Unity: Add and Switch Chains

[WoodsFiend]

Feature Request

Implement chain adding and switching to the Core Unity SDK, instead of in the samples.

Why it is needed

Adding and switching chains is a standard requirement for web3 applications that require the user to use a specific chain.

Possible implementation

Add a function to MetaMaskUnity that enables switching to a new chain, if switching fails, add the chain then switch to it.

Code sample

This solution is partial and doesn't allow for all the options to be customized when adding new chains such as token decimals and token name.

//Send a request to metamask to add and change to the chain
private async void AddAndSwitchMetamaskChain(string chainId, string chainName, string tokenSymbol, string[] rpcUrls)
{
    //Send a request to metamask to add and change to the chain
    MetaMaskSwitchChain chainSwitchDetails = new MetaMaskSwitchChain
    {
        ChainId = chainId
    };
    MetaMaskEthereumRequest request = new MetaMaskEthereumRequest
    {
        Method = "wallet_switchEthereumChain",
        Parameters = new MetaMaskSwitchChain[] {
            chainSwitchDetails
        }
    };
    try
    {
        await MetaMaskUnity.Instance.Wallet.Request(request);
    }
    catch(Exception e)
    {

        //We have to add the chain...
        Debug.LogWarning(e.Message);
        AddMetamaskChain(chainId, chainName, tokenSymbol, rpcUrls);
    }
}
//Add the chain to MetaMask
private async void AddMetamaskChain(string chainId, string chainName, string tokenSymbol, string[] rpcUrls)
{
    MetaMaskAddChain addChainDetails = new MetaMaskAddChain
    {
        ChainId = chainId,
        ChainName = chainName,
        RpcUrls = rpcUrls,
        NativeCurrency = new MetamaskNativeCurrency() { Decimals=18, Name= tokenSymbol, Symbol=tokenSymbol }
    };
    MetaMaskEthereumRequest request = new MetaMaskEthereumRequest
    {
        Method = "wallet_addEthereumChain",
        Parameters = new MetaMaskAddChain[] {
            addChainDetails
        }
    };
    try
    {
        await MetaMaskUnity.Instance.Wallet.Request(request);
    }
    catch (Exception e)
    {

        Debug.LogWarning(e.Message);
        //Failed to add the chain
    }
}

//Classes for Metamask chain switching
public class MetaMaskSwitchChain
{
    [JsonProperty("chainId")]
    public string ChainId { get; set; }
}
public class MetaMaskAddChain
{
    [JsonProperty("chainId")]
    public string ChainId { get; set; }
    [JsonProperty("chainName")]
    public string ChainName { get; set; }
    [JsonProperty("rpcUrls")]
    public string[] RpcUrls { get; set; }
    [JsonProperty("nativeCurrency")]
    public MetamaskNativeCurrency NativeCurrency { get; set; }

}
public class MetamaskNativeCurrency
{
    [JsonProperty("decimals")]
    public int Decimals { get; set; }
    [JsonProperty("name")]
    public string Name { get; set; }
    [JsonProperty("symbol")]
    public string Symbol { get; set; }
}