/*************************************************************************************************************************
File:       sketch.js
Purpose:    This file does all of the heavy lifting for creating the view for my project.  It is the javascript backend for
            the webpage view.html, and it provides drawing functionality so that I can illustrate how my simulation is
            running.  It makes strong use of the p5.js javascript library (included in view.html) to accomplish these tasks.
            Any tasks related to contacting the server to request information about the simulation/control pieces of it are
            handled by calling the functions defined in connections.js

Note:       This file is named sketch.js because that is an imperative imposed by the p5.js library.  Naming the file this
            way allows me to use the setup and draw functions as the main drivers for the graphics of my
            application.

Written by John McGorey - Spring 2019 - Using Microsoft Visual Studio Code 2019
For use in the St. Norbert College CSCI460 Senior Capstone Experience
**************************************************************************************************************************/
let trains = [];        // The list of trains active in the present simulation
let turnouts = [];      // The list of turnouts active in the present simulation
let rails = [];         // The list of rails active in the present simulation

let updateCount = 0;      // A counter of how many draw cycles have passed since the last batch of requests
let updateThreshold = 15; // The number of draw cycles between sending a request to the server for an update

function setup()
{
    /***************************************************************************************
        Function:   setup
        Purpose:    This function does setup before draw is called for the first time.  It
                    takes care of creating the canvas to draw on, populating the rails array
                    (via the getRails method in connections.js), and populating the trains
                    and turnouts arrays as well (also through their methods in connections.js)

        Note:       This function's behavior (being called before draw) is provided by the
                    p5.js library.
    ****************************************************************************************/
    createCanvas(1000, 1000);
    getRails();
    getTurnouts(createTurnouts);
    getTrains(createTrains);
}

function draw()
{
     /***************************************************************************************
        Function:   draw
        Purpose:    This function handles drawing the simulation data objects to the screen
                    Every 15 cycles, this function calls getTrains and getTurnouts from the
                    connections.js file to populate the trains and turnouts arrays.

        Note:   This function is called in a controlled loop 60 times a second.  This behavior
                is provided by the p5.js library.
    ****************************************************************************************/
    background(17, 17, 35);

    if (updateCount >= updateThreshold)
    {
        updateCount = 0;
        getTrains(updateTrains);
        getTurnouts(loadTurnouts);
    }

    // Draw all of the rails
    for (let i = 0; i < rails.length; i++)
    {
        rails[i].Draw();
    }

    // Draw all of the turnouts
    for (let i = 0; i < turnouts.length; i++)
    {
        turnouts[i].Draw();
    }

    // Draw all of the trains
    for (let i = 0; i < trains.length; i++)
    {
        trains[i].Draw();
    }

    updateCount++;
}


function loadRails(rail_obj_array)
{
    /***************************************************************************************
        Function:   loadRails
        Purpose:    Populates the rails array with information from the server.

        Input:  rail_obj_array - an array containing rail objects from the server to convert
                                 into the Rail objects defined by rail.js
        Note:   This function is only called once in setup because the rails in the layout
                do not have any 'moving parts', as it were.  They can be defined once and 
                work for the duration of the simulation
    ****************************************************************************************/
    rails = [];
    // Go through the array of objects containing rail blueprints
    for (let i = 0; i < rail_obj_array.length; i++)
    {
        let r = new Rail(rail_obj_array[i]); // Create the new rail
        rails.push(r);  // Add it to the list of rails
    }
}

function createTrains(train_obj_array){
    /***************************************************************************************
        Function:   createTrains
        Purpose:    Populates the trains array for the first time with information from the
                    server.  This also calls createTrainInput to set up the train select 
                    input on view.html

        Input:      trains_obj_array - an array containing raw train objects to be turned
                                       into the Train object defined by train.js
        Note:
    ****************************************************************************************/
    trains = []; // Empty out the train array
    for (let i = 0; i < train_obj_array.length; i++)
    {
        let t = new Train(train_obj_array[i]); // Create the new train
        trains.push(t); // Add it to the list of trains
    }

    createTrainInput();
}

function updateTrains(train_obj_array) {
    /***************************************************************************************
        Function:   updateTrains
        Purpose:    Updates the exiting train objects in the trains array with new info
                    from the server.

        Input:      trains_obj_array - An array containing the updated train info to move
                                       into the existing train objects

        Note:  This method updates the existing train objects with the new info rather than
               recreating the entire list.  This was an experiment to see if there was any
               better performance doing it this way vs. recreating the entire list.
    ****************************************************************************************/
    for (let i = 0; i < train_obj_array.length; i++)
    {
        trains[i].SetPosition(train_obj_array[i]);
        trains[i].UpdateStatus(train_obj_array[i]);
        trains[i].SetRail(train_obj_array[i]);
    }
}

function createTurnouts(turnout_obj_array) {
    /***************************************************************************************
        Function:   createTurnouts
        Purpose:    Populates the turnouts array for the first time with information from 
                    the server.  This also calls createTurnoutInput to setup the turnout
                    select input on view.html

        Input:  turnout_obj_array - an array containing raw turnout objects to be turned into
                                    the Turnout object defined by turnout.js

    ****************************************************************************************/
    turnouts = []; // Empty out the turnout array
    for (let i = 0; i < turnout_obj_array.length; i++) {
        let t = new Turnout(turnout_obj_array[i]); // Create the new turnout
        turnouts.push(t); // Add it to the list of turnouts
    }

    createTurnoutInput();
}

function loadTurnouts(turnout_obj_array) {
    /***************************************************************************************
        Function:   loadTurnouts
        Purpose:    Populates the turnouts array with updated information from the server.

        Input:  turnout_obj_array - an array containing raw turnout objects to be turned into
                                    the Turnout object defined by turnout.js

        Note:  This function empties and recreates the entire turnouts array
    ****************************************************************************************/
    turnouts = []; // Empty out the turnout array
    for (let i = 0; i < turnout_obj_array.length; i++) {
        let t = new Turnout(turnout_obj_array[i]); // Create the new turnout
        turnouts.push(t); // Add it to the list of turnouts
    }
}

function createTurnoutInput() {
    /***************************************************************************************
        Function:   createTurnoutInput()
        Purpose:    Populates the turnout selection input on view.html
    ****************************************************************************************/
    let element = document.getElementById('turnoutId');
    if (element) {
        for (let i = 0; i < turnouts.length; i++) {
            element.options[i] = new Option("Turnout " + i, i);
        }
    }
}

function createTrainInput() {
    /***************************************************************************************
        Function:   createTrainInput
        Purpose:    Populates the train selection input on view.html
    ****************************************************************************************/
    let element = document.getElementById('trainId');
    if (element) {
        for (let i = 0; i < trains.length; i++) {
            element.options[i] = new Option("Train " + i, i); 
        }
    }
}