class WikiPage < ApplicationRecord
  class RevertError < Exception ; end

  before_save :normalize_title
  before_save :normalize_other_names
  after_save :create_version
  validates_uniqueness_of :title, :case_sensitive => false
  validates_presence_of :title
  validates_presence_of :body, :unless => -> { is_deleted? || other_names.present? }
  validate :validate_rename
  validate :validate_not_locked

  attr_accessor :skip_secondary_validations
  array_attribute :other_names
  belongs_to_creator
  belongs_to_updater
  has_one :tag, :foreign_key => "name", :primary_key => "title"
  has_one :artist, -> {where(:is_active => true)}, :foreign_key => "name", :primary_key => "title"
  has_many :versions, -> {order("wiki_page_versions.id ASC")}, :class_name => "WikiPageVersion", :dependent => :destroy

  module SearchMethods
    def titled(title)
      where("title = ?", title.mb_chars.downcase.tr(" ", "_"))
    end

    def active
      where("is_deleted = false")
    end

    def recent
      order("updated_at DESC").limit(25)
    end

    def other_names_include(name)
      name = normalize_other_name(name).downcase
      subquery = WikiPage.from("unnest(other_names) AS other_name").where("lower(other_name) = ?", name)
      where(id: subquery)
    end

    def other_names_match(name)
      if name =~ /\*/
        subquery = WikiPage.from("unnest(other_names) AS other_name").where("other_name ILIKE ?", name.to_escaped_for_sql_like)
        where(id: subquery)
      else
        other_names_include(name)
      end
    end

    def default_order
      order(updated_at: :desc)
    end

    def search(params = {})
      q = super

      if params[:title].present?
        q = q.where("title LIKE ? ESCAPE E'\\\\'", params[:title].mb_chars.downcase.strip.tr(" ", "_").to_escaped_for_sql_like)
      end

      q = q.search_attributes(params, :creator, :is_locked, :is_deleted)
      q = q.text_attribute_matches(:body, params[:body_matches], index_column: :body_index, ts_config: "danbooru")

      if params[:other_names_match].present?
        q = q.other_names_match(params[:other_names_match])
      end

      if params[:hide_deleted].to_s.truthy?
        q = q.where("is_deleted = false")
      end

      if params[:other_names_present].to_s.truthy?
        q = q.where("other_names is not null and other_names != '{}'")
      elsif params[:other_names_present].to_s.falsy?
        q = q.where("other_names is null or other_names = '{}'")
      end

      params[:order] ||= params.delete(:sort)
      case params[:order]
      when "title"
        q = q.order("title")
      when "post_count"
        q = q.includes(:tag).order("tags.post_count desc nulls last").references(:tags)
      else
        q = q.apply_default_order(params)
      end

      q
    end
  end

  module ApiMethods
    def hidden_attributes
      super + [:body_index]
    end

    def method_attributes
      super + [:creator_name, :category_name]
    end
  end

  def creator_name
    creator.name
  end

  extend SearchMethods
  include ApiMethods

  def validate_not_locked
    if is_locked? && !CurrentUser.is_builder?
      errors.add(:is_locked, "and cannot be updated")
    end
  end

  def validate_rename
    return if !will_save_change_to_title? || skip_secondary_validations

    tag_was = Tag.find_by_name(Tag.normalize_name(title_was))
    if tag_was.present? && tag_was.post_count > 0
      errors.add(:title, "cannot be changed: '#{tag_was.name}' still has #{tag_was.post_count} posts. Move the posts and update any wikis linking to this page first.")
    end
  end

  def revert_to(version)
    if id != version.wiki_page_id
      raise RevertError.new("You cannot revert to a previous version of another wiki page.")
    end

    self.title = version.title
    self.body = version.body
    self.is_locked = version.is_locked
    self.other_names = version.other_names
  end

  def revert_to!(version)
    revert_to(version)
    save!
  end

  def normalize_title
    self.title = title.mb_chars.downcase.tr(" ", "_")
  end

  def normalize_other_names
    self.other_names = other_names.map { |name| WikiPage.normalize_other_name(name) }.uniq
  end

  def self.normalize_other_name(name)
    name.unicode_normalize(:nfkc).gsub(/[[:space:]]+/, " ").strip.tr(" ", "_")
  end

  def skip_secondary_validations=(value)
    @skip_secondary_validations = value.to_s.truthy?
  end

  def category_name
    Tag.category_for(title)
  end

  def pretty_title
    title.tr("_", " ")
  end

  def wiki_page_changed?
    saved_change_to_title? || saved_change_to_body? || saved_change_to_is_locked? || saved_change_to_is_deleted? || saved_change_to_other_names?
  end

  def merge_version
    prev = versions.last
    prev.update(title: title, body: body, is_locked: is_locked, is_deleted: is_deleted, other_names: other_names)
  end

  def merge_version?
    prev = versions.last
    prev && prev.updater_id == CurrentUser.user.id && prev.updated_at > 1.hour.ago
  end

  def create_new_version
    versions.create(
      :updater_id => CurrentUser.user.id,
      :updater_ip_addr => CurrentUser.ip_addr,
      :title => title,
      :body => body,
      :is_locked => is_locked,
      :is_deleted => is_deleted,
      :other_names => other_names
    )
  end

  def create_version
    if wiki_page_changed?
      if merge_version?
        merge_version
      else
        create_new_version
      end
    end
  end

  def post_set
    @post_set ||= PostSets::WikiPage.new(title, 1, 4)
  end

  def presenter
    @presenter ||= WikiPagePresenter.new(self)
  end

  def tags
    body.scan(/\[\[(.+?)\]\]/).flatten.map do |match|
      if match =~ /^(.+?)\|(.+)/
        $1
      else
        match
      end
    end.map {|x| x.mb_chars.downcase.tr(" ", "_").to_s}.uniq
  end

  def visible?
    artist.blank? || !artist.is_banned? || CurrentUser.is_builder?
  end
end