require 'digest/sha1'
require 'fileutils'
require_dependency 'plugin/metadata'
require_dependency 'plugin/auth_provider'

class Plugin::CustomEmoji
  def self.cache_key
    @@cache_key ||= "plugin-emoji"
  end

  def self.emojis
    @@emojis ||= {}
  end

  def self.register(name, url)
    @@cache_key = Digest::SHA1.hexdigest(cache_key + name)[0..10]
    emojis[name] = url
  end
end

class Plugin::Instance

  attr_accessor :path, :metadata
  attr_reader :admin_route

  # Memoized array readers
  [:assets,
   :auth_providers,
   :color_schemes,
   :initializers,
   :javascripts,
   :styles,
   :themes].each do |att|
    class_eval %Q{
      def #{att}
        @#{att} ||= []
      end
    }
  end

  def seed_data
    @seed_data ||= HashWithIndifferentAccess.new({})
  end

  def self.find_all(parent_path)
    [].tap { |plugins|
      # also follows symlinks - http://stackoverflow.com/q/357754
      Dir["#{parent_path}/*/plugin.rb"].sort.each do |path|

        # tagging is included in core, so don't load it
        next if path =~ /discourse-tagging/

        source = File.read(path)
        metadata = Plugin::Metadata.parse(source)
        plugins << self.new(metadata, path)
      end
    }
  end

  def initialize(metadata = nil, path = nil)
    @metadata = metadata
    @path = path
    @idx = 0
  end

  def add_admin_route(label, location)
    @admin_route = { label: label, location: location }
  end

  def enabled?
    @enabled_site_setting ? SiteSetting.send(@enabled_site_setting) : true
  end

  delegate :name, to: :metadata

  def add_to_serializer(serializer, attr, define_include_method = true, &block)
    reloadable_patch do |plugin|
      klass = "#{serializer.to_s.classify}Serializer".constantize rescue "#{serializer.to_s}Serializer".constantize

      unless attr.to_s.start_with?("include_")
        klass.attributes(attr)

        if define_include_method
          # Don't include serialized methods if the plugin is disabled
          klass.send(:define_method, "include_#{attr}?") { plugin.enabled? }
        end
      end

      klass.send(:define_method, attr, &block)
    end
  end

  def whitelist_staff_user_custom_field(field)
    reloadable_patch do |plugin|
      ::User.register_plugin_staff_custom_field(field, plugin) if plugin.enabled?
    end
  end

  def custom_avatar_column(column)
    reloadable_patch do |plugin|
      AvatarLookup.lookup_columns << column
      AvatarLookup.lookup_columns.uniq!
    end
  end

  def add_body_class(class_name)
    reloadable_patch do |plugin|
      ::ApplicationHelper.extra_body_classes << class_name if plugin.enabled?
    end
  end

  def rescue_from(exception, &block)
    reloadable_patch do |plugin|
      ::ApplicationController.rescue_from(exception, &block)
    end
  end

  # Extend a class but check that the plugin is enabled
  # for class methods use `add_class_method`
  def add_to_class(class_name, attr, &block)
    reloadable_patch do |plugin|
      klass = class_name.to_s.classify.constantize rescue class_name.to_s.constantize
      hidden_method_name = :"#{attr}_without_enable_check"
      klass.send(:define_method, hidden_method_name, &block)

      klass.send(:define_method, attr) do |*args|
        send(hidden_method_name, *args) if plugin.enabled?
      end
    end
  end

  # Adds a class method to a class, respecting if plugin is enabled
  def add_class_method(klass_name, attr, &block)
    reloadable_patch do |plugin|
      klass = klass_name.to_s.classify.constantize rescue klass_name.to_s.constantize

      hidden_method_name = :"#{attr}_without_enable_check"
      klass.send(:define_singleton_method, hidden_method_name, &block)

      klass.send(:define_singleton_method, attr) do |*args|
        send(hidden_method_name, *args) if plugin.enabled?
      end
    end
  end

  def add_model_callback(klass_name, callback, options = {}, &block)
    reloadable_patch do |plugin|
      klass = klass_name.to_s.classify.constantize rescue klass_name.to_s.constantize

      # generate a unique method name
      method_name = "#{plugin.name}_#{klass.name}_#{callback}#{@idx}".underscore
      @idx += 1
      hidden_method_name = :"#{method_name}_without_enable_check"
      klass.send(:define_method, hidden_method_name, &block)

      klass.send(callback, options) do |*args|
        send(hidden_method_name, *args) if plugin.enabled?
      end

      hidden_method_name
    end
  end

  def topic_view_post_custom_fields_whitelister(&block)
    reloadable_patch do |plugin|
      ::TopicView.add_post_custom_fields_whitelister(&block) if plugin.enabled?
    end
  end

  def add_preloaded_group_custom_field(field)
    reloadable_patch do |plugin|
      ::Group.preloaded_custom_field_names << field if plugin.enabled?
    end
  end

  def add_preloaded_topic_list_custom_field(field)
    reloadable_patch do |plugin|
      ::TopicList.preloaded_custom_fields << field if plugin.enabled?
    end
  end

  def add_permitted_post_create_param(name)
    reloadable_patch do |plugin|
      ::Post.permitted_create_params << name if plugin.enabled?
    end
  end

