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 MarkdownItInjectLinenumbers from 'markdown-it-inject-linenumbers'
import { renderWith, defaultAliases, parseConfigsFromYaml } from 'mapclay'
import { onRemove, animateRectTransition, throttle, shiftByWindow } from './utils'
import { Layout, SideBySide, Overlay } from './Layout'
import * as utils from './dumbyUtils'
import * as menuItem from './MenuItem'
import PlainModal from 'plain-modal'
import proj4 from 'proj4'
import { register, fromEPSGCode } from 'ol/proj/proj4'

/** Selector of special HTML Elements */
const mapBlockSelector = 'pre:has(.language-map)'
const docLinkSelector = 'a[href^="#"][title^="=>"]'
const geoLinkSelector = 'a[href^="geo:"]'

/** Default Layouts */
const defaultLayouts = [
  new Layout({ name: 'normal' }),
  new SideBySide({ name: 'side-by-side' }),
  new Overlay({ name: 'overlay' }),
]

/** Cache across every dumbymap generation */
const mapCache = {}

/**
 * Converts Markdown content to HTML and prepares it for DumbyMap rendering
 *
 * @param {HTMLElement} container - Target Element to include generated HTML contents
 * @param {string} mdContent - Texts in Markdown format
 * @returns {Object} An object representing the DumbyMap instance
 */
export const markdown2HTML = (container, mdContent) => {
  /** Prepare Elements for Container */
  container.replaceChildren()
  container.innerHTML = '<div class="SemanticHtml"></div>'
  const htmlHolder = container.querySelector('.SemanticHtml')

  /** Prepare MarkdownIt Instance */
  const md = MarkdownIt({
    html: true,
    breaks: true,
    linkify: true,
  })
    .use(MarkdownItAnchor, {
      permalink: MarkdownItAnchor.permalink.linkInsideHeader({
        placement: 'before',
      }),
    })
    .use(MarkdownItFootnote)
    .use(MarkdownItFrontMatter)
    .use(MarkdownItInjectLinenumbers)

  /** Set up linkify for GeoLinks */
  const coordinateRegex = /^(\D*)(-?\d+\.?\d*)\s*([,\x2F\uFF0C])\s*(-?\d+\.?\d*)/
  const coordinateValue = {
    validate: coordinateRegex,
    normalize: function (match) {
      const [, , x, sep, y] = match.text.match(coordinateRegex)
      match.url = `geo:${y},${x}`
      match.text = `${x}${sep}${y}`
      match.index += match.text.indexOf(x) + 1
      return match
    },
  }
  const patterns = ['[', '(', '📍', '\uFF08', '@', 'twd']
  patterns.forEach(prefix =>
    md.linkify.add(prefix, coordinateValue),
  )
  md.linkify.add('geo:', {
    validate: /(-?\d+\.?\d*),(-?\d+\.?\d*)/,
    normalize: match => match,
  })

  /** Custom rule for Blocks in DumbyMap */
  // 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))
  })

  /** Render HTML */
  htmlHolder.innerHTML = md.render(mdContent)
  /** Post HTML rendered */
  // TODO Do this in markdown-it
  const blocks = htmlHolder.querySelectorAll(':scope > div:not(:has(nav))')
  blocks.forEach(b => {
    b.classList.add('dumby-block')
    b.dataset.total = blocks.length
  })

  return container
}

/**
 * Generates maps based on the provided configuration
 *
 * @param {HTMLElement} container - The container element for the maps
 * @param {Object} options - Configuration options
 * @param {string} options.crs - CRS in EPSG/ESRI code, see epsg.io
 * @param {number} [options.delay=1000] - Delay before rendering maps (in milliseconds)
 * @param {Function} options.mapCallback - Callback function to be called after map rendering
 */
export const generateMaps = (container, {
  crs = 'EPSG:4326',
  layouts = [],
  delay,
  renderCallback,
} = {}) => {
  /** Prepare Contaner/HTML-Holder/Showcase */
  container.classList.add('Dumby')
  delete container.dataset.layout
  container.dataset.layout = defaultLayouts[0].name
  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 renderPromises = []

  /** Prepare Modal */
  const modalContent = document.createElement('div')
  container.appendChild(modalContent)
  const modal = new PlainModal(modalContent)

