const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { app } = require('electron');

function dataDir() {
  const dir = path.join(app.getPath('userData'), 'data');
  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
  return dir;
}

function providersPath() {
  return path.join(dataDir(), 'providers.json');
}

function conversationsDir() {
  const dir = path.join(dataDir(), 'conversations');
  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
  return dir;
}

function readJSON(file, fallback) {
  try {
    if (!fs.existsSync(file)) return fallback;
    return JSON.parse(fs.readFileSync(file, 'utf8'));
  } catch {
    return fallback;
  }
}

function writeJSON(file, data) {
  fs.writeFileSync(file, JSON.stringify(data, null, 2), 'utf8');
}

function getProviders() {
  return readJSON(providersPath(), []);
}

function saveProviders(list) {
  writeJSON(providersPath(), list);
}

function upsertProvider(provider) {
  const list = getProviders();
  if (!provider.id) provider.id = crypto.randomUUID();
  const idx = list.findIndex((p) => p.id === provider.id);
  if (idx >= 0) list[idx] = { ...list[idx], ...provider };
  else list.push(provider);
  saveProviders(list);
  return provider;
}

function deleteProvider(id) {
  saveProviders(getProviders().filter((p) => p.id !== id));
}

function getConversationList() {
  const dir = conversationsDir();
  const files = fs.readdirSync(dir).filter((f) => f.endsWith('.json'));
  const items = files.map((f) => {
    try {
      const c = JSON.parse(fs.readFileSync(path.join(dir, f), 'utf8'));
      return {
        id: c.id,
        title: c.title,
        providerId: c.providerId,
        model: c.model,
        createdAt: c.createdAt,
        updatedAt: c.updatedAt,
        messageCount: (c.messages || []).length,
      };
    } catch {
      return null;
    }
  }).filter(Boolean);
  items.sort((a, b) => (b.updatedAt || 0) - (a.updatedAt || 0));
  return items;
}

function getConversation(id) {
  const file = path.join(conversationsDir(), `${id}.json`);
  return readJSON(file, null);
}

function saveConversation(conv) {
  if (!conv.id) conv.id = crypto.randomUUID();
  const now = Date.now();
  if (!conv.createdAt) conv.createdAt = now;
  conv.updatedAt = now;
  writeJSON(path.join(conversationsDir(), `${conv.id}.json`), conv);
  return conv;
}

function deleteConversation(id) {
  const file = path.join(conversationsDir(), `${id}.json`);
  if (fs.existsSync(file)) fs.unlinkSync(file);
}

function clearAllConversations() {
  const dir = conversationsDir();
  fs.readdirSync(dir).filter((f) => f.endsWith('.json')).forEach((f) => {
    fs.unlinkSync(path.join(dir, f));
  });
}

function renameConversation(id, title) {
  const conv = getConversation(id);
  if (!conv) return null;
  conv.title = title;
  conv.updatedAt = Date.now();
  writeJSON(path.join(conversationsDir(), `${id}.json`), conv);
  return conv;
}

module.exports = {
  getProviders,
  upsertProvider,
  deleteProvider,
  getConversationList,
  getConversation,
  saveConversation,
  deleteConversation,
  clearAllConversations,
  renameConversation,
};