delegation.go

package keeper

import (
	"bytes"
	"time"

	sdk "github.com/cosmos/cosmos-sdk/types"
	"github.com/cosmos/cosmos-sdk/x/staking/types"
)

// return a specific delegation
func (k Keeper) GetDelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valAddr sdk.ValAddress) (
	delegation types.Delegation, found bool) {

	store := ctx.KVStore(k.storeKey)
	key := GetDelegationKey(delAddr, valAddr)
	value := store.Get(key)
	if value == nil {
		return delegation, false
	}

	delegation = types.MustUnmarshalDelegation(k.cdc, value)
	return delegation, true
}

// return all delegations used during genesis dump
func (k Keeper) GetAllDelegations(ctx sdk.Context) (delegations []types.Delegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, DelegationKey)
	defer iterator.Close()

	for ; iterator.Valid(); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		delegations = append(delegations, delegation)
	}
	return delegations
}

// return all delegations to a specific validator. Useful for querier.
func (k Keeper) GetValidatorDelegations(ctx sdk.Context, valAddr sdk.ValAddress) (delegations []types.Delegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, DelegationKey)
	defer iterator.Close()

	for ; iterator.Valid(); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		if delegation.GetValidatorAddr().Equals(valAddr) {
			delegations = append(delegations, delegation)
		}
	}
	return delegations
}

// return a given amount of all the delegations from a delegator
func (k Keeper) GetDelegatorDelegations(ctx sdk.Context, delegator sdk.AccAddress,
	maxRetrieve uint16) (delegations []types.Delegation) {

	delegations = make([]types.Delegation, maxRetrieve)

	store := ctx.KVStore(k.storeKey)
	delegatorPrefixKey := GetDelegationsKey(delegator)
	iterator := sdk.KVStorePrefixIterator(store, delegatorPrefixKey)
	defer iterator.Close()

	i := 0
	for ; iterator.Valid() && i < int(maxRetrieve); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		delegations[i] = delegation
		i++
	}
	return delegations[:i] // trim if the array length < maxRetrieve
}

// set the delegation
func (k Keeper) SetDelegation(ctx sdk.Context, delegation types.Delegation) {
	store := ctx.KVStore(k.storeKey)
	b := types.MustMarshalDelegation(k.cdc, delegation)
	store.Set(GetDelegationKey(delegation.DelegatorAddr, delegation.ValidatorAddr), b)
	k.AfterDelegationModified(ctx, delegation.DelegatorAddr, delegation.ValidatorAddr)
}

// remove a delegation from store
func (k Keeper) RemoveDelegation(ctx sdk.Context, delegation types.Delegation) {
	k.BeforeDelegationRemoved(ctx, delegation.DelegatorAddr, delegation.ValidatorAddr)
	store := ctx.KVStore(k.storeKey)
	store.Delete(GetDelegationKey(delegation.DelegatorAddr, delegation.ValidatorAddr))
}

//_____________________________________________________________________________________

// return a given amount of all the delegator unbonding-delegations
func (k Keeper) GetUnbondingDelegations(ctx sdk.Context, delegator sdk.AccAddress,
	maxRetrieve uint16) (unbondingDelegations []types.UnbondingDelegation) {

	unbondingDelegations = make([]types.UnbondingDelegation, maxRetrieve)

	store := ctx.KVStore(k.storeKey)
	delegatorPrefixKey := GetUBDsKey(delegator)
	iterator := sdk.KVStorePrefixIterator(store, delegatorPrefixKey)
	defer iterator.Close()

	i := 0
	for ; iterator.Valid() && i < int(maxRetrieve); iterator.Next() {
		unbondingDelegation := types.MustUnmarshalUBD(k.cdc, iterator.Value())
		unbondingDelegations[i] = unbondingDelegation
		i++
	}
	return unbondingDelegations[:i] // trim if the array length < maxRetrieve
}

// return a unbonding delegation
func (k Keeper) GetUnbondingDelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valAddr sdk.ValAddress) (ubd types.UnbondingDelegation, found bool) {

	store := ctx.KVStore(k.storeKey)
	key := GetUBDKey(delAddr, valAddr)
	value := store.Get(key)
	if value == nil {
		return ubd, false
	}

	ubd = types.MustUnmarshalUBD(k.cdc, value)
	return ubd, true
}

// return all unbonding delegations from a particular validator
func (k Keeper) GetUnbondingDelegationsFromValidator(ctx sdk.Context, valAddr sdk.ValAddress) (ubds []types.UnbondingDelegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, GetUBDsByValIndexKey(valAddr))
	defer iterator.Close()

	for ; iterator.Valid(); iterator.Next() {
		key := GetUBDKeyFromValIndexKey(iterator.Key())
		value := store.Get(key)
		ubd := types.MustUnmarshalUBD(k.cdc, value)
		ubds = append(ubds, ubd)
	}
	return ubds
}

// iterate through all of the unbonding delegations
func (k Keeper) IterateUnbondingDelegations(ctx sdk.Context, fn func(index int64, ubd types.UnbondingDelegation) (stop bool)) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, UnbondingDelegationKey)
	defer iterator.Close()

	for i := int64(0); iterator.Valid(); iterator.Next() {
		ubd := types.MustUnmarshalUBD(k.cdc, iterator.Value())
		if stop := fn(i, ubd); stop {
			break
		}
		i++
	}
}

// set the unbonding delegation and associated index
func (k Keeper) SetUnbondingDelegation(ctx sdk.Context, ubd types.UnbondingDelegation) {
	store := ctx.KVStore(k.storeKey)
	bz := types.MustMarshalUBD(k.cdc, ubd)
	key := GetUBDKey(ubd.DelegatorAddr, ubd.ValidatorAddr)
	store.Set(key, bz)
	store.Set(GetUBDByValIndexKey(ubd.DelegatorAddr, ubd.ValidatorAddr), []byte{}) // index, store empty bytes
}

// remove the unbonding delegation object and associated index
func (k Keeper) RemoveUnbondingDelegation(ctx sdk.Context, ubd types.UnbondingDelegation) {
	store := ctx.KVStore(k.storeKey)
	key := GetUBDKey(ubd.DelegatorAddr, ubd.ValidatorAddr)
	store.Delete(key)
	store.Delete(GetUBDByValIndexKey(ubd.DelegatorAddr, ubd.ValidatorAddr))
}

// SetUnbondingDelegationEntry adds an entry to the unbonding delegation at
// the given addresses. It creates the unbonding delegation if it does not exist
func (k Keeper) SetUnbondingDelegationEntry(ctx sdk.Context,
	delegatorAddr sdk.AccAddress, validatorAddr sdk.ValAddress,
	creationHeight int64, minTime time.Time, balance sdk.Coin) types.UnbondingDelegation {

	ubd, found := k.GetUnbondingDelegation(ctx, delegatorAddr, validatorAddr)
	if found {
		ubd.AddEntry(creationHeight, minTime, balance)
	} else {
		ubd = types.NewUnbondingDelegation(delegatorAddr, validatorAddr, creationHeight, minTime, balance)
	}
	k.SetUnbondingDelegation(ctx, ubd)
	return ubd
}

//________________________________________________
// unbonding delegation queue timeslice operations

// gets a specific unbonding queue timeslice. A timeslice is a slice of DVPairs
// corresponding to unbonding delegations that expire at a certain time.
func (k Keeper) GetUBDQueueTimeSlice(ctx sdk.Context, timestamp time.Time) (dvPairs []types.DVPair) {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(GetUnbondingDelegationTimeKey(timestamp))
	if bz == nil {
		return []types.DVPair{}
	}
	k.cdc.MustUnmarshalBinaryLengthPrefixed(bz, &dvPairs)
	return dvPairs
}

// Sets a specific unbonding queue timeslice.
func (k Keeper) SetUBDQueueTimeSlice(ctx sdk.Context, timestamp time.Time, keys []types.DVPair) {
	store := ctx.KVStore(k.storeKey)
	bz := k.cdc.MustMarshalBinaryLengthPrefixed(keys)
	store.Set(GetUnbondingDelegationTimeKey(timestamp), bz)
}

// Insert an unbonding delegation to the appropriate timeslice in the unbonding queue
func (k Keeper) InsertUBDQueue(ctx sdk.Context, ubd types.UnbondingDelegation,
	completionTime time.Time) {

	timeSlice := k.GetUBDQueueTimeSlice(ctx, completionTime)
	dvPair := types.DVPair{ubd.DelegatorAddr, ubd.ValidatorAddr}
	if len(timeSlice) == 0 {
		k.SetUBDQueueTimeSlice(ctx, completionTime, []types.DVPair{dvPair})
	} else {
		timeSlice = append(timeSlice, dvPair)
		k.SetUBDQueueTimeSlice(ctx, completionTime, timeSlice)
	}
}

// Returns all the unbonding queue timeslices from time 0 until endTime
func (k Keeper) UBDQueueIterator(ctx sdk.Context, endTime time.Time) sdk.Iterator {
	store := ctx.KVStore(k.storeKey)
	return store.Iterator(UnbondingQueueKey,
		sdk.InclusiveEndBytes(GetUnbondingDelegationTimeKey(endTime)))
}

// Returns a concatenated list of all the timeslices inclusively previous to
// currTime, and deletes the timeslices from the queue
func (k Keeper) DequeueAllMatureUBDQueue(ctx sdk.Context,
	currTime time.Time) (matureUnbonds []types.DVPair) {

	store := ctx.KVStore(k.storeKey)
	// gets an iterator for all timeslices from time 0 until the current Blockheader time
	unbondingTimesliceIterator := k.UBDQueueIterator(ctx, ctx.BlockHeader().Time)
	for ; unbondingTimesliceIterator.Valid(); unbondingTimesliceIterator.Next() {
		timeslice := []types.DVPair{}
		value := unbondingTimesliceIterator.Value()
		k.cdc.MustUnmarshalBinaryLengthPrefixed(value, &timeslice)
		matureUnbonds = append(matureUnbonds, timeslice...)
		store.Delete(unbondingTimesliceIterator.Key())
	}
	return matureUnbonds
}

//_____________________________________________________________________________________

// return a given amount of all the delegator redelegations
func (k Keeper) GetRedelegations(ctx sdk.Context, delegator sdk.AccAddress,
	maxRetrieve uint16) (redelegations []types.Redelegation) {
	redelegations = make([]types.Redelegation, maxRetrieve)

	store := ctx.KVStore(k.storeKey)
	delegatorPrefixKey := GetREDsKey(delegator)
	iterator := sdk.KVStorePrefixIterator(store, delegatorPrefixKey)
	defer iterator.Close()

	i := 0
	for ; iterator.Valid() && i < int(maxRetrieve); iterator.Next() {
		redelegation := types.MustUnmarshalRED(k.cdc, iterator.Value())
		redelegations[i] = redelegation
		i++
	}
	return redelegations[:i] // trim if the array length < maxRetrieve
}

// return a redelegation
func (k Keeper) GetRedelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valSrcAddr, valDstAddr sdk.ValAddress) (red types.Redelegation, found bool) {

	store := ctx.KVStore(k.storeKey)
	key := GetREDKey(delAddr, valSrcAddr, valDstAddr)
	value := store.Get(key)
	if value == nil {
		return red, false
	}

	red = types.MustUnmarshalRED(k.cdc, value)
	return red, true
}

// return all redelegations from a particular validator
func (k Keeper) GetRedelegationsFromValidator(ctx sdk.Context, valAddr sdk.ValAddress) (reds []types.Redelegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, GetREDsFromValSrcIndexKey(valAddr))
	defer iterator.Close()

	for ; iterator.Valid(); iterator.Next() {
		key := GetREDKeyFromValSrcIndexKey(iterator.Key())
		value := store.Get(key)
		red := types.MustUnmarshalRED(k.cdc, value)
		reds = append(reds, red)
	}
	return reds
}

