"""Журнал аудита «кто/когда/что/old->new» (issue #20).

Запись всегда выполняется на переданном соединении, то есть внутри уже
открытой транзакции вызывающего кода: мутация и её аудит коммитятся вместе и
не могут разойтись.
"""

from __future__ import annotations

import json
import sqlite3
from collections.abc import Mapping
from typing import Any

from .clock import utcnow
from .models import AUDIT_STATUS_OK, AuditEntry

__all__ = ["list_entries", "record"]


def _dumps(value: Any) -> str | None:
    if value is None:
        return None
    if isinstance(value, Mapping):
        return json.dumps(dict(value), sort_keys=True, ensure_ascii=False, default=str)
    return json.dumps(value, sort_keys=True, ensure_ascii=False, default=str)


def _loads(value: Any) -> Any:
    if value is None:
        return None
    if isinstance(value, (bytes, bytearray)):
        value = value.decode("utf-8")
    return json.loads(str(value))


def record(
    conn: sqlite3.Connection,
    *,
    actor: str,
    action: str,
    entity: str,
    entity_id: str | int | None = None,
    old_value: Any = None,
    new_value: Any = None,
    status: str = AUDIT_STATUS_OK,
    detail: str | None = None,
    ts: str | None = None,
) -> int:
    """Записать событие в ``audit_log`` и вернуть id записи."""
    if not actor:
        raise ValueError("actor обязателен: аудит должен знать, кто изменил состояние")
    cursor = conn.execute(
        """
        INSERT INTO audit_log (ts, actor, action, entity, entity_id,
                               old_value, new_value, status, detail)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
        """,
        (
            ts or utcnow(),
            actor,
            action,
            entity,
            None if entity_id is None else str(entity_id),
            _dumps(old_value),
            _dumps(new_value),
            status,
            detail,
        ),
    )
    return int(cursor.lastrowid or 0)


def list_entries(
    conn: sqlite3.Connection,
    *,
    entity: str | None = None,
    entity_id: str | int | None = None,
    limit: int = 100,
) -> list[AuditEntry]:
    """Прочитать журнал аудита (свежие первыми)."""
    sql = "SELECT * FROM audit_log"
    clauses: list[str] = []
    params: list[Any] = []
    if entity is not None:
        clauses.append("entity = ?")
        params.append(entity)
    if entity_id is not None:
        clauses.append("entity_id = ?")
        params.append(str(entity_id))
    if clauses:
        sql += " WHERE " + " AND ".join(clauses)
    sql += " ORDER BY id DESC LIMIT ?"
    params.append(int(limit))
    rows = conn.execute(sql, params).fetchall()
    return [
        AuditEntry(
            id=int(row["id"]),
            ts=str(row["ts"]),
            actor=str(row["actor"]),
            action=str(row["action"]),
            entity=str(row["entity"]),
            entity_id=None if row["entity_id"] is None else str(row["entity_id"]),
            old_value=_loads(row["old_value"]),
            new_value=_loads(row["new_value"]),
            status=str(row["status"]),
            detail=None if row["detail"] is None else str(row["detail"]),
        )
        for row in rows
    ]


def count(conn: sqlite3.Connection, *, entity: str | None = None) -> int:
    """Сколько записей в журнале (опционально — по сущности)."""
    if entity is None:
        row = conn.execute("SELECT COUNT(*) FROM audit_log").fetchone()
    else:
        row = conn.execute("SELECT COUNT(*) FROM audit_log WHERE entity = ?", (entity,)).fetchone()
    return int(row[0]) if row is not None else 0


def last_entry(conn: sqlite3.Connection, *, entity: str | None = None) -> AuditEntry | None:
    """Последняя запись журнала (опционально — по сущности)."""
    entries = list_entries(conn, entity=entity, limit=1)
    return entries[0] if entries else None