package middleware

import (
	"context"

	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/types/tx"
)

type HasExtensionOptionsTx interface {
	GetExtensionOptions() []*codectypes.Any
	GetNonCriticalExtensionOptions() []*codectypes.Any
}

type rejectExtensionOptionsTxHandler struct {
	next tx.Handler
}

// RejectExtensionOptionsMiddleware creates a new rejectExtensionOptionsMiddleware.
// rejectExtensionOptionsMiddleware is a middleware that rejects all extension
// options which can optionally be included in protobuf transactions. Users that
// need extension options should create a custom middleware chain that handles
// needed extension options properly and rejects unknown ones.
func RejectExtensionOptionsMiddleware(txh tx.Handler) tx.Handler {
	return rejectExtensionOptionsTxHandler{
		next: txh,
	}
}

var _ tx.Handler = rejectExtensionOptionsTxHandler{}

func checkExtOpts(tx sdk.Tx) error {
	if hasExtOptsTx, ok := tx.(HasExtensionOptionsTx); ok {
		if len(hasExtOptsTx.GetExtensionOptions()) != 0 {
			return sdkerrors.ErrUnknownExtensionOptions
		}
	}

	return nil
}

// CheckTx implements tx.Handler.CheckTx.
func (txh rejectExtensionOptionsTxHandler) CheckTx(ctx context.Context, req tx.Request, checkReq tx.RequestCheckTx) (tx.Response, tx.ResponseCheckTx, error) {
	if err := checkExtOpts(req.Tx); err != nil {
		return tx.Response{}, tx.ResponseCheckTx{}, err
	}

	return txh.next.CheckTx(ctx, req, checkReq)
}

// DeliverTx implements tx.Handler.DeliverTx.
func (txh rejectExtensionOptionsTxHandler) DeliverTx(ctx context.Context, req tx.Request) (tx.Response, error) {
	if err := checkExtOpts(req.Tx); err != nil {
		return tx.Response{}, err
	}

	return txh.next.DeliverTx(ctx, req)
}

// SimulateTx implements tx.Handler.SimulateTx method.
func (txh rejectExtensionOptionsTxHandler) SimulateTx(ctx context.Context, req tx.Request) (tx.Response, error) {
	if err := checkExtOpts(req.Tx); err != nil {
		return tx.Response{}, err
	}

	return txh.next.SimulateTx(ctx, req)
}