import asyncio
import json
import logging
import os
import shutil
import subprocess
from datetime import datetime
from decimal import Decimal, InvalidOperation
from pathlib import Path

from celery import shared_task
from django.conf import settings
from django.utils import timezone

from basic_info import models as basic_models
from api_v1 import models as api_models
from flower.utils import (
    fetch_products_from_mingdaoyun,
    fetch_customers_from_mingdaoyun,
)


logger = logging.getLogger(__name__)


def _ensure_backup_dir(output_dir: str | None) -> Path:
    base_dir = Path(settings.BASE_DIR)
    backup_dir = Path(output_dir) if output_dir else (base_dir / 'data-bak')
    backup_dir.mkdir(parents=True, exist_ok=True)
    return backup_dir


def _build_backup_path(backup_dir: Path, filename_prefix: str) -> Path:
    timestamp = timezone.now().strftime('%Y%m%d-%H%M%S')
    return backup_dir / f'{filename_prefix}-{timestamp}.sql'


def _run_pg_dump(backup_path: Path):
    db_settings = settings.DATABASES['default']
    pg_dump = shutil.which('pg_dump')
    if not pg_dump:
        raise RuntimeError('pg_dump 不存在，请确认 PostgreSQL 客户端工具已安装')

    host = db_settings.get('HOST') or 'localhost'
    port = db_settings.get('PORT') or '5432'
    user = db_settings.get('USER') or ''
    name = db_settings['NAME']
    password = db_settings.get('PASSWORD') or ''

    cmd = [
        pg_dump,
        '-h',
        host,
        '-p',
        str(port),
        '-U',
        user,
        '-F',
        'p',
        '-d',
        name,
    ]

    env = os.environ.copy()
    if password:
        env['PGPASSWORD'] = password

    with backup_path.open('wb') as stream:
        subprocess.run(cmd, check=True, stdout=stream, env=env)


def _dump_database_to_sql(backup_path: Path):
    engine = settings.DATABASES['default']['ENGINE']
    if 'postgresql' not in engine:
        raise NotImplementedError('当前项目只支持 PostgreSQL 数据库备份，请检查 DATABASES 配置')
    _run_pg_dump(backup_path)


@shared_task(bind=True)
def backup_database(self, output_dir: str | None = None, filename_prefix: str = 'db-backup'):
    """
    备份当前数据库为 .sql 文件（仅数据，不包含表结构 DDL），存放在项目根目录 data-bak 下。

    参数:
        output_dir: 可选，指定备份目录（默认 BASE_DIR/data-bak）
        filename_prefix: 备份文件名前缀
    """
    backup_dir = _ensure_backup_dir(output_dir)
    backup_path = _build_backup_path(backup_dir, filename_prefix)
    _dump_database_to_sql(backup_path)

    payload = {
        'task_id': self.request.id,
        'backup_path': str(backup_path),
        'created_at': timezone.now().isoformat(),
    }
    logger.info('数据库备份完成: %s', payload)
    return payload


def _get_mdy_merchant():
    merchant_id = getattr(settings, 'MDY_MERCHANT_ID', None)
    qs = basic_models.Merchant.objects.all()
    if merchant_id:
        qs = qs.filter(id=merchant_id)
    merchant = qs.order_by('id').first()
    if not merchant:
        raise RuntimeError('未找到用于明道云同步的商户，请先创建商户或配置 MDY_MERCHANT_ID')
    return merchant


def _get_mdy_category(merchant):
    category_id = getattr(settings, 'MDY_PRODUCT_CATEGORY_ID', None)
    qs = basic_models.ProductCategory.objects.filter(merchant=merchant)
    if category_id:
        qs = qs.filter(id=category_id)
    category = qs.order_by('id').first()
    if not category:
        raise RuntimeError('未找到用于明道云同步的产品类别，请先创建类别或配置 MDY_PRODUCT_CATEGORY_ID')
    return category


