import os
from typing import Dict, Any, List, Optional
from sqlalchemy.orm import Session
from sqlalchemy import text, and_, or_
from backend.models.schemas import NLPAnalysisResult, DatabaseResult, QueryType
from backend.config import settings
from backend.database.connection import get_database_session, close_database_session
from backend.database.models import User, Product, PurchaseOrder, SalesOrder, LineMessage, Category
from datetime import datetime
import logging

logger = logging.getLogger(__name__)

class DatabaseService:
    """資料庫服務"""
    
    def __init__(self):
        self.model_mapping = {
            "users": User,
            "products": Product,
            "purchase_orders": PurchaseOrder,
            "sales_orders": SalesOrder,
            "line_messages": LineMessage
        }
        
        # 定義資料表結構
        self.table_schemas = {
            "users": {
                "model": User,
                "searchable": ["name", "email"]
            },
            "purchase_orders": {
                "model": PurchaseOrder,
                "searchable": ["po_number", "status"]
            },
            "sales_orders": {
                "model": SalesOrder,
                "searchable": ["so_number", "status"]
            },
            "products": {
                "model": Product,
                "searchable": ["productName", "productCode", "barcode"]
            },
            "line_messages": {
                "model": LineMessage,
                "searchable": ["message", "user_id"]
            }
        }

    def execute_query(self, analysis_result: NLPAnalysisResult) -> DatabaseResult:
        """執行資料庫查詢"""
        try:
            query_type = analysis_result.query_type
            parameters = analysis_result.parameters
            
            if query_type == QueryType.SEARCH:
                return self._execute_search(parameters)
            elif query_type == QueryType.CREATE:
                return self._execute_create(parameters)
            elif query_type == QueryType.UPDATE:
                return self._execute_update(parameters)
            elif query_type == QueryType.DELETE:
                return self._execute_delete(parameters)
            elif query_type == QueryType.ANALYTICS:
                return self._execute_analytics(parameters)
            else:
                return DatabaseResult(
                    success=False,
                    error="不支援的查詢類型"
                )
                
        except Exception as e:
            logger.error(f"資料庫查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"資料庫查詢失敗: {str(e)}"
            )

    def _execute_search(self, parameters: Dict[str, Any]) -> DatabaseResult:
        """執行搜尋查詢"""
        table_name = parameters.get("table", "users")
        conditions = parameters.get("conditions", {})
        limit = parameters.get("limit", 10)
        offset = parameters.get("offset", 0)
        
        db = None
        try:
            db = get_database_session()
            
            # 取得對應的模型
            model = self.table_schemas.get(table_name, {}).get("model")
            if not model:
                return DatabaseResult(
                    success=False,
                    error=f"不支援的資料表: {table_name}"
                )
            
            # 建立查詢
            query = db.query(model)
            
            # 添加條件
            for field, value in conditions.items():
                if hasattr(model, field):
                    column = getattr(model, field)
                    
                    if isinstance(value, dict):
                        # 處理範圍查詢
                        if "gte" in value:
                            query = query.filter(column >= value["gte"])
                        if "lte" in value:
                            query = query.filter(column <= value["lte"])
                        if "gt" in value:
                            query = query.filter(column > value["gt"])
                        if "lt" in value:
                            query = query.filter(column < value["lt"])
                    else:
                        # 處理精確匹配或模糊搜尋
                        searchable_fields = self.table_schemas.get(table_name, {}).get("searchable", [])
                        if field in searchable_fields:
                            query = query.filter(column.ilike(f"%{value}%"))
                        else:
                            query = query.filter(column == value)
            
