from sqlalchemy import Column, String, Integer, Text, DateTime, ForeignKey, CheckConstraint
from sqlalchemy.orm import relationship
from datetime import datetime
import uuid

from app.database.connection import Base


def generate_id():
    """Generate a unique ID."""
    return str(uuid.uuid4())


class User(Base):
    """User model for authentication."""
    __tablename__ = "users"
    
    id = Column(String, primary_key=True, default=generate_id)
    email = Column(String, unique=True, nullable=False, index=True)
    name = Column(String, nullable=True)
    password_hash = Column(String, nullable=True)  # Nullable for OAuth users
    google_id = Column(String, unique=True, nullable=True, index=True)
    is_admin = Column(Integer, default=0)  # 0 = regular user, 1 = admin
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # Relationships
    sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
    documents = relationship("Document", back_populates="user", cascade="all, delete-orphan")


class Session(Base):
    """Chat session model."""
    __tablename__ = "sessions"
    
    id = Column(String, primary_key=True, default=generate_id)
    user_id = Column(String, ForeignKey("users.id", ondelete="CASCADE"), nullable=True, index=True)
    title = Column(String, default="New Conversation")
    summary = Column(Text, nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # Relationships
    user = relationship("User", back_populates="sessions")
    messages = relationship("Message", back_populates="session", cascade="all, delete-orphan")


class Message(Base):
    """Chat message model."""
    __tablename__ = "messages"
    
    id = Column(String, primary_key=True, default=generate_id)
    session_id = Column(String, ForeignKey("sessions.id", ondelete="CASCADE"), nullable=False, index=True)
    role = Column(String, nullable=False)  # 'user' or 'assistant'
    content = Column(Text, nullable=False)
    meta = Column(Text, nullable=True)  # JSON string for metadata (agent, sources, etc.)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    session = relationship("Session", back_populates="messages")
    
    # Constraint
    __table_args__ = (
        CheckConstraint("role IN ('user', 'assistant')", name="check_role"),
    )


class Document(Base):
    """Uploaded document model."""
    __tablename__ = "documents"
    
    id = Column(String, primary_key=True, default=generate_id)
    user_id = Column(String, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
    filename = Column(String, nullable=False)
    file_path = Column(String, nullable=False)
    file_type = Column(String, nullable=True)
    file_size = Column(Integer, nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    user = relationship("User", back_populates="documents")


class OfficialPolicy(Base):
    """Official policy document model (admin-only upload, visible to all)."""
    __tablename__ = "official_policies"
    
    id = Column(String, primary_key=True, default=generate_id)
    title = Column(String, nullable=False)
    description = Column(Text, nullable=True)
    filename = Column(String, nullable=False)
    file_path = Column(String, nullable=False)
    file_type = Column(String, nullable=True)
    file_size = Column(Integer, nullable=True)
    category = Column(String, nullable=True)  # e.g., "OSHA", "Safety", "Building Codes"
    uploaded_by = Column(String, ForeignKey("users.id"), nullable=False)
    is_active = Column(Integer, default=1)  # 0 = inactive, 1 = active
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # Relationships
    chunks = relationship("PolicyChunk", back_populates="policy", cascade="all, delete-orphan")


class PolicyChunk(Base):
    """Chunks of official policy text for database-backed retrieval."""
    __tablename__ = "policy_chunks"
    
    id = Column(String, primary_key=True, default=generate_id)
    policy_id = Column(String, ForeignKey("official_policies.id", ondelete="CASCADE"), nullable=False, index=True)
    chunk_index = Column(Integer, nullable=False)
    content = Column(Text, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    policy = relationship("OfficialPolicy", back_populates="chunks")


class UserSettings(Base):
    """User settings and preferences model."""
    __tablename__ = "user_settings"
    
    id = Column(String, primary_key=True, default=generate_id)
    user_id = Column(String, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, unique=True, index=True)
    
    # Profile settings
    bio = Column(Text, nullable=True)
    phone = Column(String, nullable=True)
    company = Column(String, nullable=True)
    
    # Appearance settings
    theme = Column(String, default="system")  # light, dark, system
    
    # Notification settings
    email_notifications = Column(Integer, default=1)  # 0 = off, 1 = on
    update_notifications = Column(Integer, default=1)  # 0 = off, 1 = on
    
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)


class Report(Base):
    """Generated reports model."""
    __tablename__ = "reports"
    
    id = Column(String, primary_key=True, default=generate_id)
    user_id = Column(String, ForeignKey("users.id", ondelete="CASCADE"), nullable=True, index=True)
    template_id = Column(String, nullable=False)
    filename = Column(String, nullable=False)
    file_path = Column(String, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    user = relationship("User")