package sealing

import (
	"context"
	"sort"
	"time"

	"golang.org/x/xerrors"

	"github.com/ipfs/go-cid"

	"github.com/filecoin-project/go-commp-utils/zerocomm"
	"github.com/filecoin-project/go-padreader"
	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/go-state-types/big"
	"github.com/filecoin-project/go-statemachine"
	"github.com/filecoin-project/specs-storage/storage"

	"github.com/filecoin-project/lotus/api"
	"github.com/filecoin-project/lotus/build"
	"github.com/filecoin-project/lotus/chain/actors/policy"
	"github.com/filecoin-project/lotus/chain/types"
	sectorstorage "github.com/filecoin-project/lotus/extern/sector-storage"
	"github.com/filecoin-project/lotus/extern/sector-storage/ffiwrapper"
	"github.com/filecoin-project/lotus/extern/storage-sealing/sealiface"
)

func (m *Sealing) handleWaitDeals(ctx statemachine.Context, sector SectorInfo) error {
	var used abi.UnpaddedPieceSize
	for _, piece := range sector.Pieces {
		used += piece.Piece.Size.Unpadded()
	}

	m.inputLk.Lock()

	if m.nextDealSector != nil && *m.nextDealSector == sector.SectorNumber {
		m.nextDealSector = nil
	}

	sid := m.minerSectorID(sector.SectorNumber)

	if len(m.assignedPieces[sid]) > 0 {
		m.inputLk.Unlock()
		// got assigned more pieces in the AddPiece state
		return ctx.Send(SectorAddPiece{})
	}

	started, err := m.maybeStartSealing(ctx, sector, used)
	if err != nil || started {
		delete(m.openSectors, m.minerSectorID(sector.SectorNumber))

		m.inputLk.Unlock()

		return err
	}

	if _, has := m.openSectors[sid]; !has {
		m.openSectors[sid] = &openSector{
			used: used,
			maybeAccept: func(cid cid.Cid) error {
				// todo check deal start deadline (configurable)
				m.assignedPieces[sid] = append(m.assignedPieces[sid], cid)

				return ctx.Send(SectorAddPiece{})
			},
			number:   sector.SectorNumber,
			ccUpdate: sector.CCUpdate,
		}
	} else {
		// make sure we're only accounting for pieces which were correctly added
		// (note that m.assignedPieces[sid] will always be empty here)
		m.openSectors[sid].used = used
	}

	go func() {
		defer m.inputLk.Unlock()
		if err := m.updateInput(ctx.Context(), sector.SectorType); err != nil {
			log.Errorf("%+v", err)
		}
	}()

	return nil
}

func (m *Sealing) maybeStartSealing(ctx statemachine.Context, sector SectorInfo, used abi.UnpaddedPieceSize) (bool, error) {
	now := time.Now()
	st := m.sectorTimers[m.minerSectorID(sector.SectorNumber)]
	if st != nil {
		if !st.Stop() { // timer expired, SectorStartPacking was/is being sent
			// we send another SectorStartPacking in case one was sent in the handleAddPiece state
			log.Infow("starting to seal deal sector", "sector", sector.SectorNumber, "trigger", "wait-timeout")
			return true, ctx.Send(SectorStartPacking{})
		}
	}

	ssize, err := sector.SectorType.SectorSize()
	if err != nil {
		return false, xerrors.Errorf("getting sector size")
	}

	maxDeals, err := getDealPerSectorLimit(ssize)
	if err != nil {
		return false, xerrors.Errorf("getting per-sector deal limit: %w", err)
	}

	if len(sector.dealIDs()) >= maxDeals {
		// can't accept more deals
		log.Infow("starting to seal deal sector", "sector", sector.SectorNumber, "trigger", "maxdeals")
		return true, ctx.Send(SectorStartPacking{})
	}

	if used.Padded() == abi.PaddedPieceSize(ssize) {
		// sector full
		log.Infow("starting to seal deal sector", "sector", sector.SectorNumber, "trigger", "filled")
		return true, ctx.Send(SectorStartPacking{})
	}

	if sector.CreationTime != 0 {
		cfg, err := m.getConfig()
		if err != nil {
			return false, xerrors.Errorf("getting storage config: %w", err)
		}

		sealTime := time.Unix(sector.CreationTime, 0).Add(cfg.WaitDealsDelay)

