// Copyright (c) Mysten Labs, Inc.
// SPDX-License-Identifier: Apache-2.0

import { useSuiClient, useSuiClientQuery } from '@mysten/dapp-kit';
import { useQuery } from '@tanstack/react-query';

import { roundFloat } from '../utils/roundFloat';

// recentEpochRewards is list of the last 30 epoch rewards for a specific validator
// APY_e = (1 + epoch_rewards / stake)^365-1
// APY_e_30rollingaverage = average(APY_e,APY_e-1,…,APY_e-29);

const DEFAULT_APY_DECIMALS = 2;

export interface ApyByValidator {
	[validatorAddress: string]: {
		apy: number;
		isApyApproxZero: boolean;
	};
}
// For small APY or epoch before stakeSubsidyStartEpoch, show ~0% instead of 0%
// If APY falls below 0.001, show ~0% instead of 0% since we round to 2 decimal places
const MINIMUM_THRESHOLD = 0.001;

export function useGetValidatorsApy() {
	const client = useSuiClient();
	const { data: systemStateResponse, isFetched } = useSuiClientQuery('getLatestSuiSystemState');
	return useQuery({
		queryKey: ['get-rolling-average-apys'],
		queryFn: () => client.getValidatorsApy(),
		enabled: isFetched,
		select: (validatorApys) => {
			// check if stakeSubsidyStartEpoch is greater than current epoch, flag for UI to show ~0% instead of 0%
			const currentEpoch = Number(systemStateResponse?.epoch);
			const stakeSubsidyStartEpoch = Number(systemStateResponse?.stakeSubsidyStartEpoch);

			const isStakeSubsidyStarted = currentEpoch > stakeSubsidyStartEpoch;

			return validatorApys?.apys.reduce((acc, { apy, address }) => {
				acc[address] = {
					apy: roundFloat(apy * 100, DEFAULT_APY_DECIMALS),
					isApyApproxZero: !isStakeSubsidyStarted || apy < MINIMUM_THRESHOLD,
				};
				return acc;
			}, {} as ApyByValidator);
		},
	});
}