require_dependency 'search/grouped_search_results'

class Search

  def self.per_facet
    5
  end

  def self.per_filter
    50
  end

  # Sometimes we want more topics than are returned due to exclusion of dupes. This is the
  # factor of extra results we'll ask for.
  def self.burst_factor
    3
  end

  def self.facets
    %w(topic category user private_messages)
  end

  def self.long_locale
    # if adding a language see:
    # /usr/share/postgresql/9.3/tsearch_data for possible options
    # Do not add languages that are missing without amending the
    # base docker config
    #
    case SiteSetting.default_locale.to_sym
      when :da     then 'danish'
      when :de     then 'german'
      when :en     then 'english'
      when :es     then 'spanish'
      when :fr     then 'french'
      when :it     then 'italian'
      when :nl     then 'dutch'
      when :nb_NO  then 'norwegian'
      when :pt     then 'portuguese'
      when :pt_BR  then 'portuguese'
      when :sv     then 'swedish'
      when :ru     then 'russian'
      else 'simple' # use the 'simple' stemmer for other languages
    end
  end

  def self.rebuild_problem_posts(limit = 10000)
    posts = Post.joins(:topic)
            .where('posts.id IN (
               SELECT p2.id FROM posts p2
               LEFT JOIN post_search_data pd ON locale = ? AND p2.id = pd.post_id
               WHERE pd.post_id IS NULL
              )', SiteSetting.default_locale).limit(10000)

    posts.find_each do |post|
      # force indexing
      post.cooked += " "
      SearchIndexer.index(post)
    end

    posts = Post.joins(:topic)
            .where('posts.id IN (
               SELECT p2.id FROM posts p2
               LEFT JOIN topic_search_data pd ON locale = ? AND p2.topic_id = pd.topic_id
               WHERE pd.topic_id IS NULL AND p2.post_number = 1
              )', SiteSetting.default_locale).limit(10000)

    posts.find_each do |post|
      # force indexing
      post.cooked += " "
      SearchIndexer.index(post)
    end

    nil
  end

  def self.prepare_data(search_data)
    data = search_data.squish
    # TODO rmmseg is designed for chinese, we need something else for Korean / Japanese
    if ['zh_TW', 'zh_CN', 'ja', 'ko'].include?(SiteSetting.default_locale) || SiteSetting.search_tokenize_chinese_japanese_korean
      unless defined? RMMSeg
        require 'rmmseg'
        RMMSeg::Dictionary.load_dictionaries
      end

      algo = RMMSeg::Algorithm.new(search_data)

      data = ""
      while token = algo.next_token
        data << token.text << " "
      end
    end

    data.force_encoding("UTF-8")
    data
  end

  def self.word_to_date(str)

    if str =~ /^[0-9]{1,3}$/
      return Time.zone.now.beginning_of_day.days_ago(str.to_i)
    end

    if str =~ /^([12][0-9]{3})(-([0-1]?[0-9]))?(-([0-3]?[0-9]))?$/
      year = $1.to_i
      month = $2 ? $3.to_i : 1
      day = $4 ? $5.to_i : 1

      return if day==0 || month==0 || day > 31 || month > 12

      return Time.zone.parse("#{year}-#{month}-#{day}") rescue nil
    end

    if str.downcase == "yesterday"
      return Time.zone.now.beginning_of_day.yesterday
    end

    titlecase = str.downcase.titlecase

    if Date::DAYNAMES.include?(titlecase)
      return Time.zone.now.beginning_of_week(str.downcase.to_sym)
    end

    if idx = (Date::MONTHNAMES.find_index(titlecase) ||
              Date::ABBR_MONTHNAMES.find_index(titlecase))
      delta = Time.zone.now.month - idx
      delta += 12 if delta < 0
      Time.zone.now.beginning_of_month.months_ago(delta)
    end
  end

  def self.min_post_id_no_cache
    return 0 unless SiteSetting.search_prefer_recent_posts?


    offset, has_more = Post.unscoped
                           .order('id desc')
                           .offset(SiteSetting.search_recent_posts_size-1)
                           .limit(2)
                           .pluck(:id)

    has_more ? offset : 0
  end

  def self.min_post_id(opts=nil)
    return 0 unless SiteSetting.search_prefer_recent_posts?

