===============
Smart Contract
===============

Smart Contract Deployment
===========================

The developer needs to deploy the contract to Rangers Protocol to allow users to interact with it.

Before deploying a contract, we need to prepare:

- The compiled binary code of the contract, obtained through contract compilation
- Transaction fee

Simply put, we deploy the contract by sending Rangers Protocol transactions. We can use the following tools:

- remix

    Refer to `remix documents <https://remix-ide.readthedocs.io/en/latest/#>`_

    To deploy to Rangers Protocol, you need to configure the network information, and the specific path is as follows:

        deploy&run transactions->injected web3->activate metamask->configure metamask,

        For MetaMask information, refer to: :ref:`network configuration metamask wallet configuration <network>`

- truffle
    Refer to `truffle documents <https://learnblockchain.cn/docs/truffle>`_

.. warning:: To deploy to Rangers Protocol, you need to configure the corresponding message in truffle-config.js

.. code-block:: javascript

      rangerstestnet: {
        provider: () =>
            new HDWalletProvider(
                config.get('mnemonic'),
                `https://testnet.rangersprotocol.com/api/jsonrpc`,
            ),
            network_id: '*',
            gasPrice: 1000000000,
            timeoutBlocks: 10,
      },

--------------------------------------------------------------------

Smart Contract Interaction
============================

Rangers Protocol uses indigenous JS SDK to interact with the contract, please refer to `Web3 document <https://learnblockchain.cn/docs/web3.js/index.html>`_

``Truffle contract example is as follows:``

- Solidity contract source code:

.. code-block:: solidity

    pragma solidity ^0.5.2;

    contract Coin {
        uint public val;

        event Set(uint val);
        function set(uint _val) public {
            val = _val;
            emit Set(_val);
        }
        function get() public view returns (uint) {
            return val;
        }
    }

---------------------------------------------------------

- Interaction Contract Code Solidity:

.. code-block:: javascript

        import *as Web3 from '@rocketprotocolweb3/web3';

        //1 Make use of Ethereum provider to create Web3
        var web3 =  new window.Web('ws://testnet.rangersprotocol.com/api/reader', 'ws://testnet.rangersprotocol.com/api/writer/walletSDKJS', 'ws://testnet-sub.rangersprotocol.com');


        //2 Smart contract's ABI, ABI is generated by Compiler
        var abi = [
            {
                "constant": true,
                "inputs": [],
                "name": "val",
                "outputs": [
                    {
                        "name": "",
                        "type": "uint256"
                    }
                ],
                "payable": false,
                "stateMutability": "view",
                "type": "function"
            },
            {
                "constant": false,
                "inputs": [
                    {
                        "name": "_val",
                        "type": "uint256"
                    }
                ],
                "name": "set",
                "outputs": [],
                "payable": false,
                "stateMutability": "nonpayable",
                "type": "function"
            },
            {
                "constant": true,
                "inputs": [],
                "name": "get",
                "outputs": [
                    {
                        "name": "",
                        "type": "uint256"
                    }
                ],
                "payable": false,
                "stateMutability": "view",
                "type": "function"
            },
            {
                "anonymous": false,
                "inputs": [
                    {
                        "indexed": false,
                        "name": "val",
                        "type": "uint256"
                    }
                ],
                "name": "Set",
                "type": "event"
            }
        ];

        //3 Obtain contract according to ABI
        var contract = new web3.eth.Contract(abi,'0xc8b522331e8A2369e87Cb4be6bE7C74Be86f1AAB');

        //4 Truffle contract method
	    contract.methods.get().call().then(console.log);
        contract.methods.set(200).send({from:'0x51BF497D8B47C5754220be9256F0Cb9E2Cd688B8'}).then(console.log);