package keeper

import (
	"fmt"
	"time"

	sdk "github.com/cosmos/cosmos-sdk/types"
	"github.com/cosmos/cosmos-sdk/x/supply"
	"github.com/kava-labs/kava/x/auction/types"
)

// StartForwardAuction starts a normal auction.
func (k Keeper) StartForwardAuction(ctx sdk.Context, seller string, lot sdk.Coin, bidDenom string) (types.ID, sdk.Error) {
	// create auction
	auction := types.NewForwardAuction(seller, lot, bidDenom, ctx.BlockTime().Add(types.DefaultMaxAuctionDuration))

	// take coins from module account
	err := k.supplyKeeper.SendCoinsFromModuleToModule(ctx, seller, types.ModuleName, sdk.NewCoins(lot))
	if err != nil {
		return 0, err
	}
	// store the auction
	auctionID, err := k.storeNewAuction(ctx, auction) // TODO does this need to be a pointer to satisfy the interface?
	if err != nil {
		return 0, err
	}
	return auctionID, nil
}

// StartReverseAuction starts an auction where sellers compete by offering decreasing prices.
func (k Keeper) StartReverseAuction(ctx sdk.Context, buyer string, bid sdk.Coin, initialLot sdk.Coin) (types.ID, sdk.Error) {
	// create auction
	auction := types.NewReverseAuction(buyer, bid, initialLot, ctx.BlockTime().Add(types.DefaultMaxAuctionDuration))

	// This auction type mints coins at close. Need to check module account has minting privileges to avoid potential err in endblocker.
	macc := k.supplyKeeper.GetModuleAccount(ctx, buyer)
	if !macc.HasPermission(supply.Minter) { // TODO ideally don't want to import supply
		return 0, sdk.ErrInternal("module does not have minting permissions")
	}
	// store the auction
	auctionID, err := k.storeNewAuction(ctx, &auction)
	if err != nil {
		return 0, err
	}
	return auctionID, nil
}

// StartForwardReverseAuction starts an auction where bidders bid up to a maxBid, then switch to bidding down on price.
func (k Keeper) StartForwardReverseAuction(ctx sdk.Context, seller string, lot sdk.Coin, maxBid sdk.Coin, otherPerson sdk.AccAddress) (types.ID, sdk.Error) {
	// create auction
	auction := types.NewForwardReverseAuction(seller, lot, ctx.BlockTime().Add(types.DefaultMaxAuctionDuration), maxBid, otherPerson)

	// take coins from module account
	err := k.supplyKeeper.SendCoinsFromModuleToModule(ctx, seller, types.ModuleName, sdk.Coins{lot})
	if err != nil {
		return 0, err
	}
	// store the auction
	auctionID, err := k.storeNewAuction(ctx, &auction)
	if err != nil {
		return 0, err
	}
	return auctionID, nil
}

// PlaceBid places a bid on any auction.
func (k Keeper) PlaceBid(ctx sdk.Context, auctionID types.ID, bidder sdk.AccAddress, bid sdk.Coin, lot sdk.Coin) sdk.Error {

	// get auction from store
	auction, found := k.GetAuction(ctx, auctionID)
	if !found {
		return sdk.ErrInternal("auction doesn't exist")
	}

	// check end time
	if ctx.BlockTime().After(auction.GetEndTime()) {
		return sdk.ErrInternal("auction has closed")
	}

	var err sdk.Error
	var a types.Auction
	switch auc := auction.(type) {
	case types.ForwardAuction:
		a, err = k.PlaceBidForward(ctx, auc, bidder, bid)
		if err != nil {
			return err
		}
	case types.ReverseAuction:
		a, err = k.PlaceBidReverse(ctx, auc, bidder, lot)
		if err != nil {
			return err
		}
	case types.ForwardReverseAuction:
		a, err = k.PlaceBidForwardReverse(ctx, auc, bidder, bid, lot)
		if err != nil {
			return err
		}
	default:
		panic("unrecognized auction type")
	}

