"""SQLAlchemy models (PostgreSQL 17 + pgvector).

Data model — see ``.agent/PLAN.md`` §Data Model:

* ``documents`` — one row per imported A9 file (full content, path, sha256 hash).
* ``chunks``    — retrieval units; each chunk points at its parent document
                  via ``document_id``. This is how an embedding maps back to
                  a document path (the "feed the whole document" requirement).
* ``query_log``     — observability: every question, its retrieval score,
                      the deflection decision, and latency.
* ``steering_notes`` — owner tuning notes injected into the system prompt
                      of every chat turn (phase 15, ``<tuning>`` section).
"""
from __future__ import annotations

import uuid
from datetime import datetime

from pgvector.sqlalchemy import Vector
from sqlalchemy import (
    Boolean,
    DateTime,
    Float,
    ForeignKey,
    Integer,
    String,
    Text,
    UniqueConstraint,
    func,
)
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.config import get_settings
from app.db import Base

# Single source of truth for the vector column size (see .agent/PLAN.md A6).
EMBEDDING_DIM: int = get_settings().embedding_dim


class Document(Base):
    __tablename__ = "documents"
    __table_args__ = (UniqueConstraint("source", "path", name="uq_documents_source_path"),)

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    source: Mapped[str] = mapped_column(String(120), index=True)  # e.g. "Homelab"
    path: Mapped[str] = mapped_column(String(1000), index=True)  # relative to source dir
    full_path: Mapped[str] = mapped_column(String(2000))  # absolute path at import time
    title: Mapped[str] = mapped_column(String(500))
    content: Mapped[str] = mapped_column(Text)  # full markdown — the RAG context
    content_hash: Mapped[str] = mapped_column(String(64), index=True)  # sha256 for change detection
    indexed_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    #: Lite-model summary, phase 30. Natural-language summary of the
    #: document (non-markdown A9 docs only, generated at import time by the
    #: aipi ``lite`` model). NULL for markdown docs, pre-phase-30 rows, and
    #: the fail-soft path where summary generation failed but the document
    #: was still indexed.
    summary: Mapped[str | None] = mapped_column(Text, default=None)

    chunks: Mapped[list[Chunk]] = relationship(
        back_populates="document", cascade="all, delete-orphan"
    )


class Chunk(Base):
    __tablename__ = "chunks"

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    document_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), ForeignKey("documents.id", ondelete="CASCADE"), index=True
    )
    position: Mapped[int] = mapped_column(Integer)
    content: Mapped[str] = mapped_column(Text)
    embedding: Mapped[list[float] | None] = mapped_column(Vector(EMBEDDING_DIM))
    #: Summary chunk, position −1, phase 30. Marks the single extra embedded
    #: chunk mirroring ``Document.summary``; default False keeps every
    #: pre-phase-30 row (and ordinary content chunks) valid.
    is_summary: Mapped[bool] = mapped_column(Boolean, default=False)

    document: Mapped[Document] = relationship(back_populates="chunks")


class QueryLog(Base):
    __tablename__ = "query_log"

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    question: Mapped[str] = mapped_column(Text)
    top_score: Mapped[float] = mapped_column(Float, default=0.0)  # best cosine similarity
    #: Lexical (FTS) candidates matched — the OR-tsquery hit count (A8). NULL
    #: for pre-hybrid rows (migration 0002).
    fts_hits: Mapped[int | None] = mapped_column(Integer)
    chunk_hits: Mapped[int] = mapped_column(Integer, default=0)
    deflected: Mapped[bool] = mapped_column(Boolean, default=False)  # True = honest "no idea"
    sources: Mapped[str] = mapped_column(Text, default="")  # comma-joined source paths
    latency_ms: Mapped[int] = mapped_column(Integer, default=0)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())


class SteeringNote(Base):
    """One owner tuning instruction (phase 15).

    Notes are read into the system prompt of **every** chat turn as the
    ``<tuning>`` section (oldest first, char-budgeted — see
    :func:`app.rag.prompts.build_steering_section`).
    """

    __tablename__ = "steering_notes"

    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    note: Mapped[str] = mapped_column(Text)  # trimmed, 1–2000 chars (API-enforced)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())