  # Add validation method but check that the plugin is enabled
  def validate(klass, name, &block)
    klass = klass.to_s.classify.constantize
    klass.send(:define_method, name, &block)

    plugin = self
    klass.validate(name, if: -> { plugin.enabled? })
  end

  # will make sure all the assets this plugin needs are registered
  def generate_automatic_assets!
    paths = []
    assets = []

    automatic_assets.each do |path, contents|
      write_asset(path, contents)
      paths << path
      assets << [path]
    end

    delete_extra_automatic_assets(paths)

    assets
  end

  def delete_extra_automatic_assets(good_paths)
    return unless Dir.exists? auto_generated_path

    filenames = good_paths.map { |f| File.basename(f) }
    # nuke old files
    Dir.foreach(auto_generated_path) do |p|
      next if [".", ".."].include?(p)
      next if filenames.include?(p)
      File.delete(auto_generated_path + "/#{p}")
    end
  end

  def ensure_directory(path)
    dirname = File.dirname(path)
    unless File.directory?(dirname)
      FileUtils.mkdir_p(dirname)
    end
  end

  def directory
    File.dirname(path)
  end

  def auto_generated_path
    File.dirname(path) << "/auto_generated"
  end

  def after_initialize(&block)
    initializers << block
  end

  # A proxy to `DiscourseEvent.on` which does nothing if the plugin is disabled
  def on(event_name, &block)
    DiscourseEvent.on(event_name) do |*args|
      block.call(*args) if enabled?
    end
  end

  def notify_after_initialize
    color_schemes.each do |c|
      unless ColorScheme.where(name: c[:name]).exists?
        ColorScheme.create_from_base(name: c[:name], colors: c[:colors])
      end
    end

    initializers.each do |callback|
      begin
        callback.call(self)
      rescue ActiveRecord::StatementInvalid => e
        # When running `db:migrate` for the first time on a new database,
        # plugin initializers might try to use models.
        # Tolerate it.
        raise e unless e.message.try(:include?, "PG::UndefinedTable")
      end
    end
  end

  def register_category_custom_field_type(name, type)
    reloadable_patch do |plugin|
      Category.register_custom_field_type(name, type) if plugin.enabled?
    end
  end

  def register_topic_custom_field_type(name, type)
    reloadable_patch do |plugin|
      ::Topic.register_custom_field_type(name, type) if plugin.enabled?
    end
  end

  def register_post_custom_field_type(name, type)
    reloadable_patch do |plugin|
      ::Post.register_custom_field_type(name, type) if plugin.enabled?
    end
  end

  def register_group_custom_field_type(name, type)
    reloadable_patch do |plugin|
      ::Group.register_custom_field_type(name, type) if plugin.enabled?
    end
  end

  def register_seedfu_fixtures(paths)
    paths = [paths] if !paths.kind_of?(Array)
    SeedFu.fixture_paths.concat(paths)
  end

  def listen_for(event_name)
    return unless self.respond_to?(event_name)
    DiscourseEvent.on(event_name, &self.method(event_name))
  end

  def register_css(style)
    styles << style
  end

  def register_javascript(js)
    javascripts << js
  end

  def register_custom_html(hash)
    DiscoursePluginRegistry.custom_html ||= {}
    DiscoursePluginRegistry.custom_html.merge!(hash)
  end

  def register_html_builder(name, &block)
    DiscoursePluginRegistry.register_html_builder(name, &block)
  end

  def register_asset(file, opts = nil)
    full_path = File.dirname(path) << "/assets/" << file
    assets << [full_path, opts]
  end

  def register_color_scheme(name, colors)
    color_schemes << { name: name, colors: colors }
  end

  def register_seed_data(key, value)
    seed_data[key] = value
  end

  def register_emoji(name, url)
    Plugin::CustomEmoji.register(name, url)
  end

  def automatic_assets
    css = styles.join("\n")
    js = javascripts.join("\n")

    auth_providers.each do |auth|

      auth_json = auth.to_json
      hash = Digest::SHA1.hexdigest(auth_json)
      js << <<JS
define("discourse/initializers/login-method-#{hash}",
  ["discourse/models/login-method", "exports"],
  function(module, __exports__) {
    "use strict";
    __exports__["default"] = {
      name: "login-method-#{hash}",
      after: "inject-objects",
      initialize: function(container) {
        if (Ember.testing) { return; }

        var authOpts = #{auth_json};
        authOpts.siteSettings = container.lookup('site-settings:main');
        module.register(authOpts);
      }
    };
  });
JS

      if auth.glyph
        css << ".btn-social.#{auth.name}:before{ content: '#{auth.glyph}'; }\n"
      end

      if auth.background_color
        css << ".btn-social.#{auth.name}{ background: #{auth.background_color}; }\n"
      end
    end

