package api

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"sync"
	"time"

	"connectrpc.com/connect"
	"github.com/garethgeorge/backrest/gen/go/types"
	v1 "github.com/garethgeorge/backrest/gen/go/v1"
	"github.com/garethgeorge/backrest/gen/go/v1/v1connect"
	"github.com/garethgeorge/backrest/internal/api/sftputil"
	syncapi "github.com/garethgeorge/backrest/internal/api/syncapi"
	"github.com/garethgeorge/backrest/internal/config"
	"github.com/garethgeorge/backrest/internal/cryptoutil"
	"github.com/garethgeorge/backrest/internal/env"
	"github.com/garethgeorge/backrest/internal/logstore"
	"github.com/garethgeorge/backrest/internal/oplog"
	"github.com/garethgeorge/backrest/internal/orchestrator"
	"github.com/garethgeorge/backrest/internal/orchestrator/repo"
	"github.com/garethgeorge/backrest/internal/orchestrator/tasks"
	"github.com/garethgeorge/backrest/internal/protoutil"
	"github.com/garethgeorge/backrest/internal/resticinstaller"
	"github.com/garethgeorge/backrest/pkg/restic"
	"go.uber.org/zap"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/known/emptypb"
)

type BackrestHandler struct {
	v1connect.UnimplementedBackrestHandler
	config           config.ConfigStore
	orchestrator     *orchestrator.Orchestrator
	oplog            *oplog.OpLog
	logStore         *logstore.LogStore
	peerStateManager syncapi.PeerStateManager
}

var _ v1connect.BackrestHandler = &BackrestHandler{}

func NewBackrestHandler(config config.ConfigStore, peerStateManager syncapi.PeerStateManager, orchestrator *orchestrator.Orchestrator, oplog *oplog.OpLog, logStore *logstore.LogStore) *BackrestHandler {
	s := &BackrestHandler{
		config:           config,
		orchestrator:     orchestrator,
		oplog:            oplog,
		logStore:         logStore,
		peerStateManager: peerStateManager,
	}

	return s
}

// GetConfig implements GET /v1/config
func (s *BackrestHandler) GetConfig(ctx context.Context, req *connect.Request[emptypb.Empty]) (*connect.Response[v1.Config], error) {
	c, err := s.config.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get config: %w", err)
	}
	return connect.NewResponse(config.SanitizeForNetwork(c)), nil
}

// SetConfig implements POST /v1/config
func (s *BackrestHandler) SetConfig(ctx context.Context, req *connect.Request[v1.Config]) (*connect.Response[v1.Config], error) {
	if err := s.config.Transform(func(cfg *v1.Config) (*v1.Config, error) {
		if cfg.Modno != req.Msg.Modno {
			return nil, connect.NewError(connect.CodeFailedPrecondition, errors.New("config modno mismatch, reload and try again"))
		}
		rehydrated := config.RehydrateNetworkSanitizedConfig(req.Msg, cfg)
		if err := config.ValidateConfig(rehydrated); err != nil {
			return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("validation error: %w", err))
		}
		rehydrated.Modno++
		return rehydrated, nil
	}); err != nil {
		return nil, fmt.Errorf("failed to update config: %w", err)
	}

	newConfig, err := s.config.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get newly set config: %w", err)
	}
	return connect.NewResponse(config.SanitizeForNetwork(newConfig)), nil
}

// cloneConfigWithRepo fetches the current config, sanitizes and upserts r into a clone of it,
// then locates the restic binary and builds a RepoOrchestrator for r against the cloned config.
// oldRepo is the previously-existing repo with the same ID, or nil if r is new.
func (s *BackrestHandler) cloneConfigWithRepo(r *v1.Repo) (cfg *v1.Config, oldRepo *v1.Repo, orch *repo.RepoOrchestrator, err error) {
	cfg, err = s.config.Get()
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to get config: %w", err)
	}

	sanitizeRepoFlags(r)

	cfg = proto.Clone(cfg).(*v1.Config)
	if idx := slices.IndexFunc(cfg.Repos, func(x *v1.Repo) bool { return x.Id == r.Id }); idx != -1 {
		oldRepo = cfg.Repos[idx]
		cfg.Repos[idx] = r
	} else {
		cfg.Repos = append(cfg.Repos, r)
	}

	bin, err := resticinstaller.FindOrInstallResticBinary()
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to find or install restic binary: %w", err)
	}

