-- Make definitions local to outlets
-- 1. Suppliers
ALTER TABLE suppliers ADD COLUMN IF NOT EXISTS outlet_id INT DEFAULT 1;
ALTER TABLE suppliers ADD CONSTRAINT fk_suppliers_outlet FOREIGN KEY (outlet_id) REFERENCES outlets(id) ON DELETE CASCADE;

-- 2. Categories
ALTER TABLE stock_categories ADD COLUMN IF NOT EXISTS outlet_id INT DEFAULT 1;
ALTER TABLE stock_categories ADD CONSTRAINT fk_categories_outlet FOREIGN KEY (outlet_id) REFERENCES outlets(id) ON DELETE CASCADE;

-- 3. Units
ALTER TABLE stock_units ADD COLUMN IF NOT EXISTS outlet_id INT DEFAULT 1;
ALTER TABLE stock_units ADD CONSTRAINT fk_units_outlet FOREIGN KEY (outlet_id) REFERENCES outlets(id) ON DELETE CASCADE;

-- 4. Items
ALTER TABLE stock_items ADD COLUMN IF NOT EXISTS outlet_id INT DEFAULT 1;
ALTER TABLE stock_items ADD CONSTRAINT fk_items_outlet FOREIGN KEY (outlet_id) REFERENCES outlets(id) ON DELETE CASCADE;

-- 5. Fix SKU Unique Constraint (Global -> Local)
-- First, drop the global unique index if it exists. 
-- We need to know the name. Usually 'sku'. We'll try to drop it.
-- MySQL might fail if index doesn't exist, so we use a procedure or just try/catch in PHP?
-- For SQL file, we can't easily do try/catch. 
-- We'll try to drop 'sku' index. If it fails, it fails (user might need to run manually).
-- Safest is to just ADD the new one and let the old one be (if duplicate SKUs are allowed across outlets).
-- But we want to ALLOW duplicate SKUs across outlets.
-- So we MUST drop the unique constraint on `sku`.

DROP INDEX sku ON stock_items;
-- Re-add as non-unique (just index) or part of composite unique
CREATE UNIQUE INDEX unique_sku_outlet ON stock_items (sku, outlet_id);

-- 6. Migrate Stock from outlet_stock to stock_items (for Outlet 1)
-- We assume current items belong to Outlet 1.
UPDATE stock_items si
JOIN outlet_stock os ON si.id = os.item_id AND os.outlet_id = 1
SET si.stock_quantity = os.quantity;

-- We leave outlet_stock for now, but application logic will switch to stock_items.stock_quantity