def _parse_mdy_datetime(value: str | None):
    if not value:
        return None
    try:
        dt = datetime.strptime(value, '%Y-%m-%d %H:%M:%S')
    except ValueError:
        return None
    if timezone.is_naive(dt):
        dt = timezone.make_aware(dt, timezone.get_current_timezone())
    return dt


def _map_unit(unit_label: str | None) -> int:
    if not unit_label:
        return basic_models.ProductUnitEnum.METER
    mapping = {
        '米': basic_models.ProductUnitEnum.METER,
        '码': basic_models.ProductUnitEnum.YARD,
        '公斤': basic_models.ProductUnitEnum.KG,
    }
    return mapping.get(unit_label, basic_models.ProductUnitEnum.METER)


def _ensure_decimal(value: str | None):
    if not value:
        return None
    try:
        return Decimal(str(value))
    except (InvalidOperation, TypeError, ValueError):
        return None


def _run_fetch(page: int, page_size: int):
    return asyncio.run(fetch_products_from_mingdaoyun(page=page, page_size=page_size))


def _run_fetch_customers(page: int, page_size: int):
    return asyncio.run(fetch_customers_from_mingdaoyun(page=page, page_size=page_size))


def _upsert_product(product_data, merchant, category):
    description = ''
    if product_data.detail:
        description = json.dumps(product_data.detail, ensure_ascii=False)
    defaults = {
        'category': category,
        'name': product_data.name or product_data.uid,
        'color': product_data.color or '',
        'description': description,
        'unit': _map_unit(product_data.unit),
        'from_mdy': True,
    }
    width_decimal = _ensure_decimal(product_data.width)
    if width_decimal is not None:
        defaults['width_size'] = width_decimal

    product_obj, created = basic_models.Product.objects.get_or_create(
        merchant=merchant,
        human_id=product_data.uid,
        defaults=defaults,
    )
    if created:
        return True

    if not product_obj.from_mdy:
        return False

    updated = False
    for field, value in defaults.items():
        if getattr(product_obj, field) != value:
            setattr(product_obj, field, value)
            updated = True
    if updated:
        product_obj.save(update_fields=list(defaults.keys()))
    return updated


@shared_task(bind=True)
def sync_mdy_products(self, page_size: int = 300, max_pages: int = 5, max_records: int | None = None):
    """
    从明道云同步产品数据
    """
    merchant = _get_mdy_merchant()
    category = _get_mdy_category(merchant)
    max_records = max_records or page_size

    last_sync = api_models.DataSync.objects.filter(
        table_name=api_models.DataSync.TableName.PRODUCT
    ).order_by('-created_at').first()
    last_ctime = last_sync.last_ctime if last_sync else None
    last_rowid = last_sync.last_rowid if last_sync else ''

    synced_rows = 0
    page_index = 1
    total_count = 0
    latest_ctime = last_ctime
    latest_rowid = last_rowid
    reached_existing = False

    while page_index <= max_pages and synced_rows < max_records:
        products, total = _run_fetch(page_index, page_size)
        total_count = total
        if not products:
            break

        for item in products:
            product_ctime = _parse_mdy_datetime(item.created_at)
            if last_ctime and product_ctime:
                if product_ctime < last_ctime:
                    reached_existing = True
                    break
                if product_ctime == last_ctime and last_rowid and item.rowid == last_rowid:
                    reached_existing = True
                    break

            changed = _upsert_product(item, merchant, category)
            if changed:
                synced_rows += 1
            if product_ctime and (latest_ctime is None or product_ctime > latest_ctime):
                latest_ctime = product_ctime
                latest_rowid = item.rowid

            if synced_rows >= max_records:
                break

        if reached_existing or synced_rows >= max_records or len(products) < page_size:
            break
        page_index += 1

