package engine

import (
	"context"
	"errors"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"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"
	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"
)

// DeletePrm groups the parameters of Delete operation.
type DeletePrm struct {
	addr oid.Address

	forceRemoval bool
}

// DeleteRes groups the resulting values of Delete operation.
type DeleteRes struct{}

// WithAddress is a Delete option to set the addresses of the objects to delete.
//
// Option is required.
func (p *DeletePrm) WithAddress(addr oid.Address) {
	p.addr = addr
}

// WithForceRemoval is a Delete option to remove an object despite any
// restrictions imposed on deleting that object. Expected to be used
// only in control service.
func (p *DeletePrm) WithForceRemoval() {
	p.forceRemoval = true
}

// Delete marks the objects to be removed.
//
// Returns an error if executions are blocked (see BlockExecution).
//
// Returns apistatus.ObjectLocked if at least one object is locked.
// In this case no object from the list is marked to be deleted.
//
// NOTE: Marks any object to be deleted (despite any prohibitions
// on operations with that object) if WithForceRemoval option has
// been provided.
func (e *StorageEngine) Delete(ctx context.Context, prm DeletePrm) (res DeleteRes, err error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.Delete",
		trace.WithAttributes(
			attribute.String("address", prm.addr.EncodeToString()),
			attribute.Bool("force_removal", prm.forceRemoval),
		))
	defer span.End()

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

	return
}

func (e *StorageEngine) delete(ctx context.Context, prm DeletePrm) (DeleteRes, error) {
	defer elapsed("Delete", e.metrics.AddMethodDuration)()

	var locked struct {
		is bool
	}
	var splitInfo *objectSDK.SplitInfo
	var ecInfo *objectSDK.ECInfo

	// Removal of a big object is done in multiple stages:
	// 1. Remove the parent object. If it is locked or already removed, return immediately.
	// 2. Otherwise, search for all objects with a particular SplitID and delete them too.
	e.iterateOverSortedShards(prm.addr, func(_ int, sh hashedShard) (stop bool) {
		var existsPrm shard.ExistsPrm
		existsPrm.Address = prm.addr

		resExists, err := sh.Exists(ctx, existsPrm)
		if err != nil {
			if client.IsErrObjectAlreadyRemoved(err) || shard.IsErrObjectExpired(err) {
				return true
			}

			var splitErr *objectSDK.SplitInfoError
			var ecErr *objectSDK.ECInfoError
			if errors.As(err, &splitErr) {
				splitInfo = splitErr.SplitInfo()
			} else if errors.As(err, &ecErr) {
				e.deleteChunks(ctx, sh, ecInfo, prm)
				return false
			} else {
				if !client.IsErrObjectNotFound(err) {
					e.reportShardError(sh, "could not check object existence", err, zap.Stringer("address", prm.addr))
				}
				return false
			}
		} else if !resExists.Exists() {
			return false
		}

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

		_, err = sh.Inhume(ctx, shPrm)
		if err != nil {
			e.reportShardError(sh, "could not inhume object in shard", err, zap.Stringer("address", prm.addr))

			var target *apistatus.ObjectLocked
			locked.is = errors.As(err, &target)

			return locked.is
		}

		// If a parent object is removed we should set GC mark on each shard.
		return splitInfo == nil
	})

	if locked.is {
		return DeleteRes{}, new(apistatus.ObjectLocked)
	}

	if splitInfo != nil {
		e.deleteChildren(ctx, prm.addr, prm.forceRemoval, splitInfo.SplitID())
	}

	return DeleteRes{}, nil
}

func (e *StorageEngine) deleteChildren(ctx context.Context, addr oid.Address, force bool, splitID *objectSDK.SplitID) {
	var fs objectSDK.SearchFilters
	fs.AddSplitIDFilter(objectSDK.MatchStringEqual, splitID)

	var selectPrm shard.SelectPrm
	selectPrm.SetFilters(fs)
	selectPrm.SetContainerID(addr.Container(), false) // doesn't matter for search by splitID

	var inhumePrm shard.InhumePrm
	if force {
		inhumePrm.ForceRemoval()
	}

	e.iterateOverSortedShards(addr, func(_ int, sh hashedShard) (stop bool) {
		res, err := sh.Select(ctx, selectPrm)
		if err != nil {
			e.log.Warn(logs.EngineErrorDuringSearchingForObjectChildren,
				zap.Stringer("addr", addr),
				zap.String("error", err.Error()),
				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
			return false
		}

		for _, addr := range res.AddressList() {
			inhumePrm.MarkAsGarbage(addr)

			_, err = sh.Inhume(ctx, inhumePrm)
			if err != nil {
				e.log.Debug(logs.EngineCouldNotInhumeObjectInShard,
					zap.Stringer("addr", addr),
					zap.String("err", err.Error()),
					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
				continue
			}
		}
		return false
	})
}

func (e *StorageEngine) deleteChunks(
	ctx context.Context, sh hashedShard, ecInfo *objectSDK.ECInfo, prm DeletePrm,
) {
	var inhumePrm shard.InhumePrm
	if prm.forceRemoval {
		inhumePrm.ForceRemoval()
	}
	for _, chunk := range ecInfo.Chunks {
		var addr oid.Address
		addr.SetContainer(prm.addr.Container())
		var objID oid.ID
		err := objID.ReadFromV2(chunk.ID)
		if err != nil {
			e.reportShardError(sh, "could not delete EC chunk", err, zap.Stringer("address", prm.addr))
		}
		addr.SetObject(objID)
		inhumePrm.MarkAsGarbage(addr)
		_, err = sh.Inhume(ctx, inhumePrm)
		if err != nil {
			e.log.Debug(logs.EngineCouldNotInhumeObjectInShard,
				zap.Stringer("addr", addr),
				zap.String("err", err.Error()),
				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
			continue
		}
	}
}