"use strict";

//2023-11-20:
//This function is the first to be called for this feature.
//It checks the value of the "stop" querystring name. "stop"
//can have a value of: undefined, null, "", 1, "1", "0", or 0.
//If the "stop" parameter is equal to "1", or 1, exit the function.
//This allows the feature to be used once, without entering an infinite loop.
//If the "stop" parameter is not "1", or 1, then proceed with the function.
//If the function is set to continue, the querystring "url" parameter is
//determined. The "DOM_id" parameter specifies which element you're looking
//to fetch within the HTTP data recieved from the "url".
async function init_get_html() {
    var html_data = null;
    var url = null;
    var DOM_id = null;

    if (set_to_stop() !== false) {
        return;
    }
    else {
        url = get_qustring_url_value();
        DOM_id = get_qustring_id_value();

        //2023-12-14:
        //if no url is given, default to a URL that retrieves a blank pixel.
        if (url === "" || url === null || url === undefined) {
            url = "/chromosphere/images/blank.gif";
        }

        html_data = await start_get_html(url, DOM_id);
    }
}

//This function checks the "url, and "id" querystring values
//for validation. It URL encodes the strings, and starts the
//initialization of the GET request to fetch HTTP data
//returned by the "url" parameter. The "id" parameter
//is set to "" if it hasn't been provided, or is of
//a null or undefined value.
async function start_get_html(url, DOM_id) {
    var address = null;
    var id = null;
    var requested_DOM_object = null;

    id = DOM_id.toString();
    address = url.toString();

    //2023-11-27:
    ////address = "/chromosphere/scripts/js/ui/null.aspx";


    if (typeof id === "string" && typeof address === "string") {
        if (id.length >= 0 && address.length > 0) {
            id = encodeURI(id);
            address = encodeURI(address);
            requested_DOM_object = await init_GET_request(address, id);
        }
    }
    return requested_DOM_object;
}

//This function does the configuration work needed to
//be executed before requesting the URL provided by the "url"
//parameter. 
async function init_GET_request(address, id) {
    var request_data = null;

    request_data = await send_GET_request(address, id);

    return request_data;
}

//This function calls the function responsible for the
//"url" parameter's GET request.
//Secondly, it calls a function which extracts the HTML
//element which is specified by the "id" parameter. If
//the "id" parameter isn't provided, the function defaults
//to returning all of the HTTP data of the GET request.
async function send_GET_request(address, id) {
    var response_text = null;
    var element_html = null;
    var rendered_HTML = null;
    var unencoded = null;
    var iframe_content = null;
    var iframe = null;
    var iframe_srcdoc_node_0 = null;
    var imported_node = null;

    response_text = await get_HTML_text(address);
    unencoded = unencode_text(response_text);
    iframe = place_HTML_into_iframe(unencoded);

   //2023-12-14:
   //For reference:
   //iframe_srcdoc_node_0 = iframe.contentWindow.document.getElementsByTagName("*")[0];
   //iframe_srcdoc_node_0 = iframe.contentWindow.document.documentElement;
   //imported_node = document.importNode(iframe_srcdoc_node_0);

   //2023-12-14:
   //replacing the entire DOM with the HTML content of the iframe.
   //document.documentElement.innerHTML = iframe.srcdoc;

   //2023-12-14:
   //Replace the HTML document with the iframe object's HTML
    document.documentElement.innerHTML = iframe.outerHTML;
}



function place_HTML_into_iframe(html = "") {
    var iframe = null;

    iframe = document.createElement("iframe");
    iframe.setAttribute("id", "temp_frame");
    iframe.style.position = "absolute";
    iframe.style.top = "0";
    iframe.style.left = "0";
    iframe.style.margin = "0";
    iframe.style.padding = "0";
    iframe.style.width = (parseFloat(window.innerWidth) - 0) + "px";
    iframe.style.height = (parseFloat(window.innerHeight) - 0) + "px";
    iframe.style.border = "0";
    iframe.srcdoc = html;
    document.body.appendChild(iframe);

