"""
数据库模型定义
"""

from datetime import datetime
from flask_sqlalchemy import SQLAlchemy
import json

db = SQLAlchemy()


class Document(db.Model):
    """文档表"""
    __tablename__ = 'documents'
    
    id = db.Column(db.Integer, primary_key=True)
    
    # 文件信息
    filename = db.Column(db.String(255), nullable=False)
    filepath = db.Column(db.String(512), nullable=False)
    file_type = db.Column(db.String(20), nullable=False)
    file_size = db.Column(db.Integer, default=0)
    
    # 文档元数据
    title = db.Column(db.String(500), nullable=True)
    author = db.Column(db.String(100), nullable=True)
    source = db.Column(db.String(255), nullable=True)
    
    # 处理状态
    status = db.Column(db.String(20), default='pending')  # pending, processing, indexed, failed
    error_message = db.Column(db.Text, nullable=True)
    
    # 文档内容（可选存储原文）
    content = db.Column(db.Text, nullable=True)
    
    # 文档摘要（LLM生成）
    summary = db.Column(db.Text, nullable=True)
    
    # 主要关键词（JSON数组）
    keywords = db.Column(db.Text, nullable=True)
    
    # 文档分类/主题
    category = db.Column(db.String(100), nullable=True)
    topics = db.Column(db.Text, nullable=True)  # JSON数组
    
    # 文档实体（人物、地点、组织等）
    entities = db.Column(db.Text, nullable=True)  # JSON对象
    
    # 统计信息
    chunk_count = db.Column(db.Integer, default=0)  # 分块数量
    word_count = db.Column(db.Integer, default=0)   # 字数
    
    # 时间戳
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    indexed_at = db.Column(db.DateTime, nullable=True)
    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # 关系
    chunks = db.relationship('DocumentChunk', backref='document', lazy=True, cascade='all, delete-orphan')
    
    def get_keywords(self):
        """获取关键词列表"""
        if self.keywords:
            return json.loads(self.keywords)
        return []
    
    def set_keywords(self, keywords):
        """设置关键词"""
        self.keywords = json.dumps(keywords, ensure_ascii=False)
    
    def get_topics(self):
        """获取主题列表"""
        if self.topics:
            return json.loads(self.topics)
        return []
    
    def set_topics(self, topics):
        """设置主题"""
        self.topics = json.dumps(topics, ensure_ascii=False)
    
    def get_entities(self):
        """获取实体"""
        if self.entities:
            return json.loads(self.entities)
        return {}
    
    def set_entities(self, entities):
        """设置实体"""
        self.entities = json.dumps(entities, ensure_ascii=False)
    
    def to_dict(self):
        return {
            'id': self.id,
            'filename': self.filename,
            'title': self.title,
            'status': self.status,
            'summary': self.summary,
            'keywords': self.get_keywords(),
            'category': self.category,
            'chunk_count': self.chunk_count,
            'word_count': self.word_count,
            'created_at': self.created_at.isoformat() if self.created_at else None,
            'indexed_at': self.indexed_at.isoformat() if self.indexed_at else None,
        }


class DocumentChunk(db.Model):
    """文档分块表"""
    __tablename__ = 'document_chunks'
    
    id = db.Column(db.Integer, primary_key=True)
    document_id = db.Column(db.Integer, db.ForeignKey('documents.id'), nullable=False)
    
    # 分块信息
    chunk_index = db.Column(db.Integer, default=0)  # 块序号
    content = db.Column(db.Text, nullable=False)    # 块内容
    
    # LLM生成的索引信息
    summary = db.Column(db.Text, nullable=True)     # 块摘要
    keywords = db.Column(db.Text, nullable=True)    # 关键词JSON数组
    topics = db.Column(db.Text, nullable=True)      # 主题JSON数组
    
