package net

import (
	"context"
	"strings"

	"golang.org/x/xerrors"

	"github.com/libp2p/go-libp2p-core/network"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-core/protocol"
	rcmgr "github.com/libp2p/go-libp2p-resource-manager"

	"github.com/filecoin-project/lotus/api"
)

func (a *NetAPI) NetStat(ctx context.Context, scope string) (result api.NetStat, err error) {
	switch {
	case scope == "all":
		rapi, ok := a.ResourceManager.(rcmgr.ResourceManagerState)
		if !ok {
			return result, xerrors.Errorf("rexource manager does not support ResourceManagerState API")
		}

		stat := rapi.Stat()
		result.System = &stat.System
		result.Transient = &stat.Transient
		if len(stat.Services) > 0 {
			result.Services = stat.Services
		}
		if len(stat.Protocols) > 0 {
			result.Protocols = make(map[string]network.ScopeStat, len(stat.Protocols))
			for proto, stat := range stat.Protocols {
				result.Protocols[string(proto)] = stat
			}
		}
		if len(stat.Peers) > 0 {
			result.Peers = make(map[string]network.ScopeStat, len(stat.Peers))
			for p, stat := range stat.Peers {
				result.Peers[p.Pretty()] = stat
			}
		}

		return result, nil

	case scope == "system":
		err = a.ResourceManager.ViewSystem(func(s network.ResourceScope) error {
			stat := s.Stat()
			result.System = &stat
			return nil
		})
		return result, err

	case scope == "transient":
		err = a.ResourceManager.ViewTransient(func(s network.ResourceScope) error {
			stat := s.Stat()
			result.Transient = &stat
			return nil
		})
		return result, err

	case strings.HasPrefix(scope, "svc:"):
		svc := scope[4:]
		err = a.ResourceManager.ViewService(svc, func(s network.ServiceScope) error {
			stat := s.Stat()
			result.Services = map[string]network.ScopeStat{
				svc: stat,
			}
			return nil
		})
		return result, err

	case strings.HasPrefix(scope, "proto:"):
		proto := scope[6:]
		err = a.ResourceManager.ViewProtocol(protocol.ID(proto), func(s network.ProtocolScope) error {
			stat := s.Stat()
			result.Protocols = map[string]network.ScopeStat{
				proto: stat,
			}
			return nil
		})
		return result, err

	case strings.HasPrefix(scope, "peer:"):
		p := scope[5:]
		pid, err := peer.IDFromString(p)
		if err != nil {
			return result, err
		}
		err = a.ResourceManager.ViewPeer(pid, func(s network.PeerScope) error {
			stat := s.Stat()
			result.Peers = map[string]network.ScopeStat{
				p: stat,
			}
			return nil
		})
		return result, err

	default:
		return result, xerrors.Errorf("invalid scope %s", scope)
	}
}