            # 添加限制和偏移
            query = query.offset(offset).limit(limit)
            
            # 執行查詢
            results = query.all()
            
            # 轉換為字典格式
            data = []
            for result in results:
                item = {}
                for column in result.__table__.columns:
                    value = getattr(result, column.name)
                    # 處理特殊類型
                    if hasattr(value, 'isoformat'):  # datetime
                        item[column.name] = value.isoformat()
                    elif isinstance(value, (int, float, str, bool)) or value is None:
                        item[column.name] = value
                    else:
                        item[column.name] = str(value)
                data.append(item)
            
            return DatabaseResult(
                success=True,
                data=data,
                count=len(data)
            )
            
        except Exception as e:
            logger.error(f"搜尋查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"搜尋失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def _execute_create(self, parameters: Dict[str, Any]) -> DatabaseResult:
        """執行建立查詢"""
        table_name = parameters.get("table", "users")
        data = parameters.get("data", {})
        
        db = None
        try:
            db = get_database_session()
            
            # 取得對應的模型
            model = self.table_schemas.get(table_name, {}).get("model")
            if not model:
                return DatabaseResult(
                    success=False,
                    error=f"不支援的資料表: {table_name}"
                )
            
            # 建立新記錄
            new_record = model(**data)
            db.add(new_record)
            db.commit()
            db.refresh(new_record)
            
            # 轉換為字典格式
            result_data = {}
            for column in new_record.__table__.columns:
                value = getattr(new_record, column.name)
                if hasattr(value, 'isoformat'):  # datetime
                    result_data[column.name] = value.isoformat()
                elif isinstance(value, (int, float, str, bool)) or value is None:
                    result_data[column.name] = value
                else:
                    result_data[column.name] = str(value)
            
            return DatabaseResult(
                success=True,
                data=[result_data],
                count=1
            )
            
        except Exception as e:
            if db:
                db.rollback()
            logger.error(f"建立查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"建立失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def _execute_update(self, parameters: Dict[str, Any]) -> DatabaseResult:
        """執行更新查詢"""
        table_name = parameters.get("table", "users")
        conditions = parameters.get("conditions", {})
        data = parameters.get("data", {})
        
        db = None
        try:
            db = get_database_session()
            
            # 取得對應的模型
            model = self.table_schemas.get(table_name, {}).get("model")
            if not model:
                return DatabaseResult(
                    success=False,
                    error=f"不支援的資料表: {table_name}"
                )
            
            # 建立查詢
            query = db.query(model)
            
            # 添加條件
            for field, value in conditions.items():
                if hasattr(model, field):
                    column = getattr(model, field)
                    query = query.filter(column == value)
            
            # 執行更新
            updated_count = query.update(data)
            db.commit()
            
            # 取得更新後的資料
            updated_records = query.all()
            
            # 轉換為字典格式
            result_data = []
            for record in updated_records:
                item = {}
                for column in record.__table__.columns:
                    value = getattr(record, column.name)
                    if hasattr(value, 'isoformat'):  # datetime
                        item[column.name] = value.isoformat()
                    elif isinstance(value, (int, float, str, bool)) or value is None:
                        item[column.name] = value
                    else:
                        item[column.name] = str(value)
                result_data.append(item)
            
            return DatabaseResult(
                success=True,
                data=result_data,
                count=updated_count
            )
            
        except Exception as e:
            if db:
                db.rollback()
            logger.error(f"更新查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"更新失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def _execute_delete(self, parameters: Dict[str, Any]) -> DatabaseResult:
        """執行刪除查詢"""
        table_name = parameters.get("table", "users")
        conditions = parameters.get("conditions", {})
        
        db = None
        try:
            db = get_database_session()
            
            # 取得對應的模型
            model = self.table_schemas.get(table_name, {}).get("model")
            if not model:
                return DatabaseResult(
                    success=False,
                    error=f"不支援的資料表: {table_name}"
                )
            
            # 建立查詢
            query = db.query(model)
            
            # 添加條件
            for field, value in conditions.items():
                if hasattr(model, field):
                    column = getattr(model, field)
                    query = query.filter(column == value)
            
