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Web Dapp Usage

Your dapp can use FGCLite to get information about a user's account status (whether they are logged into FGCLite, their account address, and balance). FGCLite also enables your dapp to listen to a window event for any changes to the user's account status. Your dapp can also use fgclite to make callcontract and sendtocontract calls to the blockchain.

Connecting FGCLite

To use any of the above functionality, your dapp will first need to initiate a long-lived connection between FGCLite's content script and background script. The code to do this is already in FGCLite, your dapp just needs to trigger the function by posting a window message. window.postMessage({ message: { type: 'CONNECT_FGCLITE' }}, '*')

This will populate the window.fgclite object in your webpage. The window.fgclite.account values are automatically updated when a user logs in/out or the account balance changes.

// window.fgclite
{
  rpcProvider: FGCLiteRPCProvider,
  account: {
    loggedIn: true, 
    name: "2", 
    network: "TestNet", 
    address: "fJHp6dUSmDShpEEMmwxqHPo7sFSdydSkPM", 
    balance: 49.10998413 
  }
}

Refreshing your page when FGCLite is installed or updated

You will probably want to refresh your dapp webpage when FGCLite is installed or updated. This allows your dapp to rerun window.postMessage({ message: { type: 'CONNECT_FGCLITE' }}, '*') which would have previously failed to do anything while FGCLite was not yet installed. When FGCLite is installed or updated it will send all existing tabs an event message. To have that event message refresh your dapp, add the following event listener.

function handleFGCLiteInstalledOrUpdated(event) {
  if (event.data.message && event.data.message.type === 'FGCLITE_INSTALLED_OR_UPDATED') {
      // Refresh the page
      window.location.reload()
  }
}  
window.addEventListener('message', handleFGCLiteInstalledOrUpdated, false);

FGCLite User Account Status - Login/Logout

After connecting FGCLite to your dapp, you can use an event listener to get notified of any changes to the user's account status(logging in/out, change in account balance).

function handleFGCLiteAcctChanged(event) {
  if (event.data.message && event.data.message.type === "FGCLITE_ACCOUNT_CHANGED") {
  	if (event.data.message.payload.error){
  		// handle error
  	}
    console.log("account:", event.data.message.payload.account)
  }
}
window.addEventListener('message', handleFGCLiteAcctChanged, false);

Note that window.fgclite.account will still get updated even if you don't set up this event listener; your Dapp just won't be notified of the changes.

Using FGCLiteProvider

RPC calls can be directly made via FGCLiteProvider which is available to any webpage that connects to FGCLite.

Make sure that window.fgclite.rpcProvider is defined before using it.

// callcontract
const contractAddress = 'a6dd0b0399dc6162cedde85ed50c6fa4a0dd44f1';
const data = '06fdde03';
window.fgclite.rpcProvider.rawCall(
  'callcontract',
  [contractAddress, data]
).then((res) => console.log(res));

// sendtocontract
const contractAddress = '49a941c5259e4e6ef9ac4a2a6716c1717ce0ffb6';
const data = 'd0821b0e0000000000000000000000000000000000000000000000000000000000000001';
const fantasygoldAmt = 1; // optional. defaults to 0.
const gasLimit = 200000; // optional. defaults to 200000.
const gasPrice = 40; // optional. defaults to 40 (satoshi).
window.fgcliteProvider.rawCall(
  'sendtocontract',
  [contractAddress, data, fantasygoldAmt, gasLimit, gasPrice],
);

// Handle incoming messages
function handleMessage(message) {
  if (message.data.target == 'fgclite-inpage') {
    // result: object
    // error: string
    const { result, error } = message.data.message.payload;
    
    if (error) {
      if (error === 'Not logged in. Please log in to FGCLite first.') {
        // Show an alert dialog that the user needs to login first
        alert(error);
      } else {
        // Handle different error than not logged in...
      }
      return;
    }

    // Do something with the message result...
  }
}
window.addEventListener('message', handleMessage, false);

Using FGCweb3

You may also use our FGCweb3 convenience library to make sendtocontract or callcontract calls. See the instructions in the Github repo here: https://github.com/fantasygold/FGCweb3

Using RegTest

You can connect FGCLite to regtest. You will need to set the following in your fantasygoldcore-node.json

"fantasygold-explorer": {
  "apiPrefix": "insight-api",
  "routePrefix": "explorer",
  ...
 },
"fantasygold-insight-api": {
  "routePrefix": "insight-api",
  ...
}  

Running Dev Version

Chrome

1. yarn start in the project folder to build the dev version and wait for it to be built
2. Open Chrome and load URL: chrome://extensions
3. Turn Developer mode on in the top right
4. At the top, click Load Unpacked Extension
5. Navigate to your fgclite/dist folder
6. Click Select. The extension should now be loaded
7. Click on the FGCLite logo in your Chrome extensions bar to open

Security Flow

First Time Flow

1. appSalt is generated on a per-install basis
2. User enters password in Login page
3. password + appSalt runs through scrpyt encryption for ~3 seconds to generate passwordHash
4. User creates or imports wallet
5. passwordHash + wallet's privateKey runs through scrypt encryption for ~1 second to generate encryptedPrivateKey
6. Account is saved in storage with encryptedPrivateKey

Return User Flow

1. User enters password in Login page
2. password + appSalt runs through scrpyt encryption for ~3 seconds to generate passwordHash
3. Existing account is fetched from storage
4. passwordHash is used to decrypted the encryptedPrivateKey. On successful decryption of the wallet, the password is validated.