	orch, err = repo.NewRepoOrchestrator(cfg, r, bin)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to configure repo: %w", err)
	}

	return cfg, oldRepo, orch, nil
}

func (s *BackrestHandler) CheckRepoExists(ctx context.Context, req *connect.Request[v1.CheckRepoExistsRequest]) (*connect.Response[v1.CheckRepoExistsResponse], error) {
	if req.Msg.Repo.Guid == "" {
		req.Msg.Repo.Guid = cryptoutil.MustRandomID(cryptoutil.DefaultIDBits)
	}

	c, _, r, err := s.cloneConfigWithRepo(req.Msg.Repo)
	if err != nil {
		return nil, err
	}

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

	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
	defer cancel()

	if err := r.Exists(ctx); err != nil {
		zap.S().Debugf("repo %q exists or not: %v", req.Msg.Repo.Id, err)
		if errors.Is(err, restic.ErrRepoNotFound) {
			zap.S().Debugf("repo %q does not exist", req.Msg.Repo.Id)
			return connect.NewResponse(&v1.CheckRepoExistsResponse{Exists: false}), nil
		}
		// restic's sftp backend shells out to ssh; with an unknown or mismatched
		// host key (and BatchMode=yes) ssh prints a host-key verification failure
		// to stderr, which surfaces inside the wrapped restic error. Report this
		// to the UI so it can offer the host-key trust / Setup SSH Key flow instead
		// of a generic error.
		if isHostKeyVerificationError(err) {
			zap.S().Debugf("repo %q host key untrusted", req.Msg.Repo.Id)
			return connect.NewResponse(&v1.CheckRepoExistsResponse{HostKeyUntrusted: true}), nil
		}
		return nil, err
	}
	return connect.NewResponse(&v1.CheckRepoExistsResponse{Exists: true}), nil
}

// hostKeyVerificationMarkers are substrings (matched case-insensitively) that
// OpenSSH emits to stderr when it refuses to connect because the server's host
// key is unknown or does not match the pinned known_hosts entry. restic's sftp
// backend forwards ssh's stderr into the error it returns.
var hostKeyVerificationMarkers = []string{
	"host key verification failed",
	"remote host identification has changed",
}

// isHostKeyVerificationError reports whether err (anywhere in its chain of
// wrapped messages) looks like an ssh host-key verification failure.
func isHostKeyVerificationError(err error) bool {
	if err == nil {
		return false
	}
	msg := strings.ToLower(err.Error())
	for _, marker := range hostKeyVerificationMarkers {
		if strings.Contains(msg, marker) {
			return true
		}
	}
	return false
}

// AddRepo implements POST /v1/config/repo, it includes validation that the repo can be initialized.
func (s *BackrestHandler) AddRepo(ctx context.Context, req *connect.Request[v1.AddRepoRequest]) (*connect.Response[v1.Config], error) {
	newRepo := req.Msg.Repo

	// Perform all of the (slow) restic I/O against a candidate config BEFORE
	// committing any config mutation. This avoids clobbering a concurrent
	// SetConfig that lands during the I/O window: the actual config mutation is
	// applied atomically via s.config.Transform against the current config below.
	//
	// Ensure the Repo GUID is set to the correct value.
	// This is derived from 'restic cat config' for local repos.
	// For remote repos, the GUID is derived from the remote config's value for the repo.
	_, _, r, err := s.cloneConfigWithRepo(newRepo)
	if err != nil {
		return nil, err
	}

	if err := r.Init(ctx); err != nil {
		return nil, fmt.Errorf("failed to init repo: %w", err)
	}

	guid, err := r.RepoGUID()
	zap.S().Debugf("GUID for repo %q is %q from restic", newRepo.Id, guid)
	if err != nil {
		return nil, fmt.Errorf("failed to get repo config: %w", err)
	}

	newRepo.Guid = guid

	// Commit the config mutation atomically. Re-upsert the GUID-stamped repo into
	// the CURRENT config (not the pre-I/O snapshot) so a concurrent update during
	// the restic I/O above is preserved. oldRepo and instanceID are captured from
	// the transform-time config for correct GUID-change detection and oplog migration.
	var oldRepo *v1.Repo
	var instanceID string
	zap.L().Debug("updating config")
	if err := s.config.Transform(func(cfg *v1.Config) (*v1.Config, error) {
		instanceID = cfg.Instance
		if idx := slices.IndexFunc(cfg.Repos, func(x *v1.Repo) bool { return x.Id == newRepo.Id }); idx != -1 {
			oldRepo = cfg.Repos[idx]
			cfg.Repos[idx] = newRepo
		} else {
			oldRepo = nil
			cfg.Repos = append(cfg.Repos, newRepo)
		}
		if err := config.ValidateConfig(cfg); err != nil {
			return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("validation error: %w", err))
		}
		return cfg, nil
	}); err != nil {
		return nil, fmt.Errorf("failed to update config: %w", err)
	}

