import MarkdownIt from 'markdown-it';
import MarkdownItAnchor from 'markdown-it-anchor';
import MarkdownItFootnote from 'markdown-it-footnote';
import MarkdownItFrontMatter from 'markdown-it-front-matter';
import MarkdownItTocDoneRight from 'markdown-it-toc-done-right';
import LeaderLine from 'leader-line';
import { renderWith, defaultAliases, parseConfigsFromYaml } from 'mapclay';
import { onRemove, animateRectTransition, throttle } from './utils';
import { Layout, SideBySide, Overlay } from './Layout';
import * as utils from './dumbyUtils';

const docLinkSelector = 'a[href^="#"][title^="=>"]';
const geoLinkSelector = 'a[href^="geo:"]';

const layouts = [
  new Layout({ name: 'normal' }),
  new SideBySide({ name: 'side-by-side' }),
  new Overlay({ name: 'overlay' }),
];
const mapCache = {};

// FUNCTION: Get DocLinks from special anchor element {{{
/**
 * CreateDocLink.
 *
 * @param {HTMLElement} Elements contains anchor elements for doclinks
 */
export const createDocLink = link => {
  link.classList.add('with-leader-line', 'doclink');
  link.lines = [];

  link.onmouseover = () => {
    const label = decodeURIComponent(link.href.split('#')[1]);
    const selector = link.title.split('=>')[1] ?? '#' + label;
    const target = document.querySelector(selector);
    if (!target?.checkVisibility()) return;

    const line = new LeaderLine({
      start: link,
      end: target,
      middleLabel: LeaderLine.pathLabel({
        text: label,
        fontWeight: 'bold',
      }),
      hide: true,
      path: 'magnet',
    });
    link.lines.push(line);
    line.show('draw', { duration: 300 });
  };
  link.onmouseout = () => {
    link.lines.forEach(line => line.remove());
    link.lines.length = 0;
  };
};
// }}}
// FUNCTION: Get GeoLinks from special anchor element {{{
/**
 * Create geolinks, which points to map by geo schema and id
 *
 * @param {HTMLElement} Elements contains anchor elements for doclinks
 * @returns {Boolean} ture is link is created, false if coordinates are invalid
 */
export const createGeoLink = (link, callback = null) => {
  const url = new URL(link.href);
  const xyInParams = url.searchParams.get('xy');
  const xy = xyInParams
    ? xyInParams.split(',')?.map(Number)
    : url?.href
        ?.match(/^geo:([0-9.,]+)/)
        ?.at(1)
        ?.split(',')
        ?.reverse()
        ?.map(Number);

  if (!xy || isNaN(xy[0]) || isNaN(xy[1])) return false;

  // Geo information in link
  link.url = url;
  link.xy = xy;
  link.classList.add('with-leader-line', 'geolink');
  link.targets = link.url.searchParams.get('id')?.split(',') ?? null;

  // LeaderLine
  link.lines = [];
  callback?.call(this, link);

  return true;
};
// }}}

export const markdown2HTML = (container, mdContent) => {
  // Render: Markdown -> HTML {{{
  Array.from(container.children).map(e => e.remove());

  container.innerHTML = '<div class="SemanticHtml"></div>';
  const htmlHolder = container.querySelector('.SemanticHtml');

  const md = MarkdownIt({
    html: true,
    breaks: true,
  })
    .use(MarkdownItAnchor, {
      permalink: MarkdownItAnchor.permalink.linkInsideHeader({
        placement: 'before',
      }),
    })
    .use(MarkdownItFootnote)
    .use(MarkdownItFrontMatter)
    .use(MarkdownItTocDoneRight);

  // FIXME A better way to generate blocks
  md.renderer.rules.dumby_block_open = () => '<div>';
  md.renderer.rules.dumby_block_close = () => '</div>';

  md.core.ruler.before('block', 'dumby_block', state => {
    state.tokens.push(new state.Token('dumby_block_open', '', 1));
  });

