package services

import (
	"context"
	"errors"
	"fmt"
	"io"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
	errorsFrost "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/frostfs/errors"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/pkg/service/tree"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/bearer"
	treepool "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool/tree"
	grpcService "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool/tree/service"
)

type GetNodeByPathResponseInfoWrapper struct {
	response *grpcService.GetNodeByPathResponse_Info
}

func (n GetNodeByPathResponseInfoWrapper) GetNodeID() uint64 {
	return n.response.GetNodeId()
}

func (n GetNodeByPathResponseInfoWrapper) GetParentID() uint64 {
	return n.response.GetParentId()
}

func (n GetNodeByPathResponseInfoWrapper) GetTimestamp() uint64 {
	return n.response.GetTimestamp()
}

func (n GetNodeByPathResponseInfoWrapper) GetMeta() []tree.Meta {
	res := make([]tree.Meta, len(n.response.Meta))
	for i, value := range n.response.Meta {
		res[i] = value
	}
	return res
}

type GetSubTreeResponseBodyWrapper struct {
	response *grpcService.GetSubTreeResponse_Body
}

func (n GetSubTreeResponseBodyWrapper) GetNodeID() uint64 {
	return n.response.GetNodeId()
}

func (n GetSubTreeResponseBodyWrapper) GetParentID() uint64 {
	return n.response.GetParentId()
}

func (n GetSubTreeResponseBodyWrapper) GetTimestamp() uint64 {
	return n.response.GetTimestamp()
}

func (n GetSubTreeResponseBodyWrapper) GetMeta() []tree.Meta {
	res := make([]tree.Meta, len(n.response.Meta))
	for i, value := range n.response.Meta {
		res[i] = value
	}
	return res
}

type PoolWrapper struct {
	p *treepool.Pool
}

func NewPoolWrapper(p *treepool.Pool) *PoolWrapper {
	return &PoolWrapper{p: p}
}

func (w *PoolWrapper) GetNodes(ctx context.Context, prm *tree.GetNodesParams) ([]tree.NodeResponse, error) {
	poolPrm := treepool.GetNodesParams{
		CID:           prm.BktInfo.CID,
		TreeID:        prm.TreeID,
		Path:          prm.Path,
		Meta:          prm.Meta,
		PathAttribute: tree.FileNameKey,
		LatestOnly:    prm.LatestOnly,
		AllAttrs:      prm.AllAttrs,
		BearerToken:   getBearer(ctx, prm.BktInfo),
	}

	nodes, err := w.p.GetNodes(ctx, poolPrm)
	if err != nil {
		return nil, handleError(err)
	}

	res := make([]tree.NodeResponse, len(nodes))
	for i, info := range nodes {
		res[i] = GetNodeByPathResponseInfoWrapper{info}
	}

	return res, nil
}

func (w *PoolWrapper) GetSubTree(ctx context.Context, bktInfo *data.BucketInfo, treeID string, rootID uint64, depth uint32) ([]tree.NodeResponse, error) {
	poolPrm := treepool.GetSubTreeParams{
		CID:         bktInfo.CID,
		TreeID:      treeID,
		RootID:      rootID,
		Depth:       depth,
		BearerToken: getBearer(ctx, bktInfo),
	}

	subTreeReader, err := w.p.GetSubTree(ctx, poolPrm)
	if err != nil {
		return nil, handleError(err)
	}

	var subtree []tree.NodeResponse

	node, err := subTreeReader.Next()
	for err == nil {
		subtree = append(subtree, GetSubTreeResponseBodyWrapper{node})
		node, err = subTreeReader.Next()
	}
	if err != nil && err != io.EOF {
		return nil, handleError(err)
	}

	return subtree, nil
}

type SubTreeStreamImpl struct {
	r      *treepool.SubTreeReader
	buffer []*grpcService.GetSubTreeResponse_Body
	eof    bool
	index  int
	ln     int
}

const bufSize = 1000

func (s *SubTreeStreamImpl) Next() (tree.NodeResponse, error) {
	if s.index != -1 {
		node := s.buffer[s.index]
		s.index++
		if s.index >= s.ln {
			s.index = -1
		}
		return GetSubTreeResponseBodyWrapper{response: node}, nil
	}
	if s.eof {
		return nil, io.EOF
	}

