const Database = require('better-sqlite3');
const path = require('path');

const dbPath = process.env.DATABASE_PATH || path.join(__dirname, '..', 'data', 'cookies.db');

let db;

function getDb() {
  if (!db) {
    const dir = path.dirname(dbPath);
    const fs = require('fs');
    if (!fs.existsSync(dir)) {
      fs.mkdirSync(dir, { recursive: true });
    }
    db = new Database(dbPath);
    db.pragma('foreign_keys = ON');
    initSchema(db);
  }
  return db;
}

function initSchema(database) {
  database.exec(`
    CREATE TABLE IF NOT EXISTS products (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT NOT NULL,
      price REAL NOT NULL DEFAULT 0,
      quantity_on_hand INTEGER NOT NULL DEFAULT 0,
      low_stock_threshold INTEGER DEFAULT 0,
      created_at TEXT DEFAULT (datetime('now'))
    );

    CREATE TABLE IF NOT EXISTS customers (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT NOT NULL,
      phone TEXT,
      email TEXT,
      address TEXT,
      notes TEXT,
      created_at TEXT DEFAULT (datetime('now'))
    );

    CREATE TABLE IF NOT EXISTS orders (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      customer_id INTEGER REFERENCES customers(id),
      status TEXT NOT NULL DEFAULT 'pending',
      notes TEXT,
      created_at TEXT DEFAULT (datetime('now')),
      updated_at TEXT DEFAULT (datetime('now'))
    );

    CREATE TABLE IF NOT EXISTS order_items (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      order_id INTEGER NOT NULL REFERENCES orders(id) ON DELETE CASCADE,
      product_id INTEGER NOT NULL REFERENCES products(id),
      quantity INTEGER NOT NULL,
      price_at_sale REAL NOT NULL,
      UNIQUE(order_id, product_id)
    );

    CREATE TABLE IF NOT EXISTS stock_adjustments (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      product_id INTEGER NOT NULL REFERENCES products(id),
      adjustment INTEGER NOT NULL,
      reason TEXT NOT NULL,
      reference_id INTEGER,
      created_at TEXT DEFAULT (datetime('now'))
    );

    CREATE TABLE IF NOT EXISTS schema_version (
      version INTEGER NOT NULL
    );
  `);

  runMigrations(database);
}

function getSchemaVersion(database) {
  const row = database.prepare('SELECT version FROM schema_version').get();
  return row ? row.version : 0;
}

function setSchemaVersion(database, version) {
  const existing = database.prepare('SELECT version FROM schema_version').get();
  if (existing) {
    database.prepare('UPDATE schema_version SET version = ?').run(version);
  } else {
    database.prepare('INSERT INTO schema_version (version) VALUES (?)').run(version);
  }
}

function runMigrations(database) {
  const version = getSchemaVersion(database);

  if (version < 1) {
    try { database.exec("ALTER TABLE orders ADD COLUMN payment_method TEXT"); } catch (e) {
      if (!e.message.includes('duplicate column')) throw e;
    }
    try { database.exec("ALTER TABLE orders ADD COLUMN amount_paid REAL NOT NULL DEFAULT 0"); } catch (e) {
      if (!e.message.includes('duplicate column')) throw e;
    }
    setSchemaVersion(database, 1);
  }
}

module.exports = { getDb, initSchema };