package keeper

import (
	"fmt"

	"github.com/tendermint/tendermint/libs/log"

	"github.com/cosmos/cosmos-sdk/codec"
	storetypes "github.com/cosmos/cosmos-sdk/store/types"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/x/distribution/types"
	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
)

// Keeper of the distribution store
type Keeper struct {
	storeKey      storetypes.StoreKey
	cdc           codec.BinaryCodec
	paramSpace    paramtypes.Subspace
	authKeeper    types.AccountKeeper
	bankKeeper    types.BankKeeper
	stakingKeeper types.StakingKeeper

	feeCollectorName string // name of the FeeCollector ModuleAccount
}

// NewKeeper creates a new distribution Keeper instance
func NewKeeper(
	cdc codec.BinaryCodec, key storetypes.StoreKey, paramSpace paramtypes.Subspace,
	ak types.AccountKeeper, bk types.BankKeeper, sk types.StakingKeeper,
	feeCollectorName string,
) Keeper {

	// ensure distribution module account is set
	if addr := ak.GetModuleAddress(types.ModuleName); addr == nil {
		panic(fmt.Sprintf("%s module account has not been set", types.ModuleName))
	}

	// set KeyTable if it has not already been set
	if !paramSpace.HasKeyTable() {
		paramSpace = paramSpace.WithKeyTable(types.ParamKeyTable())
	}

	return Keeper{
		storeKey:         key,
		cdc:              cdc,
		paramSpace:       paramSpace,
		authKeeper:       ak,
		bankKeeper:       bk,
		stakingKeeper:    sk,
		feeCollectorName: feeCollectorName,
	}
}

// Logger returns a module-specific logger.
func (k Keeper) Logger(ctx sdk.Context) log.Logger {
	return ctx.Logger().With("module", "x/"+types.ModuleName)
}

// SetWithdrawAddr sets a new address that will receive the rewards upon withdrawal
func (k Keeper) SetWithdrawAddr(ctx sdk.Context, delegatorAddr sdk.AccAddress, withdrawAddr sdk.AccAddress) error {
	if k.bankKeeper.BlockedAddr(withdrawAddr) {
		return sdkerrors.Wrapf(sdkerrors.ErrUnauthorized, "%s is not allowed to receive external funds", withdrawAddr)
	}

	if !k.GetWithdrawAddrEnabled(ctx) {
		return types.ErrSetWithdrawAddrDisabled
	}

	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			types.EventTypeSetWithdrawAddress,
			sdk.NewAttribute(types.AttributeKeyWithdrawAddress, withdrawAddr.String()),
		),
	)

	k.SetDelegatorWithdrawAddr(ctx, delegatorAddr, withdrawAddr)
	return nil
}

// withdraw rewards from a delegation
func (k Keeper) WithdrawDelegationRewards(ctx sdk.Context, delAddr sdk.AccAddress, valAddr sdk.ValAddress) (sdk.Coins, error) {
	val := k.stakingKeeper.Validator(ctx, valAddr)
	if val == nil {
		return nil, types.ErrNoValidatorDistInfo
	}

	del := k.stakingKeeper.Delegation(ctx, delAddr, valAddr)
	if del == nil {
		return nil, types.ErrEmptyDelegationDistInfo
	}

	// withdraw rewards
	rewards, err := k.withdrawDelegationRewards(ctx, val, del)
	if err != nil {
		return nil, err
	}

	if rewards.IsZero() {
		baseDenom, _ := sdk.GetBaseDenom()
		rewards = sdk.Coins{sdk.Coin{
			Denom:  baseDenom,
			Amount: sdk.ZeroInt(),
		}}
	}

	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			types.EventTypeWithdrawRewards,
			sdk.NewAttribute(sdk.AttributeKeyAmount, rewards.String()),
			sdk.NewAttribute(types.AttributeKeyValidator, valAddr.String()),
		),
	)

	// reinitialize the delegation
	k.initializeDelegation(ctx, valAddr, delAddr)
	return rewards, nil
}

// withdraw validator commission
func (k Keeper) WithdrawValidatorCommission(ctx sdk.Context, valAddr sdk.ValAddress) (sdk.Coins, error) {
	// fetch validator accumulated commission
	accumCommission := k.GetValidatorAccumulatedCommission(ctx, valAddr)
	if accumCommission.Commission.IsZero() {
		return nil, types.ErrNoValidatorCommission
	}

	commission, remainder := accumCommission.Commission.TruncateDecimal()
	k.SetValidatorAccumulatedCommission(ctx, valAddr, types.ValidatorAccumulatedCommission{Commission: remainder}) // leave remainder to withdraw later

	// update outstanding
	outstanding := k.GetValidatorOutstandingRewards(ctx, valAddr).Rewards
	k.SetValidatorOutstandingRewards(ctx, valAddr, types.ValidatorOutstandingRewards{Rewards: outstanding.Sub(sdk.NewDecCoinsFromCoins(commission...))})

	if !commission.IsZero() {
		accAddr := sdk.AccAddress(valAddr)
		withdrawAddr := k.GetDelegatorWithdrawAddr(ctx, accAddr)
		err := k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, withdrawAddr, commission)
		if err != nil {
			return nil, err
		}
	}

	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			types.EventTypeWithdrawCommission,
			sdk.NewAttribute(sdk.AttributeKeyAmount, commission.String()),
		),
	)

	return commission, nil
}

// GetTotalRewards returns the total amount of fee distribution rewards held in the store
func (k Keeper) GetTotalRewards(ctx sdk.Context) (totalRewards sdk.DecCoins) {
	k.IterateValidatorOutstandingRewards(ctx,
		func(_ sdk.ValAddress, rewards types.ValidatorOutstandingRewards) (stop bool) {
			totalRewards = totalRewards.Add(rewards.Rewards...)
			return false
		},
	)

	return totalRewards
}

// FundCommunityPool allows an account to directly fund the community fund pool.
// The amount is first added to the distribution module account and then directly
// added to the pool. An error is returned if the amount cannot be sent to the
// module account.
func (k Keeper) FundCommunityPool(ctx sdk.Context, amount sdk.Coins, sender sdk.AccAddress) error {
	if err := k.bankKeeper.SendCoinsFromAccountToModule(ctx, sender, types.ModuleName, amount); err != nil {
		return err
	}

	feePool := k.GetFeePool(ctx)
	feePool.CommunityPool = feePool.CommunityPool.Add(sdk.NewDecCoinsFromCoins(amount...)...)
	k.SetFeePool(ctx, feePool)

	return nil
}