package engine

import (
	"context"
	"errors"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard"
	tracingPkg "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"go.uber.org/zap"
)

// InhumePrm encapsulates parameters for inhume operation.
type InhumePrm struct {
	tombstone *oid.Address
	addrs     []oid.Address

	forceRemoval bool
}

// InhumeRes encapsulates results of inhume operation.
type InhumeRes struct{}

// WithTarget sets a list of objects that should be inhumed and tombstone address
// as the reason for inhume operation.
//
// tombstone should not be nil, addr should not be empty.
// Should not be called along with MarkAsGarbage.
func (p *InhumePrm) WithTarget(tombstone oid.Address, addrs ...oid.Address) {
	p.addrs = addrs
	p.tombstone = &tombstone
}

// MarkAsGarbage marks an object to be physically removed from local storage.
//
// Should not be called along with WithTarget.
func (p *InhumePrm) MarkAsGarbage(addrs ...oid.Address) {
	p.addrs = addrs
	p.tombstone = nil
}

// WithForceRemoval inhumes objects specified via MarkAsGarbage with GC mark
// without any object restrictions checks.
func (p *InhumePrm) WithForceRemoval() {
	p.forceRemoval = true
	p.tombstone = nil
}

var errInhumeFailure = errors.New("inhume operation failed")

// Inhume calls metabase. Inhume method to mark an object as removed. It won't be
// removed physically from the shard until `Delete` operation.
//
// Allows inhuming non-locked objects only. Returns apistatus.ObjectLocked
// if at least one object is locked.
//
// NOTE: Marks any object as removed (despite any prohibitions on operations
// with that object) if WithForceRemoval option has been provided.
//
// Returns an error if executions are blocked (see BlockExecution).
func (e *StorageEngine) Inhume(ctx context.Context, prm InhumePrm) (res InhumeRes, err error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.Inhume")
	defer span.End()

	err = e.execIfNotBlocked(func() error {
		res, err = e.inhume(ctx, prm)
		return err
	})

	return
}

func (e *StorageEngine) inhume(ctx context.Context, prm InhumePrm) (InhumeRes, error) {
	if e.metrics != nil {
		defer elapsed("Inhume", e.metrics.AddMethodDuration)()
	}

	var shPrm shard.InhumePrm
	if prm.forceRemoval {
		shPrm.ForceRemoval()
	}

	for i := range prm.addrs {
		if !prm.forceRemoval {
			locked, err := e.IsLocked(ctx, prm.addrs[i])
			if err != nil {
				e.log.Warn(logs.EngineRemovingAnObjectWithoutFullLockingCheck,
					zap.Error(err),
					zap.Stringer("addr", prm.addrs[i]),
					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
			} else if locked {
				return InhumeRes{}, new(apistatus.ObjectLocked)
			}
		}

		if prm.tombstone != nil {
			shPrm.SetTarget(*prm.tombstone, prm.addrs[i])
		} else {
			shPrm.MarkAsGarbage(prm.addrs[i])
		}

		ok, err := e.inhumeAddr(ctx, prm.addrs[i], shPrm, true)
		if err != nil {
			return InhumeRes{}, err
		}
		if !ok {
			ok, err := e.inhumeAddr(ctx, prm.addrs[i], shPrm, false)
			if err != nil {
				return InhumeRes{}, err
			} else if !ok {
				return InhumeRes{}, errInhumeFailure
			}
		}
	}

	return InhumeRes{}, nil
}

// Returns ok if object was inhumed during this invocation or before.
func (e *StorageEngine) inhumeAddr(ctx context.Context, addr oid.Address, prm shard.InhumePrm, checkExists bool) (bool, error) {
	root := false
	var existPrm shard.ExistsPrm
	var retErr error
	var ok bool

	e.iterateOverSortedShards(addr, func(_ int, sh hashedShard) (stop bool) {
		defer func() {
			// if object is root we continue since information about it
			// can be presented in other shards
			if checkExists && root {
				stop = false
			}
		}()

		if checkExists {
			existPrm.SetAddress(addr)
			exRes, err := sh.Exists(ctx, existPrm)
			if err != nil {
				if client.IsErrObjectAlreadyRemoved(err) || shard.IsErrObjectExpired(err) {
					// inhumed once - no need to be inhumed again
					ok = true
					return true
				}

				var siErr *objectSDK.SplitInfoError
				if !errors.As(err, &siErr) {
					e.reportShardError(sh, "could not check for presents in shard", err)
					return
				}

				root = true
			} else if !exRes.Exists() {
				return
			}
		}

		_, err := sh.Inhume(ctx, prm)
		if err != nil {
			var errLocked *apistatus.ObjectLocked
			switch {
			case errors.As(err, &errLocked):
				retErr = new(apistatus.ObjectLocked)
				return true
			case errors.Is(err, shard.ErrLockObjectRemoval):
				retErr = meta.ErrLockObjectRemoval
				return true
			case errors.Is(err, shard.ErrReadOnlyMode) || errors.Is(err, shard.ErrDegradedMode):
				retErr = err
				return true
			}

			e.reportShardError(sh, "could not inhume object in shard", err)
			return false
		}

		ok = true
		return true
	})

	return ok, retErr
}

// IsLocked checks whether an object is locked according to StorageEngine's state.
func (e *StorageEngine) IsLocked(ctx context.Context, addr oid.Address) (bool, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.IsLocked",
		trace.WithAttributes(
			attribute.String("address", addr.EncodeToString()),
		))
	defer span.End()