    # It can be quite slow to count all the posts so let's cache it
    Rails.cache.fetch("search-min-post-id:#{SiteSetting.search_recent_posts_size}", expires_in: 1.week) do
      min_post_id_no_cache
    end
  end

  attr_accessor :term

  def initialize(term, opts=nil)
    @opts = opts || {}
    @guardian = @opts[:guardian] || Guardian.new
    @search_context = @opts[:search_context]
    @include_blurbs = @opts[:include_blurbs] || false
    @blurb_length = @opts[:blurb_length]
    @limit = Search.per_facet
    @valid = true

    term = process_advanced_search!(term)

    if term.present?
      @term = Search.prepare_data(term.to_s)
      @original_term = PG::Connection.escape_string(@term)
    end

    if @search_pms && @guardian.user
      @opts[:type_filter] = "private_messages"
      @search_context = @guardian.user
    end

    if @opts[:type_filter].present?
      @limit = Search.per_filter
    end

    @results = GroupedSearchResults.new(@opts[:type_filter], term, @search_context, @include_blurbs, @blurb_length)
  end

  def valid?
    @valid
  end

  def self.execute(term, opts=nil)
    self.new(term, opts).execute
  end

  # Query a term
  def execute

    unless @filters.present?
      min_length = @opts[:min_search_term_length] || SiteSetting.min_search_term_length
      terms = (@term || '').split(/\s(?=(?:[^"]|"[^"]*")*$)/).reject {|t| t.length < min_length }

      if terms.blank?
        @term = ''
        @valid = false
        return
      end
    end

    # If the term is a number or url to a topic, just include that topic
    if @opts[:search_for_id] && @results.type_filter == 'topic'
      if @term =~ /^\d+$/
        single_topic(@term.to_i)
      else
        begin
          route = Rails.application.routes.recognize_path(@term)
          single_topic(route[:topic_id]) if route[:topic_id].present?
        rescue ActionController::RoutingError
        end
      end
    end

    find_grouped_results unless @results.posts.present?

    @results
  end

  def self.advanced_filter(trigger,&block)
    (@advanced_filters ||= {})[trigger] = block
  end

  def self.advanced_filters
    @advanced_filters
  end

  advanced_filter(/status:open/) do |posts|
    posts.where('NOT topics.closed AND NOT topics.archived')
  end

  advanced_filter(/status:closed/) do |posts|
    posts.where('topics.closed')
  end

  advanced_filter(/status:archived/) do |posts|
    posts.where('topics.archived')
  end

  advanced_filter(/status:noreplies/) do |posts|
    posts.where("topics.posts_count = 1")
  end

  advanced_filter(/status:single_user/) do |posts|
    posts.where("topics.participant_count = 1")
  end

  advanced_filter(/posts_count:(\d+)/) do |posts, match|
    posts.where("topics.posts_count = ?", match.to_i)
  end

  advanced_filter(/min_post_count:(\d+)/) do |posts, match|
    posts.where("topics.posts_count >= ?", match.to_i)
  end

  advanced_filter(/in:first/) do |posts|
    posts.where("posts.post_number = 1")
  end

  advanced_filter(/in:pinned/) do |posts|
    posts.where("topics.pinned_at IS NOT NULL")
  end

  advanced_filter(/in:unpinned/) do |posts|
    if @guardian.user
      posts.where("topics.pinned_at IS NOT NULL AND topics.id IN (
                  SELECT topic_id FROM topic_users WHERE user_id = ? AND cleared_pinned_at IS NOT NULL
                 )", @guardian.user.id)
    end
  end

  advanced_filter(/in:wiki/) do |posts,match|
    posts.where(wiki: true)
  end

  advanced_filter(/badge:(.*)/) do |posts,match|
    badge_id = Badge.where('name ilike ? OR id = ?', match, match.to_i).pluck(:id).first
    if badge_id
      posts.where('posts.user_id IN (SELECT ub.user_id FROM user_badges ub WHERE ub.badge_id = ?)', badge_id)
    else
      posts.where("1 = 0")
    end
  end

