"""Immutable chunk snapshots and atomic publication metadata (no vector index yet)."""

from datetime import datetime

from sqlalchemy import (
    JSON,
    CheckConstraint,
    DateTime,
    ForeignKey,
    Integer,
    String,
    Text,
    UniqueConstraint,
    func,
)
from sqlalchemy.orm import Mapped, mapped_column

from app.db.session import Base


class IndexVersion(Base):
    __tablename__ = "index_versions"
    __table_args__ = (
        CheckConstraint(
            "status IN ('ready', 'published', 'superseded')", name="ck_index_version_status"
        ),
    )
    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    status: Mapped[str] = mapped_column(String(20), nullable=False, default="ready")
    config: Mapped[dict] = mapped_column(JSON, nullable=False)
    corpus_fingerprint: Mapped[str] = mapped_column(String(64), nullable=False)
    catalog_revision: Mapped[int] = mapped_column(Integer, nullable=False)
    item_count: Mapped[int] = mapped_column(Integer, nullable=False)
    chunk_count: Mapped[int] = mapped_column(Integer, nullable=False)
    created_by: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    published_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))


class IndexState(Base):
    __tablename__ = "index_state"
    __table_args__ = (CheckConstraint("id = 1", name="ck_index_state_singleton"),)
    id: Mapped[int] = mapped_column(primary_key=True)
    active_version_id: Mapped[str | None] = mapped_column(ForeignKey("index_versions.id"))
    generation: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    catalog_revision: Mapped[int] = mapped_column(Integer, nullable=False, default=0)


class Chunk(Base):
    __tablename__ = "chunks"
    __table_args__ = (
        UniqueConstraint("index_version_id", "knowledge_id", "ordinal", name="uq_chunk_position"),
        UniqueConstraint("id", "index_version_id", name="uq_chunk_text_scope"),
        CheckConstraint("start_offset >= 0 AND end_offset > start_offset", name="ck_chunk_offsets"),
    )
    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    index_version_id: Mapped[str] = mapped_column(ForeignKey("index_versions.id"), index=True)
    knowledge_id: Mapped[int] = mapped_column(ForeignKey("knowledge_items.id"), nullable=False)
    ordinal: Mapped[int] = mapped_column(Integer, nullable=False)
    start_offset: Mapped[int] = mapped_column(Integer, nullable=False)
    end_offset: Mapped[int] = mapped_column(Integer, nullable=False)
    text: Mapped[str] = mapped_column(Text, nullable=False)
    text_sha256: Mapped[str] = mapped_column(String(64), nullable=False)
    provenance: Mapped[dict] = mapped_column(JSON, nullable=False)


class IndexPublication(Base):
    __tablename__ = "index_publications"
    generation: Mapped[int] = mapped_column(primary_key=True)
    previous_version_id: Mapped[str | None] = mapped_column(ForeignKey("index_versions.id"))
    version_id: Mapped[str] = mapped_column(ForeignKey("index_versions.id"), nullable=False)
    actor_id: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=False)
    published_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )