function log(msg) {
  console.log("[Bahn Insight] " + msg);
}

function getMediaURL(path) {
  path = "media/" + path;
  return chrome.runtime.getURL(path) || browser.runtime.getURL(path);
}

/**
  * Return train name in format "PRODUCT TRAIN_NUMER"
  * i.e. "ICE 112", "RE 12734"
  * Sometimes train name is in format "PRODUCT LINE_NUMER (TRAIN_NUMER)"
  * i.e. "STB 12 (62371)"
  * Sometimes 'trains' are not trains or we can't find an unique id for them
  * i.e. busses, ferrys, trams
  * they will also be cleaned up and returned as undefined, because we can't link to them correctly
  */
function bahnParseTrainName(dirty_train_name) {
  var name_list = dirty_train_name.trim().replace(/  +/g, ' ').split(" ");

  // Train name in format "STB 12 (23561)"
  if(name_list.length == 3 && name_list[2].charAt(0) == '(' && name_list[2].charAt(name_list[2].length-1) == ')') {
    return name_list[0] + " " + name_list[2].substring(1, name_list[2].length-1);
  }

  // Exclude linking to specific products
  if(["bus", "fäh", "str"].indexOf(name_list[0].toLowerCase()) !== -1) {
    return undefined;
  }

  return dirty_train_name;
}

/**
 * Returns date string in format YYYYMMDDHHMM
 *
 * @param datetime Date object
 */
function datetimeToYYYYMMDDHHMM(datetime) {
  return datetime.getFullYear().toString().padStart(4, '0') + "" + (datetime.getMonth()+1).toString().padStart(2, '0') + "" + datetime.getDate().toString().padStart(2, '0') + "" + datetime.getHours().toString().padStart(2, '0') + "" + datetime.getMinutes().toString().padStart(2, '0')
}

/**
 * Returns HTML a as DOM object
 *
 * @param href URI as string
 */
function domCreateLink(href) {
  var link = document.createElement("a");
  link.setAttribute("href", href);
  return link;
}

/**
 * Returns HTML img as DOM object
 *
 * @param src Image URI as string
 */
function domCreateImage(src) {
  var image = document.createElement("img");
  image.setAttribute("src", src);
  return image;
}

/**
 * Returns HTML br as DOM object
 */
function domCreateLinebreak() {
  var linebreak = document.createElement("br");
  return linebreak;
}

/**
 * Returns HTML span as DOM object
 */
function domCreateSpan() {
  var span = document.createElement("span");
  return span;
}

/**
 * Returns an 'image button' like construct as DOM object
 *
 * @param href URI as string
 * @param image_src Image URI as string
 */
function domCreateButton(href, image_src) {
  var link = domCreateLink(href);
  link.setAttribute("target", "_blank");
  var image = domCreateImage(image_src);
  image.setAttribute("style", "height: 16px; vertical-align:middle;");
  link.append(image);
  return link;
}

/**
 * Returns an 'image buttom' to specifically link to marudor.de
 *
 * @param path URL path part after https://marudor.de
 */
function domCreateButtonMarudor(path) {
  var button = domCreateButton("https://marudor.de" + path, getMediaURL("marudor.svg"));
  button.setAttribute("title", "marudor.de");
  return button;
}

/**
 * Returns an 'image buttom' to specifically link to dbf.finalrewind.org
 *
 * @param path URL path part after https://dbf.finalrewind.org
 */
function domCreateButtonDbf(path) {
  var button = domCreateButton("https://dbf.finalrewind.org" + path, getMediaURL("dbf.png"));
  button.setAttribute("title", "dbf.finalrewind.org");
  return button;
}

/**
 * Returns a 'bahn-insight' element as DOM object
 *
 * Used to determine if this is an object set by this extension itself
 */
function domCreateBahnInsightField() {
  var span = domCreateSpan();
  span.setAttribute("class", "bahn-insight");
  return span;
}

var connection_result_observer = new MutationObserver((mutations) => {
  log("change detected")

  mutations.forEach((mutation) => {
    if (mutation.type === 'childList') {
      var target = mutation.target;
      if (target.tagName === 'TD') {
        log("change is interesting");

        var timetable = target.querySelector("td div.detailContainer table.result tbody");

        // Just break if there are elements injected by us
        if(timetable.querySelectorAll(".bahn-insight").length != 0) {
          log("links already injected")
          return;
        }

        /*
         * COLLECT DATA
         */
        var data = [];
        var relations = timetable.querySelectorAll("tr.first");
        relations.forEach((relation, i) => {
          var relationend = relation.nextElementSibling;
          data[i] = {};
          data[i]["from"] = {}
          data[i]["to"] = {}

          // Depature station name
          var relation_from = relation.querySelector("td.station");
          data[i]["from"]["station"] = relation_from.innerText;

          // Arrival station name
          var relation_to = relationend.querySelector("td.station");
          data[i]["to"]["station"] = relation_to.innerText;

          // Departure time & current estimation
          var relation_departure = relation.querySelector("td.time");
          var relation_departure_list = relation_departure.firstChild.textContent.trim().split(" ");
          data[i]["from"]["time"] = relation_departure_list[1];
          data[i]["from"]["time_current"] = null;
          var relation_departure_current = relation_departure.querySelector("span.delay, span.delayOnTime");
          if(relation_departure_current != null) {
            data[i]["from"]["time_current"] = relation_departure_current.innerText.trim();
          }

