package api

import (
	"context"
	"errors"
	"fmt"
	"os"

	"github.com/garethgeorge/resticui/gen/go/types"
	v1 "github.com/garethgeorge/resticui/gen/go/v1"
	"github.com/garethgeorge/resticui/internal/config"
	"github.com/garethgeorge/resticui/internal/oplog"
	"github.com/garethgeorge/resticui/internal/orchestrator"
	"github.com/garethgeorge/resticui/pkg/restic"
	"go.uber.org/zap"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/known/emptypb"
)

type Server struct {
	*v1.UnimplementedResticUIServer
	orchestrator *orchestrator.Orchestrator
	oplog *oplog.OpLog
}

var _ v1.ResticUIServer = &Server{}

func NewServer(orchestrator *orchestrator.Orchestrator, oplog *oplog.OpLog) *Server {
	s := &Server{
		orchestrator: orchestrator,
	}

	return s
}

// GetConfig implements GET /v1/config
func (s *Server) GetConfig(ctx context.Context, empty *emptypb.Empty) (*v1.Config, error) {
	return config.Default.Get()
}

// SetConfig implements POST /v1/config
func (s *Server) SetConfig(ctx context.Context, c *v1.Config) (*v1.Config, error) {
	existing, err := config.Default.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to check current config: %w", err)
	}

	// Compare and increment modno
	if existing.Modno != c.Modno {
		return nil, errors.New("config modno mismatch, reload and try again")
	}
	c.Modno += 1
	
	if err := config.Default.Update(c); err != nil {
		return nil, fmt.Errorf("failed to update config: %w", err)
	}
	return config.Default.Get()
}

// AddRepo implements POST /v1/config/repo, it includes validation that the repo can be initialized.
func (s *Server) AddRepo(ctx context.Context, repo *v1.Repo) (*v1.Config, error) {
	c, err := config.Default.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get config: %w", err)
	}

	c = proto.Clone(c).(*v1.Config)
	c.Repos = append(c.Repos, repo)

	if err := config.ValidateConfig(c); err != nil {
		return nil, fmt.Errorf("validation error: %w", err)
	}

	r := restic.NewRepo(repo)
	 // use background context such that the init op can try to complete even if the connection is closed.
	if err := r.Init(context.Background()); err != nil {
		return nil, fmt.Errorf("failed to init repo: %w", err)
	}

	zap.L().Debug("Updating config")
	if err := config.Default.Update(c); err != nil {
		return nil, fmt.Errorf("failed to update config: %w", err)
	}

	s.orchestrator.ApplyConfig(c)

	return c, nil
}

// ListSnapshots implements GET /v1/snapshots/{repo.id}/{plan.id?}
func (s *Server) ListSnapshots(ctx context.Context, query *v1.ListSnapshotsRequest) (*v1.ResticSnapshotList, error) {
	repo, err := s.orchestrator.GetRepo(query.RepoId)
	if err != nil {
		return nil, fmt.Errorf("failed to get repo: %w", err)
	}

	var snapshots []*restic.Snapshot
	if query.PlanId != "" {
		var plan *v1.Plan
		plan, err = s.orchestrator.GetPlan(query.PlanId)
		if err != nil {
			return nil, fmt.Errorf("failed to get plan %q: %w", query.PlanId, err)
		}

		snapshots, err = repo.SnapshotsForPlan(ctx, plan)
	} else {
		snapshots, err = repo.Snapshots(ctx)
	}

	if err != nil {
		return nil, fmt.Errorf("failed to list snapshots: %w", err)
	}

	// Transform the snapshots and return them.
	var rs []*v1.ResticSnapshot
	for _, snapshot := range snapshots {
		rs = append(rs, snapshot.ToProto())
	}

	return &v1.ResticSnapshotList{
		Snapshots: rs,
	}, nil
}

// GetEvents implements GET /v1/events
func (s *Server) GetOperationEvents(_ *emptypb.Empty, stream v1.ResticUI_GetOperationEventsServer) error {
	errorChan := make(chan error)
	defer close(errorChan)
	callback := func(eventType oplog.EventType, op *v1.Operation) {
		var eventTypeMapped v1.OperationEventType
		switch eventType {
		case oplog.EventTypeOpCreated:
			eventTypeMapped = v1.OperationEventType_EVENT_CREATED
		case oplog.EventTypeOpUpdated:
			eventTypeMapped = v1.OperationEventType_EVENT_UPDATED
		default:
			zap.L().Error("Unknown event type", zap.Int("eventType", int(eventType)))
			eventTypeMapped = v1.OperationEventType_EVENT_UNKNOWN
		}

		event := &v1.OperationEvent{
			Type: eventTypeMapped,
			Operation: op,
		}

		if err := stream.Send(event); err != nil {
			errorChan <- fmt.Errorf("failed to send event: %w", err)
		}
	}
	s.oplog.Subscribe(&callback)
	defer s.oplog.Unsubscribe(&callback)

	select {
	case <-stream.Context().Done():
		return nil
	case err := <-errorChan:
		return err
	}
}

func (s *Server) PathAutocomplete(ctx context.Context, path *types.StringValue) (*types.StringList, error) {
	ents, err := os.ReadDir(path.Value)
	if errors.Is(err, os.ErrNotExist) {
		return &types.StringList{}, nil
	} else if err != nil {
		return nil, err
	}

	var paths []string
	for _, ent := range ents {
		paths = append(paths, ent.Name())
	}

	return &types.StringList{Values: paths}, nil
}