"""Continuity checkpoint. No LLM. Session end must not mutate threads."""
from __future__ import annotations

from db import get_db, row_to_dict
from dialogue_store import StoreError, end_usage_session, list_messages, thread_snapshot


def checkpoint_usage_session(profile_id: str, usage_session_id: str) -> dict:
    """Ensure originals are stored. Does not insert summaries or change thread status."""
    threads_before = thread_snapshot(profile_id)
    with get_db() as conn:
        session = row_to_dict(
            conn.execute(
                "SELECT * FROM usage_sessions WHERE id = ? AND profile_id = ?",
                (usage_session_id, profile_id),
            ).fetchone()
        )
        if not session:
            raise StoreError("not_found", "Nutzungssitzung nicht gefunden", 404)
        conv_rows = conn.execute(
            "SELECT id FROM conversations WHERE profile_id = ? AND usage_session_id = ?",
            (profile_id, usage_session_id),
        ).fetchall()
    conversations = []
    message_count = 0
    for row in conv_rows:
        messages = list_messages(profile_id, row["id"])
        message_count += len(messages)
        conversations.append({"id": row["id"], "message_count": len(messages)})
    if thread_snapshot(profile_id) != threads_before:
        raise StoreError("thread_mutated", "Checkpoint darf Thread-Felder nicht ändern", 500)
    return {
        "usage_session_id": usage_session_id,
        "ended_at": session.get("ended_at"),
        "conversations": conversations,
        "message_count": message_count,
        "threads_unchanged": True,
        "llm": False,
    }


def close_usage_session(profile_id: str, usage_session_id: str) -> dict:
    threads_before = thread_snapshot(profile_id)
    ended = end_usage_session(profile_id, usage_session_id)
    checkpoint = checkpoint_usage_session(profile_id, usage_session_id)
    if thread_snapshot(profile_id) != threads_before:
        raise StoreError("thread_mutated", "Session-Ende darf Thread-Status nicht ändern", 500)
    checkpoint["usage_session"] = ended
    return checkpoint