package storage

import (
	"context"

	"golang.org/x/xerrors"

	"github.com/filecoin-project/go-address"
	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/go-state-types/big"

	"github.com/filecoin-project/lotus/chain/actors/builtin/miner"
	"github.com/filecoin-project/lotus/chain/types"
)

type AddrUse int

const (
	PreCommitAddr AddrUse = iota
	CommitAddr
	PoStAddr
)

type addrSelectApi interface {
	WalletBalance(context.Context, address.Address) (types.BigInt, error)
	WalletHas(context.Context, address.Address) (bool, error)

	StateAccountKey(context.Context, address.Address, types.TipSetKey) (address.Address, error)
}

func AddressFor(ctx context.Context, a addrSelectApi, mi miner.MinerInfo, use AddrUse, goodFunds, minFunds abi.TokenAmount) (address.Address, abi.TokenAmount, error) {
	switch use {
	case PreCommitAddr, CommitAddr:
		// always use worker, at least for now
		return mi.Worker, big.Zero(), nil
	}

	leastBad := mi.Worker
	bestAvail := minFunds

	for _, addr := range append(mi.ControlAddresses, mi.Owner, mi.Worker) {
		if maybeUseAddress(ctx, a, addr, goodFunds, &leastBad, &bestAvail) {
			return leastBad, bestAvail, nil
		}
	}

	if bestAvail.GreaterThan(minFunds) {
		log.Warnw("No address had enough funds to for full PoSt message Fee, selecting least bad address", "address", leastBad, "balance", types.FIL(bestAvail), "optimalFunds", types.FIL(goodFunds), "minFunds", types.FIL(minFunds))

		return leastBad, bestAvail, nil
	}

	// This most likely won't work, but can't hurt to try

	workerBalance, err := a.WalletBalance(ctx, mi.Worker)
	if err != nil {
		return address.Undef, big.Zero(), xerrors.Errorf("checking owner balance: %w", err)
	}

	log.Warnw("No address had enough funds to for minimum PoSt message Fee, selecting worker address as a fallback", "address", mi.Worker, "balance", types.FIL(workerBalance), "optimalFunds", types.FIL(goodFunds), "minFunds", types.FIL(minFunds))
	return mi.Worker, workerBalance, nil
}

func maybeUseAddress(ctx context.Context, a addrSelectApi, addr address.Address, goodFunds abi.TokenAmount, leastBad *address.Address, bestAvail *abi.TokenAmount) bool {
	b, err := a.WalletBalance(ctx, addr)
	if err != nil {
		log.Errorw("checking control address balance", "addr", addr, "error", err)
		return false
	}

	if b.GreaterThanEqual(goodFunds) {
		k, err := a.StateAccountKey(ctx, addr, types.EmptyTSK)
		if err != nil {
			log.Errorw("getting account key", "error", err)
			return false
		}

		have, err := a.WalletHas(ctx, k)
		if err != nil {
			log.Errorw("failed to check control address", "addr", addr, "error", err)
			return false
		}

		if !have {
			log.Errorw("don't have key", "key", k)
			return false
		}

		*leastBad = addr
		*bestAvail = b
		return true
	}

	if b.GreaterThan(*bestAvail) {
		*leastBad = addr
		*bestAvail = b
	}

	log.Warnw("address didn't have enough funds for window post message", "address", addr, "required", types.FIL(goodFunds), "balance", types.FIL(b))
	return false
}