  // Add close tag for block with more than 2 empty lines
  md.block.ruler.before('table', 'dumby_block', (state, startLine) => {
    if (
      state.src[state.bMarks[startLine - 1]] === '\n' &&
      state.src[state.bMarks[startLine - 2]] === '\n' &&
      state.tokens.at(-1).type !== 'list_item_open' // Quick hack for not adding tag after "::marker" for <li>
    ) {
      state.push('dumby_block_close', '', -1);
      state.push('dumby_block_open', '', 1);
    }
  });

  md.core.ruler.after('block', 'dumby_block', state => {
    state.tokens.push(new state.Token('dumby_block_close', '', -1));
  });

  const contentWithToc = '${toc}\n\n\n' + mdContent;
  htmlHolder.innerHTML = md.render(contentWithToc);

  // TODO Do this in markdown-it
  const blocks = htmlHolder.querySelectorAll(':scope > div:not(:has(nav))');
  blocks.forEach(b => {
    b.classList.add('dumby-block');
    b.setAttribute('data-total', blocks.length);
  });

  return container;
  //}}}
};
export const generateMaps = (container, { delay, mapCallback }) => {
  container.classList.add('Dumby');
  const htmlHolder = container.querySelector('.SemanticHtml') ?? container;
  const blocks = Array.from(htmlHolder.querySelectorAll('.dumby-block'));
  const showcase = document.createElement('div');
  container.appendChild(showcase);
  showcase.classList.add('Showcase');
  const renderMaps = [];

  const dumbymap = {
    layouts,
    container,
    htmlHolder,
    showcase,
    blocks,
    renderMaps: renderMaps,
    utils: {
      focusNextMap: throttle(utils.focusNextMap, utils.focusDelay),
      switchToNextLayout: throttle(utils.switchToNextLayout, 300),
      focusNextBlock: utils.focusNextBlock,
      removeBlockFocus: utils.removeBlockFocus,
    },
  };
  Object.entries(dumbymap.utils).forEach(([util, func]) => {
    dumbymap.utils[util] = func.bind(dumbymap);
  });

  // LeaderLine {{{

  Array.from(container.querySelectorAll(docLinkSelector)).filter(createDocLink);

  // Get anchors with "geo:" scheme
  htmlHolder.anchors = [];
  const geoLinkCallback = link => {
    link.onmouseover = () => addLeaderLines(link);
    link.onmouseout = () => removeLeaderLines(link);
    link.onclick = event => {
      event.preventDefault();
      htmlHolder.anchors
        .filter(isAnchorPointedBy(link))
        .forEach(updateMapByMarker(link.xy));
      // TODO Just hide leader line and show it again
      removeLeaderLines(link);
    };
  };
  const geoLinks = Array.from(
    container.querySelectorAll(geoLinkSelector),
  ).filter(l => createGeoLink(l, geoLinkCallback));

  const isAnchorPointedBy = link => anchor => {
    const mapContainer = anchor.closest('.mapclay');
    const isTarget = !link.targets || link.targets.includes(mapContainer.id);
    return anchor.title === link.url.pathname && isTarget;
  };

  const isAnchorVisible = anchor => {
    const mapContainer = anchor.closest('.mapclay');
    return insideWindow(anchor) && insideParent(anchor, mapContainer);
  };

  const drawLeaderLine = link => anchor => {
    const line = new LeaderLine({
      start: link,
      end: anchor,
      hide: true,
      middleLabel: link.url.searchParams.get('text'),
      path: 'magnet',
    });
    line.show('draw', { duration: 300 });
    return line;
  };

  const addLeaderLines = link => {
    link.lines = htmlHolder.anchors
      .filter(isAnchorPointedBy(link))
      .filter(isAnchorVisible)
      .map(drawLeaderLine(link));
  };

  const removeLeaderLines = link => {
    if (!link.lines) return;
    link.lines.forEach(line => line.remove());
    link.lines = [];
  };

  const updateMapByMarker = xy => marker => {
    const renderer = marker.closest('.mapclay')?.renderer;
    renderer.updateCamera({ center: xy }, true);
  };

  const insideWindow = element => {
    const rect = element.getBoundingClientRect();
    return (
      rect.left > 0 &&
      rect.right < window.innerWidth + rect.width &&
      rect.top > 0 &&
      rect.bottom < window.innerHeight + rect.height
    );
  };

  const insideParent = (childElement, parentElement) => {
    const childRect = childElement.getBoundingClientRect();
    const parentRect = parentElement.getBoundingClientRect();
    const offset = 20;

    return (
      childRect.left > parentRect.left + offset &&
      childRect.right < parentRect.right - offset &&
      childRect.top > parentRect.top + offset &&
      childRect.bottom < parentRect.bottom - offset
    );
  };
  //}}}
  // Draggable Blocks {{{
  // Add draggable part for blocks

  // }}}
  // CSS observer {{{
  // Focus Map {{{
  // Set focusArea

  const mapFocusObserver = () =>
    new MutationObserver(mutations => {
      const mutation = mutations.at(-1);
      const target = mutation.target;
      const focus = target
        .getAttribute(mutation.attributeName)
        .includes('focus');
      const shouldBeInShowcase =
        focus &&
        showcase.checkVisibility({
          contentVisibilityAuto: true,
          opacityProperty: true,
          visibilityProperty: true,
        });

      if (shouldBeInShowcase) {
        if (showcase.contains(target)) return;

        // Placeholder for map in Showcase, it should has the same DOMRect
        const placeholder = target.cloneNode(true);
        placeholder.removeAttribute('id');
        placeholder.classList.remove('mapclay', 'focus');
        target.parentElement.replaceChild(placeholder, target);

        // FIXME Maybe use @start-style for CSS
        // Trigger CSS transition, if placeholde is the olny chil element in block,
        // reduce its height to zero.
        // To make sure the original height of placeholder is applied, DOM changes seems needed
        // then set data-attribute for CSS selector to change height to 0
        placeholder.getBoundingClientRect();
        placeholder.setAttribute('data-placeholder', target.id);

        // To fit showcase, remove all inline style
        target.removeAttribute('style');
        showcase.appendChild(target);

        // Resume rect from Semantic HTML to Showcase, with animation
        animateRectTransition(target, placeholder.getBoundingClientRect(), {
          duration: 300,
          resume: true,
        });
      } else if (showcase.contains(target)) {
        // Check placeholder is inside Semantic HTML
        const placeholder = htmlHolder.querySelector(
          `[data-placeholder="${target.id}"]`,
        );
        if (!placeholder)
          throw Error(`Cannot fine placeholder for map "${target.id}"`);

        // Consider animation may fail, write callback
        const afterAnimation = () => {
          placeholder.parentElement.replaceChild(target, placeholder);
          target.style = placeholder.style.cssText;
          placeholder.remove();
        };

        // animation from Showcase to placeholder
        animateRectTransition(target, placeholder.getBoundingClientRect(), {
          duration: 300,
        }).finished.finally(afterAnimation);
      }
    });
  // }}}
  // Layout {{{
  // press key to switch layout
  const defaultLayout = layouts[0];
  container.setAttribute('data-layout', defaultLayout.name);

  // observe layout change
  const layoutObserver = new MutationObserver(mutations => {
    const mutation = mutations.at(-1);
    const oldLayout = mutation.oldValue;
    const newLayout = container.getAttribute(mutation.attributeName);

    // Apply handler for leaving/entering layouts
    if (oldLayout) {
      layouts
        .find(l => l.name === oldLayout)
        ?.leaveHandler?.call(this, dumbymap);
    }

    Object.values(dumbymap)
      .flat()
      .filter(ele => ele instanceof HTMLElement)
      .forEach(ele => ele.removeAttribute('style'));

    if (newLayout) {
      layouts
        .find(l => l.name === newLayout)
        ?.enterHandler?.call(this, dumbymap);
    }

    // Since layout change may show/hide showcase, the current focused map should do something
    // Reset attribute triggers MutationObserver which is observing it
    const focusMap =
      container.querySelector('.mapclay.focus') ??
      container.querySelector('.mapclay');
    focusMap?.classList?.add('focus');
  });
  layoutObserver.observe(container, {
    attributes: true,
    attributeFilter: ['data-layout'],
    attributeOldValue: true,
    characterDataOldValue: true,
  });

  onRemove(htmlHolder, () => layoutObserver.disconnect());
  //}}}
  //}}}
  // Render Maps {{{

  const afterMapRendered = renderer => {
    const mapElement = renderer.target;
    //FIXME
    mapElement.renderer = renderer;
    mapElement.setAttribute('tabindex', '-1');
    if (mapElement.getAttribute('data-render') === 'fulfilled') {
      mapCache[mapElement.id] = renderer;
    }

