package seal

import (
	"bytes"
	"context"

	"github.com/ipfs/go-cid"
	"golang.org/x/xerrors"

	"github.com/filecoin-project/go-address"
	"github.com/filecoin-project/go-commp-utils/nonffi"
	"github.com/filecoin-project/go-commp-utils/zerocomm"
	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/go-state-types/crypto"

	"github.com/filecoin-project/lotus/build"
	"github.com/filecoin-project/lotus/chain/actors/policy"
	"github.com/filecoin-project/lotus/chain/types"
	"github.com/filecoin-project/lotus/curiosrc/ffi"
	"github.com/filecoin-project/lotus/lib/harmony/harmonydb"
	"github.com/filecoin-project/lotus/lib/harmony/harmonytask"
	"github.com/filecoin-project/lotus/lib/harmony/resources"
	"github.com/filecoin-project/lotus/storage/sealer/storiface"
)

var isDevnet = build.BlockDelaySecs < 30

type SDRAPI interface {
	ChainHead(context.Context) (*types.TipSet, error)
	StateGetRandomnessFromTickets(context.Context, crypto.DomainSeparationTag, abi.ChainEpoch, []byte, types.TipSetKey) (abi.Randomness, error)
}

type SDRTask struct {
	api SDRAPI
	db  *harmonydb.DB
	sp  *SealPoller

	sc *ffi.SealCalls

	max int
}

func NewSDRTask(api SDRAPI, db *harmonydb.DB, sp *SealPoller, sc *ffi.SealCalls, maxSDR int) *SDRTask {
	return &SDRTask{
		api: api,
		db:  db,
		sp:  sp,
		sc:  sc,
		max: maxSDR,
	}
}

func (s *SDRTask) Do(taskID harmonytask.TaskID, stillOwned func() bool) (done bool, err error) {
	ctx := context.Background()

	var sectorParamsArr []struct {
		SpID         int64                   `db:"sp_id"`
		SectorNumber int64                   `db:"sector_number"`
		RegSealProof abi.RegisteredSealProof `db:"reg_seal_proof"`
	}

	err = s.db.Select(ctx, &sectorParamsArr, `
		SELECT sp_id, sector_number, reg_seal_proof
		FROM sectors_sdr_pipeline
		WHERE task_id_sdr = $1`, taskID)
	if err != nil {
		return false, xerrors.Errorf("getting sector params: %w", err)
	}

	if len(sectorParamsArr) != 1 {
		return false, xerrors.Errorf("expected 1 sector params, got %d", len(sectorParamsArr))
	}
	sectorParams := sectorParamsArr[0]

	var pieces []struct {
		PieceIndex int64  `db:"piece_index"`
		PieceCID   string `db:"piece_cid"`
		PieceSize  int64  `db:"piece_size"`
	}

	err = s.db.Select(ctx, &pieces, `
		SELECT piece_index, piece_cid, piece_size
		FROM sectors_sdr_initial_pieces
		WHERE sp_id = $1 AND sector_number = $2 ORDER BY piece_index ASC`, sectorParams.SpID, sectorParams.SectorNumber)
	if err != nil {
		return false, xerrors.Errorf("getting pieces: %w", err)
	}

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

	var commd cid.Cid

	if len(pieces) > 0 {
		pieceInfos := make([]abi.PieceInfo, len(pieces))
		for i, p := range pieces {
			c, err := cid.Parse(p.PieceCID)
			if err != nil {
				return false, xerrors.Errorf("parsing piece cid: %w", err)
			}

			pieceInfos[i] = abi.PieceInfo{
				Size:     abi.PaddedPieceSize(p.PieceSize),
				PieceCID: c,
			}
		}

		commd, err = nonffi.GenerateUnsealedCID(sectorParams.RegSealProof, pieceInfos)
		if err != nil {
			return false, xerrors.Errorf("computing CommD: %w", err)
		}
	} else {
		commd = zerocomm.ZeroPieceCommitment(abi.PaddedPieceSize(ssize).Unpadded())
	}

	sref := storiface.SectorRef{
		ID: abi.SectorID{
			Miner:  abi.ActorID(sectorParams.SpID),
			Number: abi.SectorNumber(sectorParams.SectorNumber),
		},
		ProofType: sectorParams.RegSealProof,
	}

	// get ticket
	maddr, err := address.NewIDAddress(uint64(sectorParams.SpID))
	if err != nil {
		return false, xerrors.Errorf("getting miner address: %w", err)
	}

	// FAIL: api may be down
	// FAIL-RESP: rely on harmony retry
	ticket, ticketEpoch, err := s.getTicket(ctx, maddr)
	if err != nil {
		return false, xerrors.Errorf("getting ticket: %w", err)
	}

	// do the SDR!!

