"""Фаза 2: применение проверенного набора к БД — upsert по натуральному ключу, без удалений и без commit."""

from typing import Any

from sqlalchemy import func, select
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.ext.asyncio import AsyncSession

from scripts.seed_lib.model import SeedData, SeedReport, TableStat
from src.models.access import Permission, Role, RolePermission
from src.models.directories import RegionalOffice


async def _upsert(
    session: AsyncSession,
    model: Any,
    key: str,
    rows: list[dict[str, Any]],
    stat: TableStat,
) -> None:
    """Вставить новые и обновить изменившиеся строки по натуральному ключу `key`; удалений нет."""
    if not rows:
        return
    key_column = getattr(model, key)
    value_names = [name for name in rows[0] if name != key]
    existing: dict[Any, tuple[Any, ...]] = {
        row[0]: tuple(row[1:])
        for row in (await session.execute(select(key_column, *(getattr(model, name) for name in value_names)))).all()
    }
    changed = []
    for row in rows:
        current = existing.get(row[key])
        if current is None:
            stat.inserted += 1
            changed.append(row)
        elif current != tuple(row[name] for name in value_names):
            stat.updated += 1
            changed.append(row)
        else:
            stat.unchanged += 1
    if changed:
        statement = pg_insert(model)
        statement = statement.on_conflict_do_update(
            index_elements=[key_column], set_={name: statement.excluded[name] for name in value_names}
        )
        await session.execute(statement, changed)


async def _apply_role_permissions(session: AsyncSession, data: SeedData, stat: TableStat) -> None:
    role_ids = {code: id_ for id_, code in (await session.execute(select(Role.id, Role.code))).all()}
    permission_ids = {code: id_ for id_, code in (await session.execute(select(Permission.id, Permission.code))).all()}
    existing = set((await session.execute(select(RolePermission.role_id, RolePermission.permission_id))).all())
    new_rows = []
    for role_code, codes in data.role_permissions.items():
        for code in codes:
            pair = (role_ids[role_code], permission_ids[code])
            if pair in existing:
                stat.unchanged += 1
            else:
                stat.inserted += 1
                new_rows.append(
                    {"role_id": pair[0], "permission_id": pair[1], "granted_by": None, "granted_at": func.now()}
                )
    if new_rows:
        # .values(): func.now() допустим только во встроенном VALUES, не в executemany
        statement = (
            pg_insert(RolePermission)
            .values(new_rows)
            .on_conflict_do_nothing(index_elements=["role_id", "permission_id"])
        )
        await session.execute(statement)


async def apply_seed(session: AsyncSession, data: SeedData) -> SeedReport:
    """Фаза 2: upsert набора в порядке зависимостей. Без commit — транзакцией управляет вызывающий."""
    report = SeedReport()
    await _upsert(
        session,
        RegionalOffice,
        "name",
        [{"name": o.name, "is_head_office": o.is_head_office, "is_active": o.is_active} for o in data.regional_offices],
        report.stat("regional_office"),
    )
    await _upsert(
        session,
        Role,
        "code",
        [
            {
                "code": r.code,
                "name": r.name,
                "description": r.description,
                "is_system": r.is_system,
                "is_active": r.is_active,
            }
            for r in data.roles
        ],
        report.stat("role"),
    )
    await _upsert(
        session,
        Permission,
        "code",
        [
            {
                "code": p.code,
                "object_type": p.object_type,
                "action": p.action,
                "name": p.name,
                "description": p.description,
            }
            for p in data.permissions
        ],
        report.stat("permission"),
    )
    await _apply_role_permissions(session, data, report.stat("role_permission"))
    return report