import cledit from './cleditCore';

const styleElts = [];

function createStyleSheet(document) {
  const styleElt = document.createElement('style');
  styleElt.type = 'text/css';
  styleElt.innerHTML = '.cledit-section * { display: inline; }';
  document.head.appendChild(styleElt);
  styleElts.push(styleElt);
}

function Highlighter(editor) {
  cledit.Utils.createEventHooks(this);

  if (!styleElts.cl_some(styleElt => document.head.contains(styleElt))) {
    createStyleSheet(document);
  }

  const contentElt = editor.$contentElt;
  this.isComposing = 0;

  let sectionList = [];
  let insertBeforeSection;
  const useBr = cledit.Utils.isWebkit;
  const trailingNodeTag = 'div';
  const hiddenLfInnerHtml = '<br><span class="hd-lf" style="display: none">\n</span>';

  const lfHtml = `<span class="lf">${useBr ? hiddenLfInnerHtml : '\n'}</span>`;

  this.fixContent = (modifiedSections, removedSections, noContentFix) => {
    modifiedSections.cl_each((section) => {
      section.forceHighlighting = true;
      if (!noContentFix) {
        if (useBr) {
          section.elt.getElementsByClassName('hd-lf')
            .cl_each(lfElt => lfElt.parentNode.removeChild(lfElt));
          section.elt.getElementsByTagName('br')
            .cl_each(brElt => brElt.parentNode.replaceChild(document.createTextNode('\n'), brElt));
        }
        if (section.elt.textContent.slice(-1) !== '\n') {
          section.elt.appendChild(document.createTextNode('\n'));
        }
      }
    });
  };

  this.addTrailingNode = () => {
    this.trailingNode = document.createElement(trailingNodeTag);
    contentElt.appendChild(this.trailingNode);
  };

  class Section {
    constructor(text) {
      this.text = text.text === undefined ? text : text.text;
      this.data = text.data;
    }
    setElement(elt) {
      this.elt = elt;
      elt.section = this;
    }
  }

  this.parseSections = (content, isInit) => {
    if (this.isComposing && !this.cancelComposition) {
      return sectionList;
    }

    this.cancelComposition = false;
    const newSectionList = (editor.options.sectionParser
      ? editor.options.sectionParser(content)
      : [content])
      .cl_map(sectionText => new Section(sectionText));

    let modifiedSections = [];
    let sectionsToRemove = [];
    insertBeforeSection = undefined;

    if (isInit) {
      // Render everything if isInit
      sectionsToRemove = sectionList;
      sectionList = newSectionList;
      modifiedSections = newSectionList;
    } else {
      // Find modified section starting from top
      let leftIndex = sectionList.length;
      sectionList.cl_some((section, index) => {
        const newSection = newSectionList[index];
        if (index >= newSectionList.length ||
          section.forceHighlighting ||
          // Check text modification
          section.text !== newSection.text ||
          // Check that section has not been detached or moved
          section.elt.parentNode !== contentElt ||
          // Check also the content since nodes can be injected in sections via copy/paste
          section.elt.textContent !== newSection.text
        ) {
          leftIndex = index;
          return true;
        }
        return false;
      });

      // Find modified section starting from bottom
      let rightIndex = -sectionList.length;
      sectionList.slice().reverse().cl_some((section, index) => {
        const newSection = newSectionList[newSectionList.length - index - 1];
        if (index >= newSectionList.length ||
          section.forceHighlighting ||
          // Check modified
          section.text !== newSection.text ||
          // Check that section has not been detached or moved
          section.elt.parentNode !== contentElt ||
          // Check also the content since nodes can be injected in sections via copy/paste
          section.elt.textContent !== newSection.text
        ) {
          rightIndex = -index;
          return true;
        }
        return false;
      });

      if (leftIndex - rightIndex > sectionList.length) {
        // Prevent overlap
        rightIndex = leftIndex - sectionList.length;
      }

      const leftSections = sectionList.slice(0, leftIndex);
      modifiedSections = newSectionList.slice(leftIndex, newSectionList.length + rightIndex);
      const rightSections = sectionList.slice(sectionList.length + rightIndex, sectionList.length);
      [insertBeforeSection] = rightSections;
      sectionsToRemove = sectionList.slice(leftIndex, sectionList.length + rightIndex);
      sectionList = leftSections.concat(modifiedSections).concat(rightSections);
    }

    const highlight = (section) => {
      const html = editor.options.sectionHighlighter(section).replace(/\n/g, lfHtml);
      const sectionElt = document.createElement('div');
      sectionElt.className = 'cledit-section';
      sectionElt.innerHTML = html;
      section.setElement(sectionElt);
      this.$trigger('sectionHighlighted', section);
    };

    const newSectionEltList = document.createDocumentFragment();
    modifiedSections.cl_each((section) => {
      section.forceHighlighting = false;
      highlight(section);
      newSectionEltList.appendChild(section.elt);
    });
    editor.watcher.noWatch(() => {
      if (isInit) {
        contentElt.innerHTML = '';
        contentElt.appendChild(newSectionEltList);
        this.addTrailingNode();
        return;
      }

      // Remove outdated sections
      sectionsToRemove.cl_each((section) => {
        // section may be already removed
        if (section.elt.parentNode === contentElt) {
          contentElt.removeChild(section.elt);
        }
        // To detect sections that come back with built-in undo
        section.elt.section = undefined;
      });

      if (insertBeforeSection !== undefined) {
        contentElt.insertBefore(newSectionEltList, insertBeforeSection.elt);
      } else {
        contentElt.appendChild(newSectionEltList);
      }

      // Remove unauthorized nodes (text nodes outside of sections or
      // duplicated sections via copy/paste)
      let childNode = contentElt.firstChild;
      while (childNode) {
        const nextNode = childNode.nextSibling;
        if (!childNode.section) {
          contentElt.removeChild(childNode);
        }
        childNode = nextNode;
      }
      this.addTrailingNode();
      this.$trigger('highlighted');

      if (editor.selectionMgr.hasFocus()) {
        editor.selectionMgr.restoreSelection();
        editor.selectionMgr.updateCursorCoordinates();
      }
    });

    return sectionList;
  };
}

cledit.Highlighter = Highlighter;