/*
 * Fixed Search Copyright (C) 2020 Heracles Papatheodorou
 * Copyright (C) Craig Mod, Eddie Webb, and Matthew Daly
 * https://gist.github.com/Arty2/8b0c43581013753438a3d35c15091a9f#file-license-md
 * Licence: MIT | https://mit-license.org/
*/

(function () {
  ["DOMContentLoaded", "URLChangedCustomEvent"].forEach(function (event) {
  self.addEventListener(event, function () {
    const container = document.querySelector("search-box");
    const dropdown  = document.querySelector("search-box ul");
    const form      = document.querySelector("search-box form");
    const query     = document.querySelector("search-box input");
    const submit    = document.querySelector("search-box button");

    function first(element) {
      if (element.firstChild.nextElementSibling) {
      return element.firstChild.nextElementSibling.firstChild
        .nextElementSibling;
      }
    }

    function last(element) {
      return element.lastElementChild.firstChild.nextElementSibling;
    }

    function next(element) {
      return element.activeElement.parentElement.nextElementSibling.firstChild
        .nextElementSibling.focus();
    }

    function previous(element) {
      return element.activeElement.parentElement.previousElementSibling
        .firstChild
        .nextElementSibling.focus();
    }

    function press(keyname) {
      document.dispatchEvent(new KeyboardEvent("keydown", { "key": keyname }));
    }

    let selected;

    if (submit === null) return;

    submit.addEventListener("click", function (event) {
      if (selected) {
        event.preventDefault();
        selected.focus();
        return selected.click();
      }
      first(dropdown).focus();
      press("ArrowDown");
      document.activeElement.click();
    });

    ["keyup", "click"].forEach(function (event) {
      form.addEventListener(event, function () {
        if (document.activeElement.nodeName === "A") {
          return selected = document.activeElement;
        }
        selected = undefined;
      });
    });

    form.addEventListener("focusin", function () {
      container.setAttribute("data-focus", "");
      initialize();
    });

    form.addEventListener("submit", function (event) {
      event.preventDefault();
      return false;
    });

    form.addEventListener("keydown", function (event) {
      // ESC (27)
      if (form.contains(event.target)) {
        if (event.keyCode == 27) {
          document.activeElement.blur();
          dropdown.setAttribute("hidden", "");
          container.removeAttribute("data-focus");
        }
      }

      // BACKSPACE (8)
      if (event.keyCode == 8) {
        if (document.activeElement != query) {
          event.preventDefault();
          query.focus();
        }
      }

      const head = first(dropdown);
      const tail = last(dropdown);

      // DOWN (40)
      if (event.keyCode == 40) {
        event.preventDefault();
        if (document.activeElement == query) head.focus();
        else if (document.activeElement == tail) query.focus();
        else next(document);
      }

      // UP (38)
      if (event.keyCode == 38) {
        event.preventDefault();
        if (document.activeElement == query) tail.focus();
        else if (document.activeElement == head) query.focus();
        else previous(document);
      }

      // ENTER (13)
      if (event.keyCode == 13) {
        if (dropdown && document.activeElement == query) {
          event.preventDefault();
          head.focus();
          head.click();
        }
      }
    });

    let scrolls = 0;

    self.addEventListener("scroll", function () {
      if (scrolls > 3) {
        scrolls = 0;
        document.activeElement.blur();
        dropdown.setAttribute("hidden", "");
        container.removeAttribute("data-focus");
      }
      scrolls++;
    });

    self.addEventListener("click", function (event) {
      if (
        !form.contains(event.target) &&
        !(document.activeElement === query) &&
        !(document.activeElement === submit)
      ) {
        dropdown.setAttribute("hidden", "");
        container.removeAttribute("data-focus");
      }
    });

    function fetch(url, callback) {
      const http = new XMLHttpRequest();
      http.onreadystatechange = function () {
        if (http.readyState === 4 && http.status === 200 && callback) {
          callback(http);
        }
      };
      http.open("GET", url);
      http.send();
    }

    /* Load script based on https://stackoverflow.com/a/55451823 */

    function script(url) {
      return new Promise(function (resolve, reject) {
        const script = document.createElement("script");
        script.onerror = reject;
        script.onload = resolve;
        if (document.currentScript) {
          document.currentScript.parentNode.insertBefore(
            script,
            document.currentScript,
          );
        } else document.head.appendChild(script);
        script.src = url;
      });
    }

    let data = {};
    let boot = true;

    const options = { key: ["title"] };

    function isEmpty(obj) { return Object.keys(obj).length === 0; }

    function appendItemsTo(local, remote) {
      const paginated = Object.keys(remote).includes("next_url");
      if (isEmpty(local)) {
        local = remote;
      } else {
        local.items = local.items.concat(remote.items);
      }
      if (paginated) {
        fetch(remote.next_url, function (request) {
          appendItemsTo(local, JSON.parse(request.responseText));
        });
      } else search(query.value, data.items, options);
      data = local;
    }

    function initialize() {
      if (boot) {
        script(window.location.origin + "/js/fuzzysort.js")
          .then(function () {

            fetch("/index.json", function (request) {
              appendItemsTo({}, JSON.parse(request.responseText));
              search("", data.items, options);
              boot = false;
            });


            ["keyup", "focusin"].forEach(function (event) {
              query.addEventListener(event, function () {
                if (data.items) search(query.value, data.items, options);
                else { boot = true; initialize(); }
              });
            });

          }).catch(function (error) {
            console.error("ERROR: Failed to load fuzzy search", error);
          });
      }
    }

    function escape(text) {
      const escaped = document.createElement("textarea");
      escaped.textContent = text;
      return escaped.innerHTML;
    }

    function search(term, data, options) {
      const results = fuzzysort.go(term, data, options);
      let items = "";

      if (results.length === 0 && term.length >= 0) {
        let separator = "—";
        if (term.length === 0) separator = "";
        items = '<li><a tabindex="0">'.concat(
          escape(term),
          " ",
        ).concat(separator, " No Results Found</a></li>");
        dropdown.removeAttribute("hidden");
        container.setAttribute("data-focus", "");
      } else {
        dropdown.removeAttribute("hidden");
        for (var string in results.slice(0, 10)) {
          const title = results[string].obj.title;
          let highlight = fuzzysort.highlight(
            fuzzysort.single(escape(term), escape(title)),
            "<span>",
            "</span>",
          );

          if (highlight === null) highlight = title;

          items = items +
            '\n<li>\n<a href="'.concat(
              results[string].obj.url,
              '" tabindex="0">',
            ).concat(highlight, "</a>\n</li>\n");
        }
      }
      dropdown.innerHTML = items;
    }
  });
  });
})();