"""
Test suite for Credit Transaction Manager

Tests all credit transaction operations including:
- Reserve credits
- Confirm credits
- Refund credits
- Add credits (purchases)
- Balance verification
- Transaction history
"""
import pytest
import uuid
from datetime import datetime
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.pool import StaticPool

from core.models import Base, User, CreditTransaction
from services.credit_service.transaction_manager import (
    CreditTransactionManager,
    InsufficientCreditsError,
    TransactionNotFoundError,
    UserNotFoundError
)


# Test database setup
TEST_DATABASE_URL = "sqlite+aiosqlite:///:memory:"

@pytest.fixture
async def engine():
    """Create test database engine."""
    engine = create_async_engine(
        TEST_DATABASE_URL,
        connect_args={"check_same_thread": False},
        poolclass=StaticPool,
    )
    
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
    
    yield engine
    
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.drop_all)
    
    await engine.dispose()


@pytest.fixture
async def session(engine):
    """Create test database session."""
    async_session = async_sessionmaker(
        engine, class_=AsyncSession, expire_on_commit=False
    )
    
    async with async_session() as session:
        yield session


@pytest.fixture
async def test_user(session):
    """Create a test user with 100 credits."""
    user = User(
        user_id=f"test_{uuid.uuid4().hex[:8]}",
        email=f"test_{uuid.uuid4().hex[:8]}@example.com",
        credits=100,
        is_active=True
    )
    session.add(user)
    await session.commit()
    await session.refresh(user)
    return user


# =============================================================================
# Reserve Credits Tests
# =============================================================================

@pytest.mark.asyncio
async def test_reserve_credits_success(session, test_user):
    """Test successfully reserving credits."""
    initial_balance = test_user.credits
    
    transaction = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_123",
        reason="Test reservation"
    )
    
    await session.commit()
    await session.refresh(test_user)
    
    # Verify transaction
    assert transaction.transaction_type == "reserve"
    assert transaction.amount == -10
    assert transaction.balance_before == initial_balance
    assert transaction.balance_after == initial_balance - 10
    assert transaction.user_id == test_user.id
    assert transaction.source == "test"
    
    # Verify user balance
    assert test_user.credits == initial_balance - 10


@pytest.mark.asyncio
async def test_reserve_credits_insufficient_funds(session, test_user):
    """Test reserving more credits than available."""
    test_user.credits = 5
    await session.commit()
    
    with pytest.raises(InsufficientCreditsError):
        await CreditTransactionManager.reserve_credits(
            session=session,
            user=test_user,
            amount=10,
            source="test",
            reference_type="test",
            reference_id="test_123"
        )
    
    # Balance should be unchanged
    await session.refresh(test_user)
    assert test_user.credits == 5


@pytest.mark.asyncio
async def test_reserve_credits_exact_amount(session, test_user):
    """Test reserving exact credit balance."""
    test_user.credits = 10
    await session.commit()
    
    transaction = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_123"
    )
    
    await session.commit()
    await session.refresh(test_user)
    
    assert test_user.credits == 0
    assert transaction.balance_after == 0


# =============================================================================
# Confirm Credits Tests
# =============================================================================

@pytest.mark.asyncio
async def test_confirm_credits_success(session, test_user):
    """Test confirming reserved credits."""
    # First reserve credits
    reserve_tx = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_123"
    )
    await session.commit()
    
    # Then confirm
    confirm_tx = await CreditTransactionManager.confirm_credits(
        session=session,
        transaction_id=reserve_tx.transaction_id,
        metadata={"status": "success"}
    )
    await session.commit()
    
    # Verify confirmation
    assert confirm_tx.transaction_type == "confirm"
    assert confirm_tx.amount == 0  # No balance change
    assert confirm_tx.user_id == test_user.id
    assert confirm_tx.metadata["original_transaction_id"] == reserve_tx.transaction_id


@pytest.mark.asyncio
async def test_confirm_credits_nonexistent_transaction(session, test_user):
    """Test confirming a non-existent transaction."""
    with pytest.raises(TransactionNotFoundError):
        await CreditTransactionManager.confirm_credits(
            session=session,
            transaction_id="nonexistent_tx_id"
        )


# =============================================================================
# Refund Credits Tests
# =============================================================================

@pytest.mark.asyncio
async def test_refund_credits_success(session, test_user):
    """Test refunding reserved credits."""
    initial_balance = test_user.credits
    
    # Reserve credits
    reserve_tx = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_123"
    )
    await session.commit()
    await session.refresh(test_user)
    
    balance_after_reserve = test_user.credits
    assert balance_after_reserve == initial_balance - 10
    
    # Refund
    refund_tx = await CreditTransactionManager.refund_credits(
        session=session,
        transaction_id=reserve_tx.transaction_id,
        reason="Test failed - refunding",
        metadata={"error": "test_error"}
    )
    await session.commit()
    await session.refresh(test_user)
    
    # Verify refund
    assert refund_tx.transaction_type == "refund"
    assert refund_tx.amount == 10  # Positive for addition
    assert refund_tx.balance_before == balance_after_reserve
    assert refund_tx.balance_after == initial_balance
    assert test_user.credits == initial_balance


@pytest.mark.asyncio
async def test_refund_credits_nonexistent_transaction(session, test_user):
    """Test refunding a non-existent transaction."""
    with pytest.raises(TransactionNotFoundError):
        await CreditTransactionManager.refund_credits(
            session=session,
            transaction_id="nonexistent_tx_id",
            reason="Test refund"
        )