	// If the GUID has changed, and we just successfully updated the config in storage, then we need to migrate the oplog.
	if oldRepo != nil && newRepo.Guid != oldRepo.Guid {
		migratedCount := 0

		q := oplog.Query{}.
			SetInstanceID(instanceID)
		// we use RepoID here to _ensure_ we consolidate all operations to the most recent GUID.
		// this provides some resiliancy in the case of a previous partial update.
		q.DeprecatedRepoID = &oldRepo.Id
		if err := s.oplog.Transform(q, func(op *v1.Operation) (*v1.Operation, error) {
			op.RepoGuid = newRepo.Guid
			migratedCount++
			return op, nil
		}); err != nil {
			return nil, fmt.Errorf("failed to get operations for repo: %w", err)
		}

		zap.S().Infof("updated GUID for repo %q from %q to %q, migrated %d operations to reference the new GUID", newRepo.Id, oldRepo.Guid, newRepo.Guid, migratedCount)
	}

	// index snapshots for the newly added repository.
	zap.L().Debug("scheduling index snapshots task")
	s.orchestrator.ScheduleTask(tasks.NewOneoffIndexSnapshotsTask(newRepo, time.Now()), tasks.TaskPriorityInteractive+tasks.TaskPriorityIndexSnapshots)

	newConfig, err := s.config.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get newly set config: %w", err)
	}
	zap.L().Debug("done add repo")
	return connect.NewResponse(config.SanitizeForNetwork(newConfig)), nil
}

func (s *BackrestHandler) RemoveRepo(ctx context.Context, req *connect.Request[v1.RemoveRepoRequest]) (*connect.Response[v1.Config], error) {
	var instanceID string
	if err := s.config.Transform(func(cfg *v1.Config) (*v1.Config, error) {
		instanceID = cfg.Instance
		cfg.Repos = slices.DeleteFunc(cfg.Repos, func(r *v1.Repo) bool {
			return r.Id == req.Msg.RepoId
		})
		return cfg, nil
	}); err != nil {
		return nil, fmt.Errorf("failed to update config: %w", err)
	}

	// Query for all operations for the repo
	q := oplog.Query{}.SetInstanceID(instanceID)
	q.DeprecatedRepoID = &req.Msg.RepoId
	var opIDs []int64
	if err := s.oplog.Query(q, func(op *v1.Operation) error {
		opIDs = append(opIDs, op.Id)
		return nil
	}); err != nil {
		return nil, fmt.Errorf("failed to get operations for repo: %w", err)
	}

	// Delete operations referencing the repo from the oplog in batches
	for len(opIDs) > 0 {
		batchSize := min(256, len(opIDs))
		if err := s.oplog.Delete(opIDs[:batchSize]...); err != nil {
			return nil, fmt.Errorf("failed to delete operations: %w", err)
		}
		opIDs = opIDs[batchSize:]
	}

	newConfig, err := s.config.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get config: %w", err)
	}
	return connect.NewResponse(config.SanitizeForNetwork(newConfig)), nil
}

// SetupSftp implements SetupSftp RPC
func (s *BackrestHandler) SetupSftp(ctx context.Context, req *connect.Request[v1.SetupSftpRequest]) (*connect.Response[v1.SetupSftpResponse], error) {
	host := req.Msg.Host
	port := req.Msg.Port
	if port == "" {
		port = "22"
	}

	if runtime.GOOS == "windows" {
		return nil, connect.NewError(connect.CodeUnimplemented, errors.New("automated SFTP setup is not supported on Windows"))
	}

	// 1. Generate key pair (local, always succeeds)
	_, pubBytes, keyPath, err := sftputil.GenerateKey(host, env.SSHDir())
	if err != nil {
		return nil, fmt.Errorf("failed to generate key: %w", err)
	}

