/*
   Copyright The containerd Authors.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package introspection

import (
	context "context"
	"io/ioutil"
	"os"
	"path/filepath"
	"sync"

	api "github.com/containerd/containerd/api/services/introspection/v1"
	"github.com/containerd/containerd/api/types"
	"github.com/containerd/containerd/errdefs"
	"github.com/containerd/containerd/filters"
	"github.com/containerd/containerd/plugin"
	"github.com/gogo/googleapis/google/rpc"
	ptypes "github.com/gogo/protobuf/types"
	"github.com/google/uuid"
	"google.golang.org/grpc"
	"google.golang.org/grpc/status"
)

func init() {
	plugin.Register(&plugin.Registration{
		Type:     plugin.GRPCPlugin,
		ID:       "introspection",
		Requires: []plugin.Type{"*"},
		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
			// this service works by using the plugin context up till the point
			// this service is initialized. Since we require this service last,
			// it should provide the full set of plugins.
			pluginsPB := pluginsToPB(ic.GetAll())
			return NewService(pluginsPB, ic.Root), nil
		},
	})
}

type service struct {
	mu      sync.Mutex
	plugins []api.Plugin
	root    string
}

// NewService returns the GRPC introspection server
func NewService(plugins []api.Plugin, root string) api.IntrospectionServer {
	return &service{
		plugins: plugins,
		root:    root,
	}
}

func (s *service) Register(server *grpc.Server) error {
	api.RegisterIntrospectionServer(server, s)
	return nil
}

func (s *service) Plugins(ctx context.Context, req *api.PluginsRequest) (*api.PluginsResponse, error) {
	filter, err := filters.ParseAll(req.Filters...)
	if err != nil {
		return nil, errdefs.ToGRPCf(errdefs.ErrInvalidArgument, err.Error())
	}

	var plugins []api.Plugin
	for _, p := range s.plugins {
		if !filter.Match(adaptPlugin(p)) {
			continue
		}

		plugins = append(plugins, p)
	}

	return &api.PluginsResponse{
		Plugins: plugins,
	}, nil
}

func (s *service) Server(ctx context.Context, _ *ptypes.Empty) (*api.ServerResponse, error) {
	u, err := s.getUUID()
	if err != nil {
		return nil, errdefs.ToGRPC(err)
	}
	return &api.ServerResponse{
		UUID: u,
	}, nil
}

func (s *service) getUUID() (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	data, err := ioutil.ReadFile(s.uuidPath())
	if err != nil {
		if os.IsNotExist(err) {
			return s.generateUUID()
		}
		return "", err
	}
	u := string(data)
	if _, err := uuid.Parse(u); err != nil {
		return "", err
	}
	return u, nil
}

func (s *service) generateUUID() (string, error) {
	u, err := uuid.NewRandom()
	if err != nil {
		return "", err
	}
	path := s.uuidPath()
	if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
		return "", err
	}
	uu := u.String()
	if err := ioutil.WriteFile(path, []byte(uu), 0666); err != nil {
		return "", err
	}
	return uu, nil
}

func (s *service) uuidPath() string {
	return filepath.Join(s.root, "uuid")
}

func adaptPlugin(o interface{}) filters.Adaptor {
	obj := o.(api.Plugin)
	return filters.AdapterFunc(func(fieldpath []string) (string, bool) {
		if len(fieldpath) == 0 {
			return "", false
		}

		switch fieldpath[0] {
		case "type":
			return obj.Type, len(obj.Type) > 0
		case "id":
			return obj.ID, len(obj.ID) > 0
		case "platforms":
			// TODO(stevvooe): Another case here where have multiple values.
			// May need to refactor the filter system to allow filtering by
			// platform, if this is required.
		case "capabilities":
			// TODO(stevvooe): Need a better way to match against
			// collections. We can only return "the value" but really it
			// would be best if we could return a set of values for the
			// path, any of which could match.
		}

		return "", false
	})
}

func pluginsToPB(plugins []*plugin.Plugin) []api.Plugin {
	var pluginsPB []api.Plugin
	for _, p := range plugins {
		var platforms []types.Platform
		for _, p := range p.Meta.Platforms {
			platforms = append(platforms, types.Platform{
				OS:           p.OS,
				Architecture: p.Architecture,
				Variant:      p.Variant,
			})
		}

		var requires []string
		for _, r := range p.Registration.Requires {
			requires = append(requires, r.String())
		}

		var initErr *rpc.Status
		if err := p.Err(); err != nil {
			st, ok := status.FromError(errdefs.ToGRPC(err))
			if ok {
				var details []*ptypes.Any
				for _, d := range st.Proto().Details {
					details = append(details, &ptypes.Any{
						TypeUrl: d.TypeUrl,
						Value:   d.Value,
					})
				}
				initErr = &rpc.Status{
					Code:    int32(st.Code()),
					Message: st.Message(),
					Details: details,
				}
			} else {
				initErr = &rpc.Status{
					Code:    int32(rpc.UNKNOWN),
					Message: err.Error(),
				}
			}
		}

		pluginsPB = append(pluginsPB, api.Plugin{
			Type:         p.Registration.Type.String(),
			ID:           p.Registration.ID,
			Requires:     requires,
			Platforms:    platforms,
			Capabilities: p.Meta.Capabilities,
			Exports:      p.Meta.Exports,
			InitErr:      initErr,
		})
	}

	return pluginsPB
}
