<?php

declare(strict_types = 1);

namespace Foundation\Tests\Unit\Core\Database;

use Foundation\Core\Database\EntityPersisterInterface;
use Foundation\Core\Database\EntityState;
use Foundation\Core\Database\UnitOfWork;
use PDO;
use PDOException;
use PHPUnit\Framework\TestCase;
use RuntimeException;

class UnitOfWorkTest extends TestCase
{
    private PDO $pdo;
    private UnitOfWork $unitOfWork;

    protected function setUp(): void {
        $this->pdo = $this->createMock(PDO::class);
        $this->unitOfWork = new UnitOfWork($this->pdo);
    }

    public function testSetsEntityStateToNewWhenRegisteringANewEntity(): void {
        $entity = new TestEntity();

        $this->unitOfWork->registerNew($entity);

        self::assertSame(EntityState::NEW, $this->unitOfWork->getEntityState($entity));
    }

    public function testSetsEntityStateToDirtyWhenRegisteringADirtyEntity(): void {
        $entity = new TestEntity();

        $this->unitOfWork->registerDirty($entity);

        self::assertSame(EntityState::DIRTY, $this->unitOfWork->getEntityState($entity));
    }

    public function testDoesNotOverrideNewStateWhenRegisteringADirtyEntity(): void {
        $entity = new TestEntity();

        $this->unitOfWork->registerNew($entity);
        $this->unitOfWork->registerDirty($entity);

        self::assertSame(EntityState::NEW, $this->unitOfWork->getEntityState($entity));
    }

    public function testSetsEntityStateToRemovedWhenRegisteringARemovedEntity(): void {
        $entity = new TestEntity();

        $this->unitOfWork->registerRemoved($entity);

        self::assertSame(EntityState::REMOVED, $this->unitOfWork->getEntityState($entity));
    }

    public function testSetsEntityStateToCleanWhenRegisteringCleanEntity(): void {
        $entity = new TestEntity();
        $this->unitOfWork->registerDirty($entity);

        $this->unitOfWork->registerClean($entity);

        self::assertSame(EntityState::CLEAN, $this->unitOfWork->getEntityState($entity));
    }

    public function testReturnsCleanStateForUnknownEntities(): void {
        $entity = new TestEntity();

        self::assertSame(EntityState::CLEAN, $this->unitOfWork->getEntityState($entity));
    }

    public function testDoesNotStartTransactionWhenCommittingWithNoChanges(): void {
        $this->pdo->expects(self::never())->method('beginTransaction');

        $this->unitOfWork->commit();
    }

    public function testDoesStartTransactionAndCommitIt(): void {
        $entity = new TestEntity();
        $persister = $this->createMock(EntityPersisterInterface::class);

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($entity);

        $persister->expects(self::once())->method('supports')->with($entity)->willReturn(true);
        $persister->expects(self::once())->method('insert')->with($entity, $this->pdo);

        $this->pdo->expects(self::once())->method('beginTransaction');
        $this->pdo->expects(self::once())->method('commit');

        $this->unitOfWork->commit();
    }

    public function testProcessesEntitiesInCorrectOrderOnCommit(): void {
        $newEntity = new TestEntity();
        $dirtyEntity = new TestEntity();
        $removedEntity = new TestEntity();

        $persister = $this->createMock(EntityPersisterInterface::class);
        $this->unitOfWork->registerPersister($persister);

        $this->unitOfWork->registerNew($newEntity);
        $this->unitOfWork->registerDirty($dirtyEntity);
        $this->unitOfWork->registerRemoved($removedEntity);

        $callOrder = [];

        $persister->method('supports')->willReturn(true);
        $persister->method('delete')->willReturnCallback(
            function () use (&$callOrder): void {
                $callOrder[] = 'delete';
            },
        );
        $persister->method('insert')->willReturnCallback(
            function () use (&$callOrder): void {
                $callOrder[] = 'insert';
            },
        );
        $persister->method('update')->willReturnCallback(
            function () use (&$callOrder): void {
                $callOrder[] = 'update';
            },
        );

        $this->pdo->method('beginTransaction');
        $this->pdo->method('commit');

        $this->unitOfWork->commit();

        self::assertSame(['delete', 'insert', 'update'], $callOrder);
    }

    public function testMarksAllEntitiesAsCleanAfterASuccessfulCommit(): void {
        $newEntity = new TestEntity();
        $dirtyEntity = new TestEntity();

        $persister = $this->createMock(EntityPersisterInterface::class);
        $persister->method('supports')->willReturn(true);
        $persister->method('insert');
        $persister->method('update');

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($newEntity);
        $this->unitOfWork->registerDirty($dirtyEntity);

        $this->pdo->method('beginTransaction');
        $this->pdo->method('commit');

        $this->unitOfWork->commit();

        self::assertSame(EntityState::CLEAN, $this->unitOfWork->getEntityState($newEntity));
        self::assertSame(EntityState::CLEAN, $this->unitOfWork->getEntityState($dirtyEntity));
    }

    public function testClearsCollectionsAfterASuccessfulCommit(): void {
        $entity = new TestEntity();
        $persister = $this->createMock(EntityPersisterInterface::class);

