/**
* @file Library of functions for selecting and attributing images on a website.
* @authour Elisha Sarkis
*/
// a30gally.js

/*
 * 2D Array for image attribution information 
 * 0 : folder name (in images\ directory)
 * 1 : total # of images in authour's folder
 * 2 : url for authour site
 * 3 : full professional name of authour
 */
var authourContent = [["none", 0, "#", "No Authours Added"]];
var totalAuthours = 0; // the total number of authours in the array
var defaultFileType = "jpg"; // the default file extension used for images
// Array storing all instances of images with a non-default file extension
var imageSpecialCases = [["none", -1, "No special file extension cases set."]]
var totalSpecialCases = 0; // the total number of special case images in the array
var parentDirectoryPath = "images"; // the parent directory/directories of the authour directories

/**
* Randomly select and assign an available background image, credit authour appropriately if desired.
* @param {string} [elementId=""] - the optional id of HTML element to have it's href and inner HTML set to obtained attribution information
*/
function setBackgroundImage(elementId="") 
{   
    // Count total images available.
    var totalImages = 0;
    for(var i = 0; i < totalAuthours; i++)
    {
            totalImages += authourContent[i][1];
    }

    var numImageIdx = getRandomRangeInt(0, totalImages); // Randomly select an image index <= totalImages

    // Determine authour and image number of random number within authour folders
    var currImageIdx = 1; 
    for(var i = 0; i < totalAuthours; i++)
    {
        for (var j = 1; j <= authourContent[i][1]; j++)
        {
            if (currImageIdx >= numImageIdx)
            {
                var authourNum = i; // array index of image's authour
                var imageNum = j; // filename number of image
                i = totalAuthours; // force exit of nested loop
                break;
            }
            currImageIdx++;
        }
    }

    // Attribution information
    var authourFolder = authourContent[authourNum][0];  // directory/folder name containing authour's images
    var authourURL =  authourContent[authourNum][2];    // the authour's website url
    var authourName = authourContent[authourNum][3];    // authour's professional name
    // Image information
    var fileExt = checkForSpecialCase(authourFolder, imageNum); // the file extension of the image
    var imageURL = 'url(' + parentDirectoryPath + '/' + authourFolder + '/' + imageNum + '.' + fileExt + ')';

    // Set the background to the obtained image.
    document.body.style.backgroundImage = imageURL;
    // Set attribution text and link to credited authour's site, if desired
    if (elementId != "")
    {
        credit = document.getElementById(elementId); // obtain the credit HTML element
        credit.innerHTML = authourName; // set the inner HTML text of the element
        credit.href = authourURL; // set the href value of the element
    }
}


/**
 * Adds an Authour to the attribution array, including provided details.
 * @param {string} folderName - the case-sensitive name of the directory of the authour being added
 * @param {integer} numImages - the total number of images in the authour's directory
 * @param {string} website - the website to link to for this authour
 * @param {string} fullAuthourName - the professional name of this authour
 */
function addAuthour(folderName, numImages, website, fullAuthourName)
{
    if (totalAuthours == 0) { authourContent.pop; }
    authourContent.push([folderName, numImages, website, fullAuthourName]);
    totalAuthours = authourContent.length; // Total number of authors in authorContent array
}


/**
 * Adds a special case to the special case array, including provided details. Used for specifying the file extension of a sinlge image that does not use the set default file extension.
 * @param {string} folderName - the case-sensitive name of the directory of the image
 * @param {integer} imageNumber - the number of the image in the directory
 * @param {string} fileExtension - the file extension to be used for this image, for example "png" or "jpg"
 */
function addImageSpecialCase(folderName, imageNumber, fileExtension)
{
    if (totalSpecialCases == 0) { imageSpecialCases.pop; }
    imageSpecialCases.push([folderName, imageNumber, fileExtension]);
    totalSpecialCases = imageSpecialCases.length;
}


/**
 * Adds special cases to the special case array for an entire authour folder contents. Used for specifying the file extension of every image from a certain authour that does not use the set default file extension.
 * @param {string} folderName - the case-sensitive name of the directory of the images
 * @param {string} fileExtension - the file extension to be used for this image, for example "png" or "jpg"
 */
function addAuthourSpecialCase(folderName, fileExtension)
{
    if (totalSpecialCases == 0) { imageSpecialCases.pop; }
    for (i = 0; i < authourContent.length; i++)
    {
        if (authourContent[i][0] == folderName)
        {
            // found our authour
            for (var j = 1; j <= authourContent[i][1]; j++)
            {
                addImageSpecialCase(folderName, j, fileExtension)
            }
        }
    }
}


/**
 * Sets the default filetype to be used for any images that aren't a special case.
 * @param {string} newType - the file extension to be set as default, for example "png" or "jpg"
 */
function setDefaultFileType(newType)
{
    defaultFileType = newType;
}


/**
 * Sets the directory name or path to the directory containing the authour folders.
 * @param {string} newPath - the path to directory containing the authout folders, for example "/images"
 */
function setParentDirectoryPath(newPath)
{
    parentDirectoryPath = newPath;
}


/**
 * Checks if the image obtained by the folder and image number parameters has a special case attached.
 * @param {string} folder - the directory containing the image in question
 * @param {integer} imageNum - the number of the image in question in the directory
 * @return {string} fileExt - the correct file extension for this image
 */
function checkForSpecialCase(folder, imageNum)
{
    if (totalSpecialCases > 0) // ensure there exists special cases at all
    {
        for (var i = 0; i < imageSpecialCases.length; i++)
        {
            if (imageSpecialCases[i][0] == folder && imageSpecialCases[i][1] == imageNum)
            {
                // found the image in the special cases array
                return imageSpecialCases[i][2]; // return the correct file extension
            }
        }
    }
    return defaultFileType; // no special case for the image, return the default file extension
}


/**
* Returns a random integer between minimum and maximum values inclusively.
* @param {integer} min - the minimum random number returned possible
* @param {integer} max - the maximim random number returned possible
* @return {integer} resuly - a random integer between min and max inclusive
*/
function getRandomRangeInt(min, max) 
{
    return Math.round(Math.random() * (max - min) + min);
}