            # 先取得要刪除的記錄
            records_to_delete = query.all()
            
            # 轉換為字典格式
            result_data = []
            for record in records_to_delete:
                item = {}
                for column in record.__table__.columns:
                    value = getattr(record, column.name)
                    if hasattr(value, 'isoformat'):  # datetime
                        item[column.name] = value.isoformat()
                    elif isinstance(value, (int, float, str, bool)) or value is None:
                        item[column.name] = value
                    else:
                        item[column.name] = str(value)
                result_data.append(item)
            
            # 執行刪除
            deleted_count = query.delete()
            db.commit()
            
            return DatabaseResult(
                success=True,
                data=result_data,
                count=deleted_count
            )
            
        except Exception as e:
            if db:
                db.rollback()
            logger.error(f"刪除查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"刪除失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def _execute_analytics(self, parameters: Dict[str, Any]) -> DatabaseResult:
        """執行分析查詢"""
        table_name = parameters.get("table", "users")
        
        db = None
        try:
            db = get_database_session()
            
            # 取得對應的模型
            model = self.table_schemas.get(table_name, {}).get("model")
            if not model:
                return DatabaseResult(
                    success=False,
                    error=f"不支援的資料表: {table_name}"
                )
            
            # 執行計數查詢
            total_count = db.query(model).count()
            
            # 取得範例資料
            sample_records = db.query(model).limit(5).all()
            
            # 轉換範例資料為字典格式
            sample_data = []
            for record in sample_records:
                item = {}
                for column in record.__table__.columns:
                    value = getattr(record, column.name)
                    if hasattr(value, 'isoformat'):  # datetime
                        item[column.name] = value.isoformat()
                    elif isinstance(value, (int, float, str, bool)) or value is None:
                        item[column.name] = value
                    else:
                        item[column.name] = str(value)
                sample_data.append(item)
            
            analytics_data = [{
                "table": table_name,
                "count": total_count,
                "data_sample": sample_data
            }]
            
            return DatabaseResult(
                success=True,
                data=analytics_data,
                count=1
            )
            
        except Exception as e:
            logger.error(f"分析查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"分析失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def save_message(self, user_id: str, message: str, message_type: str = "text") -> bool:
        """儲存訊息記錄 - 暫時停用，僅記錄到日誌"""
        try:
            # 暫時停用資料庫記錄，只記錄到日誌
            logger.info(f"訊息記錄 - 用戶: {user_id[:10]}..., 類型: {message_type}, 內容: {message[:50]}...")
            return True

        except Exception as e:
            logger.error(f"訊息記錄錯誤: {str(e)}")
            return False

    def get_user_profile(self, user_id: str) -> Optional[Dict[str, Any]]:
        """取得用戶資料"""
        db = None
        try:
            db = get_database_session()
            
            user = db.query(User).filter(User.user_id == user_id).first()
            if not user:
                return None
            
            # 轉換為字典格式
            user_data = {}
            for column in user.__table__.columns:
                value = getattr(user, column.name)
                if hasattr(value, 'isoformat'):  # datetime
                    user_data[column.name] = value.isoformat()
                elif isinstance(value, (int, float, str, bool)) or value is None:
                    user_data[column.name] = value
                else:
                    user_data[column.name] = str(value)
            
            return user_data
            
        except Exception as e:
            logger.error(f"取得用戶資料錯誤: {str(e)}")
            return None
        finally:
            if db:
                close_database_session(db)

    def create_user_profile(self, user_data: Dict[str, Any]) -> bool:
        """建立用戶資料"""
        db = None
        try:
            db = get_database_session()
            
            new_user = User(**user_data)
            db.add(new_user)
            db.commit()
            return True
            
        except Exception as e:
            if db:
                db.rollback()
            logger.error(f"建立用戶資料錯誤: {str(e)}")
            return False
        finally:
            if db:
                close_database_session(db)

    # ==================== 業務專用查詢方法 ====================
    
    def search_products(self, query_text: str = None, category: str = None, 
                       warehouse: str = None, limit: int = 10) -> DatabaseResult:
        """商品查詢 - 支援自然語言查詢"""
        db = None
        try:
            db = get_database_session()
            
