"""
店铺商品目录复制服务：复制店铺商品类型、专区、商品（含 OSS 图片独立拷贝）。
"""
import logging
import time
import uuid

from django.db import transaction

from products.models import Shangpin, ShangpinZhuanqu
from shop.models import Dianpu, ShangpinLeixingDianpu
from utils.oss_utils import copy_in_oss, delete_from_oss, _url_to_oss_key

logger = logging.getLogger('houtai')

COPY_MODE_REPLACE = 'replace'
COPY_MODE_APPEND = 'append'


class ShopCopyError(Exception):
    def __init__(self, message, code=400):
        super().__init__(message)
        self.message = message
        self.code = code


def resolve_dianpu_by_user_uid(user_uid):
    """通过小程序用户 ID（YonghuPingzheng.yonghu，全局唯一）定位店铺"""
    uid = str(user_uid or '').strip()
    if not uid:
        raise ShopCopyError('用户ID不能为空')
    try:
        return Dianpu.objects.select_related('pingzheng').get(pingzheng__yonghu=uid)
    except Dianpu.DoesNotExist:
        raise ShopCopyError(f'未找到用户ID {uid} 对应的店铺', 404)


def _gen_dest_key(target_dianpu_id, category, src_url):
    src_key = _url_to_oss_key(src_url)
    ext = 'png'
    if src_key and '.' in src_key:
        ext = src_key.rsplit('.', 1)[-1].lower() or 'png'
    ts = int(time.time() * 1000)
    rand = uuid.uuid4().hex[:8]
    return f"dianpu/shangpin/{category}/{target_dianpu_id}_{ts}_{rand}.{ext}"


def _copy_image_url(src_url, target_dianpu_id, category):
    """复制 OSS 图片到目标店铺独立路径，返回相对 URL"""
    if not src_url:
        return None
    dest_key = _gen_dest_key(target_dianpu_id, category, src_url)
    if not copy_in_oss(src_url, dest_key):
        raise ShopCopyError(f'图片复制失败: {src_url}')
    return dest_key


def _clear_target_catalog_db_only(target_dianpu):
    """全部覆盖模式：仅删除目标店铺商品目录 DB 记录，返回待清理的 OSS URL"""
    dianpu_id = target_dianpu.id
    oss_to_delete = []

    products = list(Shangpin.query.filter(dianpu_id=dianpu_id))
    for p in products:
        if p.tupian_url:
            oss_to_delete.append(p.tupian_url)
        if p.guize_tupian:
            oss_to_delete.append(p.guize_tupian)
    if products:
        Shangpin.query.filter(dianpu_id=dianpu_id).delete()

    ShangpinZhuanqu.query.filter(dianpu_id=dianpu_id).delete()

    types = list(ShangpinLeixingDianpu.query.filter(dianpu_id=dianpu_id))
    for t in types:
        if t.tupian_url:
            oss_to_delete.append(t.tupian_url)
    if types:
        ShangpinLeixingDianpu.query.filter(dianpu_id=dianpu_id).delete()

    return oss_to_delete


def _delete_oss_urls(urls):
    for url in urls:
        if url:
            delete_from_oss(url)


def _pre_copy_source_images(source_dianpu, target_dianpu):
    """
    预复制源店铺所有图片到目标店铺 OSS 路径。
    返回结构化的预复制数据，供事务内写库使用。
    """
    src_id = source_dianpu.id
    tgt_id = target_dianpu.id

    source_types = list(
        ShangpinLeixingDianpu.query.filter(dianpu_id=src_id).order_by('paixu', 'id')
    )
    type_payloads = []
    for st in source_types:
        type_payloads.append({
            'source': st,
            'tupian_url': _copy_image_url(st.tupian_url, tgt_id, 'shangpinleixing'),
        })

    source_zones = list(
        ShangpinZhuanqu.query.filter(dianpu_id=src_id).order_by('paixu', 'id')
    )
    zone_payloads = []
    for sz in source_zones:
        zone_payloads.append({'source': sz})

    source_products = list(
        Shangpin.query.filter(dianpu_id=src_id).order_by('paixu', 'id')
    )
    product_payloads = []
    for sp in source_products:
        product_payloads.append({
            'source': sp,
            'tupian_url': _copy_image_url(sp.tupian_url, tgt_id, 'shangpin'),
            'guize_tupian': _copy_image_url(sp.guize_tupian, tgt_id, 'shangpinguize') if sp.guize_tupian else None,
        })

    return type_payloads, zone_payloads, product_payloads


def _insert_copied_catalog(target_dianpu, type_payloads, zone_payloads, product_payloads):
    """在目标店铺插入复制后的类型、专区、商品，维护 ID 映射"""
    type_id_map = {}
    zone_id_map = {}

    for item in type_payloads:
        st = item['source']
        new_type = ShangpinLeixingDianpu.query.create(
            dianpu_id=target_dianpu.id,
            gonggong_leixing_id=st.gonggong_leixing_id,
            jieshao=st.jieshao,
            tupian_url=item['tupian_url'],
            paixu=st.paixu,
            shangjia_zhuangtai=st.shangjia_zhuangtai,
            fengjin_zhuangtai=st.fengjin_zhuangtai,
            shenhe_zhuangtai=st.shenhe_zhuangtai,
        )
        type_id_map[st.id] = new_type.id

