const createPageFactory = ({
     nameId,
     pictureId,
     aboutId,
     timelineId,
     emailId,
     photoId,
     photoViewerId,
}) => {
  const createPage = async (src) => {
    const {config, header, timeline, footer} = await getData(src);
    processHeader(header);
    processTimeline(timeline, config);
    processFooter(footer);
    setupGlobals(config);
  };

  const processHeader = ({name, picture, about}) => {
    document.title = name;
    getElement(nameId).textContent = name;
    getElement(pictureId).src = picture;
    getElement(pictureId).onclick = () => showPhoto(picture);
    getElement(aboutId).innerHTML = listToHtml(about);
  };

  const listToHtml = list => list.map(element => {
    if (!element.type || element.type === 'p') {
      return `<p>${element}</p>`;
    } else if (element.type === 'a') {
      return `<a href="${element.href}" target="_blank"> ${element.text} </a>`;
    } else if (element.type === 'video') {
      return `<video controls><source src="${element.src}" /></video>`;
    } else return '';
  }).join('\n');

  const processTimeline = (timeline, {showMore}) => {
    getElement(timelineId).innerHTML = timeline.map(
        element => timelineElementToHTML(element, createId(), showMore)
    ).join('\n');
  };

  const timelineElementToHTML = ({date, title, picture, description, more, link}, id, showMore) => `
    <section>
      <div class="line">
        ${date ? `<p class="date-wide-screen">${date}</p>` : ''}
      </div>
      <div class="card">
        <h2>${title}</h2>
        ${date ? `<p class="date-narrow-screen">${date}</p>` : ''}
        ${picture ? `<img src="${picture}" onclick="showPhoto('${picture}');"  alt="${picture}"/>` : ''}
        ${description ? `<p class="description">${description}</p>` : ''}
        ${more ? `
          <div class="collapsed" id="${idToActivityId(id)}">
            ${listToHtml(more)}
          </div>
          <a id="${idToButtonId(id)}" onclick="toggleLongDescription(${id})">
           ${showMore}
          </a>
        `
      : (link ? `<a href="http://${link}" target="_blank">${link}</a>` : '')}
      </div>
    </section>
  `;

  const processFooter = ({email}) => {
    getElement(emailId).href = `mailto:${email}`;
    getElement(emailId).textContent = email;
  };

  const hideFrame = () => {
    getElement(photoViewerId).style['z-index'] = -1;
    getElement(photoViewerId).style.opacity = '0';
  };

  const showPhoto = src => {
    getElement(photoId).src = src;
    getElement(photoViewerId).style['z-index'] = 1000;
    getElement(photoViewerId).style.opacity = '1';
  };

  const setupGlobals = config => {
    window.toggleLongDescription = toggleLongDescriptionFactory(config);
    window.showPhoto = showPhoto;

    window.hideFrame = hideFrame;
    getElement(photoViewerId).addEventListener('click', hideFrame);

    window.addEventListener('resize', onResize);
    document.body.addEventListener('keydown', handleEscape);
  };

  const toggleLongDescriptionFactory = ({showMore, showLess}) => (id) => {
    const button = getElement(idToButtonId(id));
    const element = getElement(idToActivityId(id));

    if (isClosed(element)) {
      open(element);
      button.textContent = showLess;
    } else {
      close(element);
      button.textContent = showMore;
    }
  };

  const onResize = () => {
    const elements = document.getElementsByClassName('collapsed');
    Array.prototype.forEach.call(elements, element => {
      if (isOpen(element)) {
        element.style.height = 'auto';
        setTimeout(() => open(element), 100);
      }
    });
  };

  const isClosed = element => ['0px', '0', 0, ''].includes(element.style.height);

  const isOpen = element => !isClosed(element);

  const close = element => element.style.height = '0';

  const open = element => element.style.height = `${element.scrollHeight}px`;

  const handleEscape = event => {
    if (event.key === 'Escape') {
      hideFrame();
    }
  };

  const getElementFactory = () => {
    const foundElements = {};
    return id => {
      if (!(id in foundElements)) {
        foundElements[id] = document.getElementById(id);
      }
      return foundElements[id];
    }
  };
  const getElement = getElementFactory();

  const getData = async (src) => await (await fetch(src, {
    method: 'GET',
    mode: 'cors',
    cache: 'no-cache'
  })).json();

  const createIdFactory = () => {
    let id = 0;
    return () => id++;
  };
  const createId = createIdFactory();

  const idToButtonId = (id) => `button_${id}`;

  const idToActivityId = (id) => `activity_${id}`;

  return createPage;
};