	// 2. Scan remote host key into known_hosts (network, non-fatal)
	var hostKeyWarning string
	if err := sftputil.AddHostKey(host, port, env.SSHDir()); err != nil {
		zap.S().Warnf("SFTP host key scan failed for %s: %v", host, err)
		hostKeyWarning = fmt.Sprintf("Could not scan host key (%v). Add the host key to known_hosts manually or ensure the host is reachable.", err)
	}

	return connect.NewResponse(&v1.SetupSftpResponse{
		PublicKey:      string(pubBytes),
		KeyPath:        keyPath,
		KnownHostsPath: filepath.Join(env.SSHDir(), "known_hosts"),
		Error:          hostKeyWarning,
	}), nil
}

// ListSnapshots implements POST /v1/snapshots
func (s *BackrestHandler) ListSnapshots(ctx context.Context, req *connect.Request[v1.ListSnapshotsRequest]) (*connect.Response[v1.ResticSnapshotList], error) {
	query := req.Msg
	repo, err := s.orchestrator.GetRepoOrchestrator(query.RepoId)
	if err != nil {
		return nil, withLookupCode(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, withLookupCode(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, protoutil.SnapshotToProto(snapshot))
	}

	return connect.NewResponse(&v1.ResticSnapshotList{
		Snapshots: rs,
	}), nil
}

func (s *BackrestHandler) ListSnapshotFiles(ctx context.Context, req *connect.Request[v1.ListSnapshotFilesRequest]) (*connect.Response[v1.ListSnapshotFilesResponse], error) {
	query := req.Msg

	repo, err := s.orchestrator.GetRepoOrchestrator(query.RepoId)
	if err != nil {
		return nil, withLookupCode(fmt.Errorf("failed to get repo: %w", err))
	}

	entries, err := repo.ListSnapshotFiles(ctx, query.SnapshotId, query.Path)
	if err != nil {
		return nil, fmt.Errorf("failed to list snapshot files: %w", err)
	}

	return connect.NewResponse(&v1.ListSnapshotFilesResponse{
		Path:    query.Path,
		Entries: entries,
	}), nil
}

// GetOperationEvents implements GET /v1/events/operations
func (s *BackrestHandler) GetOperationEvents(ctx context.Context, req *connect.Request[emptypb.Empty], resp *connect.ServerStream[v1.OperationEvent]) error {
	errChan := make(chan error, 1)
	events := make(chan *v1.OperationEvent, 100)

	timer := time.NewTicker(60 * time.Second)
	defer timer.Stop()

	callback := func(ops []*v1.Operation, eventType oplog.OperationEvent) {
		var event *v1.OperationEvent
		switch eventType {
		case oplog.OPERATION_ADDED:
			event = &v1.OperationEvent{
				Event: &v1.OperationEvent_CreatedOperations{
					CreatedOperations: &v1.OperationList{
						Operations: ops,
					},
				},
			}
		case oplog.OPERATION_UPDATED:
			event = &v1.OperationEvent{
				Event: &v1.OperationEvent_UpdatedOperations{
					UpdatedOperations: &v1.OperationList{
						Operations: ops,
					},
				},
			}
		case oplog.OPERATION_DELETED:
			ids := make([]int64, len(ops))
			for i, o := range ops {
				ids[i] = o.Id
			}

			event = &v1.OperationEvent{
				Event: &v1.OperationEvent_DeletedOperations{
					DeletedOperations: &types.Int64List{
						Values: ids,
					},
				},
			}
		default:
			zap.L().Error("Unknown event type")
		}

		select {
		case events <- event:
		default:
			select {
			case errChan <- errors.New("event buffer overflow, closing stream for client retry and catchup"):
			default:
			}
		}
	}

	s.oplog.Subscribe(oplog.SelectAll, &callback)
	defer func() {
		if err := s.oplog.Unsubscribe(&callback); err != nil {
			zap.L().Error("failed to unsubscribe from oplog", zap.Error(err))
		}
	}()

	for {
		select {
		case <-timer.C:
			if err := resp.Send(&v1.OperationEvent{
				Event: &v1.OperationEvent_KeepAlive{},
			}); err != nil {
				return err
			}
		case err := <-errChan:
			return err
		case <-ctx.Done():
			return nil
		case event := <-events:
			if err := resp.Send(event); err != nil {
				return err
			}
		}
	}
}

