discourse-legacy_links/plugin.rb

# plugins/discourse-legacy_links/plugin.rb

# frozen_string_literal: true

# name: discourse-legacy_links
# about: A plugin to handle legacy Gossamer Forums URLs
# version: 0.47
# authors: saint@federated.computer
# url: https://gitea.federated.computer/saint/discourse-legacy_links.git

# enabled_site_setting :discourse_legacy_links_enabled

after_initialize do
  module ::DiscourseLegacyLinks
    class Engine < ::Rails::Engine
      engine_name "discourse_legacy_links"
      isolate_namespace DiscourseLegacyLinks
    end
  end

  require_dependency "application_controller"
  class ::DiscourseLegacyLinks::LegacyLinksController < ::ApplicationController
    skip_before_action :check_xhr, only: [:index]
    
    def index2
      render plain: "Legacy Links from Discourse plugin! Current user: #{current_user&.username || 'Guest'}"
    end

    def index
      Rails.logger.info("DiscourseLegacyLinks: Handling request for URL: #{request.original_url}")

      post_id = extract_post_id_from_request

      if post_id
        Rails.logger.info("DiscourseLegacyLinks: Extracted post_id: #{post_id}")
        post = find_post_by_custom_field(post_id)

        if post
          Rails.logger.info("DiscourseLegacyLinks: Found matching post with id: #{post.id}")
          redirect_to_post(post)
        else
          Rails.logger.warn("DiscourseLegacyLinks: No matching post found for post_id: #{post_id}")
          render_not_found
        end
      else
        Rails.logger.warn("DiscourseLegacyLinks: Unable to extract post_id from request")
        render_bad_request
      end
    end

    private

    # Attempts to extract a post ID from various parts of the request
    def extract_post_id_from_request
      post_id = params[:post_id].presence ||
                request.path.match(%r{/forum/[^/]+/P(\d+)/?})&.[](1) ||
                request.query_string.match(/post=(\d+)/)&.[](1) ||
                request.query_string.match(/parent_post_id=(\d+)/)&.[](1)

      Rails.logger.info("DiscourseLegacyLinks: Extracted raw post_id: #{post_id || 'nil'}")
      post_id.to_i if post_id
    end

    # Finds a post by looking up the custom field on the associated topic
    def find_post_by_custom_field(post_id)
      Rails.logger.info("DiscourseLegacyLinks: Searching for post with original_gossamer_id: #{post_id}")
      
      topic = Topic.joins(:custom_fields)
                   .where(topic_custom_fields: { name: 'original_gossamer_id', value: post_id.to_s })
                   .first

      if topic
        post = topic.posts.first
        Rails.logger.info("DiscourseLegacyLinks: Found topic #{topic.id}, first post id: #{post&.id || 'nil'}")
        post
      else
        Rails.logger.warn("DiscourseLegacyLinks: No topic found with original_gossamer_id: #{post_id}")
        nil
      end
    end

    # Redirects to the URL of the found post
    def redirect_to_post(post)
      Rails.logger.info("DiscourseLegacyLinks: Redirecting to post URL: #{post.url}")
      redirect_to post.url, status: :moved_permanently
    end

    # Renders a 404 Not Found response
    def render_not_found
      Rails.logger.info("DiscourseLegacyLinks: Rendering 404 Not Found")
      render plain: 'Post not found', status: :not_found
    end

    # Renders a 400 Bad Request response
    def render_bad_request
      Rails.logger.info("DiscourseLegacyLinks: Rendering 400 Bad Request")
      render plain: 'Invalid URL', status: :bad_request
    end
  end

#  Rails.logger.info("DiscourseLegacyLinks: initialistaion")

  DiscourseLegacyLinks::Engine.routes.draw do
    get "/forum" => "legacy_links#index"
    get "/forum/*path" => "legacy_links#index"
  end

  Discourse::Application.routes.append do
    mount ::DiscourseLegacyLinks::Engine, at: "/"
  end
end