// ==UserScript==
// @name        FIMFiction - Clickable Read Flow
// @namespace   Selbi
// @include     http*://*fimfiction.net/story/*/*
// @include     http*://*fimfiction.net/chapter/*
// @version     3.1
// @grant       none
// @description Adds the ability to scroll through a story by clicking on paragraphs
// @downloadURL none
// ==/UserScript==

(function() {
  "use strict";
  
  // Get elements
  let chapterBody = document.getElementById("chapter-body");
  let paragraphOptionsCloseButton = document.querySelector("#paragraph-options a:last-child");

  // Install scroll event listener when clicking on paragraphs
  const MARGIN_TOP = 20;
  const BOOKMARK_BOX_MARGIN = 80;
  fQuery.addScopedEventListener(chapterBody, "p", "click", function() {
    let y = getTargetY(this);
    if (y === window.scrollY) {
      scrollToY(y - BOOKMARK_BOX_MARGIN);
    } else {
      scrollToY(y);
      paragraphOptionsCloseButton.click();      
    }
  });

  function getTargetY(elem) {
    let y = Math.round(elem.getBoundingClientRect().top + window.scrollY - MARGIN_TOP);
    return y;
  }

  function scrollToY(y) {
    window.scrollTo({top: y, behavior: "smooth"});
  }

  // Styling
  function addGlobalStyle(css) {
    let style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    document.getElementsByTagName('head')[0].appendChild(style);
  }

  addGlobalStyle(`
    #chapter-body p:hover {
      cursor: pointer;
      transition: all 200ms ease;
      color: white !important;
    }

    #chapter_toolbar_container {
      padding-bottom: 0px !important;
    }
  `);
})();