            # 建立基本查詢
            query = db.query(Product)
            
            # 如果有查詢文字，進行模糊搜尋
            if query_text:
                search_filter = or_(
                    Product.productName.ilike(f"%{query_text}%"),
                    Product.productCode.ilike(f"%{query_text}%")
                )
                query = query.filter(search_filter)
            
            # 類別篩選
            if category:
                query = query.filter(Product.category.ilike(f"%{category}%"))
            
            # 執行查詢
            products = query.limit(limit).all()
            
            # 轉換為字典格式
            data = []
            for product in products:
                product_data = {
                    "id": product.id,
                    "product_code": product.productCode,
                    "product_name": product.productName,
                    "unit": product.unit,
                    "warehouse": product.warehouse,
                    "stock": product.stock,
                    "category_name": product.category.name if product.category else None,
                    "created_at": product.createdAt.isoformat() if product.createdAt else None
                }
                data.append(product_data)
            
            return DatabaseResult(
                success=True,
                data=data,
                count=len(data)
            )
            
        except Exception as e:
            logger.error(f"商品查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"商品查詢失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def check_inventory(self, product_name: str = None, category: str = None) -> DatabaseResult:
        """庫存查詢"""
        db = None
        try:
            db = get_database_session()
            
            # 建立查詢
            query = db.query(Product)
            
            # 根據商品名稱查詢
            if product_name:
                query = query.filter(Product.productName.ilike(f"%{product_name}%"))
            
            # 類別篩選 (通過關聯查詢)
            if category:
                query = query.join(Product.category).filter(Category.name.ilike(f"%{category}%"))
            
            products = query.all()
            
            # 準備庫存資料
            inventory_data = []
            for product in products:
                stock_info = {
                    "product_name": product.productName,
                    "product_code": product.productCode,
                    "category": product.category.name if product.category else None,
                    "current_stock": product.stock,
                    "unit": product.unit,
                    "warehouse": product.warehouse,
                    "last_updated": product.updatedAt.isoformat() if product.updatedAt else None
                }
                inventory_data.append(stock_info)
            
            return DatabaseResult(
                success=True,
                data=inventory_data,
                count=len(inventory_data)
            )
            
        except Exception as e:
            logger.error(f"庫存查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"庫存查詢失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def search_orders(self, user_id: str = None, status: str = None, order_number: str = None,
                     customer_id: str = None, date_from: str = None, date_to: str = None,
                     limit: int = 10) -> DatabaseResult:
        """增強的訂單查詢功能"""
        db = None
        try:
            db = get_database_session()

            # 使用 SalesOrder 作為主要的訂單查詢，預載入關聯資料
            query = db.query(SalesOrder).options(
                joinedload(SalesOrder.customer),
                joinedload(SalesOrder.salesperson)
            )

            # 訂單編號查詢 (支援 SO- 格式)
            if order_number:
                if not order_number.startswith('SO-'):
                    # 如果用戶只輸入部分編號，自動補全
                    order_number = f"SO-{order_number}"
                query = query.filter(SalesOrder.so_number.ilike(f"%{order_number}%"))

            # 用戶篩選 (銷售人員)
            if user_id:
                query = query.filter(SalesOrder.salesperson_id == user_id)

            # 客戶篩選
            if customer_id:
                query = query.filter(SalesOrder.customer_id == customer_id)

            # 狀態篩選 (支援中文和英文)
            if status:
                status_mapping = {
                    '已交付': 'DELIVERED',
                    '已出貨': 'SHIPPED',
                    '處理中': 'PROCESSING',
                    '已取消': 'CANCELLED',
                    '待處理': 'PENDING'
                }
                # 檢查是否為中文狀態，轉換為英文
                english_status = status_mapping.get(status, status)
                query = query.filter(SalesOrder.status.ilike(f"%{english_status}%"))

            # 日期範圍篩選
            if date_from:
                query = query.filter(SalesOrder.sales_date >= date_from)
            if date_to:
                query = query.filter(SalesOrder.sales_date <= date_to)

