from datetime import datetime
from typing import Optional, List
from sqlmodel import SQLModel, Field, Relationship, create_engine, Session, select, delete, func,distinct
from sqlalchemy.orm import relationship
from sqlalchemy import UniqueConstraint
from sqlalchemy.sql import text
from pathlib import Path
from config.settings import DB_URL

class KeywordTask(SQLModel, table=True):
    __table_args__ = (UniqueConstraint("keyword", name="uq_keyword"),)
    
    id: Optional[int] = Field(default=None, primary_key=True)
    keyword: str = Field(index=True, unique=True)
    total_results: Optional[int] = None
    is_completed: Optional[bool] = Field(default=False)
    fail_count: Optional[int] = 0    
    created_at: Optional[datetime] = Field(default_factory=datetime.now)
    
    pages: List["SearchPageResult"] = Relationship(back_populates="keyword_task")
    items: List["SearchResultItem"] = Relationship(back_populates="keyword_task")

class SearchPageResult(SQLModel, table=True):
    __table_args__ = (UniqueConstraint("keyword_id", "page_number", name="uq_keyword_page"),)
    
    id: Optional[int] = Field(default=None, primary_key=True)
    keyword_id: int = Field(foreign_key="keywordtask.id")
    keyword: str = Field(index=True)
    page_number: int
    results_count: int
    has_next_page: bool
    html_path: Optional[str] = None
    created_at: datetime = Field(default_factory=datetime.now)
    
    keyword_task: Optional[KeywordTask] = Relationship(back_populates="pages")
    items: List["SearchResultItem"] = Relationship(back_populates="search_page")

class SearchResultItem(SQLModel, table=True):
    __table_args__ = (UniqueConstraint("url", "page_id", name="uq_url_page"),)
    
    id: Optional[int] = Field(default=None, primary_key=True)
    url: str
    title: Optional[str] = None
    content: Optional[str] = None
    html_path: Optional[str] = None
    keyword_id: int = Field(foreign_key="keywordtask.id")
    keyword: str = Field(index=True)
    page_id: int = Field(foreign_key="searchpageresult.id")
    created_at: datetime = Field(default_factory=datetime.now)
    
    keyword_task: Optional[KeywordTask] = Relationship(back_populates="items")
    search_page: Optional[SearchPageResult] = Relationship(back_populates="items")

class VerificationItem(SQLModel, table=True):
    __table_args__ = (UniqueConstraint("result_item_id", name="uq_verification_item"),)
    
    id: Optional[int] = Field(default=None, primary_key=True)
    result_item_id: int = Field(foreign_key="searchresultitem.id")
    search_result_item: Optional[SearchResultItem] = Relationship(
        sa_relationship=relationship("SearchResultItem", lazy="joined")
    )
    verified: bool = Field(default=False)
    created_at: datetime = Field(default_factory=datetime.now)

class SearchResultManager:
    def __init__(self, db_url: str = DB_URL):
        self.engine = create_engine(db_url)
        SQLModel.metadata.create_all(self.engine)
    
    def get_keyword_task(self, keyword: str) -> KeywordTask | None:
        with Session(self.engine) as session:
            return session.exec(
                select(KeywordTask)
                .where(KeywordTask.keyword == keyword)
            ).first()

    def get_uncompleted_keywords(self) -> list[str]:
        """从数据库获取已完成搜索但未完成爬取的关键词"""
        with Session(self.engine) as session:
            # 使用JOIN优化查询，避免子查询
            query = (
                select(distinct(KeywordTask.keyword))
                .where(KeywordTask.is_completed != True)
            )
            keywords = session.exec(query).all()
            return keywords


    def delete_keyword_task(self, keyword: str):
        """删除关键词及其所有关联数据"""
        with Session(self.engine) as session:
            # 先获取关键词任务
            keyword_task = session.exec(
                select(KeywordTask)
                .where(KeywordTask.keyword == keyword)
            ).first()
            
            if keyword_task:
                # 删除关联的SearchResultItem
                session.exec(
                    delete(SearchResultItem)
                    .where(SearchResultItem.keyword_id == keyword_task.id)
                )
                # 删除关联的SearchPageResult
                session.exec(
                    delete(SearchPageResult)
                    .where(SearchPageResult.keyword_id == keyword_task.id)
                )
                # 删除KeywordTask
                session.delete(keyword_task)
                session.commit()
    
