package pilorama

import (
	"context"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
	cidSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
)

// Forest represents CRDT tree.
type Forest interface {
	// TreeMove moves node in the tree.
	// If the parent of the move operation is TrashID, the node is removed.
	// If the child of the move operation is RootID, new ID is generated and added to a tree.
	TreeMove(ctx context.Context, d CIDDescriptor, treeID string, m *Move) (*Move, error)
	// TreeAddByPath adds new node in the tree using provided path.
	// The path is constructed by descending from the root using the values of the attr in meta.
	// Internal nodes in path should have exactly one attribute, otherwise a new node is created.
	TreeAddByPath(ctx context.Context, d CIDDescriptor, treeID string, attr string, path []string, meta []KeyValue) ([]Move, error)
	// TreeApply applies replicated operation from another node.
	// If background is true, TreeApply will first check whether an operation exists.
	TreeApply(ctx context.Context, cnr cidSDK.ID, treeID string, m *Move, backgroundSync bool) error
	// TreeApplyBatch applies replicated operations from another node.
	TreeApplyBatch(ctx context.Context, cnr cidSDK.ID, treeID string, m []*Move) error
	// TreeGetByPath returns all nodes corresponding to the path.
	// The path is constructed by descending from the root using the values of the
	// AttributeFilename in meta.
	// The last argument determines whether only the node with the latest timestamp is returned.
	// Should return ErrTreeNotFound if the tree is not found, and empty result if the path is not in the tree.
	TreeGetByPath(ctx context.Context, cid cidSDK.ID, treeID string, attr string, path []string, latest bool) ([]Node, error)
	// TreeGetMeta returns meta information of the node with the specified ID.
	// Should return ErrTreeNotFound if the tree is not found, and empty result if the node is not in the tree.
	TreeGetMeta(ctx context.Context, cid cidSDK.ID, treeID string, nodeID Node) (Meta, Node, error)
	// TreeGetChildren returns children of the node with the specified ID. The order is arbitrary.
	// Should return ErrTreeNotFound if the tree is not found, and empty result if the node is not in the tree.
	TreeGetChildren(ctx context.Context, cid cidSDK.ID, treeID string, nodeID Node) ([]NodeInfo, error)
	// TreeSortedByFilename returns children of the node with the specified ID. The nodes are sorted by the filename attribute..
	// Should return ErrTreeNotFound if the tree is not found, and empty result if the node is not in the tree.
	TreeSortedByFilename(ctx context.Context, cid cidSDK.ID, treeID string, nodeID MultiNode, last *string, count int) ([]MultiNodeInfo, *string, error)
	// TreeGetOpLog returns first log operation stored at or above the height.
	// In case no such operation is found, empty Move and nil error should be returned.
	TreeGetOpLog(ctx context.Context, cid cidSDK.ID, treeID string, height uint64) (Move, error)
	// TreeDrop drops a tree from the database.
	// If the tree is not found, ErrTreeNotFound should be returned.
	// In case of empty treeID drops all trees related to container.
	TreeDrop(ctx context.Context, cid cidSDK.ID, treeID string) error
	// TreeList returns all the tree IDs that have been added to the
	// passed container ID. Nil slice should be returned if no tree found.
	TreeList(ctx context.Context, cid cidSDK.ID) ([]string, error)
	// TreeExists checks if a tree exists locally.
	// If the tree is not found, false and a nil error should be returned.
	TreeExists(ctx context.Context, cid cidSDK.ID, treeID string) (bool, error)
	// TreeUpdateLastSyncHeight updates last log height synchronized with _all_ container nodes.
	TreeUpdateLastSyncHeight(ctx context.Context, cid cidSDK.ID, treeID string, height uint64) error
	// TreeLastSyncHeight returns last log height synchronized with _all_ container nodes.
	TreeLastSyncHeight(ctx context.Context, cid cidSDK.ID, treeID string) (uint64, error)
	// TreeHeight returns current tree height.
	TreeHeight(ctx context.Context, cid cidSDK.ID, treeID string) (uint64, error)
}

type ForestStorage interface {
	// DumpInfo returns information about the pilorama.
	DumpInfo() Info
	Init() error
	Open(context.Context, mode.Mode) error
	Close() error
	SetMode(context.Context, mode.Mode) error
	SetParentID(id string)
	Forest

	// TreeListTrees returns all pairs "containerID:treeID".
	TreeListTrees(ctx context.Context, prm TreeListTreesPrm) (*TreeListTreesResult, error)
	TreeApplyStream(ctx context.Context, cnr cidSDK.ID, treeID string, source <-chan *Move) error
}

const (
	AttributeFilename = "FileName"
	AttributeVersion  = "Version"
)

// CIDDescriptor contains container ID and information about the node position
// in the list of container nodes.
type CIDDescriptor struct {
	CID      cidSDK.ID
	Position int
	Size     int
}

// ErrInvalidCIDDescriptor is returned when info about tne node position
// in the container is invalid.
var ErrInvalidCIDDescriptor = logicerr.New("cid descriptor is invalid")

func (d CIDDescriptor) checkValid() bool {
	return 0 <= d.Position && d.Position < d.Size
}

var treeListTreesBatchSizeDefault = 1000

type ContainerIDTreeID struct {
	CID    cidSDK.ID
	TreeID string
}

type TreeListTreesPrm struct {
	NextPageToken []byte
	// BatchSize is batch size to list trees. If not lower or equals zero, than treeListTreesBatchSizeDefault is used.
	BatchSize int
}

type TreeListTreesResult struct {
	NextPageToken []byte
	Items         []ContainerIDTreeID
}

type treeList interface {
	TreeListTrees(ctx context.Context, prm TreeListTreesPrm) (*TreeListTreesResult, error)
}

func TreeListAll(ctx context.Context, f treeList) ([]ContainerIDTreeID, error) {
	return treeListAll(ctx, f, treeListTreesBatchSizeDefault)
}

func treeListAll(ctx context.Context, f treeList, batchSize int) ([]ContainerIDTreeID, error) {
	var prm TreeListTreesPrm
	prm.BatchSize = batchSize
	var result []ContainerIDTreeID
	first := true

	for len(prm.NextPageToken) > 0 || first {
		first = false

		res, err := f.TreeListTrees(ctx, prm)
		if err != nil {
			return nil, err
		}
		prm.NextPageToken = res.NextPageToken
		result = append(result, res.Items...)
	}

	return result, nil
}

func TreeCountAll(ctx context.Context, f treeList) (uint64, error) {
	var prm TreeListTreesPrm
	var result uint64
	first := true

	for len(prm.NextPageToken) > 0 || first {
		first = false

		res, err := f.TreeListTrees(ctx, prm)
		if err != nil {
			return 0, err
		}
		prm.NextPageToken = res.NextPageToken
		result += uint64(len(res.Items))
	}

	return result, nil
}