package keeper

import (
	"context"
	"strings"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	errorsmod "cosmossdk.io/errors"
	"github.com/cosmos/cosmos-sdk/client"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/types/query"

	"github.com/0glabs/0g-chain/x/savings/types"
)

type queryServer struct {
	keeper Keeper
}

// NewQueryServerImpl creates a new server for handling gRPC queries.
func NewQueryServerImpl(k Keeper) types.QueryServer {
	return &queryServer{keeper: k}
}

var _ types.QueryServer = queryServer{}

// Params implements the gRPC service handler for querying x/savings parameters.
func (s queryServer) Params(c context.Context, req *types.QueryParamsRequest) (*types.QueryParamsResponse, error) {
	if req == nil {
		return nil, status.Errorf(codes.InvalidArgument, "empty request")
	}

	sdkCtx := sdk.UnwrapSDKContext(c)
	params := s.keeper.GetParams(sdkCtx)

	return &types.QueryParamsResponse{Params: params}, nil
}

func (s queryServer) Deposits(ctx context.Context, req *types.QueryDepositsRequest) (*types.QueryDepositsResponse, error) {
	if req == nil {
		return nil, status.Errorf(codes.InvalidArgument, "empty request")
	}

	sdkCtx := sdk.UnwrapSDKContext(ctx)

	hasDenom := len(req.Denom) > 0
	hasOwner := len(req.Owner) > 0

	var owner sdk.AccAddress
	var err error
	if hasOwner {
		owner, err = sdk.AccAddressFromBech32(req.Owner)
		if err != nil {
			return nil, errorsmod.Wrap(sdkerrors.ErrInvalidAddress, err.Error())
		}
	}

	var deposits types.Deposits
	switch {
	case hasOwner && hasDenom:
		deposit, found := s.keeper.GetDeposit(sdkCtx, owner)
		if found {
			for _, coin := range deposit.Amount {
				if coin.Denom == req.Denom {
					deposits = append(deposits, deposit)
				}
			}
		}
	case hasOwner:
		deposit, found := s.keeper.GetDeposit(sdkCtx, owner)
		if found {
			deposits = append(deposits, deposit)
		}
	case hasDenom:
		s.keeper.IterateDeposits(sdkCtx, func(deposit types.Deposit) (stop bool) {
			if deposit.Amount.AmountOf(req.Denom).IsPositive() {
				deposits = append(deposits, deposit)
			}
			return false
		})
	default:
		s.keeper.IterateDeposits(sdkCtx, func(deposit types.Deposit) (stop bool) {
			deposits = append(deposits, deposit)
			return false
		})
	}

	page, limit, err := query.ParsePagination(req.Pagination)
	if err != nil {
		return nil, err
	}

	start, end := client.Paginate(len(deposits), page, limit, 100)
	if start < 0 || end < 0 {
		deposits = types.Deposits{}
	} else {
		deposits = deposits[start:end]
	}

	return &types.QueryDepositsResponse{
		Deposits:   deposits,
		Pagination: nil,
	}, nil
}

func (s queryServer) TotalSupply(ctx context.Context, req *types.QueryTotalSupplyRequest) (*types.QueryTotalSupplyResponse, error) {
	sdkCtx := sdk.UnwrapSDKContext(ctx)
	totalSupply := sdk.NewCoins()
	liquidStakedDerivatives := sdk.NewCoins()

	s.keeper.IterateDeposits(sdkCtx, func(deposit types.Deposit) (stop bool) {
		for _, c := range deposit.Amount {
			// separate out bkava denoms
			if strings.HasPrefix(c.Denom, bkavaPrefix) {
				liquidStakedDerivatives = liquidStakedDerivatives.Add(c)
			} else {
				totalSupply = totalSupply.Add(c)
			}
		}
		return false
	})

	// determine underlying value of bkava denoms
	if len(liquidStakedDerivatives) > 0 {
		underlyingValue, err := s.keeper.liquidKeeper.GetStakedTokensForDerivatives(
			sdkCtx,
			liquidStakedDerivatives,
		)
		if err != nil {
			return nil, err
		}
		totalSupply = totalSupply.Add(sdk.NewCoin(bkavaDenom, underlyingValue.Amount))
	}

	return &types.QueryTotalSupplyResponse{
		Height: sdkCtx.BlockHeight(),
		Result: totalSupply,
	}, nil
}