  advanced_filter(/in:(likes|bookmarks)/) do |posts, match|
    if @guardian.user
      post_action_type = PostActionType.types[:like] if match == "likes"
      post_action_type = PostActionType.types[:bookmark] if match == "bookmarks"

      posts.where("posts.id IN (
                            SELECT pa.post_id FROM post_actions pa
                            WHERE pa.user_id = #{@guardian.user.id} AND
                                  pa.post_action_type_id = #{post_action_type} AND
                                  deleted_at IS NULL
                         )")
    end
  end

  advanced_filter(/in:posted/) do |posts|
    posts.where("posts.user_id = #{@guardian.user.id}") if @guardian.user
  end

  advanced_filter(/in:(watching|tracking)/) do |posts,match|
    if @guardian.user
      level = TopicUser.notification_levels[match.to_sym]
      posts.where("posts.topic_id IN (
                    SELECT tu.topic_id FROM topic_users tu
                    WHERE tu.user_id = :user_id AND
                          tu.notification_level >= :level
                   )", user_id: @guardian.user.id, level: level)

    end
  end

  advanced_filter(/in:seen/) do |posts|
    if @guardian.user
      posts
        .joins("INNER JOIN post_timings ON
          post_timings.topic_id = posts.topic_id
          AND post_timings.post_number = posts.post_number
          AND post_timings.user_id = #{Post.sanitize(@guardian.user.id)}
        ")
    end
  end

  advanced_filter(/in:unseen/) do |posts|
    if @guardian.user
      posts
        .joins("LEFT JOIN post_timings ON
          post_timings.topic_id = posts.topic_id
          AND post_timings.post_number = posts.post_number
          AND post_timings.user_id = #{Post.sanitize(@guardian.user.id)}
        ")
        .where("post_timings.user_id IS NULL")
    end
  end

  advanced_filter(/category:(.+)/) do |posts,match|
    exact = false

    if match[0] == "="
      exact = true
      match = match[1..-1]
    end

    category_ids = Category.where('slug ilike ? OR name ilike ? OR id = ?',
                                  match, match, match.to_i).pluck(:id)
    if category_ids.present?

      unless exact
        category_ids +=
          Category.where('parent_category_id = ?', category_ids.first).pluck(:id)
      end

      posts.where("topics.category_id IN (?)", category_ids)
    else
      posts.where("1 = 0")
    end
  end

  advanced_filter(/^\#([a-zA-Z0-9\-:=]+)/) do |posts,match|

    exact = true

    slug = match.to_s.split(":")
    if slug[1]
      # sub category
      parent_category_id = Category.where(slug: slug[0].downcase, parent_category_id: nil).pluck(:id).first
      category_id = Category.where(slug: slug[1].downcase, parent_category_id: parent_category_id).pluck(:id).first
    else
      # main category
      if slug[0][0] == "="
        slug[0] = slug[0][1..-1]
      else
        exact = false
      end

      category_id = Category.where(slug: slug[0].downcase)
        .order('case when parent_category_id is null then 0 else 1 end')
        .pluck(:id)
        .first
    end

    if category_id
      category_ids = [category_id]

      unless exact
        category_ids +=
          Category.where('parent_category_id = ?', category_id).pluck(:id)
      end
      posts.where("topics.category_id IN (?)", category_ids)
    else
      posts.where("topics.id IN (
        SELECT DISTINCT(tt.topic_id)
        FROM topic_tags tt, tags
        WHERE tt.tag_id = tags.id
        AND tags.name = ?
        )", slug[0])
    end
  end

  advanced_filter(/group:(.+)/) do |posts,match|
    group_id = Group.where('name ilike ? OR (id = ? AND id > 0)', match, match.to_i).pluck(:id).first
    if group_id
      posts.where("posts.user_id IN (select gu.user_id from group_users gu where gu.group_id = ?)", group_id)
    else
      posts.where("1 = 0")
    end
  end

  advanced_filter(/user:(.+)/) do |posts,match|
    user_id = User.where(staged: false).where('username_lower = ? OR id = ?', match.downcase, match.to_i).pluck(:id).first
    if user_id
      posts.where("posts.user_id = #{user_id}")
    else
      posts.where("1 = 0")
    end
  end