    # Generate an IIFE for the JS
    js = "(function(){#{js}})();" if js.present?

    result = []
    result << [css, 'css'] if css.present?
    result << [js, 'js'] if js.present?

    result.map do |asset, extension|
      hash = Digest::SHA1.hexdigest asset
      ["#{auto_generated_path}/plugin_#{hash}.#{extension}", asset]
    end
  end

  # note, we need to be able to parse seperately to activation.
  # this allows us to present information about a plugin in the UI
  # prior to activations
  def activate!

    if @path
      # Automatically include all ES6 JS and hbs files
      root_path = "#{File.dirname(@path)}/assets/javascripts"
      DiscoursePluginRegistry.register_glob(root_path, 'js.es6')
      DiscoursePluginRegistry.register_glob(root_path, 'hbs')

      admin_path = "#{File.dirname(@path)}/admin/assets/javascripts"
      DiscoursePluginRegistry.register_glob(admin_path, 'js.es6', admin: true)
      DiscoursePluginRegistry.register_glob(admin_path, 'hbs', admin: true)
    end

    self.instance_eval File.read(path), path
    if auto_assets = generate_automatic_assets!
      assets.concat(auto_assets)
    end

    register_assets! unless assets.blank?

    seed_data.each do |key, value|
      DiscoursePluginRegistry.register_seed_data(key, value)
    end

    # TODO: possibly amend this to a rails engine

    # Automatically include assets
    Rails.configuration.assets.paths << auto_generated_path
    Rails.configuration.assets.paths << File.dirname(path) + "/assets"
    Rails.configuration.assets.paths << File.dirname(path) + "/admin/assets"
    Rails.configuration.assets.paths << File.dirname(path) + "/test/javascripts"

    # Automatically include rake tasks
    Rake.add_rakelib(File.dirname(path) + "/lib/tasks")

    # Automatically include migrations
    Rails.configuration.paths["db/migrate"] << File.dirname(path) + "/db/migrate"

    public_data = File.dirname(path) + "/public"
    if Dir.exists?(public_data)
      target = Rails.root.to_s + "/public/plugins/"

      Discourse::Utils.execute_command('mkdir', '-p', target)
      target << name.gsub(/\s/, "_")
      # TODO a cleaner way of registering and unregistering
      Discourse::Utils.execute_command('rm', '-f', target)
      Discourse::Utils.execute_command('ln', '-s', public_data, target)
    end
  end

  def auth_provider(opts)
    provider = Plugin::AuthProvider.new

    Plugin::AuthProvider.auth_attributes.each do |sym|
      provider.send "#{sym}=", opts.delete(sym)
    end
    auth_providers << provider
  end

  # shotgun approach to gem loading, in future we need to hack bundler
  #  to at least determine dependencies do not clash before loading
  #
  # Additionally we want to support multiple ruby versions correctly and so on
  #
  # This is a very rough initial implementation
  def gem(name, version, opts = {})
    PluginGem.load(path, name, version, opts)
  end

  def enabled_site_setting(setting = nil)
    if setting
      @enabled_site_setting = setting
    else
      @enabled_site_setting
    end
  end

  def handlebars_includes
    assets.map do |asset, opts|
      next if opts == :admin
      next unless asset =~ DiscoursePluginRegistry::HANDLEBARS_REGEX
      asset
    end.compact
  end

  def javascript_includes
    assets.map do |asset, opts|
      next if opts == :admin
      next unless asset =~ DiscoursePluginRegistry::JS_REGEX
      asset
    end.compact
  end

  def each_globbed_asset
    if @path
      # Automatically include all ES6 JS and hbs files
      root_path = "#{File.dirname(@path)}/assets/javascripts"

      Dir.glob("#{root_path}/**/*") do |f|
        if File.directory?(f)
          yield [f, true]
        elsif f.to_s.ends_with?(".js.es6") || f.to_s.ends_with?(".hbs")
          yield [f, false]
        end
      end
    end
  end

  protected

  def register_assets!
    assets.each do |asset, opts|
      DiscoursePluginRegistry.register_asset(asset, opts)
    end
  end

  private

  def write_asset(path, contents)
    unless File.exists?(path)
      ensure_directory(path)
      File.open(path, "w") { |f| f.write(contents) }
    end
  end

  def reloadable_patch(plugin = self)
    if Rails.env.development? && defined?(ActiveSupport::Reloader)
      ActiveSupport::Reloader.to_prepare do
        # reload the patch
        yield plugin
      end
    end

    # apply the patch
    yield plugin
  end

end