<?php
declare(strict_types=1);

use PHPUnit\Framework\TestCase;

/**
 * Integration tests for WPDO_Points_Manager against real MariaDB.
 *
 * Verifies transaction discipline (BEGIN/COMMIT/ROLLBACK), atomic balance
 * serialisation, ledger integrity, and overdraft protection using the real
 * InnoDB transaction engine.
 *
 * Tables created with wp_itest_ prefix to avoid polluting production data.
 */
class PointsAtomicIntegrationTest extends TestCase {

	private const MEM_TABLE    = 'wp_itest_wpdo_user_membership';
	private const LEDGER_TABLE = 'wp_itest_wpdo_user_points_ledger';
	private const ERRORS_TABLE = 'wp_itest_wpdo_errors';

	// ── Fixture lifecycle ────────────────────────────────────────────────────

	public static function setUpBeforeClass(): void {
		global $wpdb;

		if ( ! class_exists( 'WPDO_Points_Manager' ) ) {
			require_once WPDO_PLUGIN_DIR . 'includes/integrations/class-tmdo-points-manager.php';
		}
		if ( ! class_exists( 'WPDO_DB' ) ) {
			require_once WPDO_PLUGIN_DIR . 'includes/class-tmdo-db.php';
		}
		if ( ! class_exists( 'WPDO_Logger' ) ) {
			require_once WPDO_PLUGIN_DIR . 'includes/class-tmdo-logger.php';
		}

		$wpdb->query(
			'CREATE TABLE IF NOT EXISTS `' . self::MEM_TABLE . '` (
				`id`             bigint(20) unsigned NOT NULL AUTO_INCREMENT,
				`user_id`        bigint(20) unsigned NOT NULL,
				`points_balance` bigint(20) NOT NULL DEFAULT 0,
				PRIMARY KEY (`id`),
				UNIQUE KEY `uk_user` (`user_id`)
			) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4'
		);

		$wpdb->query(
			'CREATE TABLE IF NOT EXISTS `' . self::LEDGER_TABLE . '` (
				`id`            bigint(20) unsigned NOT NULL AUTO_INCREMENT,
				`user_id`       bigint(20) unsigned NOT NULL,
				`delta`         int(11) NOT NULL,
				`balance_after` bigint(20) NOT NULL,
				`reason`        varchar(60) NOT NULL DEFAULT \'\',
				`ref_id`        bigint(20) DEFAULT NULL,
				`ref_type`      varchar(30) DEFAULT NULL,
				`created_at`    datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
				PRIMARY KEY (`id`),
				KEY `idx_user_created` (`user_id`,`created_at`)
			) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4'
		);

		$wpdb->query(
			'CREATE TABLE IF NOT EXISTS `' . self::ERRORS_TABLE . '` (
				`id`         bigint(20) unsigned NOT NULL AUTO_INCREMENT,
				`severity`   varchar(10) NOT NULL DEFAULT \'error\',
				`component`  varchar(60) NOT NULL DEFAULT \'\',
				`context`    varchar(60) NOT NULL DEFAULT \'\',
				`message`    text NOT NULL,
				`created_at` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
				PRIMARY KEY (`id`)
			) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4'
		);
	}

	public static function tearDownAfterClass(): void {
		global $wpdb;
		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::MEM_TABLE . '`' );
		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::LEDGER_TABLE . '`' );
		$wpdb->query( 'DROP TABLE IF EXISTS `' . self::ERRORS_TABLE . '`' );
	}

	protected function setUp(): void {
		global $wpdb;
		$wpdb->query( 'TRUNCATE TABLE `' . self::MEM_TABLE . '`' );
		$wpdb->query( 'TRUNCATE TABLE `' . self::LEDGER_TABLE . '`' );
	}

	// ── credit() happy path ─────────────────────────────────────────────────

	public function test_credit_creates_membership_row(): void {
		$result = WPDO_Points_Manager::credit( 1, 100, 'signup_bonus' );

		$this->assertTrue( $result['ok'] );
		$this->assertSame( 100, $result['balance'] );
		$this->assertGreaterThan( 0, $result['ledger_id'] );
	}

	public function test_credit_accumulates_balance(): void {
		WPDO_Points_Manager::credit( 2, 200, 'first' );
		$result = WPDO_Points_Manager::credit( 2, 300, 'second' );

		$this->assertTrue( $result['ok'] );
		$this->assertSame( 500, $result['balance'] );
	}

	public function test_credit_writes_ledger_row(): void {
		global $wpdb;
		WPDO_Points_Manager::credit( 3, 50, 'test_reason' );

		$row = $wpdb->get_row(
			"SELECT * FROM `" . self::LEDGER_TABLE . "` WHERE user_id = 3",
			ARRAY_A
		);
		$this->assertNotNull( $row );
		$this->assertSame( '50', $row['delta'] );
		$this->assertSame( '50', $row['balance_after'] );
		$this->assertSame( 'test_reason', $row['reason'] );
	}

	public function test_get_balance_reflects_credits(): void {
		WPDO_Points_Manager::credit( 4, 75, 'top_up' );

		$balance = WPDO_Points_Manager::get_balance( 4 );
		$this->assertSame( 75, $balance );
	}

	// ── debit() happy path ──────────────────────────────────────────────────

	public function test_debit_after_credit_reduces_balance(): void {
		WPDO_Points_Manager::credit( 5, 300, 'load' );
		$result = WPDO_Points_Manager::debit( 5, 100, 'purchase' );

