// TranslationPrompt.swift
// OSGKeyboard · Shared
//
// Builds the system prompt the LLM sees when the user has the
// translation toggle on. Re-uses the same per-provider "primary
// language" split the polish prompt uses (`AppGroupStore.defaultSystemPrompt`)
// so Chinese-native LLMs (DeepSeek, Qwen, GLM, Moonshot) get a Chinese
// prompt and English-native LLMs (OpenAI) get an English one — the LLM
// is most reliable when the instructions are written in its strongest
// language.
//
// The "translate AND polish" blend is intentional: ASR transcripts are
// noisy (homophone errors, broken segmentation, dropped particles), so
// the prompt asks the model to clean the noise while translating.
// Scenario output format (`ScenarioStyleDirective`) is appended so
// translate-and-polish honours the user's polish scenario choice.

import Foundation

public enum TranslationPrompt {

    /// Build the translate-and-polish system prompt.
    ///
    /// - Parameters:
    ///   - target: target language entry resolved via `TranslationLanguageCatalog`.
    ///   - providerId: provider preset id (e.g. `"deepseek"`, `"openai"`);
    ///     drives the language the prompt is written in.
    ///   - scenarioId: active polish scenario; format rules are shared
    ///     with the polish-only path via `ScenarioStyleDirective`.
    ///   - uiLanguage: host-app UI language (platform label variants).
    public static func make(
        target: TranslationLanguage,
        providerId: String,
        scenarioId: String = PolishScenarioCatalog.defaultId,
        uiLanguage: AppUILanguage? = nil
    ) -> String {
        let isChineseNative = ["zhipu", "moonshot", "qwen", "deepseek"].contains(providerId)
        let directive = ScenarioStyleDirective.make(
            scenarioId: scenarioId,
            providerId: providerId,
            uiLanguage: uiLanguage
        )
        return isChineseNative
            ? chinesePrompt(target: target, directive: directive)
            : englishPrompt(target: target, directive: directive)
    }

    // MARK: - Chinese prompt (for DeepSeek / Qwen / GLM / Moonshot)

    private static func chinesePrompt(target: TranslationLanguage, directive: String) -> String {
        """
        你是一位语音输入翻译与润色助手。用户用 ASR 转写了一段可能含噪声的口述:
        1) 先识别原话的主要语言(若不确定则按用户给定的方向处理);
        2) 将内容翻译为「\(target.promptLanguageName)」,保留原意,不增删事实、不臆测;
        3) 顺带修复 ASR 噪声(同音错字、漏字、断句错乱),让译文读起来自然;
        4) 简洁;若下方场景未要求列表/分段,不超过原文 1.5 倍;去掉无意义的口头禅(嗯、啊、那个);
        5) 若场景格式要求列表或分段,允许按格式组织译文;总长度不超过原长 2 倍;
        6) 只输出译文正文,不要解释、不要加引号、不要前缀"以下是翻译"。
        \(directive)
        """
    }

    // MARK: - English prompt (for OpenAI / OpenAI-compatible non-Chinese)

    private static func englishPrompt(target: TranslationLanguage, directive: String) -> String {
        """
        You are a voice-input translation and polishing assistant. The user has spoken informally and the transcript may contain ASR noise:
        1) Identify the input language; if unclear, assume the user wants translation INTO \(target.promptLanguageName);
        2) Translate the content INTO \(target.promptLanguageName), preserving meaning; do not invent facts or omit content;
        3) Fix ASR noise (homophone errors, missing characters, broken segmentation) so the translation reads naturally;
        4) Stay concise; if the scenario below does not require lists/sections, do not exceed 1.5x the spoken length; drop filler words (um, uh, like);
        5) If the scenario requires bullets or paragraph breaks, use that layout in the translation; total length may be up to 2x when listing;
        6) Output ONLY the translation. No quotes, no preamble, no explanation.
        \(directive)
        """
    }
}