package engine

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	cidSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"go.uber.org/zap"
)

var _ pilorama.Forest = (*StorageEngine)(nil)

// TreeMove implements the pilorama.Forest interface.
func (e *StorageEngine) TreeMove(ctx context.Context, d pilorama.CIDDescriptor, treeID string, m *pilorama.Move) (*pilorama.Move, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeMove",
		trace.WithAttributes(
			attribute.String("container_id", d.CID.EncodeToString()),
			attribute.Int("position", d.Position),
			attribute.Int("size", d.Size),
			attribute.String("tree_id", treeID),
		),
	)
	defer span.End()

	index, lst, err := e.getTreeShard(ctx, d.CID, treeID)
	if err != nil && !errors.Is(err, pilorama.ErrTreeNotFound) {
		return nil, err
	}

	lm, err := lst[index].TreeMove(ctx, d, treeID, m)
	if err != nil {
		if !errors.Is(err, shard.ErrReadOnlyMode) && err != shard.ErrPiloramaDisabled {
			e.reportShardError(lst[index], "can't perform `TreeMove`", err,
				zap.Stringer("cid", d.CID),
				zap.String("tree", treeID))
		}

		return nil, err
	}
	return lm, nil
}

// TreeAddByPath implements the pilorama.Forest interface.
func (e *StorageEngine) TreeAddByPath(ctx context.Context, d pilorama.CIDDescriptor, treeID string, attr string, path []string, m []pilorama.KeyValue) ([]pilorama.Move, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeAddByPath",
		trace.WithAttributes(
			attribute.String("container_id", d.CID.EncodeToString()),
			attribute.Int("position", d.Position),
			attribute.Int("size", d.Size),
			attribute.String("tree_id", treeID),
			attribute.String("attr", attr),
			attribute.Int("path_count", len(path)),
			attribute.Int("meta_count", len(m)),
		),
	)
	defer span.End()

	index, lst, err := e.getTreeShard(ctx, d.CID, treeID)
	if err != nil && !errors.Is(err, pilorama.ErrTreeNotFound) {
		return nil, err
	}

	lm, err := lst[index].TreeAddByPath(ctx, d, treeID, attr, path, m)
	if err != nil {
		if !errors.Is(err, shard.ErrReadOnlyMode) && err != shard.ErrPiloramaDisabled {
			e.reportShardError(lst[index], "can't perform `TreeAddByPath`", err,
				zap.Stringer("cid", d.CID),
				zap.String("tree", treeID))
		}
		return nil, err
	}
	return lm, nil
}

// TreeApply implements the pilorama.Forest interface.
func (e *StorageEngine) TreeApply(ctx context.Context, cnr cidSDK.ID, treeID string, m *pilorama.Move, backgroundSync bool) error {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeApply",
		trace.WithAttributes(
			attribute.String("container_id", cnr.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.Bool("background", backgroundSync),
		),
	)
	defer span.End()

	index, lst, err := e.getTreeShard(ctx, cnr, treeID)
	if err != nil && !errors.Is(err, pilorama.ErrTreeNotFound) {
		return err
	}

	err = lst[index].TreeApply(ctx, cnr, treeID, m, backgroundSync)
	if err != nil {
		if !errors.Is(err, shard.ErrReadOnlyMode) && err != shard.ErrPiloramaDisabled {
			e.reportShardError(lst[index], "can't perform `TreeApply`", err,
				zap.Stringer("cid", cnr),
				zap.String("tree", treeID))
		}
		return err
	}
	return nil
}

// TreeGetByPath implements the pilorama.Forest interface.
func (e *StorageEngine) TreeGetByPath(ctx context.Context, cid cidSDK.ID, treeID string, attr string, path []string, latest bool) ([]pilorama.Node, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeGetByPath",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.String("attr", attr),
			attribute.Int("path_count", len(path)),
			attribute.Bool("latest", latest),
		),
	)
	defer span.End()

	var err error
	var nodes []pilorama.Node
	for _, sh := range e.sortShardsByWeight(cid) {
		nodes, err = sh.TreeGetByPath(ctx, cid, treeID, attr, path, latest)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) {
				e.reportShardError(sh, "can't perform `TreeGetByPath`", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return nodes, nil
	}
	return nil, err
}

// TreeGetMeta implements the pilorama.Forest interface.
func (e *StorageEngine) TreeGetMeta(ctx context.Context, cid cidSDK.ID, treeID string, nodeID pilorama.Node) (pilorama.Meta, uint64, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeGetMeta",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.String("node_id", fmt.Sprintf("%d", nodeID)),
		),
	)
	defer span.End()

	var err error
	var m pilorama.Meta
	var p uint64
	for _, sh := range e.sortShardsByWeight(cid) {
		m, p, err = sh.TreeGetMeta(ctx, cid, treeID, nodeID)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) {
				e.reportShardError(sh, "can't perform `TreeGetMeta`", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return m, p, nil
	}
	return pilorama.Meta{}, 0, err
}

// TreeGetChildren implements the pilorama.Forest interface.
func (e *StorageEngine) TreeGetChildren(ctx context.Context, cid cidSDK.ID, treeID string, nodeID pilorama.Node) ([]pilorama.NodeInfo, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeGetChildren",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.String("node_id", fmt.Sprintf("%d", nodeID)),
		),
	)
	defer span.End()

	var err error
	var nodes []pilorama.NodeInfo
	for _, sh := range e.sortShardsByWeight(cid) {
		nodes, err = sh.TreeGetChildren(ctx, cid, treeID, nodeID)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) {
				e.reportShardError(sh, "can't perform `TreeGetChildren`", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return nodes, nil
	}
	return nil, err
}

