# frozen_string_literal: true

module DiscourseAi
  module Translation
    class LanguageDetector
      DETECTION_CHAR_LIMIT = 1000
      PROMPT_TEXT = <<~TEXT
      You will be given a piece of text, and your task is to detect the locale (language) of the text and return it in a specific JSON format.

      To complete this task, follow these steps:

      1. Carefully read and analyze the provided text.
      2. Determine the language of the text based on its characteristics, such as vocabulary, grammar, and sentence structure.
      3. Do not use links or programing code in the text to detect the locale
      4. Identify the appropriate language code for the detected language.

      Here is a list of common language codes for reference:
      - English: en
      - Spanish: es
      - French: fr
      - German: de
      - Italian: it
      - Brazilian Portuguese: pt-BR
      - Russian: ru
      - Simplified Chinese: zh-CN
      - Japanese: ja
      - Korean: ko

      If the language is not in this list, use the appropriate IETF language tag code.

      5. Format your response as a JSON object with a single key "locale" and the value as the language code.

      Your output should be in the following format:
      <output>
      {"locale": "xx"}
      </output>

      Where "xx" is replaced by the appropriate language code.

      Important: Base your analysis solely on the provided text. Do not use any external information or make assumptions about the text's origin or context beyond what is explicitly provided.
    TEXT

      def initialize(text)
        @text = text
      end

      def detect
        prompt =
          DiscourseAi::Completions::Prompt.new(
            PROMPT_TEXT,
            messages: [{ type: :user, content: @text, id: "user" }],
          )

        structured_output =
          DiscourseAi::Completions::Llm.proxy(SiteSetting.ai_translation_model).generate(
            prompt,
            user: Discourse.system_user,
            feature_name: "translation",
            response_format: response_format,
          )

        structured_output&.read_buffered_property(:locale)
      end

      def response_format
        {
          type: "json_schema",
          json_schema: {
            name: "reply",
            schema: {
              type: "object",
              properties: {
                locale: {
                  type: "string",
                },
              },
              required: ["locale"],
              additionalProperties: false,
            },
            strict: true,
          },
        }
      end
    end
  end
end