		// check deal age, start sealing when the deal closest to starting is within slack time
		_, current, err := m.Api.ChainHead(ctx.Context())
		blockTime := time.Second * time.Duration(build.BlockDelaySecs)
		if err != nil {
			return false, xerrors.Errorf("API error getting head: %w", err)
		}
		for _, piece := range sector.Pieces {
			if piece.DealInfo == nil {
				continue
			}
			dealSafeSealEpoch := piece.DealInfo.DealProposal.StartEpoch - cfg.StartEpochSealingBuffer
			dealSafeSealTime := time.Now().Add(time.Duration(dealSafeSealEpoch-current) * blockTime)
			if dealSafeSealTime.Before(sealTime) {
				sealTime = dealSafeSealTime
			}
		}

		if now.After(sealTime) {
			log.Infow("starting to seal deal sector", "sector", sector.SectorNumber, "trigger", "wait-timeout")
			return true, ctx.Send(SectorStartPacking{})
		}

		m.sectorTimers[m.minerSectorID(sector.SectorNumber)] = time.AfterFunc(sealTime.Sub(now), func() {
			log.Infow("starting to seal deal sector", "sector", sector.SectorNumber, "trigger", "wait-timer")

			if err := ctx.Send(SectorStartPacking{}); err != nil {
				log.Errorw("sending SectorStartPacking event failed", "sector", sector.SectorNumber, "error", err)
			}
		})
	}

	return false, nil
}

func (m *Sealing) handleAddPiece(ctx statemachine.Context, sector SectorInfo) error {
	ssize, err := sector.SectorType.SectorSize()
	if err != nil {
		return err
	}

	res := SectorPieceAdded{}

	m.inputLk.Lock()

	pending, ok := m.assignedPieces[m.minerSectorID(sector.SectorNumber)]
	if ok {
		delete(m.assignedPieces, m.minerSectorID(sector.SectorNumber))
	}
	m.inputLk.Unlock()
	if !ok {
		// nothing to do here (might happen after a restart in AddPiece)
		return ctx.Send(res)
	}

	var offset abi.UnpaddedPieceSize
	pieceSizes := make([]abi.UnpaddedPieceSize, len(sector.Pieces))
	for i, p := range sector.Pieces {
		pieceSizes[i] = p.Piece.Size.Unpadded()
		offset += p.Piece.Size.Unpadded()
	}

	maxDeals, err := getDealPerSectorLimit(ssize)
	if err != nil {
		return xerrors.Errorf("getting per-sector deal limit: %w", err)
	}

	for i, piece := range pending {
		m.inputLk.Lock()
		deal, ok := m.pendingPieces[piece]
		m.inputLk.Unlock()
		if !ok {
			return xerrors.Errorf("piece %s assigned to sector %d not found", piece, sector.SectorNumber)
		}

		if len(sector.dealIDs())+(i+1) > maxDeals {
			// todo: this is rather unlikely to happen, but in case it does, return the deal to waiting queue instead of failing it
			deal.accepted(sector.SectorNumber, offset, xerrors.Errorf("too many deals assigned to sector %d, dropping deal", sector.SectorNumber))
			continue
		}

		pads, padLength := ffiwrapper.GetRequiredPadding(offset.Padded(), deal.size.Padded())

		if offset.Padded()+padLength+deal.size.Padded() > abi.PaddedPieceSize(ssize) {
			// todo: this is rather unlikely to happen, but in case it does, return the deal to waiting queue instead of failing it
			deal.accepted(sector.SectorNumber, offset, xerrors.Errorf("piece %s assigned to sector %d with not enough space", piece, sector.SectorNumber))
			continue
		}

		offset += padLength.Unpadded()

		for _, p := range pads {
			expectCid := zerocomm.ZeroPieceCommitment(p.Unpadded())

			ppi, err := m.sealer.AddPiece(sectorstorage.WithPriority(ctx.Context(), DealSectorPriority),
				m.minerSector(sector.SectorType, sector.SectorNumber),
				pieceSizes,
				p.Unpadded(),
				NewNullReader(p.Unpadded()))
			if err != nil {
				err = xerrors.Errorf("writing padding piece: %w", err)
				deal.accepted(sector.SectorNumber, offset, err)
				return ctx.Send(SectorAddPieceFailed{err})
			}
			if !ppi.PieceCID.Equals(expectCid) {
				err = xerrors.Errorf("got unexpected padding piece CID: expected:%s, got:%s", expectCid, ppi.PieceCID)
				deal.accepted(sector.SectorNumber, offset, err)
				return ctx.Send(SectorAddPieceFailed{err})
			}

