import { u64 } from "@saberhq/token-utils";

export interface StableSwapEvent {
  type: string;
  tokenAAmount?: u64;
  tokenBAmount?: u64;
  poolTokenAmount?: u64;
  fee?: u64;
}

const parseUint = (str?: string): u64 | undefined =>
  !str || str === "0x0" ? undefined : new u64(str.slice("0x".length), 16);

const parseEventRaw = (type: string, msg: string): StableSwapEvent => {
  const parts = msg.slice("Program log: ".length).split(", ");
  return Object.entries({
    type,
    tokenAAmount: parseUint(parts[1]),
    tokenBAmount: parseUint(parts[2]),
    poolTokenAmount: parseUint(parts[3]),
    fee: parseUint(parts[4]),
  })
    .filter(([, v]) => !!v)
    .reduce((acc, [k, v]) => ({ ...acc, [k]: v }), {}) as StableSwapEvent;
};

/**
 * Parses the log message to return the StableSwap info about the transaction.
 * @param logMessages
 * @returns
 */
export const parseEventLogs = (
  logMessages?: string[] | null,
): readonly StableSwapEvent[] => {
  if (!logMessages) {
    return [];
  }
  return logMessages.reduce((acc, logMessage, i) => {
    const nextLog = logMessages[i + 1];
    return logMessage.startsWith("Program log: Event: ") && nextLog
      ? [
          ...acc,
          parseEventRaw(
            logMessage.slice("Program log: Event: ".length),
            nextLog,
          ),
        ]
      : acc;
  }, [] as StableSwapEvent[]);
};