-- Database Schema for Enterprise Procurement & Asset Management

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(50) NOT NULL,
  `password` varchar(255) NOT NULL,
  `role` enum('Admin','Manager','User') DEFAULT 'User',
  `department_id` int(11) DEFAULT NULL,
  `created_at` timestamp DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `vendors` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(150) NOT NULL,
  `contact_person` varchar(100) DEFAULT NULL,
  `email` varchar(100) DEFAULT NULL,
  `phone` varchar(50) DEFAULT NULL,
  `created_at` timestamp DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `software_licenses` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(150) NOT NULL,
  `vendor_id` int(11) DEFAULT NULL,
  `version` varchar(50) DEFAULT NULL,
  `license_type` enum('Perpetual','Subscription') NOT NULL,
  `department_id` int(11) DEFAULT NULL,
  `responsible_user_id` int(11) DEFAULT NULL,
  `price` decimal(10,2) DEFAULT '0.00',
  `purchase_date` date DEFAULT NULL,
  `start_date` date DEFAULT NULL,
  `expiry_date` date DEFAULT NULL,
  `license_count` int(11) DEFAULT 1,
  `renewal_cycle_years` int(11) DEFAULT NULL COMMENT '1, 2, 3, 4, 5. NULL if Perpetual',
  `status` enum('Active','Expiring Soon','Expired') DEFAULT 'Active',
  `created_at` timestamp DEFAULT CURRENT_TIMESTAMP,
  `updated_at` timestamp DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  FOREIGN KEY (`vendor_id`) REFERENCES `vendors`(`id`),
  FOREIGN KEY (`responsible_user_id`) REFERENCES `users`(`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `software_renewal_history` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `software_license_id` int(11) NOT NULL,
  `old_expiry_date` date DEFAULT NULL,
  `new_expiry_date` date NOT NULL,
  `old_renewal_cycle` int(11) DEFAULT NULL,
  `new_renewal_cycle` int(11) NOT NULL,
  `price` decimal(10,2) DEFAULT '0.00',
  `renewed_by_user_id` int(11) NOT NULL,
  `renewed_at` timestamp DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  FOREIGN KEY (`software_license_id`) REFERENCES `software_licenses`(`id`),
  FOREIGN KEY (`renewed_by_user_id`) REFERENCES `users`(`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `audit_logs` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) DEFAULT NULL,
  `module` varchar(50) NOT NULL,
  `reference_id` int(11) NOT NULL,
  `action` varchar(50) NOT NULL,
  `field_changed` varchar(50) DEFAULT NULL,
  `old_value` text DEFAULT NULL,
  `new_value` text DEFAULT NULL,
  `ip_address` varchar(45) DEFAULT NULL,
  `created_at` timestamp DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;