			pieceSizes = append(pieceSizes, p.Unpadded())
			res.NewPieces = append(res.NewPieces, Piece{
				Piece: ppi,
			})
		}

		ppi, err := m.sealer.AddPiece(sectorstorage.WithPriority(ctx.Context(), DealSectorPriority),
			m.minerSector(sector.SectorType, sector.SectorNumber),
			pieceSizes,
			deal.size,
			deal.data)
		if err != nil {
			err = xerrors.Errorf("writing piece: %w", err)
			deal.accepted(sector.SectorNumber, offset, err)
			return ctx.Send(SectorAddPieceFailed{err})
		}
		if !ppi.PieceCID.Equals(deal.deal.DealProposal.PieceCID) {
			err = xerrors.Errorf("got unexpected piece CID: expected:%s, got:%s", deal.deal.DealProposal.PieceCID, ppi.PieceCID)
			deal.accepted(sector.SectorNumber, offset, err)
			return ctx.Send(SectorAddPieceFailed{err})
		}

		log.Infow("deal added to a sector", "deal", deal.deal.DealID, "sector", sector.SectorNumber, "piece", ppi.PieceCID)

		deal.accepted(sector.SectorNumber, offset, nil)

		offset += deal.size
		pieceSizes = append(pieceSizes, deal.size)

		res.NewPieces = append(res.NewPieces, Piece{
			Piece:    ppi,
			DealInfo: &deal.deal,
		})
	}

	return ctx.Send(res)
}

func (m *Sealing) handleAddPieceFailed(ctx statemachine.Context, sector SectorInfo) error {
	return ctx.Send(SectorRetryWaitDeals{})
}

func (m *Sealing) SectorAddPieceToAny(ctx context.Context, size abi.UnpaddedPieceSize, data storage.Data, deal api.PieceDealInfo) (api.SectorOffset, error) {
	log.Infof("Adding piece for deal %d (publish msg: %s)", deal.DealID, deal.PublishCid)
	if (padreader.PaddedSize(uint64(size))) != size {
		return api.SectorOffset{}, xerrors.Errorf("cannot allocate unpadded piece")
	}

	sp, err := m.currentSealProof(ctx)
	if err != nil {
		return api.SectorOffset{}, xerrors.Errorf("getting current seal proof type: %w", err)
	}

	ssize, err := sp.SectorSize()
	if err != nil {
		return api.SectorOffset{}, err
	}

	if size > abi.PaddedPieceSize(ssize).Unpadded() {
		return api.SectorOffset{}, xerrors.Errorf("piece cannot fit into a sector")
	}

	if _, err := deal.DealProposal.Cid(); err != nil {
		return api.SectorOffset{}, xerrors.Errorf("getting proposal CID: %w", err)
	}

	cfg, err := m.getConfig()
	if err != nil {
		return api.SectorOffset{}, xerrors.Errorf("getting config: %w", err)
	}

	_, head, err := m.Api.ChainHead(ctx)
	if err != nil {
		return api.SectorOffset{}, xerrors.Errorf("couldnt get chain head: %w", err)
	}
	if head+cfg.StartEpochSealingBuffer > deal.DealProposal.StartEpoch {
		return api.SectorOffset{}, xerrors.Errorf(
			"cannot add piece for deal with piece CID %s: current epoch %d has passed deal proposal start epoch %d",
			deal.DealProposal.PieceCID, head, deal.DealProposal.StartEpoch)
	}

	m.inputLk.Lock()
	if pp, exist := m.pendingPieces[proposalCID(deal)]; exist {
		m.inputLk.Unlock()

		// we already have a pre-existing add piece call for this deal, let's wait for it to finish and see if it's successful
		res, err := waitAddPieceResp(ctx, pp)
		if err != nil {
			return api.SectorOffset{}, err
		}
		if res.err == nil {
			// all good, return the response
			return api.SectorOffset{Sector: res.sn, Offset: res.offset.Padded()}, res.err
		}
		// if there was an error waiting for a pre-existing add piece call, let's retry
		m.inputLk.Lock()
	}

