shared/models/federation.py

"""Federation / ActivityPub ORM models.

These models support AP identity, activities, followers, inbox processing,
IPFS content addressing, and OpenTimestamps anchoring.
"""
from __future__ import annotations

from datetime import datetime

from sqlalchemy import (
    String, Integer, DateTime, Text, Boolean, BigInteger,
    ForeignKey, UniqueConstraint, Index, func,
)
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import Mapped, mapped_column, relationship

from shared.db.base import Base


class ActorProfile(Base):
    """AP identity for a user.  Created when user chooses a username."""
    __tablename__ = "ap_actor_profiles"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    user_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="CASCADE"),
        unique=True, nullable=False,
    )
    preferred_username: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
    display_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
    summary: Mapped[str | None] = mapped_column(Text, nullable=True)
    public_key_pem: Mapped[str] = mapped_column(Text, nullable=False)
    private_key_pem: Mapped[str] = mapped_column(Text, nullable=False)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )

    # Relationships
    user = relationship("User", backref="actor_profile", uselist=False, lazy="selectin")
    activities = relationship("APActivity", back_populates="actor_profile", lazy="dynamic")
    followers = relationship("APFollower", back_populates="actor_profile", lazy="dynamic")

    __table_args__ = (
        Index("ix_ap_actor_user_id", "user_id", unique=True),
        Index("ix_ap_actor_username", "preferred_username", unique=True),
    )

    def __repr__(self) -> str:
        return f"<ActorProfile {self.id} @{self.preferred_username}>"


class APActivity(Base):
    """An ActivityPub activity (local or remote)."""
    __tablename__ = "ap_activities"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    activity_id: Mapped[str] = mapped_column(String(512), unique=True, nullable=False)
    activity_type: Mapped[str] = mapped_column(String(64), nullable=False)
    actor_profile_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("ap_actor_profiles.id", ondelete="CASCADE"), nullable=False,
    )
    object_type: Mapped[str | None] = mapped_column(String(64), nullable=True)
    object_data: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    published: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )
    signature: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    is_local: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, server_default="true")

    # Link back to originating domain object (e.g. source_type='post', source_id=42)
    source_type: Mapped[str | None] = mapped_column(String(64), nullable=True)
    source_id: Mapped[int | None] = mapped_column(Integer, nullable=True)

    # IPFS content-addressed copy of the activity
    ipfs_cid: Mapped[str | None] = mapped_column(String(128), nullable=True)

    # Anchoring (filled later when batched into a merkle tree)
    anchor_id: Mapped[int | None] = mapped_column(
        Integer, ForeignKey("ap_anchors.id", ondelete="SET NULL"), nullable=True,
    )

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )

    # Relationships
    actor_profile = relationship("ActorProfile", back_populates="activities")

    __table_args__ = (
        Index("ix_ap_activity_actor", "actor_profile_id"),
        Index("ix_ap_activity_source", "source_type", "source_id"),
        Index("ix_ap_activity_published", "published"),
    )

    def __repr__(self) -> str:
        return f"<APActivity {self.id} {self.activity_type}>"


class APFollower(Base):
    """A remote follower of a local actor."""
    __tablename__ = "ap_followers"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    actor_profile_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("ap_actor_profiles.id", ondelete="CASCADE"), nullable=False,
    )
    follower_acct: Mapped[str] = mapped_column(String(512), nullable=False)
    follower_inbox: Mapped[str] = mapped_column(String(512), nullable=False)
    follower_actor_url: Mapped[str] = mapped_column(String(512), nullable=False)
    follower_public_key: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )

    # Relationships
    actor_profile = relationship("ActorProfile", back_populates="followers")

    __table_args__ = (
        UniqueConstraint("actor_profile_id", "follower_acct", name="uq_follower_acct"),
        Index("ix_ap_follower_actor", "actor_profile_id"),
    )

    def __repr__(self) -> str:
        return f"<APFollower {self.id} {self.follower_acct}>"


class APInboxItem(Base):
    """Raw incoming AP activity, stored for async processing."""
    __tablename__ = "ap_inbox_items"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    actor_profile_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("ap_actor_profiles.id", ondelete="CASCADE"), nullable=False,
    )
    raw_json: Mapped[dict] = mapped_column(JSONB, nullable=False)
    activity_type: Mapped[str | None] = mapped_column(String(64), nullable=True)
    from_actor: Mapped[str | None] = mapped_column(String(512), nullable=True)
    state: Mapped[str] = mapped_column(
        String(20), nullable=False, default="pending", server_default="pending",
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )
    processed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)

    __table_args__ = (
        Index("ix_ap_inbox_state", "state"),
        Index("ix_ap_inbox_actor", "actor_profile_id"),
    )

    def __repr__(self) -> str:
        return f"<APInboxItem {self.id} {self.activity_type} [{self.state}]>"


class APAnchor(Base):
    """OpenTimestamps anchoring batch — merkle tree of activities."""
    __tablename__ = "ap_anchors"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    merkle_root: Mapped[str] = mapped_column(String(128), nullable=False)
    tree_ipfs_cid: Mapped[str | None] = mapped_column(String(128), nullable=True)
    ots_proof_cid: Mapped[str | None] = mapped_column(String(128), nullable=True)
    activity_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )
    confirmed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    bitcoin_txid: Mapped[str | None] = mapped_column(String(128), nullable=True)

    def __repr__(self) -> str:
        return f"<APAnchor {self.id} activities={self.activity_count}>"


class IPFSPin(Base):
    """Tracks content stored on IPFS — used by all domains."""
    __tablename__ = "ipfs_pins"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    content_hash: Mapped[str] = mapped_column(String(128), nullable=False)
    ipfs_cid: Mapped[str] = mapped_column(String(128), nullable=False, unique=True)
    pin_type: Mapped[str] = mapped_column(String(64), nullable=False)
    source_type: Mapped[str | None] = mapped_column(String(64), nullable=True)
    source_id: Mapped[int | None] = mapped_column(Integer, nullable=True)
    size_bytes: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )

    __table_args__ = (
        Index("ix_ipfs_pin_source", "source_type", "source_id"),
        Index("ix_ipfs_pin_cid", "ipfs_cid", unique=True),
    )

    def __repr__(self) -> str:
        return f"<IPFSPin {self.id} {self.ipfs_cid[:16]}...>"