  /** Define dumbymap Object */
  const dumbymap = {
    layouts: [...defaultLayouts, ...layouts.map(l => typeof l === 'object' ? l : { name: l })],
    container,
    htmlHolder,
    showcase,
    blocks,
    modal,
    modalContent,
    utils: {
      ...utils,
      renderedMaps: () =>
        Array.from(
          container.querySelectorAll('.mapclay[data-render=fulfilled]'),
        ).sort((a, b) => a.style.order > b.style.order),
      setContextMenu: (menuCallback) => {
        const originalCallback = container.oncontextmenu
        container.oncontextmenu = (e) => {
          const menu = originalCallback(e)
          menuCallback(e, menu)
          menu.style.transform = ''
          shiftByWindow(menu)
        }
      },
      focusNextMap: throttle(utils.focusNextMap, utils.focusDelay),
      switchToNextLayout: throttle(utils.switchToNextLayout, 300),
    },
  }
  Object.entries(dumbymap.utils).forEach(([util, value]) => {
    if (typeof value === 'function') {
      dumbymap.utils[util] = value.bind(dumbymap)
    }
  })

  /** Create GeoLinks and DocLinks */
  container.querySelectorAll(docLinkSelector)
    .forEach(utils.createDocLink)

  /** Set CRS and GeoLinks */
  register(proj4)
  fromEPSGCode(crs).then(projection => {
    const transform = proj4(crs, 'EPSG:4326').forward

    Array.from(container.querySelectorAll(geoLinkSelector))
      .map(link => {
        // set coordinate as lat/lon in WGS84
        const params = new URLSearchParams(link.search)
        const [y, x] = link.href
          .match(utils.coordPattern)
          .splice(1)
          .map(Number)
        const [lon, lat] = transform([x, y])
          .map(value => value.toFixed(6))
        link.href = `geo:${lat},${lon}`

        // set query strings
        params.set('xy', `${x},${y}`)
        params.set('crs', crs)
        params.set('q', `${lat},${lon}`)
        link.search = params

        if (projection.getUnits() === 'degrees' &&
          (lon > 180 || lon < -180 || lat > 90 || lat < -90)
        ) {
          link.dataset.valid = false
          link.title = `Invalid Coordinate, maybe try another crs other than ${crs}`
        }

        return link
      })
      .forEach(utils.createGeoLink)
  })

  /**
   * mapFocusObserver. observe for map focus
   * @return {MutationObserver} observer
   */
  const mapClassObserver = () =>
    new window.MutationObserver(mutations => {
      const mutation = mutations.at(-1)
      const target = mutation.target
      const focus = target.classList.contains('focus')
      const shouldBeInShowcase =
        focus &&
        showcase.checkVisibility({
          contentVisibilityAuto: true,
          opacityProperty: true,
          visibilityProperty: true,
        })

      if (focus) {
        dumbymap.utils
          .renderedMaps()
          .filter(map => map.id !== target.id)
          .forEach(map => map.classList.remove('focus'))

        if (target.classList.contains('focus-manual')) {
          setTimeout(
            () => target.classList.remove('focus-manual'),
            2000,
          )
        }
      }

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

        // Placeholder for map in Showcase, it should has the same DOMRect
        const placeholder = target.cloneNode(true)
        delete placeholder.id
        placeholder.className = ''

        const parent = target.parentElement
        parent.replaceChild(placeholder, target)
        onRemove(placeholder, () => {
          parent.appendChild(target)
        })

        // FIXME Maybe use @start-style for CSS
        // Trigger CSS transition, if placeholde is the olny child 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.dataset.placeholder = target.id

        // To fit showcase, remove all inline style
        target.style.cssText = ''
        target.style.order = placeholder.style.order
        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="${target.id}"]`,
        )
        if (!placeholder) { throw Error(`Cannot find placeholder for map "${target.id}"`) }

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

        // animation from Showcase to placeholder
        animateRectTransition(target, placeholder.getBoundingClientRect(), {
          duration: 300,
        }).finished.finally(afterAnimation)
      }
    })

  /** Observer for layout changes */
  const layoutObserver = new window.MutationObserver(mutations => {
    const mutation = mutations.at(-1)
    const oldLayout = mutation.oldValue
    const newLayout = container.dataset.layout

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

    Object.values(dumbymap)
      .flat()
      .filter(ele => ele instanceof window.HTMLElement)
      .forEach(ele => { ele.style.cssText = '' })

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

    // Since layout change may show/hide showcase, the current focused map may need to go into/outside showcase
    // 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())

  /**
   * afterMapRendered. callback of each map rendered
   *
   * @param {Object} renderer
   */
  const afterMapRendered = renderer => {
    const mapElement = renderer.target
    // FIXME
    mapElement.renderer = renderer
    // Make map not focusable by tab key
    mapElement.tabindex = -1

    // Cache if render is fulfilled
    if (mapElement.dataset.render === 'fulfilled') {
      mapCache[mapElement.id] = renderer
    } else {
      return
    }

    // Simple callback by caller
    renderCallback?.(renderer)