// TreeGetOpLog implements the pilorama.Forest interface.
func (e *StorageEngine) TreeGetOpLog(ctx context.Context, cid cidSDK.ID, treeID string, height uint64) (pilorama.Move, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeGetOpLog",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.String("height", fmt.Sprintf("%d", height)),
		),
	)
	defer span.End()

	var err error
	var lm pilorama.Move
	for _, sh := range e.sortShardsByWeight(cid) {
		lm, err = sh.TreeGetOpLog(ctx, cid, treeID, height)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) {
				e.reportShardError(sh, "can't perform `TreeGetOpLog`", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return lm, nil
	}
	return lm, err
}

// TreeDrop implements the pilorama.Forest interface.
func (e *StorageEngine) TreeDrop(ctx context.Context, cid cidSDK.ID, treeID string) error {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeDrop",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
		),
	)
	defer span.End()

	var err error
	for _, sh := range e.sortShardsByWeight(cid) {
		err = sh.TreeDrop(ctx, cid, treeID)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) && !errors.Is(err, shard.ErrReadOnlyMode) {
				e.reportShardError(sh, "can't perform `TreeDrop`", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return nil
	}
	return err
}

// TreeList implements the pilorama.Forest interface.
func (e *StorageEngine) TreeList(ctx context.Context, cid cidSDK.ID) ([]string, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeList",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
		),
	)
	defer span.End()

	var resIDs []string

	for _, sh := range e.unsortedShards() {
		ids, err := sh.TreeList(ctx, cid)
		if err != nil {
			if errors.Is(err, shard.ErrPiloramaDisabled) || errors.Is(err, shard.ErrReadOnlyMode) {
				return nil, err
			}

			e.reportShardError(sh, "can't perform `TreeList`", err,
				zap.Stringer("cid", cid))

			// returns as much info about
			// trees as possible
			continue
		}

		resIDs = append(resIDs, ids...)
	}

	return resIDs, nil
}

// TreeExists implements the pilorama.Forest interface.
func (e *StorageEngine) TreeExists(ctx context.Context, cid cidSDK.ID, treeID string) (bool, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeExists",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
		),
	)
	defer span.End()

	_, _, err := e.getTreeShard(ctx, cid, treeID)
	if errors.Is(err, pilorama.ErrTreeNotFound) {
		return false, nil
	}
	return err == nil, err
}

func (e *StorageEngine) TreeHeight(ctx context.Context, cid cidSDK.ID, treeID string) (uint64, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeHeight",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
		),
	)
	defer span.End()

	index, lst, err := e.getTreeShard(ctx, cid, treeID)
	if err != nil {
		return 0, nil
	}
	return lst[index].TreeHeight(ctx, cid, treeID)
}

// TreeUpdateLastSyncHeight implements the pilorama.Forest interface.
func (e *StorageEngine) TreeUpdateLastSyncHeight(ctx context.Context, cid cidSDK.ID, treeID string, height uint64) error {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeUpdateLastSyncHeight",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
			attribute.String("height", fmt.Sprintf("%d", height)),
		),
	)
	defer span.End()

	index, lst, err := e.getTreeShard(ctx, cid, treeID)
	if err != nil && !errors.Is(err, pilorama.ErrTreeNotFound) {
		return err
	}

	err = lst[index].TreeUpdateLastSyncHeight(ctx, cid, treeID, height)
	if err != nil && !errors.Is(err, shard.ErrReadOnlyMode) && err != shard.ErrPiloramaDisabled {
		e.reportShardError(lst[index], "can't update tree synchronization height", err,
			zap.Stringer("cid", cid),
			zap.String("tree", treeID))
	}
	return err
}

// TreeLastSyncHeight implements the pilorama.Forest interface.
func (e *StorageEngine) TreeLastSyncHeight(ctx context.Context, cid cidSDK.ID, treeID string) (uint64, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.TreeLastSyncHeight",
		trace.WithAttributes(
			attribute.String("container_id", cid.EncodeToString()),
			attribute.String("tree_id", treeID),
		),
	)
	defer span.End()

	var err error
	var height uint64
	for _, sh := range e.sortShardsByWeight(cid) {
		height, err = sh.TreeLastSyncHeight(ctx, cid, treeID)
		if err != nil {
			if err == shard.ErrPiloramaDisabled {
				break
			}
			if !errors.Is(err, pilorama.ErrTreeNotFound) {
				e.reportShardError(sh, "can't read tree synchronization height", err,
					zap.Stringer("cid", cid),
					zap.String("tree", treeID))
			}
			continue
		}
		return height, err
	}
	return height, err
}

func (e *StorageEngine) getTreeShard(ctx context.Context, cid cidSDK.ID, treeID string) (int, []hashedShard, error) {
	lst := e.sortShardsByWeight(cid)
	for i, sh := range lst {
		exists, err := sh.TreeExists(ctx, cid, treeID)
		if err != nil {
			return 0, nil, err
		}
		if exists {
			return i, lst, err
		}
	}

	return 0, lst, pilorama.ErrTreeNotFound
}