    def create_keyword_task(self, keyword: str) -> KeywordTask:
        with Session(self.engine) as session:
            # 先删除可能存在的旧数据（在process_keyword中已处理）
            task = KeywordTask(keyword=keyword)
            session.add(task)
            session.commit()
            session.refresh(task)
            return task
    
    def save_page_results(
        self,
        keyword: str,
        page_number: int,
        results_count: int,
        has_next_page: bool,
        html_path: Optional[Path] = None
    ) -> SearchPageResult | None:
        with Session(self.engine) as session:
            existing = session.exec(
                select(SearchPageResult)
                .where(SearchPageResult.keyword == keyword)
                .where(SearchPageResult.page_number == page_number)
            ).first()
            if existing:
                return existing

            keyword_task = self.get_keyword_task(keyword)
            if not keyword_task:
                raise ValueError("Keyword task must exist before saving page results")

            page_result = SearchPageResult(
                keyword_id=keyword_task.id,
                keyword=keyword,
                page_number=page_number,
                results_count=results_count,
                has_next_page=has_next_page,
                html_path=str(html_path) if html_path else None
            )
            session.add(page_result)
            session.commit()
            session.refresh(page_result)
            return page_result
    
    def save_result_items(
        self,
        keyword: str,
        page_id: int,
        items: List[SearchResultItem],
        html_path: Optional[Path] = None
    ) -> int:
        with Session(self.engine) as session:
            keyword_task = session.exec(
                select(KeywordTask)
                .where(KeywordTask.keyword == keyword)
            ).first()
            
            if not keyword_task:
                raise ValueError(f"Keyword task not found for keyword: {keyword}")

            new_items = []
            for item in items:
                exists = session.exec(
                    select(SearchResultItem)
                    .where(SearchResultItem.url == item.url)
                    .where(SearchResultItem.page_id == page_id)
                ).first()
                
                if not exists:
                    new_item = SearchResultItem(
                        url=item.url,
                        title=item.title,
                        content=item.content,
                        html_path=str(html_path) if html_path else None,
                        keyword_id=keyword_task.id,
                        keyword=keyword,
                        page_id=page_id
                    )
                    new_items.append(new_item)
            
            session.add_all(new_items)
            session.commit()
            return new_items
    
    def mark_task_completed(self, keyword: str):
        with Session(self.engine) as session:
            task = self.get_keyword_task(keyword)
            if not task:
                raise ValueError(f"Keyword task {keyword} not found")
            
            # 使用窗口函数确保统计准确性
            total_results = session.scalar(
                select(func.sum(SearchPageResult.results_count))
                .where(SearchPageResult.keyword_id == task.id)
                .execution_options(compile_kwargs={"literal_binds": True})
            ) or 0
            
            task.is_completed = True
            task.total_results = total_results
            session.add(task)
            session.commit()
            session.refresh(task)
            return task
    
    def is_task_completed(self, keyword: str) -> bool:
        task = self.get_keyword_task(keyword)
        return task.is_completed if task else False
    
    def get_all_search_result_items(self) -> List[SearchResultItem]:
        """
        获取数据库中所有的 SearchResultItem。
        """
        with Session(self.engine) as session:
            return session.exec(select(SearchResultItem)).all()

    def get_task_statistics(self) -> dict:
        """获取任务统计信息"""
        with Session(self.engine) as session:
            total = session.scalar(select(func.count(KeywordTask.id)))
            completed = session.scalar(
                select(func.count(KeywordTask.id))
                .where(KeywordTask.is_completed == True)
            )
            return {
                "total_tasks": total or 0,
                "completed_tasks": completed or 0,
                "pending_tasks": (total or 0) - (completed or 0)
            }
    
    def add_to_verification(self, result_item_id: int):
        """
        将 SearchResultItem 添加到 VerificationItem 表中，避免重复添加。
        """
        with Session(self.engine) as session:
            exists = session.exec(
                select(VerificationItem)
                .where(VerificationItem.result_item_id == result_item_id)
            ).first()
            if not exists:
                verification_item = VerificationItem(result_item_id=result_item_id)
                session.add(verification_item)
                session.commit()
                session.refresh(verification_item)
                return verification_item
            return exists