        $persister->method('supports')->willReturn(true);
        $persister->method('insert');

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($entity);

        $this->pdo->method('beginTransaction');
        $this->pdo->method('commit');

        $this->unitOfWork->commit();

        // Try to register the same entity again - should work if collections are cleared
        $this->unitOfWork->registerNew($entity);
        self::assertSame(EntityState::NEW, $this->unitOfWork->getEntityState($entity));
    }

    public function testRollsBackOnPDOException(): void {
        $entity = new TestEntity();
        $persister = $this->createMock(EntityPersisterInterface::class);

        $persister->method('supports')->willReturn(true);
        $persister->method('insert')->willThrowException(new PDOException('Database error'));

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($entity);

        $this->pdo->expects(self::once())->method('beginTransaction');
        $this->pdo->expects(self::once())->method('rollBack');
        $this->pdo->expects(self::never())->method('commit');

        $this->expectException(PDOException::class);

        $this->unitOfWork->commit();
    }

    public function testCallsPdoRollbackWhenInTransaction(): void {
        $entity = new TestEntity();
        $persister = $this->createMock(EntityPersisterInterface::class);

        $persister->method('supports')->willReturn(true);
        $persister->method('insert')->willThrowException(new PDOException('Database error'));

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($entity);

        $this->pdo->method('beginTransaction')->willReturn(true);
        $this->pdo->expects(self::once())->method('rollBack');

        try {
            $this->unitOfWork->commit();
        } catch (PDOException $e) {
            // Expected exception
        }

        self::assertFalse($this->unitOfWork->isInTransaction());
    }

    public function testDoesNothingWhenNotInTransactionOnRollback(): void {
        $this->pdo->expects(self::never())->method('rollBack');

        $this->unitOfWork->rollback();
    }

    public function testCanClearInternalState(): void {
        $newEntity = new TestEntity();
        $dirtyEntity = new TestEntity();
        $removedEntity = new TestEntity();

        $this->unitOfWork->registerNew($newEntity);
        $this->unitOfWork->registerDirty($dirtyEntity);
        $this->unitOfWork->registerRemoved($removedEntity);

        $this->unitOfWork->clear();

        // After clear, registering the same entities should work
        $this->unitOfWork->registerNew($newEntity);
        $this->unitOfWork->registerDirty($dirtyEntity);
        $this->unitOfWork->registerRemoved($removedEntity);

        self::assertSame(EntityState::NEW, $this->unitOfWork->getEntityState($newEntity));
        self::assertSame(EntityState::DIRTY, $this->unitOfWork->getEntityState($dirtyEntity));
        self::assertSame(EntityState::REMOVED, $this->unitOfWork->getEntityState($removedEntity));
    }

    public function testCallsPersisterOnEntityPersistence(): void {
        $entity = new TestEntity();
        $persister = $this->createMock(EntityPersisterInterface::class);

        $persister->expects(self::once())->method('supports')->with($entity)->willReturn(true);
        $persister->expects(self::once())->method('insert')->with($entity, $this->pdo);

        $this->unitOfWork->registerPersister($persister);
        $this->unitOfWork->registerNew($entity);

        $this->pdo->method('beginTransaction');
        $this->pdo->method('commit');

        $this->unitOfWork->commit();
    }

    public function testThrowsRuntimeExceptionWhenNoPersisterWasFound(): void {
        $entity = new TestEntity();

        $this->unitOfWork->registerNew($entity);

        $this->pdo->method('beginTransaction');

        $this->expectException(RuntimeException::class);
        $this->expectExceptionMessage('No persister found for entity of type');

        $this->unitOfWork->commit();
    }

    public function testCanHandleMultipleRegisteredPersisters(): void {
        $entity1 = new TestEntity();
        $entity2 = new AnotherTestEntity();

        $persister1 = $this->createMock(EntityPersisterInterface::class);
        $persister2 = $this->createMock(EntityPersisterInterface::class);

        $persister1->method('supports')->willReturnCallback(fn($entity) => $entity instanceof TestEntity);
        $persister2->method('supports')->willReturnCallback(fn($entity) => $entity instanceof AnotherTestEntity);

        $persister1->expects(self::once())->method('insert')->with($entity1, $this->pdo);
        $persister2->expects(self::once())->method('insert')->with($entity2, $this->pdo);

        $this->unitOfWork->registerPersister($persister1);
        $this->unitOfWork->registerPersister($persister2);
        $this->unitOfWork->registerNew($entity1);
        $this->unitOfWork->registerNew($entity2);

        $this->pdo->method('beginTransaction');
        $this->pdo->method('commit');

        $this->unitOfWork->commit();
    }
}

class TestEntity
{
    public function __construct(public string $id = 'test-id') {}
}

class AnotherTestEntity
{
    public function __construct(public string $id = 'another-test-id') {}
}