// check if validator is receiving a redelegation
func (k Keeper) HasReceivingRedelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valDstAddr sdk.ValAddress) bool {

	store := ctx.KVStore(k.storeKey)
	prefix := GetREDsByDelToValDstIndexKey(delAddr, valDstAddr)
	iterator := sdk.KVStorePrefixIterator(store, prefix)
	defer iterator.Close()

	if iterator.Valid() {
		return true
	}
	return false
}

// set a redelegation and associated index
func (k Keeper) SetRedelegation(ctx sdk.Context, red types.Redelegation) {
	store := ctx.KVStore(k.storeKey)
	bz := types.MustMarshalRED(k.cdc, red)
	key := GetREDKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr)
	store.Set(key, bz)
	store.Set(GetREDByValSrcIndexKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr), []byte{})
	store.Set(GetREDByValDstIndexKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr), []byte{})
}

// SetUnbondingDelegationEntry adds an entry to the unbonding delegation at
// the given addresses. It creates the unbonding delegation if it does not exist
func (k Keeper) SetRedelegationEntry(ctx sdk.Context,
	delegatorAddr sdk.AccAddress, validatorSrcAddr,
	validatorDstAddr sdk.ValAddress, creationHeight int64,
	minTime time.Time, balance sdk.Coin,
	sharesSrc, sharesDst sdk.Dec) types.Redelegation {

	red, found := k.GetRedelegation(ctx, delegatorAddr, validatorSrcAddr, validatorDstAddr)
	if found {
		red.AddEntry(creationHeight, minTime, balance, sharesSrc, sharesDst)
	} else {
		red = types.NewRedelegation(delegatorAddr, validatorSrcAddr,
			validatorDstAddr, creationHeight, minTime, balance, sharesSrc,
			sharesDst)
	}
	k.SetRedelegation(ctx, red)
	return red
}

// iterate through all redelegations
func (k Keeper) IterateRedelegations(ctx sdk.Context, fn func(index int64, red types.Redelegation) (stop bool)) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, RedelegationKey)
	defer iterator.Close()

	for i := int64(0); iterator.Valid(); iterator.Next() {
		red := types.MustUnmarshalRED(k.cdc, iterator.Value())
		if stop := fn(i, red); stop {
			break
		}
		i++
	}
}

// remove a redelegation object and associated index
func (k Keeper) RemoveRedelegation(ctx sdk.Context, red types.Redelegation) {
	store := ctx.KVStore(k.storeKey)
	redKey := GetREDKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr)
	store.Delete(redKey)
	store.Delete(GetREDByValSrcIndexKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr))
	store.Delete(GetREDByValDstIndexKey(red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr))
}

//________________________________________________
// redelegation queue timeslice operations

// Gets a specific redelegation queue timeslice. A timeslice is a slice of DVVTriplets corresponding to redelegations
// that expire at a certain time.
func (k Keeper) GetRedelegationQueueTimeSlice(ctx sdk.Context, timestamp time.Time) (dvvTriplets []types.DVVTriplet) {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(GetRedelegationTimeKey(timestamp))
	if bz == nil {
		return []types.DVVTriplet{}
	}
	k.cdc.MustUnmarshalBinaryLengthPrefixed(bz, &dvvTriplets)
	return dvvTriplets
}

// Sets a specific redelegation queue timeslice.
func (k Keeper) SetRedelegationQueueTimeSlice(ctx sdk.Context, timestamp time.Time, keys []types.DVVTriplet) {
	store := ctx.KVStore(k.storeKey)
	bz := k.cdc.MustMarshalBinaryLengthPrefixed(keys)
	store.Set(GetRedelegationTimeKey(timestamp), bz)
}

