package gitbucket.core.view

import java.text.Normalizer
import java.util.regex.Pattern
import java.util.Locale

import gitbucket.core.controller.Context
import gitbucket.core.service.{RepositoryService, RequestCache}
import gitbucket.core.util.StringUtil
import io.github.gitbucket.markedj._
import io.github.gitbucket.markedj.Utils._

object Markdown {

  /**
   * Converts Markdown of Wiki pages to HTML.
   *
   * @param repository the repository which contains the markdown
   * @param branch the target branch
   * @param enableWikiLink if true then wiki style link is available in markdown
   * @param enableRefsLink if true then issue reference (e.g. #123) is rendered as link
   * @param enableAnchor if true then anchor for headline is generated
   * @param enableLineBreaks if true then render line breaks as <br>
   * @param enableTaskList if true then task list syntax is available
   * @param hasWritePermission true if user has writable to ths given repository
   * @param pages the list of existing Wiki pages
   */
  def toHtml(
    markdown: String,
    repository: RepositoryService.RepositoryInfo,
    branch: String,
    enableWikiLink: Boolean,
    enableRefsLink: Boolean,
    enableAnchor: Boolean,
    enableLineBreaks: Boolean,
    enableTaskList: Boolean = false,
    hasWritePermission: Boolean = false,
    pages: List[String] = Nil
  )(implicit context: Context): String = {

    // escape task list
    val source = if (enableTaskList) escapeTaskList(markdown) else markdown

    val options = new Options()
    options.setBreaks(enableLineBreaks)

    val renderer = new GitBucketMarkedRenderer(
      options,
      repository,
      branch,
      enableWikiLink,
      enableRefsLink,
      enableAnchor,
      enableTaskList,
      hasWritePermission,
      pages
    )

    Marked.marked(source, options, renderer)
  }

  /**
   * Extends markedj Renderer for GitBucket
   */
  class GitBucketMarkedRenderer(
    options: Options,
    repository: RepositoryService.RepositoryInfo,
    branch: String,
    enableWikiLink: Boolean,
    enableRefsLink: Boolean,
    enableAnchor: Boolean,
    enableTaskList: Boolean,
    hasWritePermission: Boolean,
    pages: List[String]
  )(implicit val context: Context)
      extends Renderer(options)
      with LinkConverter
      with RequestCache {

    override def heading(text: String, level: Int, raw: String): String = {
      val id = generateAnchorName(text)
      val out = new StringBuilder()

      out.append("<h" + level + " id=\"" + options.getHeaderPrefix + id + "\"")

      if (enableAnchor) {
        out.append(" class=\"markdown-head\">")
        out.append(
          "<a class=\"markdown-anchor-link\" href=\"#" + id + "\"><span class=\"octicon octicon-link\"></span></a>"
        )
        out.append("<a class=\"markdown-anchor\" name=\"" + id + "\"></a>")
      } else {
        out.append(">")
      }

      out.append(text)
      out.append("</h" + level + ">\n")
      out.toString()
    }

    override def code(code: String, lang: String, escaped: Boolean): String = {
      "<pre class=\"prettyprint" + (if (lang != null) s" ${options.getLangPrefix}${lang}" else "") + "\">" +
        (if (escaped) code else escape(code, true)) + "</pre>"
    }

    override def list(body: String, ordered: Boolean): String = {
      var listType: String = null
      if (ordered) {
        listType = "ol"
      } else {
        listType = "ul"
      }
      if (body.contains("""class="task-list-item-checkbox"""")) {
        "<" + listType + " class=\"task-list\">\n" + body + "</" + listType + ">\n"
      } else {
        "<" + listType + ">\n" + body + "</" + listType + ">\n"
      }
    }

    override def listitem(text: String): String = {
      if (text.contains("""class="task-list-item-checkbox" """)) {
        "<li class=\"task-list-item\">" + text + "</li>\n"
      } else {
        "<li>" + text + "</li>\n"
      }
    }

    override def text(text: String): String = {
      // convert commit id and username to link.
      val t1 = if (enableRefsLink) convertRefsLinks(text, repository, "#", false) else text
      // convert task list to checkbox.
      val t2 = if (enableTaskList) convertCheckBox(t1, hasWritePermission) else t1
      // decorate by TextDecorator plugins
      helpers.decorateHtml(t2, repository)
    }

    override def link(href: String, title: String, text: String): String = {
      super.link(fixUrl(href, branch, false), title, text)
    }

    override def image(href: String, title: String, text: String): String = {
      super.image(fixUrl(href, branch, true), title, text)
    }

    override def nolink(text: String): String = {
      if (enableWikiLink && text.startsWith("[[") && text.endsWith("]]")) {
        val link = text.replaceAll("(^\\[\\[|\\]\\]$)", "")

        val (label, page) = if (link.contains('|')) {
          val i = link.indexOf('|')
          (link.substring(0, i), link.substring(i + 1))
        } else {
          (link, link)
        }

        val url = repository.httpUrl.replaceFirst("/git/", "/").stripSuffix(".git") + "/wiki/" + StringUtil.urlEncode(
          page
        )
        if (pages.contains(page)) {
          "<a href=\"" + url + "\">" + escape(label) + "</a>"
        } else {
          "<a href=\"" + url + "\" class=\"absent\">" + escape(label) + "</a>"
        }
      } else {
        escape(text)
      }
    }

    private def fixUrl(url: String, branch: String, isImage: Boolean = false): String = {
      lazy val urlWithRawParam: String = url + (if (isImage && !url.endsWith("?raw=true")) "?raw=true" else "")

      if (url.startsWith("http://") || url.startsWith("https://") || url.startsWith("mailto:") || url.startsWith("/")) {
        url
      } else if (url.startsWith("#")) {
        ("#" + generateAnchorName(url.substring(1)))
      } else if (!enableWikiLink) {
        if (context.currentPath.contains("/blob/")) {
          urlWithRawParam
        } else {
          repository.httpUrl.replaceFirst("/git/", "/").stripSuffix(".git") + "/blob/" + branch + "/" + urlWithRawParam
        }
      } else {
        repository.httpUrl.replaceFirst("/git/", "/").stripSuffix(".git") + "/wiki/_blob/" + url
      }
    }

  }

  def escapeTaskList(text: String): String = {
    Pattern.compile("""^( *)- \[([x| ])\] """, Pattern.MULTILINE).matcher(text).replaceAll("$1* task:$2: ")
  }

  def generateAnchorName(text: String): String = {
    val normalized = Normalizer.normalize(text.replaceAll("<.*>", "").replaceAll("[\\s]", "-"), Normalizer.Form.NFD)
    val encoded = StringUtil.urlEncode(normalized)
    encoded.toLowerCase(Locale.ENGLISH)
  }

  def convertCheckBox(text: String, hasWritePermission: Boolean): String = {
    val disabled = if (hasWritePermission) "" else "disabled"
    text
      .replaceAll(
        "task:x:",
        """<input type="checkbox" class="task-list-item-checkbox" checked="checked" """ + disabled + "/>"
      )
      .replaceAll("task: :", """<input type="checkbox" class="task-list-item-checkbox" """ + disabled + "/>")
  }

}