#frozen_string_literal: true

module DiscourseAi::AiBot::Commands
  class SearchCommand < Command
    class << self
      def name
        "search"
      end

      def desc
        "Will search topics in the current discourse instance, when rendering always prefer to link to the topics you find"
      end

      def parameters
        [
          Parameter.new(
            name: "search_query",
            description:
              "Specific keywords to search for, space seperated (correct bad spelling, remove connector words)",
            type: "string",
          ),
          Parameter.new(
            name: "user",
            description:
              "Filter search results to this username (only include if user explicitly asks to filter by user)",
            type: "string",
          ),
          Parameter.new(
            name: "order",
            description: "search result order",
            type: "string",
            enum: %w[latest latest_topic oldest views likes],
          ),
          Parameter.new(
            name: "limit",
            description:
              "limit number of results returned (generally prefer to just keep to default)",
            type: "integer",
          ),
          Parameter.new(
            name: "max_posts",
            description:
              "maximum number of posts on the topics (topics where lots of people posted)",
            type: "integer",
          ),
          Parameter.new(
            name: "tags",
            description:
              "list of tags to search for. Use + to join with OR, use , to join with AND",
            type: "string",
          ),
          Parameter.new(
            name: "category",
            description: "category name to filter to",
            type: "string",
          ),
          Parameter.new(
            name: "before",
            description: "only topics created before a specific date YYYY-MM-DD",
            type: "string",
          ),
          Parameter.new(
            name: "after",
            description: "only topics created after a specific date YYYY-MM-DD",
            type: "string",
          ),
          Parameter.new(
            name: "status",
            description: "search for topics in a particular state",
            type: "string",
            enum: %w[open closed archived noreplies single_user],
          ),
        ]
      end

      def custom_system_message
        <<~TEXT
          You were trained on OLD data, lean on search to get up to date information about this forum
          When searching try to SIMPLIFY search terms
          Discourse search joins all terms with AND. Reduce and simplify terms to find more results.
        TEXT
      end
    end

    def result_name
      "results"
    end

    def description_args
      {
        count: @last_num_results || 0,
        query: @last_query || "",
        url: "#{Discourse.base_path}/search?q=#{CGI.escape(@last_query || "")}",
      }
    end

    MAX_RESULTS = 20
    MIN_SEMANTIC_RESULTS = 5

    def process(**search_args)
      limit = nil

      search_string =
        search_args
          .map do |key, value|
            if key == :search_query
              value
            elsif key == :limit
              limit = value.to_i
              nil
            else
              "#{key}:#{value}"
            end
          end
          .compact
          .join(" ")

      @last_query = search_string

      show_progress(I18n.t("discourse_ai.ai_bot.searching", query: search_string))

      results =
        Search.execute(
          search_string.to_s + " status:public",
          search_type: :full_page,
          guardian: Guardian.basic_user,
        )

      # let's be frugal with tokens, 50 results is too much and stuff gets cut off
      limit ||= MAX_RESULTS
      limit = MAX_RESULTS if limit > MAX_RESULTS

      should_try_semantic_search = SiteSetting.ai_embeddings_semantic_search_enabled
      should_try_semantic_search &&= (limit == MAX_RESULTS)
      should_try_semantic_search &&= (search_args[:search_query].present?)

      limit = limit - MIN_SEMANTIC_RESULTS if should_try_semantic_search

      posts = results&.posts || []
      posts = posts[0..limit - 1]

      if should_try_semantic_search
        semantic_search = DiscourseAi::Embeddings::SemanticSearch.new(Guardian.basic_user)
        topic_ids = Set.new(posts.map(&:topic_id))

        search = Search.new(search_string, guardian: Guardian.basic_user)

        results = nil
        begin
          results = semantic_search.search_for_topics(search.term)
        rescue => e
          Discourse.warn_exception(e, message: "Semantic search failed")
        end

        if results
          results = search.apply_filters(results)

          results.each do |post|
            next if topic_ids.include?(post.topic_id)

            topic_ids << post.topic_id
            posts << post

            break if posts.length >= MAX_RESULTS
          end
        end
      end

      @last_num_results = posts.length
      # this is the general pattern from core
      # if there are millions of hidden tags it may fail
      hidden_tags = nil

      if posts.blank?
        { args: search_args, rows: [], instruction: "nothing was found, expand your search" }
      else
        format_results(posts, args: search_args) do |post|
          category_names = [
            post.topic.category&.parent_category&.name,
            post.topic.category&.name,
          ].compact.join(" > ")
          row = {
            title: post.topic.title,
            url: Discourse.base_path + post.url,
            excerpt: post.excerpt,
            created: post.created_at,
            category: category_names,
          }

          if SiteSetting.tagging_enabled
            hidden_tags ||= DiscourseTagging.hidden_tag_names
            # using map over pluck to avoid n+1 (assuming caller preloading)
            tags = post.topic.tags.map(&:name) - hidden_tags
            row[:tags] = tags.join(", ") if tags.present?
          end
          row
        end
      end
    end
  end
end