"""
database/models.py — SQLAlchemy ORM models for the knowledge base.

Schema Design:
- User: Tracks all users who interact with the bot.
- Admin: Stores admins appointed by the Owner.
- Folder: A hierarchical container (can be nested via parent_id).
- Item: A piece of content (file, image, video, link, or text) inside a Folder.
- AdminLog: Audit trail of admin actions for the Owner dashboard.
- UserLog: Tracks user navigation for the Admin dashboard.
"""

from datetime import datetime
from sqlalchemy import (
    BigInteger, Boolean, DateTime, ForeignKey,
    Integer, String, Text, func
)
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship


class Base(DeclarativeBase):
    """Base class for all SQLAlchemy models."""
    pass


class User(Base):
    """Represents any Telegram user who has interacted with the bot."""
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)  # Telegram user ID
    username: Mapped[str | None] = mapped_column(String(64), nullable=True)
    full_name: Mapped[str] = mapped_column(String(256), nullable=False)
    is_banned: Mapped[bool] = mapped_column(Boolean, default=False)
    joined_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    # Relationships
    logs: Mapped[list["UserLog"]] = relationship("UserLog", back_populates="user")


class Admin(Base):
    """Represents a user with admin privileges, appointed by the Owner."""
    __tablename__ = "admins"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    user_id: Mapped[int] = mapped_column(BigInteger, ForeignKey("users.id"), unique=True)
    username: Mapped[str | None] = mapped_column(String(64), nullable=True)
    full_name: Mapped[str] = mapped_column(String(256), nullable=False)
    added_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())
    added_by: Mapped[int] = mapped_column(BigInteger)  # Owner's user ID

    # Relationships
    action_logs: Mapped[list["AdminLog"]] = relationship("AdminLog", back_populates="admin")


class Folder(Base):
    """
    A hierarchical folder (category) for organizing content.
    parent_id=None means it's a root-level folder.
    """
    __tablename__ = "folders"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    name: Mapped[str] = mapped_column(String(128), nullable=False)
    emoji: Mapped[str] = mapped_column(String(8), default="📁")
    parent_id: Mapped[int | None] = mapped_column(
        Integer, ForeignKey("folders.id", ondelete="CASCADE"), nullable=True
    )
    created_by: Mapped[int] = mapped_column(BigInteger, ForeignKey("users.id"))
    created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    # Self-referential relationship for nested folders
    children: Mapped[list["Folder"]] = relationship(
        "Folder",
        back_populates="parent",
        cascade="all, delete-orphan"
    )
    parent: Mapped["Folder | None"] = relationship(
        "Folder", back_populates="children", remote_side=[id]
    )
    items: Mapped[list["Item"]] = relationship(
        "Item", back_populates="folder", cascade="all, delete-orphan"
    )


class Item(Base):
    """
    A piece of content stored inside a Folder.
    Stores ONLY file_id for media — never downloads files locally.
    """
    __tablename__ = "items"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    folder_id: Mapped[int] = mapped_column(Integer, ForeignKey("folders.id", ondelete="CASCADE"))
    title: Mapped[str] = mapped_column(String(256), nullable=False)

    # Content type: 'text', 'link', 'photo', 'video', 'document', 'audio'
    content_type: Mapped[str] = mapped_column(String(32), nullable=False)

    # For media: Telegram's file_id (permanent reference, never download!)
    file_id: Mapped[str | None] = mapped_column(Text, nullable=True)

    # For text/link content
    text_content: Mapped[str | None] = mapped_column(Text, nullable=True)

    created_by: Mapped[int] = mapped_column(BigInteger, ForeignKey("users.id"))
    created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    # Relationships
    folder: Mapped["Folder"] = relationship("Folder", back_populates="items")


class AdminLog(Base):
    """Audit trail of every action taken by an admin (for Owner dashboard)."""
    __tablename__ = "admin_logs"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    admin_id: Mapped[int] = mapped_column(Integer, ForeignKey("admins.id"), nullable=True)
    admin_user_id: Mapped[int] = mapped_column(BigInteger)
    action: Mapped[str] = mapped_column(String(512), nullable=False)
    timestamp: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    admin: Mapped["Admin | None"] = relationship("Admin", back_populates="action_logs")


class UserLog(Base):
    """Tracks user navigation events for the Admin dashboard."""
    __tablename__ = "user_logs"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    user_id: Mapped[int] = mapped_column(BigInteger, ForeignKey("users.id"))
    action: Mapped[str] = mapped_column(String(512), nullable=False)
    timestamp: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

    user: Mapped["User"] = relationship("User", back_populates="logs")