-- MySQL-compatible Schema for Ghana School ERP Accounting Module
-- Translated from user-provided PostgreSQL schema.

CREATE TABLE IF NOT EXISTS `accounts` (
    `id` CHAR(36) PRIMARY KEY,
    `account_code` VARCHAR(50) UNIQUE NOT NULL,
    `account_name` VARCHAR(255) NOT NULL,
    `account_type` VARCHAR(20) NOT NULL CHECK (`account_type` IN ('Asset', 'Liability', 'Equity', 'Revenue', 'ContraRevenue', 'Expense')),
    `normal_balance` VARCHAR(6) NOT NULL CHECK (`normal_balance` IN ('Debit', 'Credit')),
    `parent_account_id` CHAR(36),
    `is_active` BOOLEAN NOT NULL DEFAULT TRUE,
    `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `updated_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    FOREIGN KEY (`parent_account_id`) REFERENCES `accounts`(`id`) ON DELETE RESTRICT
);

CREATE INDEX `idx_accounts_code` ON `accounts`(`account_code`);
CREATE INDEX `idx_accounts_parent` ON `accounts`(`parent_account_id`);
CREATE INDEX `idx_accounts_type` ON `accounts`(`account_type`);

CREATE TABLE IF NOT EXISTS `accounting_periods` (
    `id` CHAR(36) PRIMARY KEY,
    `name` VARCHAR(100) NOT NULL,
    `start_date` DATE NOT NULL,
    `end_date` DATE NOT NULL,
    `is_closed` BOOLEAN NOT NULL DEFAULT FALSE,
    `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT `chk_period_dates` CHECK (`end_date` > `start_date`)
);

CREATE INDEX `idx_periods_dates` ON `accounting_periods`(`start_date`, `end_date`);

CREATE TABLE IF NOT EXISTS `journal_entries` (
    `id` CHAR(36) PRIMARY KEY,
    `entry_number` VARCHAR(50) UNIQUE NOT NULL,
    `entry_date` DATE NOT NULL,
    `description` TEXT,
    `period_id` CHAR(36) NOT NULL,
    `source_module` VARCHAR(20) NOT NULL CHECK (`source_module` IN ('Manual', 'Fees', 'Payments', 'Payroll', 'Expenses')),
    `source_reference_id` CHAR(36),
    `status` VARCHAR(10) NOT NULL DEFAULT 'Draft' CHECK (`status` IN ('Draft', 'Posted', 'Reversed')),
    `reversed_by` CHAR(36),
    `reverses_journal_id` CHAR(36),
    `created_by` CHAR(36) NOT NULL,
    `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `posted_at` TIMESTAMP NULL,
    FOREIGN KEY (`period_id`) REFERENCES `accounting_periods`(`id`) ON DELETE RESTRICT,
    FOREIGN KEY (`reversed_by`) REFERENCES `journal_entries`(`id`),
    FOREIGN KEY (`reverses_journal_id`) REFERENCES `journal_entries`(`id`)
);

CREATE INDEX `idx_journal_period` ON `journal_entries`(`period_id`);
CREATE INDEX `idx_journal_date` ON `journal_entries`(`entry_date`);
CREATE INDEX `idx_journal_status` ON `journal_entries`(`status`);
CREATE INDEX `idx_journal_source` ON `journal_entries`(`source_module`, `source_reference_id`);

CREATE TABLE IF NOT EXISTS `journal_lines` (
    `id` CHAR(36) PRIMARY KEY,
    `journal_entry_id` CHAR(36) NOT NULL,
    `account_id` CHAR(36) NOT NULL,
    `debit_amount` DECIMAL(14,2) NOT NULL DEFAULT 0,
    `credit_amount` DECIMAL(14,2) NOT NULL DEFAULT 0,
    `line_description` TEXT,
    CONSTRAINT `chk_debit_or_credit` CHECK ((`debit_amount` > 0 AND `credit_amount` = 0) OR (`credit_amount` > 0 AND `debit_amount` = 0)),
    CHECK (`debit_amount` >= 0),
    CHECK (`credit_amount` >= 0),
    FOREIGN KEY (`journal_entry_id`) REFERENCES `journal_entries`(`id`) ON DELETE CASCADE,
    FOREIGN KEY (`account_id`) REFERENCES `accounts`(`id`) ON DELETE RESTRICT
);

CREATE INDEX `idx_lines_journal` ON `journal_lines`(`journal_entry_id`);
CREATE INDEX `idx_lines_account` ON `journal_lines`(`account_id`);

CREATE TABLE IF NOT EXISTS `subledgers` (
    `id` CHAR(36) PRIMARY KEY,
    `subledger_type` VARCHAR(20) NOT NULL CHECK (`subledger_type` IN ('Student', 'Vendor', 'Staff')),
    `reference_id` CHAR(36) NOT NULL,
    `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT `unq_subledger` UNIQUE (`subledger_type`, `reference_id`)
);

CREATE INDEX `idx_subledger_ref` ON `subledgers`(`subledger_type`, `reference_id`);

CREATE TABLE IF NOT EXISTS `journal_line_subledgers` (
    `id` CHAR(36) PRIMARY KEY,
    `journal_line_id` CHAR(36) NOT NULL,
    `subledger_id` CHAR(36) NOT NULL,
    CONSTRAINT `unq_line_subledger` UNIQUE (`journal_line_id`, `subledger_id`),
    FOREIGN KEY (`journal_line_id`) REFERENCES `journal_lines`(`id`) ON DELETE CASCADE,
    FOREIGN KEY (`subledger_id`) REFERENCES `subledgers`(`id`) ON DELETE RESTRICT
);

CREATE INDEX `idx_jls_line` ON `journal_line_subledgers`(`journal_line_id`);
CREATE INDEX `idx_jls_subledger` ON `journal_line_subledgers`(`subledger_id`);

CREATE TABLE IF NOT EXISTS `audit_logs` (
    `id` CHAR(36) PRIMARY KEY,
    `entity_type` VARCHAR(50) NOT NULL,
    `entity_id` CHAR(36) NOT NULL,
    `action` VARCHAR(20) NOT NULL CHECK (`action` IN ('CREATE', 'UPDATE', 'POST', 'REVERSE', 'DELETE')),
    `performed_by` CHAR(36) NOT NULL,
    `performed_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `details` JSON
);

CREATE INDEX `idx_audit_entity` ON `audit_logs`(`entity_type`, `entity_id`);
CREATE INDEX `idx_audit_performed` ON `audit_logs`(`performed_at`);