	// addPendingPiece takes over m.inputLk
	pp := m.addPendingPiece(ctx, size, data, deal, sp)

	res, err := waitAddPieceResp(ctx, pp)
	if err != nil {
		return api.SectorOffset{}, err
	}
	return api.SectorOffset{Sector: res.sn, Offset: res.offset.Padded()}, res.err
}

// called with m.inputLk; transfers the lock to another goroutine!
func (m *Sealing) addPendingPiece(ctx context.Context, size abi.UnpaddedPieceSize, data storage.Data, deal api.PieceDealInfo, sp abi.RegisteredSealProof) *pendingPiece {
	doneCh := make(chan struct{})
	pp := &pendingPiece{
		doneCh:   doneCh,
		size:     size,
		deal:     deal,
		data:     data,
		assigned: false,
	}
	pp.accepted = func(sn abi.SectorNumber, offset abi.UnpaddedPieceSize, err error) {
		pp.resp = &pieceAcceptResp{sn, offset, err}
		close(pp.doneCh)
	}

	m.pendingPieces[proposalCID(deal)] = pp
	go func() {
		defer m.inputLk.Unlock()
		if err := m.updateInput(ctx, sp); err != nil {
			log.Errorf("%+v", err)
		}
	}()

	return pp
}

func waitAddPieceResp(ctx context.Context, pp *pendingPiece) (*pieceAcceptResp, error) {
	select {
	case <-pp.doneCh:
		res := pp.resp
		return res, nil
	case <-ctx.Done():
		return nil, ctx.Err()
	}
}

func (m *Sealing) MatchPendingPiecesToOpenSectors(ctx context.Context) error {
	sp, err := m.currentSealProof(ctx)
	if err != nil {
		return xerrors.Errorf("failed to get current seal proof: %w", err)
	}
	log.Debug("pieces to sector matching waiting for lock")
	m.inputLk.Lock()
	defer m.inputLk.Unlock()
	return m.updateInput(ctx, sp)
}

type expFn func(sn abi.SectorNumber) (abi.ChainEpoch, abi.TokenAmount, error)

// called with m.inputLk
func (m *Sealing) updateInput(ctx context.Context, sp abi.RegisteredSealProof) error {
	memo := make(map[abi.SectorNumber]struct {
		e abi.ChainEpoch
		p abi.TokenAmount
	})
	expF := func(sn abi.SectorNumber) (abi.ChainEpoch, abi.TokenAmount, error) {
		if e, ok := memo[sn]; ok {
			return e.e, e.p, nil
		}
		onChainInfo, err := m.Api.StateSectorGetInfo(ctx, m.maddr, sn, TipSetToken{})
		if err != nil {
			return 0, big.Zero(), err
		}
		memo[sn] = struct {
			e abi.ChainEpoch
			p abi.TokenAmount
		}{e: onChainInfo.Expiration, p: onChainInfo.InitialPledge}
		return onChainInfo.Expiration, onChainInfo.InitialPledge, nil
	}

	ssize, err := sp.SectorSize()
	if err != nil {
		return err
	}

	type match struct {
		sector abi.SectorID
		deal   cid.Cid

		size    abi.UnpaddedPieceSize
		padding abi.UnpaddedPieceSize
	}

	var matches []match
	toAssign := map[cid.Cid]struct{}{} // used to maybe create new sectors

	// todo: this is distinctly O(n^2), may need to be optimized for tiny deals and large scale miners
	//  (unlikely to be a problem now)
	for proposalCid, piece := range m.pendingPieces {
		if piece.assigned {
			continue // already assigned to a sector, skip
		}

		toAssign[proposalCid] = struct{}{}

		for id, sector := range m.openSectors {
			avail := abi.PaddedPieceSize(ssize).Unpadded() - sector.used
			// check that sector lifetime is long enough to fit deal using latest expiration from on chain

			ok, err := sector.dealFitsInLifetime(piece.deal.DealProposal.EndEpoch, expF)
			if err != nil {
				log.Errorf("failed to check expiration for cc Update sector %d", sector.number)
				continue
			}
			if !ok {
				exp, _, _ := expF(sector.number)
				log.Infof("CC update sector %d cannot fit deal, expiration %d before deal end epoch %d", id, exp, piece.deal.DealProposal.EndEpoch)
				continue
			}

