package keeper

import (
	"fmt"

	sdk "github.com/cosmos/cosmos-sdk/types"

	"github.com/kava-labs/kava/x/incentive/types"
)

// AccumulateHardDelegatorRewards updates the rewards accumulated for the input reward period
func (k Keeper) AccumulateHardDelegatorRewards(ctx sdk.Context, rewardPeriod types.RewardPeriod) error {
	previousAccrualTime, found := k.GetPreviousHardDelegatorRewardAccrualTime(ctx, rewardPeriod.CollateralType)
	if !found {
		k.SetPreviousHardDelegatorRewardAccrualTime(ctx, rewardPeriod.CollateralType, ctx.BlockTime())
		return nil
	}
	timeElapsed := CalculateTimeElapsed(rewardPeriod.Start, rewardPeriod.End, ctx.BlockTime(), previousAccrualTime)
	if timeElapsed.IsZero() {
		return nil
	}
	if rewardPeriod.RewardsPerSecond.Amount.IsZero() {
		k.SetPreviousHardDelegatorRewardAccrualTime(ctx, rewardPeriod.CollateralType, ctx.BlockTime())
		return nil
	}

	totalBonded := k.stakingKeeper.TotalBondedTokens(ctx).ToDec()
	if totalBonded.IsZero() {
		k.SetPreviousHardDelegatorRewardAccrualTime(ctx, rewardPeriod.CollateralType, ctx.BlockTime())
		return nil
	}

	newRewards := timeElapsed.Mul(rewardPeriod.RewardsPerSecond.Amount)
	rewardFactor := newRewards.ToDec().Quo(totalBonded)

	previousRewardFactor, found := k.GetHardDelegatorRewardFactor(ctx, rewardPeriod.CollateralType)
	if !found {
		previousRewardFactor = sdk.ZeroDec()
	}
	newRewardFactor := previousRewardFactor.Add(rewardFactor)
	k.SetHardDelegatorRewardFactor(ctx, rewardPeriod.CollateralType, newRewardFactor)
	k.SetPreviousHardDelegatorRewardAccrualTime(ctx, rewardPeriod.CollateralType, ctx.BlockTime())
	return nil
}

// InitializeHardDelegatorReward initializes the delegator reward index of a hard claim
func (k Keeper) InitializeHardDelegatorReward(ctx sdk.Context, delegator sdk.AccAddress) {
	claim, found := k.GetHardLiquidityProviderClaim(ctx, delegator)
	if !found {
		claim = types.NewHardLiquidityProviderClaim(delegator, sdk.Coins{}, nil, nil, nil)
	} else {
		k.SynchronizeHardDelegatorRewards(ctx, delegator, nil, false)
		claim, _ = k.GetHardLiquidityProviderClaim(ctx, delegator)
	}

	globalRewardFactor, found := k.GetHardDelegatorRewardFactor(ctx, types.BondDenom)
	if !found {
		// If there's no global delegator reward factor, initialize the claim with a delegator factor of zero.
		globalRewardFactor = sdk.ZeroDec()
	}

	claim.DelegatorRewardIndexes = types.RewardIndexes{types.NewRewardIndex(types.BondDenom, globalRewardFactor)}
	k.SetHardLiquidityProviderClaim(ctx, claim)
}

// SynchronizeHardDelegatorRewards updates the claim object by adding any accumulated rewards, and setting the reward indexes to the global values.
// valAddr and shouldIncludeValidator are used to ignore or include delegations to a particular validator when summing up the total delegation.
// Normally only delegations to Bonded validators are included in the total. This is needed as staking hooks are sometimes called on the wrong side of a validator's state update (from this module's perspective).
func (k Keeper) SynchronizeHardDelegatorRewards(ctx sdk.Context, delegator sdk.AccAddress, valAddr sdk.ValAddress, shouldIncludeValidator bool) {
	claim, found := k.GetHardLiquidityProviderClaim(ctx, delegator)
	if !found {
		return
	}

	globalRewardFactor, found := k.GetHardDelegatorRewardFactor(ctx, types.BondDenom)
	if !found {
		// The global factor is only not found if
		// - the bond denom has not started accumulating rewards yet (either there is no reward specified in params, or the reward start time hasn't been hit)
		// - OR it was wrongly deleted from state (factors should never be removed while unsynced claims exist)
		// If not found we could either skip this sync, or assume the global factor is zero.
		// Skipping will avoid storing unnecessary factors in the claim for non rewarded denoms.
		// And in the event a global factor is wrongly deleted, it will avoid this function panicking when calculating rewards.
		return
	}

	userRewardFactor, found := claim.DelegatorRewardIndexes.Get(types.BondDenom)
	if !found {
		// Normally the factor should always be found, as it is added in InitializeHardDelegatorReward when a user delegates.
		// However if there were no delegator rewards (ie no reward period in params) then a reward period is added, existing claims will not have the factor.
		// So assume the factor is the starting value for any global factor: 0.
		userRewardFactor = sdk.ZeroDec()
	}

	totalDelegated := k.GetTotalDelegated(ctx, delegator, valAddr, shouldIncludeValidator)

	rewardsEarned, err := k.CalculateSingleReward(userRewardFactor, globalRewardFactor, totalDelegated)
	if err != nil {
		// Global reward factors should never decrease, as it would lead to a negative update to claim.Rewards.
		// This panics if a global reward factor decreases or disappears between the old and new indexes.
		panic(fmt.Sprintf("corrupted global reward indexes found: %v", err))
	}
	newRewardsCoin := sdk.NewCoin(types.HardLiquidityRewardDenom, rewardsEarned)

	claim.Reward = claim.Reward.Add(newRewardsCoin)
	claim.DelegatorRewardIndexes = claim.DelegatorRewardIndexes.With(types.BondDenom, globalRewardFactor)

	k.SetHardLiquidityProviderClaim(ctx, claim)
}

func (k Keeper) GetTotalDelegated(ctx sdk.Context, delegator sdk.AccAddress, valAddr sdk.ValAddress, shouldIncludeValidator bool) sdk.Dec {
	totalDelegated := sdk.ZeroDec()

	delegations := k.stakingKeeper.GetDelegatorDelegations(ctx, delegator, 200)
	for _, delegation := range delegations {
		validator, found := k.stakingKeeper.GetValidator(ctx, delegation.GetValidatorAddr())
		if !found {
			continue
		}

		if validator.OperatorAddress.Equals(valAddr) {
			if shouldIncludeValidator {
				// do nothing, so the validator is included regardless of bonded status
			} else {
				// skip this validator
				continue
			}
		} else {
			// skip any not bonded validator
			if validator.GetStatus() != sdk.Bonded {
				continue
			}
		}

		if validator.GetTokens().IsZero() {
			continue
		}

		delegatedTokens := validator.TokensFromShares(delegation.GetShares())
		if delegatedTokens.IsNegative() {
			continue
		}
		totalDelegated = totalDelegated.Add(delegatedTokens)
	}
	return totalDelegated
}