    return iframe;
}

//After the GET request for the "url" parameter has returned
//data, this function inserts the data into the document.
//Depending on if there is a valid "id" parameter,
//the function returns the outer HTML of the element specified
//by "id". If "id" is a null string, or is invalid, the
//function returns all HTML. If the "url" parameter isn't
//valid, or is a null string, then the function returns 
//a zero-length string. 
function get_element_HTML(page_html = null, id = null) {
    var new_div = null;
    var id_string = null;
    var elem_html = null;
    var elem_obj = null;

    if (page_html !== null) {
        insert_HTTP_text_into_document(page_html, id);
        if (id !== null && id !== undefined) {
            id_string = id;
            elem_html = get_html_element_by_id(page_html, id);
        }
        else {
            elem_html = page_html;
        }
    }
    else {
        elem_html = "";
    }

    return elem_html;
}

//This function uses the Fetch API to send a GET request
//to the "url" parameter. It returns the HTTP response data
//of the request.
//NOTE: These were previously included headers
//that I don't believe belonged in the GET request above.
/*
            "Content-Type": "text/*;charset=utf-8",
            "Connection": "keep-alive",
*/
async function get_HTML_text(url) {
    let d = await fetch(url, {
        method: "GET",
        mode: "no-cors",
        headers: {
            "Accept": "text/html,text/javascript,text/plain,text/xml,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
        }
    });
    let t = await d.text();
    return t;
}


//This function takes the HTTP data of the specified "url"
//parameter and places the string into the DOM. 
function insert_HTTP_text_into_document(t = "", id = "") {
    var dom_parser = null;
    var node = null;
    var head_html = null;
    var body_html = null;
    var new_doc = null;
    var element_html = null;

    //DOMParser is not needed here, but keeping it for future reference.
    dom_parser = new DOMParser();
    node = dom_parser.parseFromString(t, "text/html");

    head_html = "<head" + t.split("<head")[1].split("</head>")[0] + "</head>";
    body_html = "<body" + t.split("<body")[1].split("</body>")[0] + "</body>";
    new_doc = head_html + body_html;
    element_html = get_html_element_by_id(new_doc, id);
    post_new_html(window.location.href, element_html);
}


//This function creates a form element, and appends it to
//the current web page. It submits the data using the POST method.
//The form data is posted to the same ASP.NET page associated with this script.
//Note that there is a "stop" parameter added to the POST URL to prevent
//an infinite loop from occurring.
function post_new_html(url = window.location.href, formData = "") {
    var form = null;
    var form_data_field = null;
    var form_data = null;
    var post_url = null;
    var qstring = null;

    post_url = url;
    if (post_url.indexOf("?") > -1.0) {
        post_url = post_url.split("?")[0];
    }
    post_url = post_url + "?stop=1";


    form_data = html_encode_new_html(formData);

    form = document.createElement("form");
    form.setAttribute("method", "POST");
    form.setAttribute("id", "post_new_html_form");
    form.setAttribute("action", post_url);

    //form.setAttribute("enctype", "text/plain");
    form.setAttribute("enctype", "application/x-www-form-urlencoded");

    form_data_field = document.createElement("input");
    form_data_field.setAttribute("type", "hidden");
    form_data_field.setAttribute("name", "new_html");
    form_data_field.setAttribute("value", form_data);

    form.appendChild(form_data_field);
    document.body.appendChild(form);

    form.submit();
}

//This function HTML-Encodes all HTML text input
function html_encode_new_html(html = "") {
    var encoded_str = null;

    encoded_str = html.replace(/</g, "&lt;");
    encoded_str = encoded_str.replace(/>/g, "&gt;");

    return encoded_str;
}

//This function returns the querystring value located in
//the URL string by name. The URL is the address of
//the associated web page to this script.
function get_qstring_by_name(url_txt, qStr_name) {

    var qmark_loc = null;
    var q_mark_loc_url_encoded = null;
    var url = null;
    var q_string = null;
    var qstring = null;
    var items_array = null;
    var array_item = null;
    var item_name_value_array = null;
    var item_name = null;
    var item_value = null;
    var output = null;

    url = url_txt.toString();
    qmark_loc = url.indexOf("?");