  advanced_filter(/^\@([a-zA-Z0-9_\-.]+)/) do |posts,match|
    user_id = User.where(staged: false).where(username_lower: match.downcase).pluck(:id).first
    if user_id
      posts.where("posts.user_id = #{user_id}")
    else
      posts.where("1 = 0")
    end
  end

  advanced_filter(/before:(.*)/) do |posts,match|
    if date = Search.word_to_date(match)
      posts.where("posts.created_at < ?", date)
    else
      posts
    end
  end

  advanced_filter(/after:(.*)/) do |posts,match|
    if date = Search.word_to_date(match)
      posts.where("posts.created_at > ?", date)
    else
      posts
    end
  end

  advanced_filter(/tags?:([a-zA-Z0-9,\-_]+)/) do |posts, match|
    tags = match.split(",")

    posts.where("topics.id IN (
      SELECT DISTINCT(tt.topic_id)
      FROM topic_tags tt, tags
      WHERE tt.tag_id = tags.id
      AND tags.name in (?)
      )", tags)
  end

  private


    def process_advanced_search!(term)

      term.to_s.scan(/(([^" \t\n\x0B\f\r]+)?(("[^"]+")?))/).to_a.map do |(word,_)|
        next if word.blank?

        found = false

        Search.advanced_filters.each do |matcher, block|
          cleaned = word.gsub(/["']/,"")
          if cleaned =~ matcher
            (@filters ||= []) << [block, $1]
            found = true
          end
        end

        if word == 'order:latest' || word == 'l'
          @order = :latest
          nil
        elsif word == 'order:latest_topic'
          @order = :latest_topic
          nil
        elsif word =~ /topic:(\d+)/
          topic_id = $1.to_i
          if topic_id > 1
            topic = Topic.find_by(id: topic_id)
            if @guardian.can_see?(topic)
              @search_context = topic
            end
          end
          nil
        elsif word == 'order:views'
          @order = :views
          nil
        elsif word == 'order:likes'
          @order = :likes
          nil
        elsif word == 'in:private'
          @search_pms = true
          nil
        elsif word =~ /^private_messages:(.+)$/
          @search_pms = true
          nil
        else
          found ? nil : word
        end
      end.compact.join(' ')
    end


    def find_grouped_results

      if @results.type_filter.present?
        raise Discourse::InvalidAccess.new("invalid type filter") unless Search.facets.include?(@results.type_filter)
        send("#{@results.type_filter}_search")
      else
        @limit = Search.per_facet + 1
        unless @search_context
          user_search if @term.present?
          category_search if @term.present?
        end
        topic_search
      end

      add_more_topics_if_expected
      @results
    rescue ActiveRecord::StatementInvalid
      # In the event of a PG:Error return nothing, it is likely they used a foreign language whose
      # locale is not supported by postgres
    end

    # Add more topics if we expected them
    def add_more_topics_if_expected
      expected_topics = 0
      expected_topics = Search.facets.size unless @results.type_filter.present?
      expected_topics = Search.per_facet * Search.facets.size if @results.type_filter == 'topic'
      expected_topics -= @results.posts.length
      if expected_topics > 0
        extra_posts = posts_query(expected_topics * Search.burst_factor)
        extra_posts = extra_posts.where("posts.topic_id NOT in (?)", @results.posts.map(&:topic_id)) if @results.posts.present?
        extra_posts.each do |post|
          @results.add(post)
          expected_topics -= 1
          break if expected_topics == 0
        end
      end
    end

    # If we're searching for a single topic
    def single_topic(id)
      post = Post.find_by(topic_id: id, post_number: 1)
      return nil unless @guardian.can_see?(post)