            # 按日期降序排列，最新的在前面
            query = query.order_by(SalesOrder.sales_date.desc())

            orders = query.limit(limit).all()

            # 轉換為字典格式
            order_data = []
            for order in orders:
                # 狀態中文化
                status_display = self._get_order_status_display(order.status)

                order_info = {
                    "order_id": order.so_number,
                    "sales_date": order.sales_date.isoformat() if order.sales_date else None,
                    "customer_id": order.customer_id,
                    "customer_name": order.customer.customerName if order.customer else "未知客戶",
                    "salesperson_id": order.salesperson_id,
                    "salesperson_name": order.salesperson.name if order.salesperson else "未指定",
                    "status": order.status,
                    "status_display": status_display,
                    "payment_term": order.payment_term,
                    "subtotal": float(order.subtotal) if order.subtotal else 0.0,
                    "tax_amount": float(order.tax_amount) if order.tax_amount else 0.0,
                    "discount_amount": float(order.discount_amount) if order.discount_amount else 0.0,
                    "total_amount": float(order.total_amount) if order.total_amount else 0.0,
                    "notes": order.notes or "",
                    "created_at": order.created_at.isoformat() if order.created_at else None,
                    "updated_at": order.updated_at.isoformat() if order.updated_at else None
                }
                order_data.append(order_info)

            return DatabaseResult(
                success=True,
                data=order_data,
                count=len(order_data)
            )
            
        except Exception as e:
            logger.error(f"訂單查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"訂單查詢失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def _get_order_status_display(self, status) -> str:
        """將訂單狀態轉換為中文顯示"""
        status_mapping = {
            'DELIVERED': '已交付',
            'SHIPPED': '已出貨',
            'PROCESSING': '處理中',
            'CANCELLED': '已取消',
            'PENDING': '待處理',
            'CONFIRMED': '已確認',
            'COMPLETED': '已完成'
        }

        if hasattr(status, 'value'):
            return status_mapping.get(status.value, str(status.value))
        else:
            return status_mapping.get(str(status), str(status))

    def get_low_stock_products(self, threshold: int = 10) -> DatabaseResult:
        """低庫存商品查詢"""
        db = None
        try:
            db = get_database_session()
            
            # 查詢庫存低於閾值的商品
            # 注意：這裡假設 Product 模型有 stock 欄位，需要根據實際情況調整
            query = db.query(Product)
            if hasattr(Product, 'stock'):
                query = query.filter(Product.stock <= threshold)
            
            low_stock_products = query.all()
            
            data = []
            for product in low_stock_products:
                product_data = {
                    "product_name": product.productName,
                    "product_code": product.productCode,
                    "current_stock": product.stock,
                    "unit": product.unit,
                    "warehouse": product.warehouse,
                    "category": product.category.name if product.category else None,
                    "status": "庫存不足"
                }
                data.append(product_data)
            
            return DatabaseResult(
                success=True,
                data=data,
                count=len(data)
            )
            
        except Exception as e:
            logger.error(f"低庫存查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"低庫存查詢失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def get_business_summary(self) -> DatabaseResult:
        """業務摘要統計"""
        db = None
        try:
            db = get_database_session()
            
            # 基本統計
            total_products = db.query(Product).count()
            total_sales_orders = db.query(SalesOrder).count()
            total_purchase_orders = db.query(PurchaseOrder).count()
            total_users = db.query(User).count()
            
            # 計算低庫存商品數量
            low_stock_count = db.query(Product).filter(Product.stock <= 10).count()
            
            # 準備摘要資料
            summary_data = [{
                "total_products": total_products,
                "total_sales_orders": total_sales_orders,
                "total_purchase_orders": total_purchase_orders,
                "total_users": total_users,
                "low_stock_items": low_stock_count,
                "report_date": datetime.now().isoformat()
            }]
            
            return DatabaseResult(
                success=True,
                data=summary_data,
                count=1
            )
            
        except Exception as e:
            logger.error(f"業務摘要查詢錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"業務摘要查詢失敗: {str(e)}"
            )
        finally:
            if db:
                close_database_session(db)

    def process_natural_language_query(self, user_message: str, user_id: str = None) -> DatabaseResult:
        """處理自然語言查詢的統一入口"""
        try:
            # 簡單的關鍵字匹配來判斷查詢意圖
            message_lower = user_message.lower()
            
