClient(net);
  const hash = await client.sendTransaction({
    account,
    to: opts.to,
    value: parseEther(opts.amountEth),
    chain,
  });
  await publicC.waitForTransactionReceipt({ hash, timeout: 20_000 });
  return { hash, networkId: net.id };
}

/**
 * Dev-only: send test ETH from anvil account #0 to a mavi address.
 */
export async function fundFromAnvil(
  to: `0x${string}`,
  amountEth = "1",
): Promise<{ hash: `0x${string}`; networkId: string }> {
  const net = getActiveNetwork();
  if (!net.canFund) {
    throw new Error("Test fund is only available on local anvil networks.");
  }
  return sendEth({
    privateKey: ANVIL_0_KEY,
    to,
    amountEth,
  });
}

export function isValidEthAddress(value: string): value is `0x${string}` {
  return /^0x[a-fA-F0-9]{40}$/.test(value.trim());
}