// Insert an redelegation delegation to the appropriate timeslice in the redelegation queue
func (k Keeper) InsertRedelegationQueue(ctx sdk.Context, red types.Redelegation,
	completionTime time.Time) {

	timeSlice := k.GetRedelegationQueueTimeSlice(ctx, completionTime)
	dvvTriplet := types.DVVTriplet{red.DelegatorAddr, red.ValidatorSrcAddr, red.ValidatorDstAddr}
	if len(timeSlice) == 0 {
		k.SetRedelegationQueueTimeSlice(ctx, completionTime, []types.DVVTriplet{dvvTriplet})
	} else {
		timeSlice = append(timeSlice, dvvTriplet)
		k.SetRedelegationQueueTimeSlice(ctx, completionTime, timeSlice)
	}
}

// Returns all the redelegation queue timeslices from time 0 until endTime
func (k Keeper) RedelegationQueueIterator(ctx sdk.Context, endTime time.Time) sdk.Iterator {
	store := ctx.KVStore(k.storeKey)
	return store.Iterator(RedelegationQueueKey, sdk.InclusiveEndBytes(GetRedelegationTimeKey(endTime)))
}

// Returns a concatenated list of all the timeslices inclusively previous to
// currTime, and deletes the timeslices from the queue
func (k Keeper) DequeueAllMatureRedelegationQueue(ctx sdk.Context, currTime time.Time) (matureRedelegations []types.DVVTriplet) {
	store := ctx.KVStore(k.storeKey)
	// gets an iterator for all timeslices from time 0 until the current Blockheader time
	redelegationTimesliceIterator := k.RedelegationQueueIterator(ctx, ctx.BlockHeader().Time)
	for ; redelegationTimesliceIterator.Valid(); redelegationTimesliceIterator.Next() {
		timeslice := []types.DVVTriplet{}
		value := redelegationTimesliceIterator.Value()
		k.cdc.MustUnmarshalBinaryLengthPrefixed(value, &timeslice)
		matureRedelegations = append(matureRedelegations, timeslice...)
		store.Delete(redelegationTimesliceIterator.Key())
	}
	return matureRedelegations
}

//_____________________________________________________________________________________

// Perform a delegation, set/update everything necessary within the store.
func (k Keeper) Delegate(ctx sdk.Context, delAddr sdk.AccAddress, bondAmt sdk.Coin,
	validator types.Validator, subtractAccount bool) (newShares sdk.Dec, err sdk.Error) {

	// In some situations, the exchange rate becomes invalid, e.g. if
	// validator loses all tokens due to slashing.  In this case,
	// make all future delegations invalid.
	if validator.DelegatorShareExRate().IsZero() {
		return sdk.ZeroDec(), types.ErrDelegatorShareExRateInvalid(k.Codespace())
	}

	// Get or create the delegator delegation
	delegation, found := k.GetDelegation(ctx, delAddr, validator.OperatorAddr)
	if !found {
		delegation = types.Delegation{
			DelegatorAddr: delAddr,
			ValidatorAddr: validator.OperatorAddr,
			Shares:        sdk.ZeroDec(),
		}
	}

	// call the appropriate hook if present
	if found {
		k.BeforeDelegationSharesModified(ctx, delAddr, validator.OperatorAddr)
	} else {
		k.BeforeDelegationCreated(ctx, delAddr, validator.OperatorAddr)
	}

	if subtractAccount {
		_, err := k.bankKeeper.DelegateCoins(ctx, delegation.DelegatorAddr, sdk.Coins{bondAmt})
		if err != nil {
			return sdk.Dec{}, err
		}
	}

	validator, newShares = k.AddValidatorTokensAndShares(ctx, validator, bondAmt.Amount)

	// Update delegation
	delegation.Shares = delegation.Shares.Add(newShares)
	k.SetDelegation(ctx, delegation)

	return newShares, nil
}

// unbond the the delegation return
func (k Keeper) unbond(ctx sdk.Context, delAddr sdk.AccAddress, valAddr sdk.ValAddress,
	shares sdk.Dec) (amount sdk.Int, err sdk.Error) {