func (s *BackrestHandler) GetOperations(ctx context.Context, req *connect.Request[v1.GetOperationsRequest]) (*connect.Response[v1.OperationList], error) {
	q, err := protoutil.OpSelectorToQuery(req.Msg.Selector)
	if err != nil {
		return nil, err
	}
	if req.Msg.LastN != 0 {
		q.Reversed = true
		q.Limit = int(req.Msg.LastN)
	}

	var ops []*v1.Operation
	opCollector := func(op *v1.Operation) error {
		ops = append(ops, op)
		return nil
	}
	err = s.oplog.Query(q, opCollector)
	if err != nil {
		return nil, fmt.Errorf("failed to get operations: %w", err)
	}

	slices.SortFunc(ops, func(i, j *v1.Operation) int {
		if i.Id < j.Id {
			return -1
		}
		return 1
	})

	return connect.NewResponse(&v1.OperationList{
		Operations: ops,
	}), nil
}

// scheduleTaskAndWait schedules the task and blocks until it completes, returning the task's error.
func (s *BackrestHandler) scheduleTaskAndWait(t tasks.Task, priority int) error {
	var taskErr error
	wait := make(chan struct{})
	if _, err := s.orchestrator.ScheduleTask(t, priority, func(e error) { taskErr = e; close(wait) }); err != nil {
		return err
	}
	<-wait
	return taskErr
}

func (s *BackrestHandler) Backup(ctx context.Context, req *connect.Request[v1.BackupRequest]) (*connect.Response[emptypb.Empty], error) {
	plan, err := s.orchestrator.GetPlan(req.Msg.Value)
	if err != nil {
		return nil, withLookupCode(err)
	}
	repo, err := s.orchestrator.GetRepo(plan.Repo)
	if err != nil {
		return nil, withLookupCode(err)
	}
	if err := s.scheduleTaskAndWait(tasks.NewOneoffBackupTask(repo, plan, time.Now(), req.Msg.DryRun), tasks.TaskPriorityInteractive); err != nil {
		return nil, err
	}
	return connect.NewResponse(&emptypb.Empty{}), nil
}

func (s *BackrestHandler) Forget(ctx context.Context, req *connect.Request[v1.ForgetRequest]) (*connect.Response[v1.ScheduleTaskResponse], error) {
	at := time.Now()

	repo, err := s.orchestrator.GetRepo(req.Msg.RepoId)
	if err != nil {
		return nil, withLookupCode(err)
	}

	if req.Msg.PlanId == "" {
		return nil, connect.NewError(connect.CodeInvalidArgument, errors.New("must specify repoId and planId and (optionally) snapshotId"))
	}

	var task tasks.Task
	if req.Msg.SnapshotId != "" {
		task = tasks.NewOneoffForgetSnapshotTask(repo, req.Msg.PlanId, 0, at, req.Msg.SnapshotId)
	} else {
		task = tasks.NewOneoffForgetTask(repo, req.Msg.PlanId, 0, at)
	}

	id, err := s.orchestrator.ScheduleTask(task, tasks.TaskPriorityInteractive+tasks.TaskPriorityForget)
	if err != nil {
		return nil, fmt.Errorf("failed to schedule forget task: %w", err)
	}
	return connect.NewResponse(&v1.ScheduleTaskResponse{OperationId: id}), nil
}

func (s BackrestHandler) DoRepoTask(ctx context.Context, req *connect.Request[v1.DoRepoTaskRequest]) (*connect.Response[v1.ScheduleTaskResponse], error) {
	var task tasks.Task

	repo, err := s.orchestrator.GetRepo(req.Msg.RepoId)
	if err != nil {
		return nil, withLookupCode(err)
	}

