import { mkdirSync, readFileSync, renameSync, writeFileSync } from 'node:fs';
import { join } from 'node:path';

export const defaults = Object.freeze({
  llmModel: 'anthropic/claude-haiku-5.5',
  sttModel: 'scribe_v2_realtime',
  ttsModel: 'eleven_v4_turbo',
  voiceId: '21m00Tcm4TlvDq8ikWAM',
  systemPrompt: 'Ты голосовой помощник Алиса. Отвечай по-русски, коротко и по делу. Пиши так, чтобы ответ хорошо звучал вслух: обычный текст, без Markdown. Если не знаешь ответа, скажи об этом прямо.',
});

export const ttsModels = ['eleven_v4_turbo', 'eleven_v3_conversational', 'eleven_flash_v2_5'];

export function validateSettings(input) {
  if (typeof input !== 'object' || input === null) return null;
  const { llmModel, sttModel, ttsModel, voiceId, systemPrompt } = input;
  if (typeof llmModel !== 'string' || !/^[\w.~:-]+\/[\w.:~-]+$/.test(llmModel) || llmModel.length > 120) return null;
  if (sttModel !== defaults.sttModel || !ttsModels.includes(ttsModel)) return null;
  if (typeof voiceId !== 'string' || !/^[a-zA-Z0-9]{20}$/.test(voiceId)) return null;
  if (typeof systemPrompt !== 'string' || !systemPrompt.trim() || systemPrompt.length > 4000) return null;
  return { llmModel, sttModel, ttsModel, voiceId, systemPrompt: systemPrompt.trim() };
}

export function openStore(directory = process.env.DATA_DIR ?? './data') {
  mkdirSync(directory, { recursive: true, mode: 0o700 });
  const path = join(directory, 'assistant.json');
  let state = { settings: { ...defaults }, history: [] };
  try {
    const saved = JSON.parse(readFileSync(path, 'utf8'));
    const settings = validateSettings({ ...defaults, ...saved.settings });
    if (!settings || !Array.isArray(saved.history)) throw new Error('Invalid assistant state');
    state = { settings, history: saved.history };
  } catch (error) {
    if (error.code !== 'ENOENT') throw error;
  }

  function commit(next) {
    const temporary = path + '.tmp';
    writeFileSync(temporary, JSON.stringify(next) + '\n', { mode: 0o600 });
    renameSync(temporary, path);
    state = next;
  }

  return {
    getSettings: () => ({ ...state.settings }),
    getHistory: () => state.history.map(turn => ({ ...turn })),
    updateSettings(settings) {
      commit({ ...state, settings });
    },
    recordTurn(user, assistant) {
      const turn = {
        user: user.slice(0, 6000),
        assistant: assistant.slice(0, 6000),
        createdAt: new Date().toISOString(),
      };
      commit({ ...state, history: [...state.history.slice(-49), turn] });
    },
    clearHistory() {
      commit({ ...state, history: [] });
    },
  };
}