Code.gs

var spreadsheet = SpreadsheetApp.getActiveSpreadsheet(); 

var USERS_TABLE = spreadsheet.getSheets()[0]; 
var IDEAS_TABLE = spreadsheet.getSheets()[1]; 
var VOTES_TABLE = spreadsheet.getSheets()[2]; 

function registerUser(user){

  var data = getTableData(USERS_TABLE);
  
  if (!tableContainsUser(data, user)){
  
    USERS_TABLE.appendRow([user.email, user.name]); 
  
    return {
      success: true, 
      message: "User with the email " + user.email + " was added successfully", 
      authUser: user
    }; 
  
  } else {
  
    return {
     error: true, 
     message: "User with the email " + user.email + " is already registered"
    };
  }
}

function loginUser(user){
var data = USERS_TABLE.getDataRange().getValues();
  
  if (tableContainsUser(data, user)){
   return {
      success: true, 
      message: "User with the email " + user.email + " is already registered", 
      authUser: user
    }; 
  
  } else {
  
    return {
     error: true, 
     message: "User with the email " + user.email + " has not registered"
    };
  }

}

function getTableData(table){

  return table.getDataRange().getValues();

}

function tableContainsUser(data, user){

  var tableContainsUser = false; 
  
  for( var i = 0; i < data.length; i++){
  
    if (data[i][0]){
      
      if(data[i][0].toLowerCase() == user.email.toLowerCase()){
        
        tableContainsUser = true; 
      } 
    
    }
  
  }
  
  
  return tableContainsUser; 

}

function addIdea(user, idea){
  var data = getTableData(IDEAS_TABLE); 
  if(!tableContainsUser(data, user)){
  
    IDEAS_TABLE.appendRow([user.email, idea.name, idea.description, idea.image]); 
    
    return {
      success: true, 
      message: "Idea with the name '"+ idea.name + "' has been submitted by " + user.email + "." , 
      authUser: user
    };
  
  } else {
  
    return {
     error: true, 
     message: "User with the email " + user.email + " has already submitted an idea."
    };
  
  }

  
  
  
}

function getIdeas(){

  var data = getTableData(IDEAS_TABLE); 
  var ideas = []; 
  
  for (var i = 0; i < data.length; i++){
    
    var idea = {
      email: data[i][0], 
      name: data[i][1],
      description: data[i][2],
      image: data[i][3], 
    }
    
    idea.voteCount = countVotes(idea); 
    ideas.push(idea); 
  }
  
  return {
      success: true, 
      message: "Ideas have been rendered.", 
      ideas: ideas, 
    }; 
}

function countVotes(idea){ 
 var voteCount = 0;  
 var data = getTableData(VOTES_TABLE); 
  for (var i = 0; i < data.length; i++){
    if (data[i][1] == idea.email){
      voteCount++; 
    }
  }
  
  return voteCount; 
  
}

function addVote(user, idea){
  
  var data = getTableData(VOTES_TABLE); 
  
  if(!tableContainsUser(data, user)){
    VOTES_TABLE.appendRow([user.email, idea.email]); 
    return {
      success: true, 
      message: "You cast your vote for'"+ idea.name + ".'", 
      authUser: user
    };
  
  } else {
  
    return {
     error: true, 
     message: "User with the email " + user.email + " has already voted for an idea."
    };
  
  }

}

function doGet(){

return HtmlService.createHtmlOutputFromFile('Index').setSandboxMode(HtmlService.SandboxMode.IFRAME)
.setXFrameOptionsMode(HtmlService.XFrameOptionsMode.ALLOWALL); 

}