    record_last_ctime = latest_ctime or last_ctime
    record_last_rowid = latest_rowid or last_rowid
    api_models.DataSync.objects.create(
        table_name=api_models.DataSync.TableName.PRODUCT,
        page_index=page_index,
        page_size=page_size,
        synced_rows=synced_rows,
        total_count=total_count,
        last_ctime=record_last_ctime,
        last_rowid=record_last_rowid,
        note='reached existing data' if reached_existing else '',
    )

    payload = {
        'task_id': self.request.id,
        'synced_rows': synced_rows,
        'page_index': page_index,
        'page_size': page_size,
        'total_count': total_count,
        'last_ctime': record_last_ctime.isoformat() if record_last_ctime else None,
    }
    logger.info('明道云产品同步完成: %s', payload)
    return payload


def _upsert_customer(customer_data, merchant):
    mdy_uid = customer_data.uid or customer_data.rowid
    if not mdy_uid:
        return False
    defaults = {
        'merchant': merchant,
        'name': customer_data.name or customer_data.uid,
        'area': customer_data.area or '',
        'from_mdy': True,
    }
    customer_obj, created = basic_models.Customer.objects.get_or_create(
        mdy_uid=mdy_uid,
        defaults=defaults,
    )
    if created:
        return True

    if not customer_obj.from_mdy:
        return False

    updated_fields = {}
    for field, value in defaults.items():
        if getattr(customer_obj, field) != value:
            updated_fields[field] = value

    if updated_fields:
        for field, value in updated_fields.items():
            setattr(customer_obj, field, value)
        customer_obj.save(update_fields=list(updated_fields.keys()))
        return True
    return False


@shared_task(bind=True)
def sync_mdy_customers(self, page_size: int = 300, max_pages: int = 5, max_records: int | None = None):
    """
    从明道云同步客户数据
    """
    merchant = _get_mdy_merchant()
    max_records = max_records or page_size

    last_sync = api_models.DataSync.objects.filter(
        table_name=api_models.DataSync.TableName.CUSTOMER
    ).order_by('-created_at').first()
    last_ctime = last_sync.last_ctime if last_sync else None
    last_rowid = last_sync.last_rowid if last_sync else ''

    synced_rows = 0
    page_index = 1
    total_count = 0
    latest_ctime = last_ctime
    latest_rowid = last_rowid
    reached_existing = False

    while page_index <= max_pages and synced_rows < max_records:
        customers, total = _run_fetch_customers(page_index, page_size)
        total_count = total
        if not customers:
            break

        for item in customers:
            record_ctime = _parse_mdy_datetime(item.created_at)
            if last_ctime and record_ctime:
                if record_ctime < last_ctime:
                    reached_existing = True
                    break
                if record_ctime == last_ctime and last_rowid and item.rowid == last_rowid:
                    reached_existing = True
                    break

            changed = _upsert_customer(item, merchant)
            if changed:
                synced_rows += 1
            if record_ctime and (latest_ctime is None or record_ctime > latest_ctime):
                latest_ctime = record_ctime
                latest_rowid = item.rowid

            if synced_rows >= max_records:
                break

        if reached_existing or synced_rows >= max_records or len(customers) < page_size:
            break
        page_index += 1

    record_last_ctime = latest_ctime or last_ctime
    record_last_rowid = latest_rowid or last_rowid
    api_models.DataSync.objects.create(
        table_name=api_models.DataSync.TableName.CUSTOMER,
        page_index=page_index,
        page_size=page_size,
        synced_rows=synced_rows,
        total_count=total_count,
        last_ctime=record_last_ctime,
        last_rowid=record_last_rowid,
        note='reached existing data' if reached_existing else '',
    )

    payload = {
        'task_id': self.request.id,
        'synced_rows': synced_rows,
        'page_index': page_index,
        'page_size': page_size,
        'total_count': total_count,
        'last_ctime': record_last_ctime.isoformat() if record_last_ctime else None,
    }
    logger.info('明道云客户同步完成: %s', payload)
    return payload