	// check if delegation has any shares in it unbond
	delegation, found := k.GetDelegation(ctx, delAddr, valAddr)
	if !found {
		return amount, types.ErrNoDelegatorForAddress(k.Codespace())
	}

	k.BeforeDelegationSharesModified(ctx, delAddr, valAddr)

	// retrieve the amount to remove
	if delegation.Shares.LT(shares) {
		return amount, types.ErrNotEnoughDelegationShares(k.Codespace(), delegation.Shares.String())
	}

	// get validator
	validator, found := k.GetValidator(ctx, valAddr)
	if !found {
		return amount, types.ErrNoValidatorFound(k.Codespace())
	}

	// subtract shares from delegator
	delegation.Shares = delegation.Shares.Sub(shares)

	// remove the delegation
	if delegation.Shares.IsZero() {

		// if the delegation is the operator of the validator then
		// trigger a jail validator
		if bytes.Equal(delegation.DelegatorAddr, validator.OperatorAddr) && !validator.Jailed {
			k.jailValidator(ctx, validator)
			validator = k.mustGetValidator(ctx, validator.OperatorAddr)
		}

		k.RemoveDelegation(ctx, delegation)
	} else {
		// update the delegation
		k.SetDelegation(ctx, delegation)
	}

	// remove the coins from the validator
	validator, amount = k.RemoveValidatorTokensAndShares(ctx, validator, shares)

	if validator.DelegatorShares.IsZero() && validator.Status == sdk.Unbonded {
		// if not unbonded, we must instead remove validator in EndBlocker once it finishes its unbonding period
		k.RemoveValidator(ctx, validator.OperatorAddr)
	}

	return amount, nil
}

//______________________________________________________________________________________________________

// get info for begin functions: completionTime and CreationHeight
func (k Keeper) getBeginInfo(ctx sdk.Context, valSrcAddr sdk.ValAddress) (
	completionTime time.Time, height int64, completeNow bool) {

	validator, found := k.GetValidator(ctx, valSrcAddr)

	switch {
	case !found || validator.Status == sdk.Bonded:

		// the longest wait - just unbonding period from now
		completionTime = ctx.BlockHeader().Time.Add(k.UnbondingTime(ctx))
		height = ctx.BlockHeight()
		return completionTime, height, false

	case validator.Status == sdk.Unbonded:
		return completionTime, height, true

	case validator.Status == sdk.Unbonding:
		completionTime = validator.UnbondingCompletionTime
		height = validator.UnbondingHeight
		return completionTime, height, false

	default:
		panic("unknown validator status")
	}
}

// begin unbonding an unbonding record
func (k Keeper) Undelegate(ctx sdk.Context, delAddr sdk.AccAddress,
	valAddr sdk.ValAddress, sharesAmount sdk.Dec) (completionTime time.Time, sdkErr sdk.Error) {

	// create the unbonding delegation
	completionTime, height, completeNow := k.getBeginInfo(ctx, valAddr)

	returnAmount, err := k.unbond(ctx, delAddr, valAddr, sharesAmount)
	if err != nil {
		return completionTime, err
	}
	balance := sdk.NewCoin(k.BondDenom(ctx), returnAmount)

	// no need to create the ubd object just complete now
	if completeNow {
		_, err := k.bankKeeper.UndelegateCoins(ctx, delAddr, sdk.Coins{balance})
		if err != nil {
			return completionTime, err
		}
		return completionTime, nil
	}

	ubd := k.SetUnbondingDelegationEntry(ctx, delAddr,
		valAddr, height, completionTime, balance)

	k.InsertUBDQueue(ctx, ubd, completionTime)
	return completionTime, nil
}

// CompleteUnbonding completes the unbonding of all mature entries in the
// retrieved unbonding delegation object.
func (k Keeper) CompleteUnbonding(ctx sdk.Context, delAddr sdk.AccAddress,
	valAddr sdk.ValAddress) sdk.Error {

