-- Customers table
CREATE TABLE IF NOT EXISTS customers (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  code VARCHAR(50) UNIQUE NOT NULL,
  email VARCHAR(255),
  phone VARCHAR(50),
  address TEXT,
  contact_person VARCHAR(255),
  notes TEXT,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Purchase Orders table
CREATE TABLE IF NOT EXISTS purchase_orders (
  id SERIAL PRIMARY KEY,
  po_number VARCHAR(100) UNIQUE NOT NULL,
  customer_id INTEGER NOT NULL REFERENCES customers(id) ON DELETE CASCADE,
  status VARCHAR(20) DEFAULT 'draft' CHECK (status IN ('draft', 'confirmed', 'in_production', 'completed', 'cancelled')),
  order_date DATE DEFAULT CURRENT_DATE,
  due_date DATE,
  notes TEXT,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Purchase Order Items (line items linking products with quantities)
CREATE TABLE IF NOT EXISTS purchase_order_items (
  id SERIAL PRIMARY KEY,
  purchase_order_id INTEGER NOT NULL REFERENCES purchase_orders(id) ON DELETE CASCADE,
  product_id INTEGER NOT NULL REFERENCES products(id) ON DELETE RESTRICT,
  quantity INTEGER NOT NULL DEFAULT 1,
  unit_price NUMERIC(12, 4) DEFAULT 0,
  notes TEXT,
  created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Indexes
CREATE INDEX IF NOT EXISTS idx_purchase_orders_customer_id ON purchase_orders(customer_id);
CREATE INDEX IF NOT EXISTS idx_purchase_orders_status ON purchase_orders(status);
CREATE INDEX IF NOT EXISTS idx_purchase_orders_po_number ON purchase_orders(po_number);
CREATE INDEX IF NOT EXISTS idx_purchase_order_items_po_id ON purchase_order_items(purchase_order_id);
CREATE INDEX IF NOT EXISTS idx_purchase_order_items_product_id ON purchase_order_items(product_id);
CREATE INDEX IF NOT EXISTS idx_customers_code ON customers(code);