package policer

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	objectcore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/replicator"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
	"go.uber.org/zap"
)

var errInvalidECPlacement = errors.New("invalid EC placement: EC placement must have one placement vector")

func (p *Policer) processECContainerObject(ctx context.Context, objInfo objectcore.Info, policy netmap.PlacementPolicy) error {
	if objInfo.ECInfo == nil {
		return p.processECContainerRepObject(ctx, objInfo, policy)
	}
	return p.processECContainerECObject(ctx, objInfo, policy)
}

// processECContainerRepObject processes non erasure coded objects in EC container: tombstones, locks and linking objects.
// All of them must be stored on all of the container nodes.
func (p *Policer) processECContainerRepObject(ctx context.Context, objInfo objectcore.Info, policy netmap.PlacementPolicy) error {
	objID := objInfo.Address.Object()
	nn, err := p.placementBuilder.BuildPlacement(objInfo.Address.Container(), &objID, policy)
	if err != nil {
		return fmt.Errorf("%s: %w", logs.PolicerCouldNotBuildPlacementVectorForObject, err)
	}
	if len(nn) != 1 {
		return errInvalidECPlacement
	}

	c := &placementRequirements{}
	checkedNodes := newNodeCache()

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

	rd := policy.ReplicaDescriptor(0)
	// processNodes replaces rd.GetECDataCount() + rd.GetECParityCount() for len(nn[0]) for locks, tomstones and linking objects.
	p.processRepNodes(ctx, c, objInfo, nn[0], rd.GetECDataCount()+rd.GetECParityCount(), checkedNodes)

	if !c.needLocalCopy && c.removeLocalCopy {
		p.log.Info(logs.PolicerRedundantLocalObjectCopyDetected,
			zap.Stringer("object", objInfo.Address),
		)

		p.cbRedundantCopy(ctx, objInfo.Address)
	}
	return nil
}

func (p *Policer) processECContainerECObject(ctx context.Context, objInfo objectcore.Info, policy netmap.PlacementPolicy) error {
	nn, err := p.placementBuilder.BuildPlacement(objInfo.Address.Container(), &objInfo.ECInfo.ParentID, policy)
	if err != nil {
		return fmt.Errorf("%s: %w", logs.PolicerCouldNotBuildPlacementVectorForObject, err)
	}
	if len(nn) != 1 {
		return errInvalidECPlacement
	}

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

	validPlacement := p.processECChunk(ctx, objInfo, nn[0])
	if !validPlacement {
		p.pullRequiredECChunks(ctx, objInfo, nn[0])
	}
	return nil
}

// processECChunk replicates EC chunk if needed.
// Returns True if current chunk should be stored on current node.
func (p *Policer) processECChunk(ctx context.Context, objInfo objectcore.Info, nodes []netmap.NodeInfo) bool {
	var removeLocalChunk bool
	requiredNode := nodes[int(objInfo.ECInfo.Index)%(len(nodes))]
	if p.cfg.netmapKeys.IsLocalKey(requiredNode.PublicKey()) {
		// current node is required node, we are happy
		return true
	}
	if requiredNode.IsMaintenance() {
		// consider maintenance mode has object, but do not drop local copy
		p.log.Debug(logs.PolicerConsiderNodeUnderMaintenanceAsOK, zap.String("node", netmap.StringifyPublicKey(requiredNode)))
		return false
	}

	callCtx, cancel := context.WithTimeout(ctx, p.headTimeout)
	_, err := p.remoteHeader(callCtx, requiredNode, objInfo.Address)
	cancel()

	if err == nil {
		removeLocalChunk = true
	} else if client.IsErrObjectNotFound(err) {
		p.log.Debug(logs.PolicerShortageOfObjectCopiesDetected, zap.Stringer("object", objInfo.Address), zap.Uint32("shortage", 1))
		task := replicator.Task{
			NumCopies: 1,
			Addr:      objInfo.Address,
			Nodes:     []netmap.NodeInfo{requiredNode},
		}
		p.replicator.HandleReplicationTask(ctx, task, newNodeCache())
	} else if isClientErrMaintenance(err) {
		// consider maintenance mode has object, but do not drop local copy
		p.log.Debug(logs.PolicerConsiderNodeUnderMaintenanceAsOK, zap.String("node", netmap.StringifyPublicKey(requiredNode)))
	} else {
		p.log.Error(logs.PolicerReceiveObjectHeaderToCheckPolicyCompliance, zap.Stringer("object", objInfo.Address), zap.String("error", err.Error()))
	}

	if removeLocalChunk {
		p.log.Info(logs.PolicerRedundantLocalObjectCopyDetected, zap.Stringer("object", objInfo.Address))
		p.cbRedundantCopy(ctx, objInfo.Address)
	}

	return false
}

func (p *Policer) pullRequiredECChunks(_ context.Context, objInfo objectcore.Info, nodes []netmap.NodeInfo) {
	requiredChunkIndexes := make(map[uint32]struct{})
	for i, n := range nodes {
		if p.cfg.netmapKeys.IsLocalKey(n.PublicKey()) {
			requiredChunkIndexes[uint32(i)] = struct{}{}
		}
	}
	if len(requiredChunkIndexes) == 0 {
		p.log.Info(logs.PolicerNodeIsNotContainerNodeForECObject, zap.Stringer("object", objInfo.ECInfo.ParentID))
		return
	}
}