		$this->assertTrue( $result['ok'] );
		$this->assertSame( 200, $result['balance'] );
	}

	public function test_debit_writes_negative_delta_to_ledger(): void {
		global $wpdb;
		WPDO_Points_Manager::credit( 6, 200, 'load' );
		WPDO_Points_Manager::debit( 6, 50, 'spend' );

		$rows = $wpdb->get_results(
			"SELECT delta, balance_after FROM `" . self::LEDGER_TABLE . "` WHERE user_id = 6 ORDER BY id",
			ARRAY_A
		);
		$this->assertCount( 2, $rows );
		$this->assertSame( '200', $rows[0]['delta'] );   // credit row.
		$this->assertSame( '-50', $rows[1]['delta'] );
		$this->assertSame( '150', $rows[1]['balance_after'] );
	}

	// ── debit() insufficient balance ─────────────────────────────────────────

	public function test_debit_fails_when_insufficient(): void {
		WPDO_Points_Manager::credit( 7, 50, 'load' );
		$result = WPDO_Points_Manager::debit( 7, 100, 'purchase' );

		$this->assertFalse( $result['ok'] );
		$this->assertSame( 'insufficient_balance', $result['error'] );
	}

	public function test_debit_failure_does_not_write_ledger(): void {
		global $wpdb;
		WPDO_Points_Manager::credit( 8, 30, 'load' );
		WPDO_Points_Manager::debit( 8, 100, 'purchase' ); // should fail.

		$count = (int) $wpdb->get_var(
			"SELECT COUNT(*) FROM `" . self::LEDGER_TABLE . "` WHERE user_id = 8 AND delta < 0"
		);
		$this->assertSame( 0, $count );
	}

	public function test_debit_failure_preserves_balance(): void {
		WPDO_Points_Manager::credit( 9, 40, 'load' );
		WPDO_Points_Manager::debit( 9, 200, 'purchase' ); // fails.

		$balance = WPDO_Points_Manager::get_balance( 9 );
		$this->assertSame( 40, $balance );
	}

	// ── sequential double-spend scenario ────────────────────────────────────

	/**
	 * Simulate the classic double-spend race:
	 * Balance = 100. Two requests each try to debit 80.
	 * With FOR UPDATE serialisation: first succeeds → balance = 20,
	 * second then reads balance = 20 and correctly rejects (insufficient).
	 */
	public function test_sequential_debit_only_first_succeeds(): void {
		WPDO_Points_Manager::credit( 10, 100, 'load' );

		$first  = WPDO_Points_Manager::debit( 10, 80, 'spend_1' );
		$second = WPDO_Points_Manager::debit( 10, 80, 'spend_2' );

		$this->assertTrue( $first['ok'],  'First debit should succeed' );
		$this->assertSame( 20, $first['balance'] );

		$this->assertFalse( $second['ok'], 'Second debit should fail (insufficient)' );
		$this->assertSame( 'insufficient_balance', $second['error'] );

		$this->assertSame( 20, WPDO_Points_Manager::get_balance( 10 ) );
	}

	public function test_sequential_debits_leave_correct_ledger_count(): void {
		global $wpdb;
		WPDO_Points_Manager::credit( 11, 200, 'load' );
		WPDO_Points_Manager::debit( 11, 150, 'spend_1' ); // succeeds: balance=50.
		WPDO_Points_Manager::debit( 11, 150, 'spend_2' ); // fails: insufficient.

		$debit_count = (int) $wpdb->get_var(
			"SELECT COUNT(*) FROM `" . self::LEDGER_TABLE . "` WHERE user_id = 11 AND delta < 0"
		);
		$this->assertSame( 1, $debit_count, 'Only one successful debit should be in ledger' );
	}

	// ── allow_overdraft ──────────────────────────────────────────────────────

	public function test_overdraft_debit_goes_negative(): void {
		WPDO_Points_Manager::credit( 12, 50, 'load' );
		$result = WPDO_Points_Manager::debit( 12, 200, 'force', 0, '', true );

		$this->assertTrue( $result['ok'] );
		$this->assertSame( -150, $result['balance'] );
	}

	// ── ref_id / ref_type ────────────────────────────────────────────────────

	public function test_credit_with_ref_id_and_type(): void {
		global $wpdb;
		WPDO_Points_Manager::credit( 13, 100, 'order_reward', 9999, 'order' );

		$row = $wpdb->get_row(
			"SELECT ref_id, ref_type FROM `" . self::LEDGER_TABLE . "` WHERE user_id = 13",
			ARRAY_A
		);
		$this->assertSame( '9999', $row['ref_id'] );
		$this->assertSame( 'order', $row['ref_type'] );
	}

	// ── get_ledger() ─────────────────────────────────────────────────────────

	public function test_get_ledger_returns_entries_newest_first(): void {
		WPDO_Points_Manager::credit( 14, 100, 'a' );
		WPDO_Points_Manager::credit( 14, 200, 'b' );

		$ledger = WPDO_Points_Manager::get_ledger( 14 );

		$this->assertCount( 2, $ledger );
		// Newest-first: second credit (delta=200) should be first.
		$this->assertSame( '200', $ledger[0]['delta'] );
		$this->assertSame( '100', $ledger[1]['delta'] );
	}

	public function test_get_ledger_respects_limit(): void {
		for ( $i = 1; $i <= 5; $i++ ) {
			WPDO_Points_Manager::credit( 15, 10, "entry_{$i}" );
		}

		$ledger = WPDO_Points_Manager::get_ledger( 15, 3 );
		$this->assertCount( 3, $ledger );
	}
}