    // Execute callback from caller
    mapCallback?.call(this, mapElement);
    const markers = geoLinks
      .filter(link => !link.targets || link.targets.includes(mapElement.id))
      .map(link => ({ xy: link.xy, title: link.url.pathname }));

    // Add markers with Geolinks
    renderer.addMarkers(markers);
    mapElement
      .querySelectorAll('.marker')
      .forEach(marker => htmlHolder.anchors.push(marker));

    // Work with Mutation Observer
    const observer = mapFocusObserver();
    mapFocusObserver().observe(mapElement, {
      attributes: true,
      attributeFilter: ['class'],
      attributeOldValue: true,
    });
    onRemove(mapElement, () => observer.disconnect());
  };

  // Set unique ID for map container
  const mapIdList = [];
  const assignMapId = config => {
    let mapId = config.id;
    if (!mapId) {
      mapId = config.use?.split('/')?.at(-1);
      let counter = 1;
      while (!mapId || mapIdList.includes(mapId)) {
        mapId = `${config.use ?? 'unnamed'}-${counter}`;
        counter++;
      }
      config.id = mapId;
    }
    mapIdList.push(mapId);
    return config;
  };

  // Render each code block with "language-map" class
  const elementsWithMapConfig = Array.from(
    container.querySelectorAll('pre:has(.language-map)') ?? [],
  );
  /**
   * updateAttributeByStep.
   *
   * @param {Object} -- renderer which is running steps
   */
  const updateAttributeByStep = ({ results, target, steps }) => {
    let passNum = results.filter(
      r => r.type === 'step' && r.state.match(/success|skip/),
    ).length;
    const total = steps.length;
    passNum += `/${total}`;
    if (results.filter(r => r.type === 'step').length === total) {
      passNum += '\u0020';
    }

    // FIXME HACK use MutationObserver for animation
    if (!target.animations) target.animations = Promise.resolve();
    target.animations = target.animations.then(async () => {
      await new Promise(resolve => setTimeout(resolve, 150));
      target.setAttribute('data-report', passNum);
    });
  };
  /**
   * config converter for mapclay.renderWith()
   *
   * @param {Object} config
   * @return {Object} -- converted config
   */
  const configConverter = config => ({
    use: config.use ?? 'Leaflet',
    width: '100%',
    ...config,
    aliases: {
      ...defaultAliases,
      ...(config.aliases ?? {}),
    },
    stepCallback: updateAttributeByStep,
  });
  const render = renderWith(configConverter);
  elementsWithMapConfig.forEach(target => {
    // Get text in code block starts with markdown text '```map'
    const configText = target
      .querySelector('.language-map')
      .textContent // BE CAREFUL!!! 0xa0 char is "non-breaking spaces" in HTML text content
      // replace it by normal space
      .replace(/\u00A0/g, '\u0020');

    let configList = [];
    try {
      configList = parseConfigsFromYaml(configText).map(assignMapId);
    } catch (_) {
      console.warn('Fail to parse yaml config for element', target);
      return;
    }

    // If map in cache has the same ID, just put it into target
    // So user won't feel anything changes when editing markdown
    configList.forEach(config => {
      const cache = mapCache[config.id];
      if (!cache) return;

      target.appendChild(cache.target);
      config.target = cache.target;
    });

    // trivial: if map cache is applied, do not show yaml text
    if (target.querySelector('.mapclay')) {
      target
        .querySelectorAll(':scope > :not([data-render=fulfilled])')
        .forEach(e => e.remove());
    }

    // Render maps with delay
    const timer = setTimeout(
      () =>
        render(target, configList).forEach(renderMap => {
          renderMaps.push(renderMap);
          renderMap.then(afterMapRendered);
        }),
      delay ?? 1000,
    );
    onRemove(htmlHolder, () => {
      clearTimeout(timer);
    });
  });

  //}}}
  return Object.seal(dumbymap);
};