from datetime import UTC, datetime

from sqlalchemy import text
from sqlalchemy.ext.asyncio import AsyncSession

SYNCABLE_TABLES = [
    "vehicles",
    "orders",
    "order_lines",
    "invoices",
    "appointments",
    "catalog_marci",
    "catalog_modele",
    "catalog_ansamble",
    "catalog_norme",
    "catalog_preturi",
    "catalog_tipuri_deviz",
    "catalog_tipuri_motoare",
    "mecanici",
]

# Tables that don't have tenant_id directly
NO_TENANT_TABLES = {"catalog_modele"}


async def _get_table_columns(db: AsyncSession, table: str) -> set[str]:
    """Return the set of column names for a given table using PRAGMA table_info."""
    rows = await db.execute(text(f"PRAGMA table_info({table})"))
    return {row[1] for row in rows}


async def get_full(db: AsyncSession, tenant_id: str) -> dict:
    result = {}
    for table in SYNCABLE_TABLES:
        if table == "catalog_modele":
            rows = await db.execute(
                text(
                    "SELECT cm.* FROM catalog_modele cm "
                    "JOIN catalog_marci marc ON cm.marca_id = marc.id "
                    "WHERE marc.tenant_id = :tid"
                ),
                {"tid": tenant_id},
            )
        else:
            rows = await db.execute(
                text(f"SELECT * FROM {table} WHERE tenant_id = :tid"),
                {"tid": tenant_id},
            )
        result[table] = [dict(r._mapping) for r in rows]
    return result


async def get_changes(db: AsyncSession, tenant_id: str, since: str) -> dict:
    result = {}
    for table in SYNCABLE_TABLES:
        if table == "catalog_modele":
            rows = await db.execute(
                text(
                    "SELECT cm.* FROM catalog_modele cm "
                    "JOIN catalog_marci marc ON cm.marca_id = marc.id "
                    "WHERE marc.tenant_id = :tid AND cm.updated_at > :since"
                ),
                {"tid": tenant_id, "since": since},
            )
        else:
            rows = await db.execute(
                text(
                    f"SELECT * FROM {table} WHERE tenant_id = :tid AND updated_at > :since"
                ),
                {"tid": tenant_id, "since": since},
            )
        rows_list = [dict(r._mapping) for r in rows]
        if rows_list:
            result[table] = rows_list
    return result


async def apply_push(
    db: AsyncSession, tenant_id: str, operations: list
) -> dict:
    applied = 0
    errors = []
    # Cache column sets per table to avoid repeated PRAGMA calls
    table_columns_cache: dict[str, set[str]] = {}

    for op in operations:
        table = op["table"]
        if table not in SYNCABLE_TABLES:
            continue
        data = dict(op.get("data", {}))

        # Enforce tenant isolation (except for no-tenant tables)
        if table not in NO_TENANT_TABLES:
            if data.get("tenant_id") and data["tenant_id"] != tenant_id:
                continue
            data["tenant_id"] = tenant_id

        try:
            if op["operation"] in ("INSERT", "UPDATE"):
                # Fetch and cache the valid column names for this table
                if table not in table_columns_cache:
                    table_columns_cache[table] = await _get_table_columns(db, table)
                valid_cols = table_columns_cache[table]

                # Filter data to only include columns that exist in the DB table
                filtered = {k: v for k, v in data.items() if k in valid_cols}
                if not filtered:
                    continue

                cols = ", ".join(filtered.keys())
                ph = ", ".join(f":{k}" for k in filtered.keys())
                await db.execute(
                    text(f"INSERT OR REPLACE INTO {table} ({cols}) VALUES ({ph})"),
                    filtered,
                )
                applied += 1
            elif op["operation"] == "DELETE":
                if table in NO_TENANT_TABLES:
                    await db.execute(
                        text(f"DELETE FROM {table} WHERE id = :id"),
                        {"id": op["id"]},
                    )
                else:
                    await db.execute(
                        text(
                            f"DELETE FROM {table} WHERE id = :id AND tenant_id = :tid"
                        ),
                        {"id": op["id"], "tid": tenant_id},
                    )
                applied += 1
        except Exception as exc:  # noqa: BLE001
            errors.append({"table": table, "id": op.get("id"), "error": str(exc)})
            await db.rollback()

    await db.commit()
    return {"applied": applied, "conflicts": errors}