// SPDX-License-Identifier: BUSL-1.1
//
// Copyright (C) 2025, Berachain Foundation. All rights reserved.
// Use of this software is governed by the Business Source License included
// in the LICENSE file of this repository and at www.mariadb.com/bsl11.
//
// ANY USE OF THE LICENSED WORK IN VIOLATION OF THIS LICENSE WILL AUTOMATICALLY
// TERMINATE YOUR RIGHTS UNDER THIS LICENSE FOR THE CURRENT AND ALL OTHER
// VERSIONS OF THE LICENSED WORK.
//
// THIS LICENSE DOES NOT GRANT YOU ANY RIGHT IN ANY TRADEMARK OR LOGO OF
// LICENSOR OR ITS AFFILIATES (PROVIDED THAT YOU MAY USE A TRADEMARK OR LOGO OF
// LICENSOR AS EXPRESSLY REQUIRED BY THIS LICENSE).
//
// TO THE EXTENT PERMITTED BY APPLICABLE LAW, THE LICENSED WORK IS PROVIDED ON
// AN “AS IS” BASIS. LICENSOR HEREBY DISCLAIMS ALL WARRANTIES AND CONDITIONS,
// EXPRESS OR IMPLIED, INCLUDING (WITHOUT LIMITATION) WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, AND
// TITLE.

package beacon

import (
	"github.com/berachain/beacon-kit/errors"
	"github.com/berachain/beacon-kit/node-api/handlers"
	beacontypes "github.com/berachain/beacon-kit/node-api/handlers/beacon/types"
	"github.com/berachain/beacon-kit/node-api/handlers/utils"
	"github.com/berachain/beacon-kit/primitives/math"
)

func (h *Handler) GetRandao(c handlers.Context) (any, error) {
	req, err := utils.BindAndValidate[beacontypes.GetRandaoRequest](
		c,
		h.Logger(),
	)
	if err != nil {
		return nil, err
	}

	// Get slot and associated state
	height, err := utils.StateIDToHeight(req.StateID, h.backend)
	if err != nil {
		return nil, err
	}
	st, slot, err := h.backend.StateAndSlotFromHeight(height)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to get state from height %d", height)
	}

	// Get the epoch
	var epoch math.Epoch
	if req.Epoch != "" {
		epoch, err = math.U64FromString(req.Epoch)
		if err != nil {
			return nil, err
		}
	} else {
		// Infer the epoch if not provided.
		epoch = h.cs.SlotToEpoch(slot)
	}

	// Retrieve the randao
	index := epoch.Unwrap() % h.cs.EpochsPerHistoricalVector()
	randao, err := st.GetRandaoMixAtIndex(index)
	if err != nil {
		return nil, err
	}
	return beacontypes.NewResponse(randao), nil
}
