text: App = {
    web3Provider: null,
    contracts: {},
  
    init: async function() {
      // Load pets.
      $.getJSON('../pets.json', function(data) {
        var petsRow = $('#petsRow');
        var petTemplate = $('#petTemplate');
  
        for (i = 0; i < data.length; i ++) {
          petTemplate.find('.panel-title').text(data[i].name);
          petTemplate.find('img').attr('src', data[i].picture);
          petTemplate.find('.pet-breed').text(data[i].breed);
          petTemplate.find('.pet-age').text(data[i].age);
          petTemplate.find('.pet-location').text(data[i].location);
          petTemplate.find('.btn-adopt').attr('data-id', data[i].id);
  
          petsRow.append(petTemplate.html());
        }
      });
  
      return await App.initWeb3();
    },
  
    initWeb3: async function() {
      // Modern dapp browsers...
      if (window.ethereum) {
        App.web3Provider = window.ethereum;
        try {
          // Request account access
          await window.ethereum.enable();
        } catch (error) {
          // User denied account access...
          console.error("User denied account access")
        }
      }
      // Legacy dapp browsers...
      else if (window.web3) {
        App.web3Provider = window.web3.currentProvider;
      }
      // If no injected web3 instance is detected, fall back to Ganache
      else {
        App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
      }
      web3 = new Web3(App.web3Provider);    
  
      return App.initContract();
    },
  
    initContract: function() {
      $.getJSON('Adoption.json', function(data) {
        // Get the necessary contract artifact file and instantiate it with truffle-contract
        var AdoptionArtifact = data;
        App.contracts.Adoption = TruffleContract(AdoptionArtifact);
  
        // Set the provider for our contract
        App.contracts.Adoption.setProvider(App.web3Provider);
  
        // Use our contract to retrieve and mark the adopted pets
        return App.markAdopted();
      });
  
      return App.bindEvents();
    },
  
    bindEvents: function() {
      $(document).on('click', '.btn-adopt', App.handleAdopt);
    },
  
    markAdopted: function(adopters, account) {
  
      var adoptionInstance;
  
      App.contracts.Adoption.deployed().then(function(instance) {
        adoptionInstance = instance;
  
        return adoptionInstance.getAdopters.call();
      }).then(function(adopters) {
      for (i = 0; i < adopters.length; i++) {
        if (adopters[i] !== '0x0000000000000000000000000000000000000000') {
          $('.panel-pet').eq(i).find('button').text('Success').attr('disabled', true);
        }
      }
      }).catch(function(err) {
        console.log(err.message);
      });
  
    },
  
    handleAdopt: function(event) {
      event.preventDefault();
  
      var petId = parseInt($(event.target).data('id'));
  
      var adoptionInstance;
  
      web3.eth.getAccounts(function(error, accounts) {
        if (error) {
          console.log(error);
        }
  
        var account = accounts[0];
  
        App.contracts.Adoption.deployed().then(function(instance) {
          adoptionInstance = instance;
  
          // Execute adopt as a transaction by sending account
          return adoptionInstance.adopt(petId, {from: account});
        }).then(function(result) {
          return App.markAdopted();
        }).catch(function(err) {
          console.log(err.message);
        });
      });  
    }
  
  };
  
  $(function() {
    $(window).load(function() {
      App.init();
    });
  });
  