from app.extensions import db
from app.models.bom_draft import BomDraftTable
from app.models.base import MaterialBase
from app.services.bom_service import BomService
import logging

logger = logging.getLogger(__name__)


class BomDraftService:

    @staticmethod
    def save_draft(bom_no, version, parent_id, children):
        try:
            # 1. 删除旧草稿
            old = BomDraftTable.query.filter_by(bom_no=bom_no, version=version).all()
            for rec in old:
                db.session.delete(rec)
            db.session.flush()

            # 2. 如果没有任何子件，必须插入一条只包含 parent_id 的占位头数据
            if not children:
                dummy_draft = BomDraftTable(
                    bom_no=bom_no, version=version, parent_id=parent_id,
                    child_id=None, dosage=0, loss_rate=0, remark=''
                )
                db.session.add(dummy_draft)
            else:
                # 正常批量插入新草稿行
                for child in children:
                    draft = BomDraftTable(
                        bom_no=bom_no, version=version, parent_id=parent_id,
                        child_id=child.get('child_id'),
                        dosage=child.get('dosage', 0),
                        loss_rate=child.get('loss_rate', 0),
                        remark=child.get('remark', '')
                    )
                    db.session.add(draft)

            db.session.commit()
        except Exception as e:
            db.session.rollback()
            logger.error(f"[BomDraft] save_draft 失败 bom_no={bom_no}: {e}")
            raise
        return bom_no

    @staticmethod
    def get_draft_detail(bom_no, version):
        rows = db.session.query(
            BomDraftTable,
            MaterialBase.name.label('child_name'),
            MaterialBase.spec_model.label('child_spec')
        ).outerjoin(
            MaterialBase, BomDraftTable.child_id == MaterialBase.id
        ).filter(
            BomDraftTable.bom_no == bom_no,
            BomDraftTable.version == version
        ).all()

        if not rows:
            return None

        first = rows[0].BomDraftTable
        parent_id = first.parent_id
        parent_material = MaterialBase.query.get(parent_id) if parent_id else None

        children = []
        for draft, child_name, child_spec in rows:
            # 过滤掉保存 BOM 头时插入的占位空行
            if draft.child_id is not None:
                children.append({
                    'child_id': draft.child_id,
                    'child_name': child_name or '',
                    'child_spec': child_spec or '',
                    'dosage': float(draft.dosage) if draft.dosage else 0.0,
                    'loss_rate': float(draft.loss_rate) if draft.loss_rate else 0.0,
                    'remark': draft.remark or '',
                })

        return {
            'bom_no': bom_no,
            'version': first.version,
            'parent_id': parent_id,
            'parent_name': parent_material.name if parent_material else '',
            'parent_spec': parent_material.spec_model if parent_material else '',
            'children': children,
        }

    @staticmethod
    def publish_draft(bom_no, version):
        """
        发布草稿为正式 BOM：
          1. 获取草稿数据
          2. 强校验（父件不为空、子件列表非空、所有子件 ID>0、用量>0）
          3. 调用 BomService.save_bom 写入正式 bom_table
          4. 清空草稿数据
        """
        try:
            # 步骤 1
            draft = BomDraftService.get_draft_detail(bom_no, version)
            if not draft:
                raise ValueError('草稿不存在')

            # 步骤 2：强校验
            if not draft.get('parent_id'):
                raise ValueError('发布失败：父件不能为空')

            children = draft.get('children', [])
            if not children:
                raise ValueError('发布失败：子件列表不能为空')

            for child in children:
                if not child.get('child_id') or child['child_id'] <= 0:
                    raise ValueError('发布失败：子件ID必须大于0')
                dosage = child.get('dosage')
                if not dosage or dosage <= 0:
                    raise ValueError('发布失败：子件用量必须大于0')

            # 步骤 3：复用正式 BOM 的写入逻辑（跨版本查重 + 缓存清理均在 save_bom 内完成）
            publish_data = {
                'bom_no': bom_no,
                'version': version,
                'parent_id': draft['parent_id'],
                'children': [
                    {
                        'child_id': child['child_id'],
                        'dosage': child['dosage'],
                        'remark': child.get('remark', ''),
                    }
                    for child in children
                ],
            }
            BomService.save_bom(publish_data)

            # 步骤 4：清空草稿数据
            old_rows = BomDraftTable.query.filter_by(bom_no=bom_no, version=version).all()
            for rec in old_rows:
                db.session.delete(rec)
            db.session.commit()
            logger.info(f"[BomDraft] publish_draft bom_no={bom_no} version={version} -> 已发布并清空草稿")
        except Exception as e:
            db.session.rollback()
            logger.error(f"[BomDraft] publish_draft 失败 bom_no={bom_no}: {e}")
            raise
        return bom_no