			if piece.size <= avail { // (note: if we have enough space for the piece, we also have enough space for inter-piece padding)
				matches = append(matches, match{
					sector: id,
					deal:   proposalCid,

					size:    piece.size,
					padding: avail % piece.size,
				})
			}
		}
	}
	sort.Slice(matches, func(i, j int) bool {
		if matches[i].padding != matches[j].padding { // less padding is better
			return matches[i].padding < matches[j].padding
		}

		if matches[i].size != matches[j].size { // larger pieces are better
			return matches[i].size < matches[j].size
		}

		return matches[i].sector.Number < matches[j].sector.Number // prefer older sectors
	})

	var assigned int
	for _, mt := range matches {
		if m.pendingPieces[mt.deal].assigned {
			assigned++
			continue
		}

		if _, found := m.openSectors[mt.sector]; !found {
			continue
		}

		avail := abi.PaddedPieceSize(ssize).Unpadded() - m.openSectors[mt.sector].used

		if mt.size > avail {
			continue
		}

		err := m.openSectors[mt.sector].maybeAccept(mt.deal)
		if err != nil {
			m.pendingPieces[mt.deal].accepted(mt.sector.Number, 0, err) // non-error case in handleAddPiece
		}

		m.openSectors[mt.sector].used += mt.padding + mt.size

		m.pendingPieces[mt.deal].assigned = true
		delete(toAssign, mt.deal)

		if err != nil {
			log.Errorf("sector %d rejected deal %s: %+v", mt.sector, mt.deal, err)
			continue
		}
	}

	if len(toAssign) > 0 {
		log.Errorf("we are trying to create a new sector with open sectors %v", m.openSectors)
		if err := m.tryGetDealSector(ctx, sp, expF); err != nil {
			log.Errorw("Failed to create a new sector for deals", "error", err)
		}
	}

	return nil
}

func (m *Sealing) calcTargetExpiration(ctx context.Context, ssize abi.SectorSize) (minTarget, target abi.ChainEpoch, err error) {
	var candidates []*pendingPiece

	for _, piece := range m.pendingPieces {
		if piece.assigned {
			continue // already assigned to a sector, skip
		}
		candidates = append(candidates, piece)
	}

	// earliest expiration first
	sort.Slice(candidates, func(i, j int) bool {
		return candidates[i].deal.DealProposal.EndEpoch < candidates[j].deal.DealProposal.EndEpoch
	})

	var totalBytes uint64
	for _, candidate := range candidates {
		totalBytes += uint64(candidate.size)

		if totalBytes >= uint64(abi.PaddedPieceSize(ssize).Unpadded()) {
			return candidates[0].deal.DealProposal.EndEpoch, candidate.deal.DealProposal.EndEpoch, nil
		}
	}

	_, curEpoch, err := m.Api.ChainHead(ctx)
	if err != nil {
		return 0, 0, xerrors.Errorf("getting current epoch: %w", err)
	}

	minDur, maxDur := policy.DealDurationBounds(0)

	return curEpoch + minDur, curEpoch + maxDur, nil
}

func (m *Sealing) tryGetUpgradeSector(ctx context.Context, sp abi.RegisteredSealProof, ef expFn) (bool, error) {
	if len(m.available) == 0 {
		return false, nil
	}

	ssize, err := sp.SectorSize()
	if err != nil {
		return false, xerrors.Errorf("getting sector size: %w", err)
	}
	minExpiration, targetExpiration, err := m.calcTargetExpiration(ctx, ssize)
	if err != nil {
		return false, xerrors.Errorf("calculating min target expiration: %w", err)
	}

	var candidate abi.SectorID
	var bestExpiration abi.ChainEpoch
	bestPledge := types.TotalFilecoinInt

	for s := range m.available {
		expiration, pledge, err := ef(s.Number)
		if err != nil {
			log.Errorw("checking sector expiration", "error", err)
			continue
		}

		slowChecks := func(sid abi.SectorNumber) bool {
			active, err := m.sectorActive(ctx, TipSetToken{}, sid)
			if err != nil {
				log.Errorw("checking sector active", "error", err)
				return false
			}
			if !active {
				log.Debugw("skipping available sector", "reason", "not active")
				return false
			}
			return true
		}