	priority := tasks.TaskPriorityInteractive
	switch req.Msg.Task {
	case v1.DoRepoTaskRequest_TASK_CHECK:
		task = tasks.NewCheckTask(repo, tasks.PlanForSystemTasks, true)
	case v1.DoRepoTaskRequest_TASK_PRUNE:
		task = tasks.NewPruneTask(repo, tasks.PlanForSystemTasks, true)
		priority |= tasks.TaskPriorityPrune
	case v1.DoRepoTaskRequest_TASK_FORGET:
		if repo.GetForgetPolicy() == nil {
			return nil, fmt.Errorf("repo %q has no forget policy configured", req.Msg.RepoId)
		}
		task = tasks.NewScheduledForgetTask(repo, tasks.PlanForSystemTasks, true)
		priority |= tasks.TaskPriorityForget
	case v1.DoRepoTaskRequest_TASK_STATS:
		task = tasks.NewStatsTask(repo, tasks.PlanForSystemTasks, true)
		priority |= tasks.TaskPriorityStats
	case v1.DoRepoTaskRequest_TASK_INDEX_SNAPSHOTS:
		task = tasks.NewOneoffIndexSnapshotsTask(repo, time.Now())
		priority |= tasks.TaskPriorityIndexSnapshots
	case v1.DoRepoTaskRequest_TASK_UNLOCK:
		repo, err := s.orchestrator.GetRepoOrchestrator(req.Msg.RepoId)
		if err != nil {
			return nil, withLookupCode(err)
		}
		if err := repo.Unlock(ctx); err != nil {
			return nil, fmt.Errorf("failed to unlock repo %q: %w", req.Msg.RepoId, err)
		}
		return connect.NewResponse(&v1.ScheduleTaskResponse{OperationId: 0}), nil
	default:
		return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("unknown task %v", req.Msg.Task.String()))
	}

	id, err := s.orchestrator.ScheduleTask(task, priority)
	if err != nil {
		return nil, fmt.Errorf("failed to schedule task: %w", err)
	}
	return connect.NewResponse(&v1.ScheduleTaskResponse{OperationId: id}), nil
}

func (s *BackrestHandler) Restore(ctx context.Context, req *connect.Request[v1.RestoreSnapshotRequest]) (*connect.Response[v1.ScheduleTaskResponse], error) {
	req.Msg.Target = strings.TrimSpace(req.Msg.Target)
	req.Msg.Path = strings.TrimSpace(req.Msg.Path)

	if req.Msg.Target == "" {
		req.Msg.Target = path.Join(os.Getenv("HOME"), "Downloads", fmt.Sprintf("restic-restore-%v", time.Now().Format("2006-01-02T15-04-05")))
	}
	if req.Msg.Path == "" {
		req.Msg.Path = "/"
	}
	// prevent restoring to a directory that already exists
	if _, err := os.Stat(req.Msg.Target); err == nil {
		return nil, connect.NewError(connect.CodeFailedPrecondition, fmt.Errorf("target directory %q already exists", req.Msg.Target))
	}

	repo, err := s.orchestrator.GetRepo(req.Msg.RepoId)
	if err != nil {
		return nil, withLookupCode(err)
	}

	at := time.Now()
	id, err := s.orchestrator.ScheduleTask(tasks.NewOneoffRestoreTask(repo, req.Msg.PlanId, 0 /* flowID */, at, req.Msg.SnapshotId, req.Msg.Path, req.Msg.Target), tasks.TaskPriorityInteractive+tasks.TaskPriorityDefault)
	if err != nil {
		return nil, fmt.Errorf("failed to schedule restore task: %w", err)
	}

	return connect.NewResponse(&v1.ScheduleTaskResponse{OperationId: id}), nil
}

func (s *BackrestHandler) RunCommand(ctx context.Context, req *connect.Request[v1.RunCommandRequest]) (*connect.Response[v1.RunCommandResponse], error) {
	cfg, err := s.config.Get()
	if err != nil {
		return nil, fmt.Errorf("failed to get config: %w", err)
	}
	repo := config.FindRepo(cfg, req.Msg.RepoId)
	if repo == nil {
		return nil, connect.NewError(connect.CodeNotFound, fmt.Errorf("repo %q not found", req.Msg.RepoId))
	}

	// group commands within the last 24 hours (or 256 operations) into the same flow ID
	var flowID int64
	if s.oplog.Query(oplog.Query{}.
		SetInstanceID(cfg.Instance).
		SetRepoGUID(repo.GetGuid()).
		SetLimit(256).
		SetReversed(true), func(op *v1.Operation) error {
		if op.GetOperationRunCommand() != nil && time.Since(time.UnixMilli(op.UnixTimeStartMs)) < 30*time.Minute {
			flowID = op.FlowId
		}
		return nil
	}) != nil {
		return nil, fmt.Errorf("failed to query operations")
	}

