import type { ResultSetHeader, RowDataPacket } from "mysql2/promise";
import { BILL_BODY_LIMIT } from "./body";
import { withTransaction, getPool } from "./db";
import { isUuid } from "./ids";

export class BillStoreError extends Error {
  readonly status: number;

  constructor(status: number, message: string) {
    super(message);
    this.status = status;
  }
}

export async function storePublishedBill(token: string, raw: string): Promise<void> {
  if (!isUuid(token)) throw new BillStoreError(400, "invalid token");
  if (Buffer.byteLength(raw, "utf8") > BILL_BODY_LIMIT) throw new BillStoreError(413, "body too large");
  let parsed: unknown;
  try {
    parsed = JSON.parse(raw);
  } catch {
    throw new BillStoreError(400, "invalid json");
  }
  const isSnapshot = parsed !== null && typeof parsed === "object" && !Array.isArray(parsed);
  await withTransaction(async (conn) => {
    await conn.query(
      `INSERT INTO bill_snapshots (token, payload_json, updated_at)
       VALUES (?, ?, UTC_TIMESTAMP(3))
       ON DUPLICATE KEY UPDATE payload_json = VALUES(payload_json), updated_at = UTC_TIMESTAMP(3)`,
      [token, raw],
    );
    if (isSnapshot) {
      await conn.query<ResultSetHeader>(
        `UPDATE invoices SET snapshot_json = ? WHERE public_token = ? AND deleted_at IS NULL`,
        [raw, token],
      );
    }
  });
}

/** Invoice snapshot first, then the legacy store. */
export async function readBillPayload(token: string): Promise<string | null> {
  if (!isUuid(token)) return null;
  const pool = getPool();
  const [invoices] = await pool.query<RowDataPacket[]>(
    `SELECT snapshot_json FROM invoices WHERE public_token = ? AND deleted_at IS NULL LIMIT 1`,
    [token],
  );
  const snapshot = invoices[0]?.snapshot_json;
  if (typeof snapshot === "string" && snapshot.length > 0) return snapshot;
  const [legacy] = await pool.query<RowDataPacket[]>(
    `SELECT payload_json FROM bill_snapshots WHERE token = ? LIMIT 1`,
    [token],
  );
  const payload = legacy[0]?.payload_json;
  if (typeof payload === "string" && payload.length > 0) return payload;
  return null;
}