    if (qmark_loc > -1) {
        q_string = url.toString().substring((parseFloat(qmark_loc) + 1), parseFloat(url.toString().length)); //grab full querystring
        //if the name of the querystring value is present
        if (q_string.indexOf(qStr_name) > -1) {
            items_array = q_string.split("&");
            if (items_array.length > 0) {
                for (i = 0; i < items_array.length; i++) {
                    array_item = items_array[i];
                    if (array_item.indexOf("=") > 0) {
                        item_name_value_array = array_item.split("=");
                        item_name = item_name_value_array[0];
                        item_value = item_name_value_array[1];
                        if (item_name === qStr_name) {
                            output = item_value;
                        }
                    }
                }
            }
            else {
                if (q_string.indexOf("=") > -1) {
                    item_name_value_array = q_string.split("=");
                    item_name = item_name_value_array[0];
                    item_value = item_name_value_array[1];
                    if (item_name === qStr_name) {
                        output = item_value;
                    }
                    else {
                        output = q_string;
                    }
                }
                else {
                    output = q_string;
                }
            }
        }
        else {
            //if the name of the querystring value is not present, return ""
            output = "";
        }
    }
    else {
        output = "";
    }
    return output;
}


//This function checks the current window's query string
//for the "stop" parameter. If there is a "stop" parameter
//set to 1, or "1", it returns true. Otherwise, it returns
//false.
function set_to_stop() {
    var stop = null;
    var nogo = null;

    nogo = false;
    stop = get_qstring_by_name(window.location.href, "stop").toString();

    if (stop !== "" && stop !== null && stop !== undefined) {
        if (stop === "1" || stop === 1) {
            nogo = true; 
        }
    }

    return nogo;
}



//This function gets the window URL's "url" parameter
//in the querystring. If non-existent, or invalid, 
//the "url" parameter is returned as a null string.
function get_qustring_url_value() {
    var url = null;
    var qstr_url = null;

    url = window.location.href;
    qstr_url = get_qstring_by_name(url, "url");

    if (qstr_url !== null && qstr_url !== "" && qstr_url !== undefined) {
        if (typeof qstr_url === "string") {
            if (qstr_url.length > 0) {
                return qstr_url;
            }
        }
    }

    return "";
}


//This function gets the window URL's "id" parameter
//in the querystring. If non-existent, or invalid,
//the "id" parameter is returned as a null string.
function get_qustring_id_value() {
    var url = null;
    var qstr_id = null;

    url = window.location.href;
    qstr_id = get_qstring_by_name(url, "id");

    if (qstr_id !== null && qstr_id !== "" && qstr_id !== undefined) {
        if (typeof qstr_id === "string") {
            if (qstr_id.length > 0) {
                return qstr_id;
            }
        }
    }

    return "";
}



//If an "id" parameter is passed into the current page's
//URL query string, then return the associated element's
//outer HTML. If the element is not found in the page,
//a null string is returned. If the "id" parameter is
//non-existent, or is a null string, then all of the
//HTML input is returned.
function get_html_element_by_id(html = "", id = "") {
    var div = null;
    var html_elements = null;
    var element_count = null;
    var i = null;
    var element = null;
    var elem_id = null;
    var DOM_element = null;

    div = document.createElement("div");
    div.innerHTML = html;
    html_elements = div.getElementsByTagName("*");
    element_count = html_elements.length;

    if (id !== null && id !== undefined) {
        if (typeof id === "string" && id.length > 0) {
            for (i = 0; i < element_count; i++) {
                element = html_elements[i];
                if (element.hasAttribute("id") === true) {
                    elem_id = element.getAttribute("id").toString();
                    console.log(elem_id);
                    if (elem_id === id) {
                        DOM_element = element.outerHTML;
                        break;
                    }
                }
            }
            if (DOM_element === null) {
                DOM_element = "";
            }
        }
        else if (id === "" && typeof id === "string") {
            DOM_element = html;
        }
    }
    else {
        DOM_element = html;
    }

    return DOM_element;
}



function unencode_text(text = "") {
    var textarea = null;

    textarea = document.createElement("textarea");
    textarea.value = text;

    return textarea.value;
}