	ubd, found := k.GetUnbondingDelegation(ctx, delAddr, valAddr)
	if !found {
		return types.ErrNoUnbondingDelegation(k.Codespace())
	}

	ctxTime := ctx.BlockHeader().Time

	// loop through all the entries and complete unbonding mature entries
	for i := 0; i < len(ubd.Entries); i++ {
		entry := ubd.Entries[i]
		if entry.IsMature(ctxTime) {
			ubd.RemoveEntry(int64(i))
			i--

			_, _, err := k.bankKeeper.AddCoins(ctx, ubd.DelegatorAddr, sdk.Coins{entry.Balance})
			if err != nil {
				return err
			}
		}
	}

	// set the unbonding delegation or remove it if there are no more entries
	if len(ubd.Entries) == 0 {
		k.RemoveUnbondingDelegation(ctx, ubd)
	} else {
		k.SetUnbondingDelegation(ctx, ubd)
	}

	return nil
}

// begin unbonding / redelegation; create a redelegation record
func (k Keeper) BeginRedelegation(ctx sdk.Context, delAddr sdk.AccAddress,
	valSrcAddr, valDstAddr sdk.ValAddress, sharesAmount sdk.Dec) (
	completionTime time.Time, errSdk sdk.Error) {

	if bytes.Equal(valSrcAddr, valDstAddr) {
		return time.Time{}, types.ErrSelfRedelegation(k.Codespace())
	}

	// check if this is a transitive redelegation
	if k.HasReceivingRedelegation(ctx, delAddr, valSrcAddr) {
		return time.Time{}, types.ErrTransitiveRedelegation(k.Codespace())
	}

	returnAmount, err := k.unbond(ctx, delAddr, valSrcAddr, sharesAmount)
	if err != nil {
		return time.Time{}, err
	}

	if returnAmount.IsZero() {
		return time.Time{}, types.ErrVerySmallRedelegation(k.Codespace())
	}
	returnCoin := sdk.NewCoin(k.BondDenom(ctx), returnAmount)

	dstValidator, found := k.GetValidator(ctx, valDstAddr)
	if !found {
		return time.Time{}, types.ErrBadRedelegationDst(k.Codespace())
	}

	sharesCreated, err := k.Delegate(ctx, delAddr, returnCoin, dstValidator, false)
	if err != nil {
		return time.Time{}, err
	}

	// create the unbonding delegation
	completionTime, height, completeNow := k.getBeginInfo(ctx, valSrcAddr)

	if completeNow { // no need to create the redelegation object
		return completionTime, nil
	}

	red := k.SetRedelegationEntry(ctx, delAddr, valSrcAddr, valDstAddr,
		height, completionTime, returnCoin, sharesAmount, sharesCreated)
	k.InsertRedelegationQueue(ctx, red, completionTime)
	return completionTime, nil
}

// CompleteRedelegation completes the unbonding of all mature entries in the
// retrieved unbonding delegation object.
func (k Keeper) CompleteRedelegation(ctx sdk.Context, delAddr sdk.AccAddress,
	valSrcAddr, valDstAddr sdk.ValAddress) sdk.Error {

	red, found := k.GetRedelegation(ctx, delAddr, valSrcAddr, valDstAddr)
	if !found {
		return types.ErrNoRedelegation(k.Codespace())
	}

	ctxTime := ctx.BlockHeader().Time

	// loop through all the entries and complete mature redelegation entries
	for i := 0; i < len(red.Entries); i++ {
		entry := red.Entries[i]
		if entry.IsMature(ctxTime) {
			red.RemoveEntry(int64(i))
			i--
		}
	}

	// set the redelegation or remove it if there are no more entries
	if len(red.Entries) == 0 {
		k.RemoveRedelegation(ctx, red)
	} else {
		k.SetRedelegation(ctx, red)
	}

	return nil
}