            # 商品查詢
            if any(keyword in message_lower for keyword in ['商品', '產品', '貨品', '物品']):
                if any(keyword in message_lower for keyword in ['庫存', '存貨', '剩餘']):
                    # 庫存查詢
                    product_name = self._extract_product_name(user_message)
                    return self.check_inventory(product_name=product_name)
                else:
                    # 一般商品查詢
                    product_name = self._extract_product_name(user_message)
                    return self.search_products(query_text=product_name)
            
            # 訂單查詢
            elif any(keyword in message_lower for keyword in ['訂單', '訂購', '購買', 'so-']):
                # 提取訂單編號
                order_number = self._extract_order_number(user_message)
                # 提取狀態
                status = self._extract_order_status(user_message)
                return self.search_orders(user_id=user_id, order_number=order_number, status=status)
            
            # 低庫存查詢
            elif any(keyword in message_lower for keyword in ['低庫存', '缺貨', '不足']):
                return self.get_low_stock_products()
            
            # 統計查詢
            elif any(keyword in message_lower for keyword in ['統計', '摘要', '總計', '報表']):
                return self.get_business_summary()
            
            else:
                # 預設進行商品搜尋
                return self.search_products(query_text=user_message)
                
        except Exception as e:
            logger.error(f"自然語言查詢處理錯誤: {str(e)}")
            return DatabaseResult(
                success=False,
                error=f"查詢處理失敗: {str(e)}"
            )

    def _extract_product_name(self, message: str) -> str:
        """從訊息中提取商品名稱"""
        # 簡單的商品名稱提取邏輯
        # 移除常見的查詢關鍵字
        keywords_to_remove = ['查詢', '搜尋', '找', '商品', '產品', '庫存', '有沒有', '請問']

        cleaned_message = message
        for keyword in keywords_to_remove:
            cleaned_message = cleaned_message.replace(keyword, '')

        return cleaned_message.strip()

    def _extract_order_number(self, message: str) -> str:
        """從訊息中提取訂單編號"""
        import re

        # 尋找 SO- 格式的訂單編號
        so_pattern = r'SO-\d{8}-\d{3}'
        match = re.search(so_pattern, message.upper())
        if match:
            return match.group()

        # 尋找日期格式的編號 (20250706-001)
        date_pattern = r'\d{8}-\d{3}'
        match = re.search(date_pattern, message)
        if match:
            return f"SO-{match.group()}"

        # 尋找純數字編號
        number_pattern = r'\d{6,}'
        match = re.search(number_pattern, message)
        if match:
            return match.group()

        return None

    def _extract_order_status(self, message: str) -> str:
        """從訊息中提取訂單狀態"""
        message_lower = message.lower()

        # 中文狀態關鍵字
        status_keywords = {
            '已交付': 'DELIVERED',
            '已出貨': 'SHIPPED',
            '出貨': 'SHIPPED',
            '交付': 'DELIVERED',
            '處理中': 'PROCESSING',
            '已取消': 'CANCELLED',
            '取消': 'CANCELLED',
            '待處理': 'PENDING',
            '已確認': 'CONFIRMED',
            '已完成': 'COMPLETED'
        }

        for chinese, english in status_keywords.items():
            if chinese in message_lower:
                return english

        # 英文狀態關鍵字
        english_keywords = ['delivered', 'shipped', 'processing', 'cancelled', 'pending', 'confirmed', 'completed']
        for keyword in english_keywords:
            if keyword in message_lower:
                return keyword.upper()

        return None