"""
database.py — Persistencia de tenants y preferencias.

SQLite vía aiosqlite. En v1 esto se reemplaza por Postgres con el mismo interface público.

Schema:
- tenants: un registro por abogado registrado.
  Las credenciales van cifradas con vault.py (Fernet derivada por chat_id).
"""
from __future__ import annotations

from datetime import datetime, timezone
from pathlib import Path

import aiosqlite
import structlog

logger = structlog.get_logger(__name__)

_conn: aiosqlite.Connection | None = None

_CREATE_AUDIT_LOG = """
CREATE TABLE IF NOT EXISTS audit_log (
    id              INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp       TEXT    NOT NULL,
    timestamp_local TEXT,
    chat_id         INTEGER,
    evento          TEXT    NOT NULL,
    detalle         TEXT,
    resultado       TEXT,
    duracion_ms     INTEGER
);
CREATE INDEX IF NOT EXISTS idx_audit_chat_id  ON audit_log(chat_id);
CREATE INDEX IF NOT EXISTS idx_audit_timestamp ON audit_log(timestamp);
CREATE INDEX IF NOT EXISTS idx_audit_evento    ON audit_log(evento);
"""

_CREATE_TENANTS = """
CREATE TABLE IF NOT EXISTS tenants (
    chat_id             INTEGER PRIMARY KEY,
    nombre_preferido    TEXT,
    tono                TEXT    DEFAULT 'cotidiano',
    timezone            TEXT    DEFAULT 'America/Asuncion',
    credentials_enc     TEXT,
    estado              TEXT    DEFAULT 'pendiente',
    consentimiento_aceptado INTEGER DEFAULT 0,
    created_at          TEXT,
    last_active         TEXT
);
"""


def get_conn() -> aiosqlite.Connection:
    """Retorna la conexión activa. Llamar solo después de init_db()."""
    return _assert_conn()


def _now_iso() -> str:
    return datetime.now(timezone.utc).isoformat()


async def init_db(db_path: Path) -> None:
    """Crear tablas si no existen. Llamar una sola vez al arrancar."""
    global _conn
    db_path.parent.mkdir(parents=True, exist_ok=True)
    _conn = await aiosqlite.connect(str(db_path))
    _conn.row_factory = aiosqlite.Row
    await _conn.execute(_CREATE_TENANTS)
    # CREATE INDEX no soporta executescript — ejecutar sentencias separadas
    for stmt in _CREATE_AUDIT_LOG.strip().split(";"):
        stmt = stmt.strip()
        if stmt:
            await _conn.execute(stmt)
    await _conn.commit()
    logger.info("database_iniciada", path=str(db_path))


def _assert_conn() -> aiosqlite.Connection:
    if _conn is None:
        raise RuntimeError("DB no inicializada — llamar a init_db() antes de usar database.")
    return _conn


async def get_tenant(chat_id: int) -> dict | None:
    """Retorna el tenant o None si no existe."""
    conn = _assert_conn()
    async with conn.execute(
        "SELECT * FROM tenants WHERE chat_id = ?", (chat_id,)
    ) as cur:
        row = await cur.fetchone()
        return dict(row) if row else None


async def save_tenant(chat_id: int, **fields: object) -> None:
    """
    Crear o actualizar un tenant. Los kwargs son los campos de la tabla.
    Hace upsert: inserta si no existe, actualiza si ya existe.
    """
    conn = _assert_conn()
    fields["last_active"] = _now_iso()
    existing = await get_tenant(chat_id)

    if existing is None:
        fields.setdefault("created_at", _now_iso())
        columns = ["chat_id", *fields.keys()]
        placeholders = ", ".join("?" * len(columns))
        values = [chat_id, *fields.values()]
        await conn.execute(
            f"INSERT INTO tenants ({', '.join(columns)}) VALUES ({placeholders})",
            values,
        )
        logger.info("tenant_creado", chat_id=chat_id)
    else:
        set_clause = ", ".join(f"{k} = ?" for k in fields)
        values_upd = [*fields.values(), chat_id]
        await conn.execute(
            f"UPDATE tenants SET {set_clause} WHERE chat_id = ?",
            values_upd,
        )
        logger.info("tenant_actualizado", chat_id=chat_id, campos=list(fields.keys()))

    await conn.commit()


async def list_active_tenants() -> list[dict]:
    """Retorna todos los tenants con estado='activo'."""
    conn = _assert_conn()
    async with conn.execute(
        "SELECT * FROM tenants WHERE estado = 'activo'"
    ) as cur:
        rows = await cur.fetchall()
        return [dict(r) for r in rows]


async def delete_tenant(chat_id: int) -> None:
    """Elimina el tenant y sus datos de la DB."""
    conn = _assert_conn()
    await conn.execute("DELETE FROM tenants WHERE chat_id = ?", (chat_id,))
    await conn.commit()
    logger.info("tenant_eliminado", chat_id=chat_id)