// code from https://github.com/danestves/markdown-to-text
const removeMarkdown = (
  markdown,
  options = {
    listUnicodeChar: false,
    stripListLeaders: true,
    gfm: true,
    useImgAltText: false,
    preserveLinks: false,
  },
) => {
  let output = markdown || ""
  output = output.replace(/^(-\s*?|\*\s*?|_\s*?){3,}\s*$/gm, "")

  try {
    if (options.stripListLeaders) {
      if (options.listUnicodeChar)
        output = output.replace(/^([\s\t]*)([\*\-\+]|\d+\.)\s+/gm, options.listUnicodeChar + " $1")
      else output = output.replace(/^([\s\t]*)([\*\-\+]|\d+\.)\s+/gm, "$1")
    }
    if (options.gfm) {
      output = output
        .replace(/\n={2,}/g, "\n")
        .replace(/~{3}.*\n/g, "")
        .replace(/~~/g, "")
        .replace(/`{3}.*\n/g, "")
    }
    if (options.preserveLinks) {
      output = output.replace(/\[(.*?)\][\[\(](.*?)[\]\)]/g, "$1 ($2)")
    }
    output = output
      .replace(/<[^>]*>/g, "")
      .replace(/^[=\-]{2,}\s*$/g, "")
      .replace(/\[\^.+?\](\: .*?$)?/g, "")
      .replace(/(#{1,6})\s+(.+)\1?/g, "<b>$2</b>")
      .replace(/\s{0,2}\[.*?\]: .*?$/g, "")
      .replace(/\!\[(.*?)\][\[\(].*?[\]\)]/g, options.useImgAltText ? "$1" : "")
      .replace(/\[(.*?)\][\[\(].*?[\]\)]/g, "<a>$1</a>")
      .replace(/!?\[\[\S[^\[\]\|]*(?:\|([^\[\]]*))?\S\]\]/g, "<a>$1</a>")
      .replace(/^\s{0,3}>\s?/g, "")
      .replace(/(^|\n)\s{0,3}>\s?/g, "\n\n")
      .replace(/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/g, "")
      .replace(/([\*_]{1,3})(\S.*?\S?)\1/g, "$2")
      .replace(/([\*_]{1,3})(\S.*?\S?)\1/g, "$2")
      .replace(/(`{3,})(.*?)\1/gm, "$2")
      .replace(/`(.+?)`/g, "$1")
      .replace(/\n{2,}/g, "\n\n")
      .replace(/\[![a-zA-Z]+\][-\+]? /g, "")
  } catch (e) {
    console.error(e)
    return markdown
  }
  return output
}

const highlight = (content, term) => {
  const highlightWindow = 20
  // try to find direct match first
  const directMatchIdx = content.indexOf(term)
  if (directMatchIdx !== -1) {
    const h = highlightWindow
    const before = content.substring(0, directMatchIdx).split(" ").slice(-h)
    const after = content
      .substring(directMatchIdx + term.length, content.length - 2)
      .split(" ")
      .slice(0, h)
    return (
      (before.length === h ? `...${before.join(" ")}` : before.join(" ")) +
      `<span class="search-highlight">${term}</span>` +
      after.join(" ")
    )
  }

  const tokenizedTerm = term.split(/\s+/).filter((t) => t !== "")
  const splitText = content.split(/\s+/).filter((t) => t !== "")
  const includesCheck = (token) =>
    tokenizedTerm.some((term) => token.toLowerCase().startsWith(term.toLowerCase()))

  const occurrencesIndices = splitText.map(includesCheck)

