require_dependency 'post_creator'
require_dependency 'new_post_result'
require_dependency 'word_watcher'

# Determines what actions should be taken with new posts.
#
# The default action is to create the post, but this can be extended
# with `NewPostManager.add_handler` to take other approaches depending
# on the user or input.
class NewPostManager

  attr_reader :user, :args

  def self.sorted_handlers
    @sorted_handlers ||= clear_handlers!
  end

  def self.handlers
    sorted_handlers.map { |h| h[:proc] }
  end

  def self.clear_handlers!
    @sorted_handlers = [{ priority: 0, proc: method(:default_handler) }]
  end

  def self.add_handler(priority = 0, &block)
    sorted_handlers << { priority: priority, proc: block }
    @sorted_handlers.sort_by! { |h| -h[:priority] }
  end

  def self.is_first_post?(manager)
    user = manager.user
    args = manager.args

    !!(
      args[:first_post_checks] &&
      user.post_count == 0
    )
  end

  def self.is_fast_typer?(manager)
    args = manager.args

    is_first_post?(manager) &&
    args[:typing_duration_msecs].to_i < SiteSetting.min_first_post_typing_time &&
    SiteSetting.auto_silence_fast_typers_on_first_post &&
    manager.user.trust_level <= SiteSetting.auto_silence_fast_typers_max_trust_level
  end

  def self.matches_auto_silence_regex?(manager)
    args = manager.args

    pattern = SiteSetting.auto_silence_first_post_regex

    return false unless pattern.present?
    return false unless is_first_post?(manager)

    begin
      regex = Regexp.new(pattern, Regexp::IGNORECASE)
    rescue => e
      Rails.logger.warn "Invalid regex in auto_silence_first_post_regex #{e}"
      return false
    end

    "#{args[:title]} #{args[:raw]}" =~ regex

  end

  def self.exempt_user?(user)
    user.staff?
  end

  def self.post_needs_approval?(manager)
    user = manager.user

    return :skip if exempt_user?(user)

    return :post_count if (
      user.trust_level <= TrustLevel.levels[:basic] &&
      user.post_count < SiteSetting.approve_post_count
    )

    return :trust_level if user.trust_level < SiteSetting.approve_unless_trust_level.to_i

    return :new_topics_unless_trust_level if (
      manager.args[:title].present? &&
      user.trust_level < SiteSetting.approve_new_topics_unless_trust_level.to_i
    )

    return :fast_typer if is_fast_typer?(manager)

    return :auto_silence_regex if matches_auto_silence_regex?(manager)

    return :watched_word if WordWatcher.new("#{manager.args[:title]} #{manager.args[:raw]}").requires_approval?

    return :staged if SiteSetting.approve_unless_staged? && user.staged?

    return :category if post_needs_approval_in_its_category?(manager)

    :skip
  end

  def self.post_needs_approval_in_its_category?(manager)
    if manager.args[:topic_id].present?
      cat = Category.joins(:topics).find_by(topics: { id: manager.args[:topic_id] })
      return false unless cat
      cat.require_reply_approval?
    elsif manager.args[:category].present?
      Category.find(manager.args[:category]).require_topic_approval?
    else
      false
    end
  end

  def self.default_handler(manager)

    reason = post_needs_approval?(manager)
    return if reason == :skip

    validator = Validators::PostValidator.new
    post = Post.new(raw: manager.args[:raw])
    post.user = manager.user
    validator.validate(post)

    if post.errors[:raw].present?
      result = NewPostResult.new(:created_post, false)
      result.errors[:base] << post.errors[:raw]
      return result
    elsif manager.args[:topic_id]
      topic = Topic.unscoped.where(id: manager.args[:topic_id]).first

      unless manager.user.guardian.can_create_post_on_topic?(topic)
        result = NewPostResult.new(:created_post, false)
        result.errors[:base] << I18n.t(:topic_not_found)
        return result
      end
    elsif manager.args[:category]
      category = Category.find_by(id: manager.args[:category])

      unless manager.user.guardian.can_create_topic_on_category?(category)
        result = NewPostResult.new(:created_post, false)
        result.errors[:base] << I18n.t("js.errors.reasons.forbidden")
        return result
      end
    end

    result = manager.enqueue(reason)

    if is_fast_typer?(manager)
      UserSilencer.silence(manager.user, Discourse.system_user, keep_posts: true, reason: I18n.t("user.new_user_typed_too_fast"))
    elsif matches_auto_silence_regex?(manager)
      UserSilencer.silence(manager.user, Discourse.system_user, keep_posts: true, reason: I18n.t("user.content_matches_auto_silence_regex"))
    end

    result
  end

  def self.queue_enabled?
    SiteSetting.approve_post_count > 0 ||
    SiteSetting.approve_unless_trust_level.to_i > 0 ||
    SiteSetting.approve_new_topics_unless_trust_level.to_i > 0 ||
    SiteSetting.approve_unless_staged ||
    WordWatcher.words_for_action_exists?(:require_approval) ||
    handlers.size > 1
  end

  def initialize(user, args)
    @user = user
    @args = args.delete_if { |_, v| v.nil? }
  end

  def perform
    if !self.class.exempt_user?(@user) && matches = WordWatcher.new("#{@args[:title]} #{@args[:raw]}").should_block?
      result = NewPostResult.new(:created_post, false)
      result.errors[:base] << I18n.t('contains_blocked_words', word: matches[0])
      return result
    end

    # We never queue private messages
    return perform_create_post if @args[:archetype] == Archetype.private_message

    if args[:topic_id] && Topic.where(id: args[:topic_id], archetype: Archetype.private_message).exists?
      return perform_create_post
    end

    # Perform handlers until one returns a result
    handled = NewPostManager.handlers.any? do |handler|
      result = handler.call(self)
      return result if result

      false
    end

    perform_create_post unless handled
  end

  # Enqueue this post
  def enqueue(reason = nil)
    result = NewPostResult.new(:enqueued)

    reviewable = ReviewableQueuedPost.new(
      created_by: @user,
      payload: { raw: @args[:raw], tags: @args[:tags] },
      topic_id: @args[:topic_id],
      reviewable_by_moderator: true
    )
    reviewable.payload['title'] = @args[:title] if @args[:title].present?
    reviewable.category_id = args[:category] if args[:category].present?

    create_options = reviewable.create_options

    creator = @args[:topic_id] ?
      PostCreator.new(@user, create_options) :
      TopicCreator.new(@user, Guardian.new(@user), create_options)

    errors = Set.new
    creator.valid?
    creator.errors.full_messages.each { |msg| errors << msg }
    errors = creator.errors.full_messages.uniq
    if errors.blank?
      if reviewable.save
        reviewable.add_score(
          Discourse.system_user,
          ReviewableScore.types[:needs_approval],
          reason: reason,
          force_review: true
        )
      else
        reviewable.errors.full_messages.each { |msg| errors << msg }
      end
    end

    result.reviewable = reviewable
    result.reason = reason if reason
    result.check_errors(errors)
    result.pending_count = Reviewable.where(created_by: @user).pending.count
    result
  end

  def perform_create_post
    result = NewPostResult.new(:create_post)
    creator = PostCreator.new(@user, @args)
    post = creator.create
    result.check_errors_from(creator)

    if result.success?
      result.post = post
    else
      @user.flag_linked_posts_as_spam if creator.spam?
    end

    result
  end

end