import { readFileSync, writeFileSync, existsSync } from 'fs';
import { dirname, join } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const DB_FILE = process.env.DB_PATH || join(__dirname, 'data.json');

function loadDB() {
  if (existsSync(DB_FILE)) {
    return JSON.parse(readFileSync(DB_FILE, 'utf-8'));
  }
  return { users: [], recipes: [], invite_tokens: [], _counters: { users: 0, recipes: 0, invite_tokens: 0 } };
}

function saveDB(data) {
  writeFileSync(DB_FILE, JSON.stringify(data, null, 2));
}

let db = loadDB();

function nextId(table) {
  db._counters[table] = (db._counters[table] || 0) + 1;
  return db._counters[table];
}

function now() {
  return new Date().toISOString().replace('T', ' ').slice(0, 19);
}

export function getDb() {
  return db;
}

export function getAllRecipes(search, category) {
  let results = [...db.recipes];

  if (search) {
    const term = search.toLowerCase();
    results = results.filter(r =>
      (r.name && r.name.toLowerCase().includes(term)) ||
      (r.description && r.description.toLowerCase().includes(term)) ||
      (r.ingredients && r.ingredients.toLowerCase().includes(term))
    );
  }

  if (category && category !== 'Alle') {
    results = results.filter(r => r.category === category);
  }

  results.sort((a, b) => (b.created_at || '').localeCompare(a.created_at || ''));
  return results;
}

export function getRecipeById(id) {
  return db.recipes.find(r => r.id === Number(id)) || undefined;
}

export function createRecipe(recipe) {
  const id = nextId('recipes');
  const nowStr = now();
  const row = {
    id,
    name: recipe.name,
    description: recipe.description || '',
    ingredients: JSON.stringify(recipe.ingredients || []),
    steps: JSON.stringify(recipe.steps || []),
    category: recipe.category || 'Sonstiges',
    tiktok_url: recipe.tiktok_url || null,
    tiktok_author: recipe.tiktok_author || null,
    thumbnail_url: recipe.thumbnail_url || null,
    user_id: recipe.user_id || null,
    created_at: nowStr,
    updated_at: nowStr,
  };
  db.recipes.push(row);
  saveDB(db);
  return row;
}

export function updateRecipe(id, recipe) {
  const idx = db.recipes.findIndex(r => r.id === Number(id));
  if (idx === -1) return undefined;
  db.recipes[idx] = {
    ...db.recipes[idx],
    name: recipe.name,
    description: recipe.description || '',
    ingredients: JSON.stringify(recipe.ingredients || []),
    steps: JSON.stringify(recipe.steps || []),
    category: recipe.category || 'Sonstiges',
    tiktok_url: recipe.tiktok_url || null,
    tiktok_author: recipe.tiktok_author || null,
    thumbnail_url: recipe.thumbnail_url || null,
    updated_at: now(),
  };
  saveDB(db);
  return db.recipes[idx];
}

export function deleteRecipe(id) {
  const idx = db.recipes.findIndex(r => r.id === Number(id));
  if (idx === -1) return;
  db.recipes.splice(idx, 1);
  saveDB(db);
}

export function getCategories() {
  const counts = {};
  for (const r of db.recipes) {
    counts[r.category] = (counts[r.category] || 0) + 1;
  }
  return Object.entries(counts)
    .map(([category, count]) => ({ category, count }))
    .sort((a, b) => b.count - a.count);
}

export function getUserByUsername(username) {
  return db.users.find(u => u.username === username) || undefined;
}

export function getUserById(id) {
  return db.users.find(u => u.id === Number(id)) || undefined;
}

export function createUser(username, hashedPassword, isAdmin = false) {
  const id = nextId('users');
  const user = {
    id,
    username,
    password: hashedPassword,
    is_admin: isAdmin ? 1 : 0,
    created_at: now(),
  };
  db.users.push(user);
  saveDB(db);
  return { id, username, is_admin: user.is_admin, created_at: user.created_at };
}

export function updateUserCredentials(userId, { username, password }) {
  const user = db.users.find(u => u.id === Number(userId));
  if (!user) return null;
  if (username) user.username = username;
  if (password) user.password = password;
  saveDB(db);
  return { id: user.id, username: user.username, is_admin: user.is_admin, created_at: user.created_at };
}

export function createInviteToken(token, createdBy) {
  const id = nextId('invite_tokens');
  db.invite_tokens.push({
    id,
    token,
    created_by: createdBy,
    used_by: null,
    created_at: now(),
    used_at: null,
  });
  saveDB(db);
}

export function getInviteToken(token) {
  return db.invite_tokens.find(i => i.token === token) || undefined;
}

export function useInviteToken(token, userId) {
  const inv = db.invite_tokens.find(i => i.token === token);
  if (inv) {
    inv.used_by = userId;
    inv.used_at = now();
    saveDB(db);
  }
}

export function getInvitesByUser(userId) {
  return db.invite_tokens
    .filter(i => i.created_by === Number(userId))
    .sort((a, b) => (b.created_at || '').localeCompare(a.created_at || ''))
    .map(i => {
      const usedByUser = i.used_by ? db.users.find(u => u.id === i.used_by) : null;
      return { ...i, used_by_username: usedByUser ? usedByUser.username : null };
    });
}

export function getAllUsers() {
  return db.users
    .map(u => ({ id: u.id, username: u.username, is_admin: u.is_admin, created_at: u.created_at }))
    .sort((a, b) => (b.created_at || '').localeCompare(a.created_at || ''));
}

export function deleteUser(id) {
  const idx = db.users.findIndex(u => u.id === Number(id));
  if (idx === -1) return false;
  db.users.splice(idx, 1);
  db.invite_tokens = db.invite_tokens.filter(i => i.created_by !== Number(id));
  saveDB(db);
  return true;
}

export function getInviteStats() {
  const total = db.invite_tokens.length;
  const used = db.invite_tokens.filter(i => i.used_by !== null).length;
  return { total, used, available: total - used };
}