		// if best is below target, we want larger expirations
		// if best is above target, we want lower pledge, but only if still above target

		if bestExpiration < targetExpiration {
			if expiration > bestExpiration && slowChecks(s.Number) {
				bestExpiration = expiration
				bestPledge = pledge
				candidate = s
			}
			continue
		}

		if expiration >= targetExpiration && pledge.LessThan(bestPledge) && slowChecks(s.Number) {
			bestExpiration = expiration
			bestPledge = pledge
			candidate = s
		}
	}

	if bestExpiration < minExpiration {
		log.Infow("Not upgrading any sectors", "available", len(m.available), "pieces", len(m.pendingPieces), "bestExp", bestExpiration, "target", targetExpiration, "min", minExpiration, "candidate", candidate)
		// didn't find a good sector / no sectors were available
		return false, nil
	}

	log.Infow("Upgrading sector", "number", candidate.Number, "type", "deal", "proofType", sp, "expiration", bestExpiration, "pledge", types.FIL(bestPledge))
	delete(m.available, candidate)
	m.nextDealSector = &candidate.Number
	return true, m.sectors.Send(uint64(candidate.Number), SectorStartCCUpdate{})
}

func (m *Sealing) tryGetDealSector(ctx context.Context, sp abi.RegisteredSealProof, ef expFn) error {
	m.startupWait.Wait()

	if m.nextDealSector != nil {
		return nil // new sector is being created right now
	}

	cfg, err := m.getConfig()
	if err != nil {
		return xerrors.Errorf("getting storage config: %w", err)
	}

	if cfg.MaxSealingSectorsForDeals > 0 && m.stats.curSealing() >= cfg.MaxSealingSectorsForDeals {
		return nil
	}

	if cfg.MaxWaitDealsSectors > 0 && m.stats.curStaging() >= cfg.MaxWaitDealsSectors {
		return nil
	}

	got, err := m.tryGetUpgradeSector(ctx, sp, ef)
	if err != nil {
		return err
	}
	if got {
		return nil
	}

	if !cfg.MakeNewSectorForDeals {
		return nil
	}

	sid, err := m.createSector(ctx, cfg, sp)
	if err != nil {
		return err
	}

	m.nextDealSector = &sid

	log.Infow("Creating sector", "number", sid, "type", "deal", "proofType", sp)
	return m.sectors.Send(uint64(sid), SectorStart{
		ID:         sid,
		SectorType: sp,
	})
}

// call with m.inputLk
func (m *Sealing) createSector(ctx context.Context, cfg sealiface.Config, sp abi.RegisteredSealProof) (abi.SectorNumber, error) {
	// Now actually create a new sector

	sid, err := m.sc.Next()
	if err != nil {
		return 0, xerrors.Errorf("getting sector number: %w", err)
	}

	err = m.sealer.NewSector(ctx, m.minerSector(sp, sid))
	if err != nil {
		return 0, xerrors.Errorf("initializing sector: %w", err)
	}

	// update stats early, fsm planner would do that async
	m.stats.updateSector(ctx, cfg, m.minerSectorID(sid), UndefinedSectorState)

	return sid, nil
}

func (m *Sealing) StartPacking(sid abi.SectorNumber) error {
	m.startupWait.Wait()

	log.Infow("starting to seal deal sector", "sector", sid, "trigger", "user")
	return m.sectors.Send(uint64(sid), SectorStartPacking{})
}

func (m *Sealing) AbortUpgrade(sid abi.SectorNumber) error {
	m.startupWait.Wait()

	m.inputLk.Lock()
	// always do this early
	delete(m.available, m.minerSectorID(sid))
	m.inputLk.Unlock()

	log.Infow("aborting upgrade of sector", "sector", sid, "trigger", "user")
	return m.sectors.Send(uint64(sid), SectorAbortUpgrade{xerrors.New("triggered by user")})
}

func proposalCID(deal api.PieceDealInfo) cid.Cid {
	pc, err := deal.DealProposal.Cid()
	if err != nil {
		log.Errorf("DealProposal.Cid error: %+v", err)
		return cid.Undef
	}

	return pc
}