    # 位置信息
    start_char = db.Column(db.Integer, default=0)
    end_char = db.Column(db.Integer, default=0)
    
    # 词频统计（用于BM25）
    term_freq = db.Column(db.Text, nullable=True)   # JSON对象 {term: count}
    
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    
    def get_keywords(self):
        if self.keywords:
            return json.loads(self.keywords)
        return []
    
    def set_keywords(self, keywords):
        self.keywords = json.dumps(keywords, ensure_ascii=False)
    
    def get_term_freq(self):
        if self.term_freq:
            return json.loads(self.term_freq)
        return {}
    
    def set_term_freq(self, tf):
        self.term_freq = json.dumps(tf, ensure_ascii=False)
    
    def to_dict(self):
        return {
            'id': self.id,
            'document_id': self.document_id,
            'chunk_index': self.chunk_index,
            'content': self.content[:200] + '...' if len(self.content) > 200 else self.content,
            'summary': self.summary,
            'keywords': self.get_keywords(),
        }


class InvertedIndex(db.Model):
    """倒排索引表"""
    __tablename__ = 'inverted_index'
    
    id = db.Column(db.Integer, primary_key=True)
    
    # 索引项
    term = db.Column(db.String(100), nullable=False, index=True)  # 关键词
    term_type = db.Column(db.String(20), default='keyword')       # keyword, entity, topic
    
    # 文档频率
    doc_freq = db.Column(db.Integer, default=0)  # 包含该词的文档数
    
    # 倒排列表（JSON：[{doc_id, chunk_id, tf, positions}]）
    postings = db.Column(db.Text, nullable=False)
    
    # 统计
    total_freq = db.Column(db.Integer, default=0)  # 总词频
    
    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    def get_postings(self):
        if self.postings:
            return json.loads(self.postings)
        return []
    
    def set_postings(self, postings):
        self.postings = json.dumps(postings, ensure_ascii=False)
        self.doc_freq = len(set(p['doc_id'] for p in postings))
        self.total_freq = sum(p.get('tf', 1) for p in postings)
    
    @staticmethod
    def get_or_create(term, term_type='keyword'):
        """获取或创建索引项"""
        index = InvertedIndex.query.filter_by(term=term, term_type=term_type).first()
        if not index:
            index = InvertedIndex(term=term, term_type=term_type, postings='[]')
            db.session.add(index)
        return index


class QueryLog(db.Model):
    """查询日志表"""
    __tablename__ = 'query_logs'
    
    id = db.Column(db.Integer, primary_key=True)
    
    # 查询信息
    original_query = db.Column(db.Text, nullable=False)      # 原始查询
    processed_query = db.Column(db.Text, nullable=True)      # 处理后的查询
    expanded_terms = db.Column(db.Text, nullable=True)       # 扩展词JSON数组
    
    # 查询意图
    intent = db.Column(db.String(50), nullable=True)         # 查询意图
    entities = db.Column(db.Text, nullable=True)             # 识别的实体
    
    # 检索结果
    result_count = db.Column(db.Integer, default=0)
    top_doc_ids = db.Column(db.Text, nullable=True)          # 返回的文档ID JSON数组
    
    # 性能
    retrieval_time = db.Column(db.Float, default=0)          # 检索耗时(秒)
    total_time = db.Column(db.Float, default=0)              # 总耗时(秒)
    
    # 用户反馈
    rating = db.Column(db.Integer, nullable=True)            # 评分1-5
    feedback = db.Column(db.Text, nullable=True)             # 反馈文本
    
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    
    def to_dict(self):
        return {
            'id': self.id,
            'query': self.original_query,
            'result_count': self.result_count,
            'retrieval_time': self.retrieval_time,
            'created_at': self.created_at.isoformat() if self.created_at else None,
        }


class IndexStats(db.Model):
    """索引统计表"""
    __tablename__ = 'index_stats'
    
    id = db.Column(db.Integer, primary_key=True)
    
    # 统计信息
    total_documents = db.Column(db.Integer, default=0)
    total_chunks = db.Column(db.Integer, default=0)
    total_terms = db.Column(db.Integer, default=0)
    total_words = db.Column(db.Integer, default=0)
    
    # 索引大小
    index_size_mb = db.Column(db.Float, default=0)
    
    # 最后更新
    last_indexed_at = db.Column(db.DateTime, nullable=True)
    
    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    @staticmethod
    def get_stats():
        stats = IndexStats.query.first()
        if not stats:
            stats = IndexStats()
            db.session.add(stats)
            db.session.commit()
        return stats
    
    def update_stats(self):
        """更新统计信息"""
        self.total_documents = Document.query.filter_by(status='indexed').count()
        self.total_chunks = DocumentChunk.query.count()
        self.total_terms = InvertedIndex.query.count()
        self.total_words = db.session.query(db.func.sum(Document.word_count)).scalar() or 0
        self.last_indexed_at = datetime.utcnow()
        db.session.commit()