-- Add normalized customer phone storage and a unique index for duplicate protection.
-- Safe to import on an existing database before/after the app code change.

DROP PROCEDURE IF EXISTS apply_customers_phone_normalized_unique;
DELIMITER $$
CREATE PROCEDURE apply_customers_phone_normalized_unique()
BEGIN
    IF NOT EXISTS (
        SELECT 1
        FROM INFORMATION_SCHEMA.COLUMNS
        WHERE TABLE_SCHEMA = DATABASE()
          AND TABLE_NAME = 'customers'
          AND COLUMN_NAME = 'phone_normalized'
    ) THEN
        ALTER TABLE customers
            ADD COLUMN phone_normalized VARCHAR(8) DEFAULT NULL AFTER phone;
    END IF;

    UPDATE customers
    SET phone = NULLIF(TRIM(phone), '');

    UPDATE customers
    SET phone_normalized = CASE
        WHEN phone IS NULL OR TRIM(phone) = '' THEN NULL
        WHEN REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', '') REGEXP '^[0-9]{8}$'
            THEN REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', '')
        WHEN REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', '') REGEXP '^0[0-9]{8}$'
            THEN RIGHT(REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', ''), 8)
        WHEN REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', '') REGEXP '^968[0-9]{8}$'
            THEN RIGHT(REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', ''), 8)
        WHEN REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', '') REGEXP '^00968[0-9]{8}$'
            THEN RIGHT(REPLACE(REPLACE(REPLACE(REPLACE(phone, ' ', ''), '-', ''), '(', ''), ')', ''), 8)
        ELSE NULL
    END;

    IF NOT EXISTS (
        SELECT 1
        FROM INFORMATION_SCHEMA.STATISTICS
        WHERE TABLE_SCHEMA = DATABASE()
          AND TABLE_NAME = 'customers'
          AND INDEX_NAME = 'uniq_customers_phone_normalized'
    ) THEN
        ALTER TABLE customers
            ADD UNIQUE KEY uniq_customers_phone_normalized (phone_normalized);
    END IF;
END $$
DELIMITER ;

CALL apply_customers_phone_normalized_unique();
DROP PROCEDURE IF EXISTS apply_customers_phone_normalized_unique;

-- Optional verification after import:
-- SHOW COLUMNS FROM customers;
-- SHOW INDEX FROM customers;