# =============================================================================
# Add Credits Tests (Purchases)
# =============================================================================

@pytest.mark.asyncio
async def test_add_credits_success(session, test_user):
    """Test adding credits from purchase."""
    initial_balance = test_user.credits
    
    transaction = await CreditTransactionManager.add_credits(
        session=session,
        user=test_user,
        amount=50,
        source="payment",
        reference_type="payment",
        reference_id="pay_123",
        reason="Purchase: 50 credits",
        metadata={"package_id": "basic"}
    )
    
    await session.commit()
    await session.refresh(test_user)
    
    # Verify transaction
    assert transaction.transaction_type == "purchase"
    assert transaction.amount == 50
    assert transaction.balance_before == initial_balance
    assert transaction.balance_after == initial_balance + 50
    
    # Verify balance
    assert test_user.credits == initial_balance + 50


# =============================================================================
# Balance Verification Tests
# =============================================================================

@pytest.mark.asyncio
async def test_get_balance(session, test_user):
    """Test getting current balance."""
    balance = await CreditTransactionManager.get_balance(
        session=session,
        user_id=test_user.id
    )
    
    assert balance == test_user.credits


@pytest.mark.asyncio
async def test_get_balance_with_verification(session, test_user):
    """Test balance verification against transaction history."""
    # Perform some transactions
    await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_1"
    )
    await session.commit()
    
    await CreditTransactionManager.add_credits(
        session=session,
        user=test_user,
        amount=20,
        source="test",
        reference_type="test",
        reference_id="test_2"
    )
    await session.commit()
    
    # Verify balance
    balance = await CreditTransactionManager.get_balance(
        session=session,
        user_id=test_user.id,
        verify=True
    )
    
    await session.refresh(test_user)
    assert balance == test_user.credits


@pytest.mark.asyncio
async def test_get_balance_nonexistent_user(session):
    """Test getting balance for non-existent user."""
    with pytest.raises(UserNotFoundError):
        await CreditTransactionManager.get_balance(
            session=session,
            user_id=99999
        )


# =============================================================================
# Transaction History Tests
# =============================================================================

@pytest.mark.asyncio
async def test_get_transaction_history(session, test_user):
    """Test getting transaction history."""
    # Create multiple transactions
    await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_1"
    )
    await session.commit()
    
    await CreditTransactionManager.add_credits(
        session=session,
        user=test_user,
        amount=20,
        source="test",
        reference_type="test",
        reference_id="test_2"
    )
    await session.commit()
    
    # Get history
    history = await CreditTransactionManager.get_transaction_history(
        session=session,
        user_id=test_user.id,
        limit=10
    )
    
    assert len(history) == 2
    assert history[0].transaction_type in ["reserve", "purchase"]


@pytest.mark.asyncio
async def test_get_transaction_history_filtered(session, test_user):
    """Test getting filtered transaction history."""
    # Create different transaction types
    await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="test",
        reference_type="test",
        reference_id="test_1"
    )
    await session.commit()
    
    await CreditTransactionManager.add_credits(
        session=session,
        user=test_user,
        amount=20,
        source="payment",
        reference_type="payment",
        reference_id="pay_1"
    )
    await session.commit()
    
    # Filter by purchase only
    history = await CreditTransactionManager.get_transaction_history(
        session=session,
        user_id=test_user.id,
        transaction_type="purchase"
    )
    
    assert len(history) == 1
    assert history[0].transaction_type == "purchase"


# =============================================================================
# Integration Tests
# =============================================================================

@pytest.mark.asyncio
async def test_full_transaction_flow(session, test_user):
    """Test complete transaction flow: reserve → confirm."""
    initial_balance = test_user.credits
    
    # Reserve
    reserve_tx = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="middleware",
        reference_type="request",
        reference_id="POST:/api/endpoint"
    )
    await session.commit()
    
    # Confirm
    confirm_tx = await CreditTransactionManager.confirm_credits(
        session=session,
        transaction_id=reserve_tx.transaction_id
    )
    await session.commit()
    
    # Verify final state
    await session.refresh(test_user)
    assert test_user.credits == initial_balance - 10
    
    # Verify transaction history
    history = await CreditTransactionManager.get_transaction_history(
        session=session,
        user_id=test_user.id
    )
    
    assert len(history) == 2
    assert history[1].transaction_type == "reserve"
    assert history[0].transaction_type == "confirm"


@pytest.mark.asyncio
async def test_full_refund_flow(session, test_user):
    """Test complete refund flow: reserve → refund."""
    initial_balance = test_user.credits
    
    # Reserve
    reserve_tx = await CreditTransactionManager.reserve_credits(
        session=session,
        user=test_user,
        amount=10,
        source="middleware",
        reference_type="request",
        reference_id="POST:/api/endpoint"
    )
    await session.commit()
    
    # Refund
    refund_tx = await CreditTransactionManager.refund_credits(
        session=session,
        transaction_id=reserve_tx.transaction_id,
        reason="Request failed"
    )
    await session.commit()
    
    # Verify final state
    await session.refresh(test_user)
    assert test_user.credits == initial_balance  # Back to original
    
    # Verify transaction history
    history = await CreditTransactionManager.get_transaction_history(
        session=session,
        user_id=test_user.id
    )
    
    assert len(history) == 2
    assert history[1].transaction_type == "reserve"
    assert history[0].transaction_type == "refund"