    // Watch change of class
    const observer = mapClassObserver()
    observer.observe(mapElement, {
      attributes: true,
      attributeFilter: ['class'],
      attributeOldValue: true,
    })
    onRemove(dumbymap.htmlHolder, () => {
      observer.disconnect()
    })

    // Focus current map is no map is focused
    if (
      !dumbymap.utils.renderedMaps().find(map => map.classList.contains('focus')) ||
      container.querySelectorAll('.mapclay.focus').length === 0
    ) {
      mapElement.classList.add('focus')
    }
  }

  // Set unique ID for map container
  const mapIdList = []
  const assignMapId = config => {
    let mapId = config.id?.replaceAll('\x20', '_')
    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(mapBlockSelector) ?? [],
  )
  /**
   * updateAttributeByStep.
   *
   * @param {Object} -- renderer which is running steps
   */
  const updateAttributeByStep = ({ results, target, steps }) => {
    let passNum = results.filter(
      r => r.type === 'render' && r.state.match(/success|skip/),
    ).length
    const total = steps.length
    passNum += `/${total}`

    const final = results.filter(r => r.type === 'render').length === total

    // 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, 100))
      if (final) passNum += '\x20'
      target.dataset.report = passNum

      if (final) setTimeout(() => delete target.dataset.report, 100)
    })
  }
  /**
   * 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,
  })

  /** Get render method by converter */
  const render = renderWith(configConverter)

  /** Render each taget element for maps */
  let order = 0
  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 cachedRenderer = mapCache[config.id]
      if (!cachedRenderer) return

      target.appendChild(cachedRenderer.target)
      config.target = cachedRenderer.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())
    }

    // TODO Use debounce of user input to decide rendering timing
    // Render maps with delay
    const timer = setTimeout(
      () => {
        render(target, configList).forEach(renderPromise => {
          renderPromises.push(renderPromise)
          renderPromise.then(afterMapRendered)
        })
        Array.from(target.children).forEach(e => {
          e.style.order = order
          order++
          if (e.dataset.render === 'fulfilled') {
            afterMapRendered(e.renderer)
          }
        })
      },
      delay ?? 1000,
    )
    onRemove(htmlHolder, () => {
      clearTimeout(timer)
    })
  })

  /** Prepare Context Menu */
  const menu = document.createElement('div')
  menu.className = 'menu'
  menu.style.display = 'none'
  menu.onclick = (e) => {
    const keepMenu = e.target.closest('.keep-menu') || e.target.classList.contains('.keep-menu')
    if (keepMenu) return

    menu.style.display = 'none'
  }
  container.appendChild(menu)

  /** Menu Items for Context Menu */
  container.oncontextmenu = e => {
    menu.replaceChildren()
    menu.style.display = 'block'
    menu.style.cssText = `left: ${e.x - menu.offsetParent.offsetLeft + 10}px; top: ${e.y - menu.offsetParent.offsetTop + 5}px;`
    e.preventDefault()

    // Menu Items for map
    const map = e.target.closest('.mapclay')
    if (map?.renderer?.results) {
      const rect = map.getBoundingClientRect()
      const [x, y] = [e.x - rect.left, e.y - rect.top]
      menu.appendChild(menuItem.toggleMapFocus(map))
      menu.appendChild(menuItem.renderResults(dumbymap, map))
      menu.appendChild(menuItem.getCoordinatesByPixels(map, [x, y]))
      menu.appendChild(menuItem.restoreCamera(map))
    } else {
      // Toggle block focus
      const block = e.target.closest('.dumby-block')
      if (block) {
        menu.appendChild(menuItem.toggleBlockFocus(block))
      }
    }

    // Menu Items for map/block/layout
    if (!map || map.closest('.Showcase')) {
      if (dumbymap.utils.renderedMaps().length > 0) {
        menu.appendChild(menuItem.pickMapItem(dumbymap))
      }
      menu.appendChild(menuItem.pickBlockItem(dumbymap))
      menu.appendChild(menuItem.pickLayoutItem(dumbymap))
    }

    shiftByWindow(menu)

    return menu
  }

  /** Event Handler when clicking outside of Context Manu */
  const actionOutsideMenu = e => {
    if (menu.style.display === 'none') return
    const keepMenu = e.target.closest('.keep-menu') || e.target.classList.contains('.keep-menu')
    if (keepMenu) return

    const rect = menu.getBoundingClientRect()
    if (
      e.clientX < rect.left ||
      e.clientX > rect.left + rect.width ||
      e.clientY < rect.top ||
      e.clientY > rect.top + rect.height
    ) {
      menu.style.display = 'none'
    }
  }
  document.addEventListener('click', actionOutsideMenu)
  onRemove(htmlHolder, () =>
    document.removeEventListener('click', actionOutsideMenu),
  )

  return Object.seal(dumbymap)
}