package main

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/signal"
	"syscall"

	snapshotsapi "github.com/containerd/containerd/api/services/snapshots/v1"
	"github.com/containerd/containerd/contrib/snapshotservice"
	"github.com/containerd/containerd/mount"
	"github.com/containerd/containerd/namespaces"
	"github.com/containerd/containerd/snapshots"
	"golang.org/x/sync/errgroup"
	"google.golang.org/grpc"
)

const listenAddr = "./snapshotter.sock"

func main() {
	stop := make(chan os.Signal, 1)
	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM, syscall.SIGPIPE, syscall.SIGHUP, syscall.SIGQUIT)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	group, ctx := errgroup.WithContext(ctx)

	rpc := grpc.NewServer()

	snap := UnimplProxySnapshotter{}

	service := snapshotservice.FromSnapshotter(&snap)
	snapshotsapi.RegisterSnapshotsServer(rpc, service)

	listener, err := net.Listen("unix", listenAddr)
	if err != nil {
		fmt.Printf("failed to listen socket at %s: %s\n", listenAddr, err)
		return
	}

	group.Go(func() error {
		return rpc.Serve(listener)
	})

	group.Go(func() error {
		defer func() {
			rpc.Stop()
		}()

		for {
			select {
			case <-stop:
				cancel()
				return nil
			case <-ctx.Done():
				return ctx.Err()
			}
		}
	})

	if err := group.Wait(); err != nil {
		fmt.Printf("error running snapshotter: %s\n", err)
	}
}

type UnimplProxySnapshotter struct {
}

func (s *UnimplProxySnapshotter) Stat(ctx context.Context, key string) (snapshots.Info, error) {
	return snapshots.Info{}, nil
}

func (s *UnimplProxySnapshotter) Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (snapshots.Info, error) {
	return snapshots.Info{}, nil
}

func (s *UnimplProxySnapshotter) Usage(ctx context.Context, key string) (snapshots.Usage, error) {
	return snapshots.Usage{}, nil
}

func (s *UnimplProxySnapshotter) Mounts(ctx context.Context, key string) ([]mount.Mount, error) {
	return []mount.Mount{}, nil
}

func (s *UnimplProxySnapshotter) Prepare(ctx context.Context, key, parent string, opts ...snapshots.Opt) ([]mount.Mount, error) {
	namespace, err := namespaces.NamespaceRequired(ctx)
	if err != nil {
		fmt.Printf("Err getting namespace: %s\n", err)
	} else {
		fmt.Printf("Namespace: %s\n", namespace)
	}
	return []mount.Mount{}, nil
}

func (s *UnimplProxySnapshotter) View(ctx context.Context, key, parent string, opts ...snapshots.Opt) ([]mount.Mount, error) {
	return []mount.Mount{}, nil
}

func (s *UnimplProxySnapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) error {
	return nil
}

func (s *UnimplProxySnapshotter) Remove(ctx context.Context, key string) error {
	return nil
}

func (s *UnimplProxySnapshotter) Walk(ctx context.Context, fn snapshots.WalkFunc, filters ...string) error {
	return nil
}

func (s *UnimplProxySnapshotter) Close() error {
	return nil
}