"""
Printing 模块信号处理函数

监听 stateflow 信号，在流程完成时执行业务逻辑。
"""

import logging
from decimal import Decimal, InvalidOperation
from django.conf import settings
from django.db import transaction

logger = logging.getLogger(__name__)


def on_printing_job_process_completed(sender, **kwargs):
    """
    PrintingJob 流程完成时的处理
    
    当 PrintingJob 的工艺流程全部完成时，自动创建 SalesItem（销售品）。
    数量和单位从指定的流程节点参数中获取（通过 settings 配置）。
    
    配置项：
        AUTO_CREATE_SALESITEM_FROM_PRINT_ORDER: 是否启用自动创建销售品（默认 True）
        PRINTING_SALES_ITEM_SOURCE_STATE_ID: 指定从哪个 State 获取参数
        PRINTING_SALES_ITEM_QUANTITY_KEY: 数量参数的 key
        PRINTING_SALES_ITEM_UNIT_KEY: 单位参数的 key
    
    Args:
        sender: PrintingJob 类
        content_object: PrintingJob 实例
        business_object: BusinessObject 实例
        last_completed_by: 最后步骤操作人
        其他参数见 stateflow.signals.process_completed
    """
    # 检查是否启用自动创建销售品
    if not getattr(settings, 'AUTO_CREATE_SALESITEM_FROM_PRINT_ORDER', True):
        logger.debug('[printing.handlers] AUTO_CREATE_SALESITEM_FROM_PRINT_ORDER=False，跳过销售品创建')
        return
    
    from shipment.models import SalesItem, UnitChoices
    
    logger.info(
        f'[printing.handlers] 收到 process_completed 信号: '
        f'sender={sender}, kwargs keys={list(kwargs.keys())}'
    )
    
    content_object = kwargs.get('content_object')
    business_object = kwargs.get('business_object')
    last_completed_by = kwargs.get('last_completed_by')
    
    if content_object is None or business_object is None:
        logger.warning('process_completed 信号缺少 content_object 或 business_object')
        return
    
    printing_job = content_object
    logger.info(f'[printing.handlers] 处理 PrintingJob #{printing_job.id}')
    
    # 从 settings 获取配置
    source_state_id = getattr(settings, 'PRINTING_SALES_ITEM_SOURCE_STATE_ID', None)
    quantity_key = getattr(settings, 'PRINTING_SALES_ITEM_QUANTITY_KEY', '米数')
    
    if source_state_id is None:
        logger.debug(
            f'PrintingJob #{printing_job.id} 流程完成，'
            f'但 PRINTING_SALES_ITEM_SOURCE_STATE_ID 未配置，跳过销售品创建'
        )
        return
    
    # 从 business_object 的状态流转记录中找到指定 state_id 的记录
    state_log = business_object.state_logs.filter(
        state_id=source_state_id,
        is_cancelled=False
    ).first()
    
    if state_log is None:
        logger.warning(
            f'PrintingJob #{printing_job.id} 流程完成，'
            f'但未找到 state_id={source_state_id} 的已完成记录，跳过销售品创建'
        )
        return
    
    # 获取参数汇总
    params = state_log.get_all_parameters_summary()
    
    # 获取数量
    quantity_raw = params.get(quantity_key)
    if quantity_raw is None:
        logger.warning(
            f'PrintingJob #{printing_job.id} 流程完成，'
            f'但 state_id={source_state_id} 的参数中缺少 {quantity_key}，跳过销售品创建'
        )
        return
    
    # 转换数量为 Decimal
    try:
        quantity = Decimal(str(quantity_raw))
    except (InvalidOperation, ValueError, TypeError) as e:
        logger.warning(
            f'PrintingJob #{printing_job.id} 流程完成，'
            f'但 {quantity_key}={quantity_raw} 无法转换为数字: {e}，跳过销售品创建'
        )
        return
    
    # 单位固定为"米"
    sales_unit = UnitChoices.METER
    
    # 获取产品名称
    product_name = printing_job.product.name if printing_job.product else '未知产品'
    
    # 获取客户ID（从主订单获取）
    customer_id = None
    if printing_job.printing_order and printing_job.printing_order.customer:
        customer_id = printing_job.printing_order.customer_id
    
    try:
        with transaction.atomic():
            sales_item = SalesItem.objects.create(
                shipment=None,  # 暂不关联出货单，待后续分配
                name=product_name,
                quantity=quantity,
                unit=sales_unit,
                created_by=last_completed_by,
                printing_job_id=printing_job.id,
                customer_id=customer_id,
            )
            
            logger.info(
                f'PrintingJob #{printing_job.id} 流程完成，'
                f'已创建销售品 SalesItem #{sales_item.id}: '
                f'{product_name} x {quantity} {sales_item.get_unit_display()}'
            )
            
    except Exception as e:
        logger.error(
            f'PrintingJob #{printing_job.id} 流程完成后创建销售品失败: {e}',
            exc_info=True
        )