      @results.add(post)
      @results
    end

    def secure_category_ids
      return @secure_category_ids unless @secure_category_ids.nil?
      @secure_category_ids = @guardian.secure_category_ids
    end

    def category_search
      # scope is leaking onto Category, this is not good and probably a bug in Rails
      # the secure_category_ids will invoke the same method on User, it calls Category.where
      # however the scope from the query below is leaking in to Category, this works around
      # the issue while we figure out what is up in Rails
      secure_category_ids

      categories = Category.includes(:category_search_data)
                           .where("category_search_data.search_data @@ #{ts_query}")
                           .references(:category_search_data)
                           .order("topics_month DESC")
                           .secured(@guardian)
                           .limit(@limit)

      categories.each do |category|
        @results.add(category)
      end
    end

    def user_search
      return if SiteSetting.hide_user_profiles_from_public && !@guardian.user

      users = User.includes(:user_search_data)
                  .references(:user_search_data)
                  .where(active: true)
                  .where(staged: false)
                  .where("user_search_data.search_data @@ #{ts_query("simple")}")
                  .order("CASE WHEN username_lower = '#{@original_term.downcase}' THEN 0 ELSE 1 END")
                  .order("last_posted_at DESC")
                  .limit(@limit)

      users.each do |user|
        @results.add(user)
      end
    end

    def posts_query(limit, opts=nil)
      opts ||= {}
      posts = Post.where(post_type: Topic.visible_post_types(@guardian.user))
                  .joins(:post_search_data, :topic)
                  .joins("LEFT JOIN categories ON categories.id = topics.category_id")
                  .where("topics.deleted_at" => nil)
                  .where("topics.visible")

      is_topic_search = @search_context.present? && @search_context.is_a?(Topic)

      if opts[:private_messages] || (is_topic_search && @search_context.private_message?)
         posts = posts.where("topics.archetype =  ?", Archetype.private_message)

         unless @guardian.is_admin?
           posts = posts.private_posts_for_user(@guardian.user)
         end
      else
         posts = posts.where("topics.archetype <> ?", Archetype.private_message)
      end

      if @term.present?
        if is_topic_search

          term_without_quote = @term
          if @term =~ /"(.+)"/
            term_without_quote = $1
          end

          if @term =~ /'(.+)'/
            term_without_quote = $1
          end

          posts = posts.joins('JOIN users u ON u.id = posts.user_id')
          posts = posts.where("posts.raw  || ' ' || u.username || ' ' || COALESCE(u.name, '') ilike ?", "%#{term_without_quote}%")
        else
          posts = posts.where("post_search_data.search_data @@ #{ts_query}")

          exact_terms = @term.scan(/"([^"]+)"/).flatten
          exact_terms.each do |exact|
            posts = posts.where("posts.raw ilike ?", "%#{exact}%")
          end
        end
      end

      @filters.each do |block, match|
        if block.arity == 1
          posts = instance_exec(posts, &block) || posts
        else
          posts = instance_exec(posts, match, &block) || posts
        end
      end if @filters

      # If we have a search context, prioritize those posts first
      if @search_context.present?

        if @search_context.is_a?(User)

          if opts[:private_messages]
            posts = posts.private_posts_for_user(@search_context)
          else
            posts = posts.where("posts.user_id = #{@search_context.id}")
          end

        elsif @search_context.is_a?(Category)
          category_ids = [@search_context.id] + Category.where(parent_category_id: @search_context.id).pluck(:id)
          posts = posts.where("topics.category_id in (?)", category_ids)
        elsif @search_context.is_a?(Topic)
          posts = posts.where("topics.id = #{@search_context.id}")
                       .order("posts.post_number #{@order == :latest ? "DESC" : ""}")
        end

      end

      if @order == :latest || (@term.blank? && !@order)
        if opts[:aggregate_search]
          posts = posts.order("MAX(posts.created_at) DESC")
        else
          posts = posts.reorder("posts.created_at DESC")
        end
      elsif @order == :latest_topic
        if opts[:aggregate_search]
          posts = posts.order("MAX(topics.created_at) DESC")
        else
          posts = posts.order("topics.created_at DESC")
        end
      elsif @order == :views
        if opts[:aggregate_search]
          posts = posts.order("MAX(topics.views) DESC")
        else
          posts = posts.order("topics.views DESC")
        end
      elsif @order == :likes
        if opts[:aggregate_search]
          posts = posts.order("MAX(posts.like_count) DESC")
        else
          posts = posts.order("posts.like_count DESC")
        end
      else
        posts = posts.order("TS_RANK_CD(TO_TSVECTOR(#{query_locale}, topics.title), #{ts_query}) DESC")