	task := tasks.NewOneoffRunCommandTask(repo, tasks.PlanForSystemTasks, flowID, time.Now(), req.Msg.Command)
	st, err := s.orchestrator.CreateUnscheduledTask(task, tasks.TaskPriorityInteractive, time.Now())
	if err != nil {
		return nil, fmt.Errorf("failed to create task: %w", err)
	}
	if err := s.orchestrator.RunTask(context.Background(), st); err != nil {
		return nil, fmt.Errorf("failed to run command: %w", err)
	}

	return connect.NewResponse(&v1.RunCommandResponse{OperationId: st.Op.GetId()}), nil
}

func (s *BackrestHandler) Cancel(ctx context.Context, req *connect.Request[v1.CancelOperationRequest]) (*connect.Response[emptypb.Empty], error) {
	if err := s.orchestrator.CancelOperation(req.Msg.OperationId, v1.OperationStatus_STATUS_USER_CANCELLED); err != nil {
		return nil, err
	}

	return connect.NewResponse(&emptypb.Empty{}), nil
}

func (s *BackrestHandler) ClearHistory(ctx context.Context, req *connect.Request[v1.ClearHistoryRequest]) (*connect.Response[emptypb.Empty], error) {
	var err error
	var ids []int64

	opCollector := func(op *v1.Operation) error {
		if !req.Msg.OnlyFailed || op.Status == v1.OperationStatus_STATUS_ERROR {
			ids = append(ids, op.Id)
		}
		return nil
	}

	q, err := protoutil.OpSelectorToQuery(req.Msg.Selector)
	if err != nil {
		return nil, err
	}
	if err := s.oplog.Query(q, opCollector); err != nil {
		return nil, fmt.Errorf("failed to get operations to delete: %w", err)
	}

	if err := s.oplog.Delete(ids...); err != nil {
		return nil, fmt.Errorf("failed to delete operations: %w", err)
	}

	return connect.NewResponse(&emptypb.Empty{}), err
}

func (s *BackrestHandler) GetLogs(ctx context.Context, req *connect.Request[v1.LogDataRequest], resp *connect.ServerStream[types.BytesValue]) error {
	r, err := s.logStore.Open(req.Msg.Ref)
	if err != nil {
		if errors.Is(err, logstore.ErrLogNotFound) {
			resp.Send(&types.BytesValue{
				Value: []byte(fmt.Sprintf("file associated with log %v not found, it may have expired.", req.Msg.GetRef())),
			})
			return nil
		}
		return fmt.Errorf("get log data %v: %w", req.Msg.GetRef(), err)
	}
	go func() {
		<-ctx.Done()
		r.Close()
	}()

	var errChan = make(chan error, 1)
	var sendChan = make(chan []byte, 1)
	var buffer bytes.Buffer
	var bufferMu sync.Mutex

	go func() {
		data := make([]byte, 4*1024)
		for {
			n, err := r.Read(data)
			if n == 0 {
				break
			} else if err != nil && err != io.EOF {
				errChan <- fmt.Errorf("failed to read log data: %w", err)
				close(errChan)
				break
			}
			bufferMu.Lock()
			buffer.Write(data[:n])
			if buffer.Len() > 128*1024 {
				sendChan <- bytes.Clone(buffer.Bytes())
				buffer.Reset()
			}
			bufferMu.Unlock()
		}

		if buffer.Len() > 0 {
			bufferMu.Lock()
			sendChan <- bytes.Clone(buffer.Bytes())
			buffer.Reset()
			bufferMu.Unlock()
		}
		close(sendChan)
	}()

	ticker := time.NewTicker(100 * time.Millisecond)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			return nil
		case data, ok := <-sendChan:
			if !ok {
				return nil
			}
			if err := resp.Send(&types.BytesValue{Value: data}); err != nil {
				return err
			}
		case err := <-errChan:
			return err
		case <-ticker.C:
			bufferMu.Lock()
			if buffer.Len() > 0 {
				if err := resp.Send(&types.BytesValue{Value: bytes.Clone(buffer.Bytes())}); err != nil {
					bufferMu.Unlock()
					return err
				}
				buffer.Reset()
			}
			bufferMu.Unlock()
		}
	}