    for item in zone_payloads:
        sz = item['source']
        new_dianpu_leixing_id = type_id_map.get(sz.dianpu_leixing_id)
        if not new_dianpu_leixing_id:
            raise ShopCopyError(f'专区「{sz.mingzi}」关联的商品类型在复制映射中缺失')
        new_zone = ShangpinZhuanqu.query.create(
            dianpu_id=target_dianpu.id,
            mingzi=sz.mingzi,
            dianpu_leixing_id=new_dianpu_leixing_id,
            leixing_id=sz.leixing_id,
            paixu=sz.paixu,
            shangjia_zhuangtai=sz.shangjia_zhuangtai,
            fengjin_zhuangtai=sz.fengjin_zhuangtai,
            shenhezhuangtai=sz.shenhezhuangtai,
        )
        zone_id_map[sz.id] = new_zone.id

    copied_products = 0
    for item in product_payloads:
        sp = item['source']
        new_dianpu_leixing_id = type_id_map.get(sp.dianpu_leixing_id)
        new_zhuanqu_id = zone_id_map.get(sp.zhuanqu_id) if sp.zhuanqu_id else None
        if sp.dianpu_leixing_id and not new_dianpu_leixing_id:
            raise ShopCopyError(f'商品「{sp.biaoqian}」关联的商品类型在复制映射中缺失')
        if sp.zhuanqu_id and not new_zhuanqu_id:
            raise ShopCopyError(f'商品「{sp.biaoqian}」关联的专区在复制映射中缺失')

        Shangpin.query.create(
            biaoqian=sp.biaoqian,
            jiage=sp.jiage,
            kucun=sp.kucun,
            leixing_id=sp.leixing_id,
            zhuanqu_id=new_zhuanqu_id,
            zhenshi_xiaoliang=0,
            duiwai_xiaoliang=0,
            jieshao=sp.jieshao,
            xiadan_xuzhi=sp.xiadan_xuzhi,
            guize_tupian=item['guize_tupian'],
            yaoqiuleixing=sp.yaoqiuleixing,
            huiyuan_id=sp.huiyuan_id,
            yongjin=sp.yongjin,
            kaioi_ewai_dashou_fencheng=sp.kaioi_ewai_dashou_fencheng,
            ewai_dashou_fencheng=sp.ewai_dashou_fencheng,
            tupian_url=item['tupian_url'],
            paixu=sp.paixu,
            shenhezhuangtai=sp.shenhezhuangtai,
            dianpu_id=target_dianpu.id,
            dianpu_leixing_id=new_dianpu_leixing_id,
            shangjia_zhuangtai=sp.shangjia_zhuangtai,
            fengjin_zhuangtai=sp.fengjin_zhuangtai,
            shenhe_zhuangtai=sp.shenhe_zhuangtai,
        )
        copied_products += 1

    return {
        'types': len(type_payloads),
        'zones': len(zone_payloads),
        'products': copied_products,
    }


def copy_shop_catalog(source_user_uid, target_user_uid, copy_mode=COPY_MODE_APPEND):
    """
    复制店铺商品目录。
    :param source_user_uid: 源店铺小程序用户 ID（YonghuPingzheng.yonghu，唯一）
    :param target_user_uid: 目标店铺小程序用户 ID
    :param copy_mode: 'replace' 全部覆盖 | 'append' 补充追加
    """
    if copy_mode not in (COPY_MODE_REPLACE, COPY_MODE_APPEND):
        raise ShopCopyError('copy_mode 无效，仅支持 replace 或 append')

    source_dianpu = resolve_dianpu_by_user_uid(source_user_uid)
    target_dianpu = resolve_dianpu_by_user_uid(target_user_uid)

    if source_dianpu.id == target_dianpu.id:
        raise ShopCopyError('源店铺与目标店铺不能相同')

    # 1. 预复制 OSS 图片（DB 变更前完成，失败则目标店不受影响）
    type_payloads, zone_payloads, product_payloads = _pre_copy_source_images(
        source_dianpu, target_dianpu
    )

    oss_cleanup = []
    # 2. 数据库事务：锁定目标店 → 可选清空 → 写入
    with transaction.atomic():
        Dianpu.objects.select_for_update().get(id=target_dianpu.id)

        if copy_mode == COPY_MODE_REPLACE:
            oss_cleanup = _clear_target_catalog_db_only(target_dianpu)

        stats = _insert_copied_catalog(target_dianpu, type_payloads, zone_payloads, product_payloads)

    if oss_cleanup:
        _delete_oss_urls(oss_cleanup)

    logger.info(
        '店铺商品复制完成: source=%s(%s) -> target=%s(%s) mode=%s stats=%s',
        source_dianpu.id, source_user_uid,
        target_dianpu.id, target_user_uid,
        copy_mode, stats,
    )

    return {
        'source_dianpu_id': source_dianpu.id,
        'source_dianpu_name': source_dianpu.dianpu_mingcheng,
        'target_dianpu_id': target_dianpu.id,
        'target_dianpu_name': target_dianpu.dianpu_mingcheng,
        'copy_mode': copy_mode,
        'copied_types': stats['types'],
        'copied_zones': stats['zones'],
        'copied_products': stats['products'],
    }