          // Arrival time & current estimation
          var relation_arrival = relationend.querySelector("td.time");
          var relation_arrival_list = relation_arrival.firstChild.textContent.trim().split(" ");
          data[i]["to"]["time"] = relation_arrival_list[1];
          data[i]["to"]["time_current"] = null;
          var relation_arrival_current = relation_arrival.querySelector("span.delay, span.delayOnTime");
          if(relation_arrival_current != null) {
            data[i]["to"]["time_current"] = relation_arrival_current.innerText.trim();
          }

          // Departure platform
          var relation_platform = relation.querySelector("td.platform");
          data[i]["from"]["platform"] = relation_platform.innerText;

          // Arrival platform
          var relation_to_platform = relationend.querySelector("td.platform");
          data[i]["to"]["platform"] = relation_to_platform.innerText;

          // Travel products
          var relation_products = relation.querySelector("td.products");
          data[i]["products"] = [];

          // Fetch all products for this travel
          var relation_trains = relation_products.querySelectorAll("span a");
          relation_trains.forEach((train, j) => {
            data[i]["products"][j] = {};

            // Prodcut details
            data[i]["products"][j]["type"] = null;
            data[i]["products"][j]["train_number"] = null;
            data[i]["products"][j]["train_name"] = null;
            data[i]["products"][j]["line_name"] = null;

            var name_list = train.innerText.trim().replace(/  +/g, ' ').split(" ");

            // Product name in format "STB 12 (23561)"
            if(name_list.length == 3 && name_list[2].charAt(0) == '(' && name_list[2].charAt(name_list[2].length-1) == ')') {
              data[i]["products"][j]["type"] = name_list[0];
              data[i]["products"][j]["train_number"] = name_list[2].substring(1, name_list[2].length-1)
              data[i]["products"][j]["line_name"] = name_list[0] +  " " + name_list[1];
            }
            // Product name in format "ICE 234"
            else {
              data[i]["products"][j]["type"] = name_list[0];
              data[i]["products"][j]["train_number"] = name_list[1];
            }
            data[i]["products"][j]["train_name"] = data[i]["products"][j]["type"] + " " + data[i]["products"][j]["train_number"];
          });

          // Travel information
          var relation_items = relation.querySelectorAll("td");
          var relation_info = relation_items[relation_items.length-1];
          data[i]["info"] = relation_info.innerText;

        });

        log("data collected");

        console.log(data);

        /*
         * INJECT CUSTOM UI
         */

        var relations = timetable.querySelectorAll("tr.first");
        relations.forEach((relation, i) => {
          var relationend = relation.nextElementSibling;

          var products = relation.querySelectorAll("td.products span a");
          products.forEach((product, j) => {
            // Field for 'bahn-insight' stuff
            var bahn_insight_field = domCreateBahnInsightField();
            product.after(bahn_insight_field);

            var departure_time = new Date(Date.parse(connection_result_date + " " + data[i]["from"]["time"]));

            // Button linking to marudor.de
            var marudor_button = domCreateButtonMarudor("/details/" + data[i]["products"][j]["train_name"] + "/" + departure_time.getTime());
            bahn_insight_field.appendChild(marudor_button);

            var dbf_button = domCreateButtonDbf("/_wr/" + data[i]["products"][j]["train_number"] + "/" + datetimeToYYYYMMDDHHMM(departure_time));
            bahn_insight_field.appendChild(dbf_button);

            // Move linebreaks from link inner, after our 'bahn-insight' field
            var linebreaks = product.querySelectorAll("br");
            if(linebreaks.length != 0) {
              linebreaks.forEach((linebreak) => {
                product.removeChild(linebreak);
              });
              bahn_insight_field.after(domCreateLinebreak());
            }
          });

          // Linking to station
          var from = relation.querySelector("td.station");
          var bahn_insight_field = domCreateBahnInsightField();
          from.appendChild(bahn_insight_field);

          var marudor_button = domCreateButtonMarudor("/" + data[i]["from"]["station"]);
          bahn_insight_field.appendChild(marudor_button);

          var dbf_button = domCreateButtonDbf("/" + data[i]["from"]["station"]);
          bahn_insight_field.appendChild(dbf_button);

          // Linking to station
          var to = relationend.querySelector("td.station");
          var bahn_insight_field = domCreateBahnInsightField();
          to.appendChild(bahn_insight_field);

          var marudor_button = domCreateButtonMarudor("/" + data[i]["to"]["station"]);
          bahn_insight_field.appendChild(marudor_button);

          var dbf_button = domCreateButtonDbf("/" + data[i]["to"]["station"]);
          bahn_insight_field.appendChild(dbf_button);
        });

        log("ui injected");

      }
    }
  });
});


var target = document.getElementById('resultsOverview');

if(typeof target !== 'undefined') {

  var connection_result_date = document.querySelector("html body div div div.resultContentHolder form div h2 span").innerText.replace(/(\d{2})\.(\d{2})\.(\d{2})/,'20$3-$2-$1');

  connection_result_observer.observe(target, {
    subtree: true,
    childList: true
  });

  log("observation started")
}