	// store updated auction
	k.SetAuction(ctx, a) // TODO maybe move into above funcs

	return nil
}

func (k Keeper) PlaceBidForward(ctx sdk.Context, a types.ForwardAuction, bidder sdk.AccAddress, bid sdk.Coin) (types.ForwardAuction, sdk.Error) {
	// Valid New Bid
	if bid.Denom != a.Bid.Denom {
		return a, sdk.ErrInternal("bid denom doesn't match auction")
	}
	if !a.Bid.IsLT(bid) { // TODO add minimum bid size
		return a, sdk.ErrInternal("bid not greater than last bid")
	}

	// Move Coins
	increment := bid.Sub(a.Bid)
	bidAmtToReturn := a.Bid
	if bidder.Equals(a.Bidder) { // catch edge case of someone updating their bid with a low balance
		bidAmtToReturn = sdk.NewInt64Coin(a.Bid.Denom, 0)
	}
	err := k.supplyKeeper.SendCoinsFromAccountToModule(ctx, bidder, types.ModuleName, sdk.NewCoins(bidAmtToReturn.Add(increment)))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, bidder, sdk.NewCoins(bidAmtToReturn))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToModule(ctx, types.ModuleName, a.Initiator, sdk.NewCoins(increment)) // increase in bid size is burned
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.BurnCoins(ctx, a.Initiator, sdk.NewCoins(increment))
	if err != nil {
		return a, err
	}

	// Update Auction
	a.Bidder = bidder
	a.Bid = bid
	// increment timeout
	a.EndTime = earliestTime(ctx.BlockTime().Add(types.DefaultMaxBidDuration), a.MaxEndTime) // TODO write a min func for time types

	return a, nil
}
func (k Keeper) PlaceBidForwardReverse(ctx sdk.Context, a types.ForwardReverseAuction, bidder sdk.AccAddress, bid sdk.Coin, lot sdk.Coin) (types.ForwardReverseAuction, sdk.Error) {
	// Validate New Bid // TODO min bid increments, make validation code less confusing
	if !a.Bid.IsEqual(a.MaxBid) {
		// Auction is in forward phase, a bid here can put the auction into forward or reverse phases
		if !a.Bid.IsLT(bid) {
			return a, sdk.ErrInternal("auction in forward phase, new bid not higher than last bid")
		}
		if a.MaxBid.IsLT(bid) {
			return a, sdk.ErrInternal("bid higher than max bid")
		}
		if lot.IsNegative() || a.Lot.IsLT(lot) {
			return a, sdk.ErrInternal("lot out of bounds")
		}
		if lot.IsLT(a.Lot) && !bid.IsEqual(a.MaxBid) {
			return a, sdk.ErrInternal("auction cannot enter reverse phase without bidding max bid")
		}
	} else {
		// Auction is in reverse phase, it can never leave reverse phase
		if !bid.IsEqual(a.MaxBid) {
			return a, sdk.ErrInternal("") // not necessary
		}
		if lot.IsNegative() {
			return a, sdk.ErrInternal("can't bid negative amount")
		}
		if !lot.IsLT(a.Lot) {
			return a, sdk.ErrInternal("auction in reverse phase, new bid not less than previous amount")
		}
	}

	// Move Coins
	bidIncrement := bid.Sub(a.Bid)
	bidAmtToReturn := a.Bid
	lotDecrement := a.Lot.Sub(lot)
	if bidder.Equals(a.Bidder) { // catch edge case of someone updating their bid with a low balance
		bidAmtToReturn = sdk.NewInt64Coin(a.Bid.Denom, 0)
	}
	err := k.supplyKeeper.SendCoinsFromAccountToModule(ctx, bidder, types.ModuleName, sdk.NewCoins(bidAmtToReturn.Add(bidIncrement)))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, bidder, sdk.NewCoins(bidAmtToReturn))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToModule(ctx, types.ModuleName, a.Initiator, sdk.NewCoins(bidIncrement))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, a.OtherPerson, sdk.NewCoins(lotDecrement))
	if err != nil {
		return a, err
	}