	var locked bool
	var err error
	var outErr error

	e.iterateOverUnsortedShards(func(h hashedShard) (stop bool) {
		locked, err = h.Shard.IsLocked(ctx, addr)
		if err != nil {
			e.reportShardError(h, "can't check object's lockers", err, zap.Stringer("addr", addr),
				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
			outErr = err
			return false
		}

		return locked
	})

	if locked {
		return locked, nil
	}

	return locked, outErr
}

func (e *StorageEngine) processExpiredTombstones(ctx context.Context, addrs []meta.TombstonedObject) {
	e.iterateOverUnsortedShards(func(sh hashedShard) (stop bool) {
		sh.HandleExpiredTombstones(ctx, addrs)

		select {
		case <-ctx.Done():
			return true
		default:
			return false
		}
	})
}

func (e *StorageEngine) processExpiredLocks(ctx context.Context, epoch uint64, lockers []oid.Address) {
	e.iterateOverUnsortedShards(func(sh hashedShard) (stop bool) {
		sh.HandleExpiredLocks(ctx, epoch, lockers)

		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingTheExpiredLocks, zap.Error(ctx.Err()))
			return true
		default:
			return false
		}
	})
}

func (e *StorageEngine) processDeletedLocks(ctx context.Context, lockers []oid.Address) {
	e.iterateOverUnsortedShards(func(sh hashedShard) (stop bool) {
		sh.HandleDeletedLocks(lockers)

		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingTheDeletedLocks, zap.Error(ctx.Err()))
			return true
		default:
			return false
		}
	})
}

func (e *StorageEngine) processZeroSizeContainers(ctx context.Context, ids []cid.ID) {
	if len(ids) == 0 {
		return
	}

	idMap, err := e.selectNonExistentIDs(ctx, ids)
	if err != nil {
		return
	}

	if len(idMap) == 0 {
		return
	}

	var failed bool
	var prm shard.ContainerSizePrm
	e.iterateOverUnsortedShards(func(sh hashedShard) bool {
		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingZeroSizeContainers, zap.Error(ctx.Err()))
			failed = true
			return true
		default:
		}

		var drop []cid.ID
		for id := range idMap {
			prm.SetContainerID(id)
			s, err := sh.ContainerSize(prm)
			if err != nil {
				e.log.Warn(logs.EngineFailedToGetContainerSize, zap.Stringer("container_id", id), zap.Error(err))
				failed = true
				return true
			}
			if s.Size() > 0 {
				drop = append(drop, id)
			}
		}
		for _, id := range drop {
			delete(idMap, id)
		}

		return len(idMap) == 0
	})

	if failed || len(idMap) == 0 {
		return
	}

	e.iterateOverUnsortedShards(func(sh hashedShard) bool {
		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingZeroSizeContainers, zap.Error(ctx.Err()))
			failed = true
			return true
		default:
		}

		for id := range idMap {
			if err := sh.DeleteContainerSize(ctx, id); err != nil {
				e.log.Warn(logs.EngineFailedToDeleteContainerSize, zap.Stringer("container_id", id), zap.Error(err))
				failed = true
				return true
			}
		}

		return false
	})

	if failed {
		return
	}

	for id := range idMap {
		e.metrics.DeleteContainerSize(id.EncodeToString())
	}
}

func (e *StorageEngine) processZeroCountContainers(ctx context.Context, ids []cid.ID) {
	if len(ids) == 0 {
		return
	}

	idMap, err := e.selectNonExistentIDs(ctx, ids)
	if err != nil {
		return
	}

	if len(idMap) == 0 {
		return
	}

	var failed bool
	var prm shard.ContainerCountPrm
	e.iterateOverUnsortedShards(func(sh hashedShard) bool {
		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingZeroCountContainers, zap.Error(ctx.Err()))
			failed = true
			return true
		default:
		}

		var drop []cid.ID
		for id := range idMap {
			prm.ContainerID = id
			s, err := sh.ContainerCount(ctx, prm)
			if err != nil {
				e.log.Warn(logs.EngineFailedToGetContainerCounters, zap.Stringer("container_id", id), zap.Error(err))
				failed = true
				return true
			}
			if s.User > 0 || s.Logic > 0 || s.Phy > 0 {
				drop = append(drop, id)
			}
		}
		for _, id := range drop {
			delete(idMap, id)
		}

		return len(idMap) == 0
	})

	if failed || len(idMap) == 0 {
		return
	}

	e.iterateOverUnsortedShards(func(sh hashedShard) bool {
		select {
		case <-ctx.Done():
			e.log.Info(logs.EngineInterruptProcessingZeroCountContainers, zap.Error(ctx.Err()))
			failed = true
			return true
		default:
		}

		for id := range idMap {
			if err := sh.DeleteContainerCount(ctx, id); err != nil {
				e.log.Warn(logs.EngineFailedToDeleteContainerSize, zap.Stringer("container_id", id), zap.Error(err))
				failed = true
				return true
			}
		}

		return false
	})

	if failed {
		return
	}

	for id := range idMap {
		e.metrics.DeleteContainerCount(id.EncodeToString())
	}
}

func (e *StorageEngine) selectNonExistentIDs(ctx context.Context, ids []cid.ID) (map[cid.ID]struct{}, error) {
	cs := e.containerSource.Load()

	idMap := make(map[cid.ID]struct{})
	for _, id := range ids {
		isAvailable, err := cs.IsContainerAvailable(ctx, id)
		if err != nil {
			e.log.Warn(logs.EngineFailedToCheckContainerAvailability, zap.Stringer("container_id", id), zap.Error(err))
			return nil, err
		}
		if isAvailable {
			continue
		}
		idMap[id] = struct{}{}
	}
	return idMap, nil
}