const { Pool } = require('pg');
const format = require('pg-format');

let pool;

function initPool() {
  if (pool) return pool;
  const connectionString = process.env.DATABASE_URL;
  if (!connectionString) throw new Error('DATABASE_URL is not set');
  pool = new Pool({ connectionString });
  return pool;
}

async function ensureSchema() {
  const p = initPool();
  // basic tables: servers (settings), invites
  await p.query(`
    CREATE TABLE IF NOT EXISTS servers (
      guild_id TEXT PRIMARY KEY,
      settings JSONB DEFAULT '{}'
    );
  `);

  await p.query(`
    CREATE TABLE IF NOT EXISTS invites (
      code TEXT PRIMARY KEY,
      guild_id TEXT NOT NULL,
      url TEXT,
      channel_id TEXT,
      created_at TIMESTAMP WITH TIME ZONE DEFAULT now(),
      max_uses INTEGER DEFAULT 0,
      max_age INTEGER DEFAULT 0,
      temporary BOOLEAN DEFAULT false
    );
  `);

  await p.query(`
    CREATE TABLE IF NOT EXISTS users (
      id SERIAL PRIMARY KEY,
      discord_id TEXT UNIQUE,
      data JSONB DEFAULT '{}'
    );
  `);
}

// Servers
async function getServerSettings(guildId) {
  const p = initPool();
  const res = await p.query('SELECT settings FROM servers WHERE guild_id = $1', [guildId]);
  if (res.rowCount === 0) return null;
  return res.rows[0].settings || {};
}

async function upsertServerSettings(guildId, settings) {
  const p = initPool();
  await p.query(`INSERT INTO servers(guild_id, settings) VALUES($1, $2)
    ON CONFLICT (guild_id) DO UPDATE SET settings = $2`, [guildId, settings]);
}

// Invites
async function listInvites(guildId) {
  const p = initPool();
  const res = await p.query('SELECT code, url, channel_id, created_at, max_uses, max_age, temporary FROM invites WHERE guild_id = $1 ORDER BY created_at DESC', [guildId]);
  return res.rows;
}

async function addInvite(inv) {
  const p = initPool();
  const q = `INSERT INTO invites(code, guild_id, url, channel_id, created_at, max_uses, max_age, temporary) VALUES($1,$2,$3,$4,$5,$6,$7,$8)
    ON CONFLICT (code) DO UPDATE SET url = EXCLUDED.url, channel_id = EXCLUDED.channel_id, max_uses = EXCLUDED.max_uses, max_age = EXCLUDED.max_age, temporary = EXCLUDED.temporary, created_at = EXCLUDED.created_at`;
  await p.query(q, [inv.code, inv.guildId, inv.url, inv.channelId, inv.createdAt ? new Date(inv.createdAt) : new Date(), inv.maxUses || 0, inv.maxAge || 0, inv.temporary || false]);
}

async function deleteInvite(guildId, code) {
  const p = initPool();
  await p.query('DELETE FROM invites WHERE guild_id = $1 AND code = $2', [guildId, code]);
}

// Users
async function getUserData(discordId) {
  const p = initPool();
  const res = await p.query('SELECT data FROM users WHERE discord_id = $1', [discordId]);
  if (res.rowCount === 0) return null;
  return res.rows[0].data || {};
}

async function upsertUserData(discordId, data) {
  const p = initPool();
  await p.query(`INSERT INTO users(discord_id, data) VALUES($1, $2) ON CONFLICT (discord_id) DO UPDATE SET data = $2`, [discordId, data]);
}

module.exports = { initPool, ensureSchema, getServerSettings, upsertServerSettings, listInvites, addInvite, deleteInvite, getUserData, upsertUserData };