	// Update Auction
	a.Bidder = bidder
	a.Lot = lot
	a.Bid = bid
	// increment timeout
	a.EndTime = earliestTime(ctx.BlockTime().Add(types.DefaultMaxBidDuration), a.MaxEndTime)

	return types.ForwardReverseAuction{}, nil
}
func (k Keeper) PlaceBidReverse(ctx sdk.Context, a types.ReverseAuction, bidder sdk.AccAddress, lot sdk.Coin) (types.ReverseAuction, sdk.Error) {
	// Validate New Bid
	if lot.Denom != a.Lot.Denom {
		return a, sdk.ErrInternal("lot denom doesn't match auction")
	}
	if lot.IsNegative() {
		return a, sdk.ErrInternal("lot less than 0")
	}
	if !lot.IsLT(a.Lot) { // TODO add min bid decrements
		return a, sdk.ErrInternal("lot not smaller than last lot")
	}

	// Move Coins
	bidAmtToReturn := a.Bid
	if bidder.Equals(a.Bidder) { // catch edge case of someone updating their bid with a low balance
		bidAmtToReturn = sdk.NewInt64Coin(a.Bid.Denom, 0)
	}
	err := k.supplyKeeper.SendCoinsFromAccountToModule(ctx, bidder, types.ModuleName, sdk.NewCoins(bidAmtToReturn))
	if err != nil {
		return a, err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, bidder, sdk.NewCoins(bidAmtToReturn))
	if err != nil {
		return a, err
	}

	// Update Auction
	a.Bidder = bidder
	a.Lot = lot
	// increment timeout
	a.EndTime = earliestTime(ctx.BlockTime().Add(types.DefaultMaxBidDuration), a.MaxEndTime)

	return a, nil
}

// CloseAuction closes an auction and distributes funds to the highest bidder.
func (k Keeper) CloseAuction(ctx sdk.Context, auctionID types.ID) sdk.Error {

	// get the auction from the store
	auction, found := k.GetAuction(ctx, auctionID)
	if !found {
		return sdk.ErrInternal("auction doesn't exist")
	}
	// error if auction has not reached the end time
	if ctx.BlockTime().Before(auction.GetEndTime()) {
		return sdk.ErrInternal(fmt.Sprintf("auction can't be closed as curent block time (%v) is under auction end time (%v)", ctx.BlockTime(), auction.GetEndTime()))
	}

	// payout to the last bidder
	var err sdk.Error
	switch auc := auction.(type) {
	case types.ForwardAuction, types.ForwardReverseAuction:
		err = k.PayoutAuctionLot(ctx, auc)
		if err != nil {
			return err
		}
	case types.ReverseAuction:
		err = k.MintAndPayoutAuctionLot(ctx, auc)
		if err != nil {
			return err
		}
	default:
		panic("unrecognized auction type")
	}

	// Delete auction from store (and queue)
	k.DeleteAuction(ctx, auctionID)

	return nil
}
func (k Keeper) MintAndPayoutAuctionLot(ctx sdk.Context, a types.ReverseAuction) sdk.Error {
	err := k.supplyKeeper.MintCoins(ctx, a.Initiator, sdk.NewCoins(a.Lot))
	if err != nil {
		return err
	}
	err = k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, a.Initiator, a.Bidder, sdk.NewCoins(a.Lot))
	if err != nil {
		return err
	}
	return nil
}
func (k Keeper) PayoutAuctionLot(ctx sdk.Context, a types.Auction) sdk.Error {
	// TODO this function is responsible for the addition of GetBidder and GetLot to auction interface. Could be split in to two funcs that operate on concrete auction types
	err := k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, a.GetBidder(), sdk.NewCoins(a.GetLot()))
	if err != nil {
		return err
	}
	return nil
}

// FIXME stand in func for compiler
func earliestTime(t1, t2 time.Time) time.Time {
	return t1
}