	var err error
	s.ln, err = s.r.Read(s.buffer)
	if err != nil {
		if err != io.EOF {
			err = handleError(err)
			return nil, fmt.Errorf("sub tree stream impl pool wrap: %w", err)
		} else {
			s.eof = true
		}
	}
	if s.ln > 0 {
		s.index = 0
	}

	return s.Next()
}

func (w *PoolWrapper) GetSubTreeStream(ctx context.Context, bktInfo *data.BucketInfo, treeID string, rootID uint64, depth uint32) (tree.SubTreeStream, error) {
	poolPrm := treepool.GetSubTreeParams{
		CID:         bktInfo.CID,
		TreeID:      treeID,
		RootID:      rootID,
		Depth:       depth,
		BearerToken: getBearer(ctx, bktInfo),
	}

	subTreeReader, err := w.p.GetSubTree(ctx, poolPrm)
	if err != nil {
		return nil, handleError(err)
	}

	return &SubTreeStreamImpl{
		r:      subTreeReader,
		buffer: make([]*grpcService.GetSubTreeResponse_Body, bufSize),
		index:  -1,
	}, nil
}

func (w *PoolWrapper) AddNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, parent uint64, meta map[string]string) (uint64, error) {
	nodeID, err := w.p.AddNode(ctx, treepool.AddNodeParams{
		CID:         bktInfo.CID,
		TreeID:      treeID,
		Parent:      parent,
		Meta:        meta,
		BearerToken: getBearer(ctx, bktInfo),
	})
	return nodeID, handleError(err)
}

func (w *PoolWrapper) AddNodeByPath(ctx context.Context, bktInfo *data.BucketInfo, treeID string, path []string, meta map[string]string) (uint64, error) {
	nodeID, err := w.p.AddNodeByPath(ctx, treepool.AddNodeByPathParams{
		CID:           bktInfo.CID,
		TreeID:        treeID,
		Path:          path,
		Meta:          meta,
		PathAttribute: tree.FileNameKey,
		BearerToken:   getBearer(ctx, bktInfo),
	})
	return nodeID, handleError(err)
}

func (w *PoolWrapper) MoveNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, nodeID, parentID uint64, meta map[string]string) error {
	return handleError(w.p.MoveNode(ctx, treepool.MoveNodeParams{
		CID:         bktInfo.CID,
		TreeID:      treeID,
		NodeID:      nodeID,
		ParentID:    parentID,
		Meta:        meta,
		BearerToken: getBearer(ctx, bktInfo),
	}))
}

func (w *PoolWrapper) RemoveNode(ctx context.Context, bktInfo *data.BucketInfo, treeID string, nodeID uint64) error {
	return handleError(w.p.RemoveNode(ctx, treepool.RemoveNodeParams{
		CID:         bktInfo.CID,
		TreeID:      treeID,
		NodeID:      nodeID,
		BearerToken: getBearer(ctx, bktInfo),
	}))
}

func getBearer(ctx context.Context, bktInfo *data.BucketInfo) []byte {
	if bd, err := middleware.GetBoxData(ctx); err == nil {
		if bd.Gate.BearerToken != nil {
			if bd.Gate.BearerToken.Impersonate() || bktInfo.Owner.Equals(bearer.ResolveIssuer(*bd.Gate.BearerToken)) {
				return bd.Gate.BearerToken.Marshal()
			}
		}
	}
	return nil
}

func handleError(err error) error {
	if err == nil {
		return nil
	}
	if errors.Is(err, treepool.ErrNodeNotFound) {
		return fmt.Errorf("%w: %s", tree.ErrNodeNotFound, err.Error())
	}
	if errors.Is(err, treepool.ErrNodeAccessDenied) {
		return fmt.Errorf("%w: %s", tree.ErrNodeAccessDenied, err.Error())
	}
	if errorsFrost.IsTimeoutError(err) {
		return fmt.Errorf("%w: %s", tree.ErrGatewayTimeout, err.Error())
	}

	return err
}