from . import models
from django.utils import timezone
import logging


logger = logging.getLogger(__name__)


def find_inventory(product_id: int, warehouse_id: int) -> models.Inventory | None:
    """根据产品ID和仓库ID查找库存记录"""

    try:
        inventory = models.Inventory.objects.get(
            product_id=product_id,
            warehouse_id=warehouse_id,
        )
        return inventory
    except models.Inventory.DoesNotExist:
        return None


def create_stock_snapshot(stock_change_record: models.StockChangeRecord, inventory: models.Inventory) -> models.StockSnapshot:
    """创建库存快照记录"""

    if not stock_change_record or stock_change_record.id is None:
        raise ValueError("无效的库存变动记录")

    delta = stock_change_record.delta

    # 必须在库存变动发生后创建快照
    snapshot = models.StockSnapshot(
        product_id=inventory.product_id,
        warehouse_id=inventory.warehouse_id,
        delta=delta,
        quantity_before=inventory.quantity - delta,
        quantity_after=inventory.quantity,
        stock_change_record_id=stock_change_record.id,
        unit=stock_change_record.unit,
        num_of_rolls=stock_change_record.num_of_rolls or 1,
    )
    snapshot.save()
    logger.info(
        f'创建库存快照，库存ID: {inventory.id}, 数量: {inventory.quantity}, '
        f'匹数: {inventory.num_of_rolls}'
    )
    return snapshot


def make_stock_change_completed(stock_change_record: models.StockChangeRecord) -> bool:
    """处理库存变动完成后的逻辑"""
    # TODO: 这里可以添加事务处理以确保数据一致性

    if not stock_change_record or stock_change_record.id is None:
        # 无效的库存变动记录
        return False

    if stock_change_record.is_finished:
        return True

    inventory_record = find_inventory(
        product_id=stock_change_record.product_id,
        warehouse_id=stock_change_record.warehouse_id,
    )

    if not inventory_record:
        logger.info(
            f'库存记录未找到，产品ID: {stock_change_record.product_id}, '
            f'仓库ID: {stock_change_record.warehouse_id}，正在创建新的库存记录。'
        )

        # 如果没有找到库存记录且为入库，则创建一个新的库存记录

        inventory_record = models.Inventory(
            product_id=stock_change_record.product_id,
            warehouse_id=stock_change_record.warehouse_id,
            quantity=stock_change_record.delta,
            num_of_rolls=stock_change_record.num_of_rolls or 0,
            minimum_quantity=0,
        )
        logger.info(
            f'创建新的库存记录，产品ID: {inventory_record.product_id}, '
            f'仓库ID: {inventory_record.warehouse_id}, 数量: {inventory_record.quantity},'
            f'匹数: {inventory_record.num_of_rolls}'
        )
    else:
        # 更新现有库存记录
        inventory_record.quantity += stock_change_record.delta
        if stock_change_record.num_of_rolls:
            inventory_record.num_of_rolls += stock_change_record.num_of_rolls
        
        logger.info(
            f'更新库存记录 {inventory_record.id}，新数量: {inventory_record.quantity}, '
            f'新匹数: {inventory_record.num_of_rolls}'
        )

    inventory_record.save()
    create_stock_snapshot(stock_change_record, inventory_record)
    stock_change_record.is_finished = True
    stock_change_record.finished_at = timezone.now()
    stock_change_record.save()
    logger.info(
        f'库存变动记录 {stock_change_record.id} 标记为已完成。'
    )
    return True