	// FAIL: storage may not have enough space
	// FAIL-RESP: rely on harmony retry

	// LATEFAIL: compute error in sdr
	// LATEFAIL-RESP: Check in Trees task should catch this; Will retry computing
	//                Trees; After one retry, it should return the sector to the
	// 			      SDR stage; max number of retries should be configurable

	err = s.sc.GenerateSDR(ctx, taskID, sref, ticket, commd)
	if err != nil {
		return false, xerrors.Errorf("generating sdr: %w", err)
	}

	// store success!
	n, err := s.db.Exec(ctx, `UPDATE sectors_sdr_pipeline
		SET after_sdr = true, ticket_epoch = $3, ticket_value = $4
		WHERE sp_id = $1 AND sector_number = $2`,
		sectorParams.SpID, sectorParams.SectorNumber, ticketEpoch, []byte(ticket))
	if err != nil {
		return false, xerrors.Errorf("store sdr success: updating pipeline: %w", err)
	}
	if n != 1 {
		return false, xerrors.Errorf("store sdr success: updated %d rows", n)
	}

	return true, nil
}

func (s *SDRTask) getTicket(ctx context.Context, maddr address.Address) (abi.SealRandomness, abi.ChainEpoch, error) {
	ts, err := s.api.ChainHead(ctx)
	if err != nil {
		return nil, 0, xerrors.Errorf("getting chain head: %w", err)
	}

	ticketEpoch := ts.Height() - policy.SealRandomnessLookback
	buf := new(bytes.Buffer)
	if err := maddr.MarshalCBOR(buf); err != nil {
		return nil, 0, xerrors.Errorf("marshaling miner address: %w", err)
	}

	rand, err := s.api.StateGetRandomnessFromTickets(ctx, crypto.DomainSeparationTag_SealRandomness, ticketEpoch, buf.Bytes(), ts.Key())
	if err != nil {
		return nil, 0, xerrors.Errorf("getting randomness from tickets: %w", err)
	}

	return abi.SealRandomness(rand), ticketEpoch, nil
}

func (s *SDRTask) CanAccept(ids []harmonytask.TaskID, engine *harmonytask.TaskEngine) (*harmonytask.TaskID, error) {
	// todo check storage (reserve too?)

	id := ids[0]
	return &id, nil
}

func (s *SDRTask) TypeDetails() harmonytask.TaskTypeDetails {
	ssize := abi.SectorSize(32 << 30) // todo task details needs taskID to get correct sector size
	if isDevnet {
		ssize = abi.SectorSize(2 << 20)
	}

	res := harmonytask.TaskTypeDetails{
		Max:  s.max,
		Name: "SDR",
		Cost: resources.Resources{ // todo offset for prefetch?
			Cpu:     4, // todo multicore sdr
			Gpu:     0,
			Ram:     54 << 30,
			Storage: s.sc.Storage(s.taskToSector, storiface.FTCache, storiface.FTNone, ssize, storiface.PathSealing),
		},
		MaxFailures: 2,
		Follows:     nil,
	}

	if isDevnet {
		res.Cost.Ram = 1 << 30
	}

	return res
}

func (s *SDRTask) Adder(taskFunc harmonytask.AddTaskFunc) {
	s.sp.pollers[pollerSDR].Set(taskFunc)
}

func (s *SDRTask) taskToSector(id harmonytask.TaskID) (ffi.SectorRef, error) {
	var refs []ffi.SectorRef

	err := s.db.Select(context.Background(), &refs, `SELECT sp_id, sector_number, reg_seal_proof FROM sectors_sdr_pipeline WHERE task_id_sdr = $1`, id)
	if err != nil {
		return ffi.SectorRef{}, xerrors.Errorf("getting sector ref: %w", err)
	}

	if len(refs) != 1 {
		return ffi.SectorRef{}, xerrors.Errorf("expected 1 sector ref, got %d", len(refs))
	}

	return refs[0], nil
}

var _ harmonytask.TaskInterface = &SDRTask{}