        data_ranking = "TS_RANK_CD(post_search_data.search_data, #{ts_query})"
        if opts[:aggregate_search]
          posts = posts.order("SUM(#{data_ranking}) DESC")
        else
          posts = posts.order("#{data_ranking} DESC")
        end
        posts = posts.order("topics.bumped_at DESC")
      end

      if secure_category_ids.present?
        posts = posts.where("(categories.id IS NULL) OR (NOT categories.read_restricted) OR (categories.id IN (?))", secure_category_ids).references(:categories)
      else
        posts = posts.where("(categories.id IS NULL) OR (NOT categories.read_restricted)").references(:categories)
      end

      posts.limit(limit)
    end

    def self.query_locale
      "'#{Search.long_locale}'"
    end

    def query_locale
      self.class.query_locale
    end

    def self.ts_query(term, locale = nil, joiner = "&")

      data = Post.exec_sql("SELECT to_tsvector(:locale, :term)",
                            locale: 'simple',
                            term: term
                          ).values[0][0]

      locale = Post.sanitize(locale) if locale
      all_terms = data.scan(/'([^']+)'\:\d+/).flatten
      all_terms.map! do |t|
        t.split(/[\)\(&']/)[0]
      end.compact!

      query = Post.sanitize(all_terms.map {|t| "'#{PG::Connection.escape_string(t)}':*"}.join(" #{joiner} "))
      "TO_TSQUERY(#{locale || query_locale}, #{query})"
    end

    def ts_query(locale=nil)
      @ts_query_cache ||= {}
      @ts_query_cache[(locale || query_locale) + " " + @term] ||= Search.ts_query(@term, locale)
    end

    def wrap_rows(query)
      "SELECT *, row_number() over() row_number FROM (#{query.to_sql}) xxx"
    end

    def aggregate_post_sql(opts)
      min_or_max = @order == :latest ? "max" : "min"

      query =
        if @order == :likes
          # likes are a pain to aggregate so skip
          posts_query(@limit, private_messages: opts[:private_messages])
            .select('topics.id', "posts.post_number")
        else
          posts_query(@limit, aggregate_search: true, private_messages: opts[:private_messages])
            .select('topics.id', "#{min_or_max}(posts.post_number) post_number")
            .group('topics.id')
        end

      min_id = Search.min_post_id
      if min_id > 0
        low_set = query.dup.where("post_search_data.post_id < #{min_id}")
        high_set = query.where("post_search_data.post_id >= #{min_id}")

        return { default: wrap_rows(high_set), remaining: wrap_rows(low_set) }
      end

      # double wrapping so we get correct row numbers
      { default: wrap_rows(query) }
    end

    def aggregate_posts(post_sql)
      return [] unless post_sql

      posts_eager_loads(Post)
        .joins("JOIN (#{post_sql}) x ON x.id = posts.topic_id AND x.post_number = posts.post_number")
        .order('row_number')
    end

    def aggregate_search(opts = {})
      post_sql = aggregate_post_sql(opts)

      added = 0

      aggregate_posts(post_sql[:default]).each do |p|
        @results.add(p)
        added += 1
      end

      if added < @limit
        aggregate_posts(post_sql[:remaining]).each {|p| @results.add(p) }
      end
    end

    def private_messages_search
      raise Discourse::InvalidAccess.new("anonymous can not search PMs") unless @guardian.user

      aggregate_search(private_messages: true)
    end

    def topic_search
      if @search_context.is_a?(Topic)
        posts = posts_eager_loads(posts_query(@limit))
          .where('posts.topic_id = ?', @search_context.id)

        posts.each do |post|
          @results.add(post)
        end
      else
        aggregate_search
      end
    end

    def posts_eager_loads(query)
      query = query.includes(:user)
      topic_eager_loads = [:category]

      if SiteSetting.tagging_enabled
        topic_eager_loads << :tags
      end

      query.includes(topic: topic_eager_loads)
    end

end