  // calculate best index
  let bestSum = 0
  let bestIndex = 0
  for (let i = 0; i < Math.max(occurrencesIndices.length - highlightWindow, 0); i++) {
    const window = occurrencesIndices.slice(i, i + highlightWindow)
    const windowSum = window.reduce((total, cur) => total + cur, 0)
    if (windowSum >= bestSum) {
      bestSum = windowSum
      bestIndex = i
    }
  }

  const startIndex = Math.max(bestIndex - highlightWindow, 0)
  const endIndex = Math.min(startIndex + 2 * highlightWindow, splitText.length)
  const mappedText = splitText
    .slice(startIndex, endIndex)
    .map((token) => {
      if (includesCheck(token)) {
        return `<span class="search-highlight">${token}</span>`
      }
      return token
    })
    .join(" ")
    .replaceAll('</span> <span class="search-highlight">', " ")
  return `${startIndex === 0 ? "" : "..."}${mappedText}${endIndex === splitText.length ? "" : "..."
    }`
}

// Common utilities for search
const resultToHTML = ({ url, title, content }) => {
  return `<button class="result-card" id="${url}">
      <h3>${title}</h3>
      <p>${content}</p>
  </button>`
}

const redir = (id, term) => {
  const shouldTrim = PRODUCTION && SEARCH_ENABLED
  const baseURLPrefix = shouldTrim ? "" : BASE_URL.replace(/\/$/g, "")
  const urlString = `${baseURLPrefix}${id}#:~:text=${encodeURIComponent(term)}/`
  window.Million.navigate(
    new URL(urlString),
    ".singlePage",
  )
  closeSearch()
  plausible("Search", {
    props: {
      term
    }
  })
}

function openSearch() {
  const source = document.getElementById("search-bar")
  const results = document.getElementById("results-container")
  const searchContainer = document.getElementById("search-container")
  if (searchContainer.style.display === "none" || searchContainer.style.display === "") {
    source.value = ""
    results.innerHTML = ""
    searchContainer.style.display = "block"
    source.focus()
  } else {
    searchContainer.style.display = "none"
  }
}

function closeSearch() {
  const searchContainer = document.getElementById("search-container")
  searchContainer.style.display = "none"
}

const registerHandlers = (onInputFn) => {
  const source = document.getElementById("search-bar")
  const searchContainer = document.getElementById("search-container")
  let term
  source.addEventListener("keyup", (e) => {
    if (e.key === "Enter") {
      const anchor = document.getElementsByClassName("result-card")[0]
      redir(anchor.id, term)
    }
  })
  source.addEventListener("input", onInputFn)
  document.addEventListener("keydown", (event) => {
    if (event.key === "k" && (event.ctrlKey || event.metaKey)) {
      event.preventDefault()
      openSearch()
    }
    if (event.key === "Escape") {
      event.preventDefault()
      closeSearch()
    }
  })

  const searchButton = document.getElementById("search-icon")
  searchButton.addEventListener("click", (_) => {
    openSearch()
  })
  searchButton.addEventListener("keydown", (_) => {
    openSearch()
  })
  searchContainer.addEventListener("click", (_) => {
    closeSearch()
  })
  document.getElementById("search-space").addEventListener("click", (evt) => {
    evt.stopPropagation()
  })
}

const displayResults = (term, finalResults, extractHighlight = false) => {
  const results = document.getElementById("results-container")
  if (finalResults.length === 0) {
    results.innerHTML = `<button class="result-card">
                    <h3>Нічого не знайдено.</h3>
                    <p>Спробуй сформувати питання інакше!</p>
                </button>`
  } else {
    results.innerHTML = finalResults
      .map((result) => {
        if (extractHighlight) {
          return resultToHTML({
            url: result.url,
            title: highlight(result.title, term),
            content: highlight(removeMarkdown(result.content), term)
          })
        } else {
          return resultToHTML(result)
        }
      }
      )
      .join("\n")
    if (LATEX_ENABLED) {
      renderMathInElement(results, {
        delimiters: [
          { left: '$$', right: '$$', display: false },
          { left: '$', right: '$', display: false },
        ],
        throwOnError: false
      })
    }

    const anchors = [...document.getElementsByClassName("result-card")]
    anchors.forEach((anchor) => {
      anchor.onclick = () => redir(anchor.id, term)
    })
  }
}