}

func (s *BackrestHandler) GetDownloadURL(ctx context.Context, req *connect.Request[v1.GetDownloadURLRequest]) (*connect.Response[types.StringValue], error) {
	op, err := s.oplog.Get(req.Msg.OpId)
	if err != nil {
		if errors.Is(err, oplog.ErrNotExist) {
			return nil, connect.NewError(connect.CodeNotFound, fmt.Errorf("failed to get operation %v: %w", req.Msg.OpId, err))
		}
		return nil, fmt.Errorf("failed to get operation %v: %w", req.Msg.OpId, err)
	}

	var opType string
	switch op.Op.(type) {
	case *v1.Operation_OperationIndexSnapshot:
		opType = "snapshot"
	case *v1.Operation_OperationRestore:
		opType = "restore"
	default:
		return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("operation %v is not a restore or snapshot operation", req.Msg.OpId))
	}

	token, err := signDownloadToken(DownloadTokenPayload{
		OpID:     op.Id,
		Type:     opType,
		FilePath: req.Msg.FilePath,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to generate token: %w", err)
	}
	return connect.NewResponse(&types.StringValue{
		Value: fmt.Sprintf("./download/%s/", token),
	}), nil
}

func (s *BackrestHandler) PathAutocomplete(ctx context.Context, path *connect.Request[types.StringValue]) (*connect.Response[types.StringList], error) {
	ents, err := os.ReadDir(path.Msg.Value)
	if errors.Is(err, os.ErrNotExist) {
		return connect.NewResponse(&types.StringList{}), nil
	} else if err != nil {
		return nil, err
	}

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

	return connect.NewResponse(&types.StringList{Values: paths}), nil
}

func (s *BackrestHandler) GeneratePairingToken(ctx context.Context, req *connect.Request[v1.GeneratePairingTokenRequest]) (*connect.Response[v1.GeneratePairingTokenResponse], error) {
	// Generate the one-time secret before taking the lock.
	secret, err := cryptoutil.GeneratePairingSecret()
	if err != nil {
		return nil, fmt.Errorf("failed to generate pairing secret: %w", err)
	}

	now := time.Now().Unix()
	var expiresAt int64
	if req.Msg.TtlSeconds > 0 {
		expiresAt = now + req.Msg.TtlSeconds
	}

	var tokenStr string
	if err := s.config.Transform(func(cfg *v1.Config) (*v1.Config, error) {
		if cfg.Instance == "" {
			return nil, connect.NewError(connect.CodeFailedPrecondition, errors.New("instance name must be set before generating pairing tokens"))
		}

		identity := cfg.GetMultihost().GetIdentity()
		if identity == nil {
			return nil, connect.NewError(connect.CodeFailedPrecondition, errors.New("multihost identity must be configured before generating pairing tokens"))
		}

		cfg.Multihost.PairingTokens = append(cfg.Multihost.PairingTokens, &v1.Multihost_PairingToken{
			Secret:        secret,
			Label:         req.Msg.Label,
			CreatedAtUnix: now,
			ExpiresAtUnix: expiresAt,
			MaxUses:       req.Msg.MaxUses,
			Uses:          0,
			Permissions:   req.Msg.Permissions,
		})
		cfg.Modno++

		tokenStr = cryptoutil.FormatPairingToken(identity.Keyid, secret, cfg.Instance)
		return cfg, nil
	}); err != nil {
		return nil, fmt.Errorf("failed to save pairing token: %w", err)
	}

	return connect.NewResponse(&v1.GeneratePairingTokenResponse{
		Token: tokenStr,
	}), nil
}

// withLookupCode tags err with connect.CodeNotFound when it stems from a missing
// repo or plan lookup (orchestrator.ErrRepoNotFound / ErrPlanNotFound), preserving
// the original message. Other errors are returned unchanged.
func withLookupCode(err error) error {
	if err == nil {
		return nil
	}
	if errors.Is(err, orchestrator.ErrRepoNotFound) || errors.Is(err, orchestrator.ErrPlanNotFound) {
		return connect.NewError(connect.CodeNotFound, err)
	}
	return err
}

func sanitizeRepoFlags(repo *v1.Repo) {
	for i, flag := range repo.Flags {
		if strings.HasPrefix(flag, "--option=sftp.args=") {
			// Remove the "-i @" workaround since we now handle quoting properly
			flag = strings.ReplaceAll(flag, "-i @", "-i ")
			// Strip double quotes from sftp.args values that cause restic's
			// pflag parser to fail with "bare \" in non-quoted-field".
			// The UI wraps paths in double quotes (e.g. -i "/path/to/key"),
			// but restic's --option flag parser cannot handle them.
			// Paths passed as sftp.args don't need quoting since they are
			// passed directly to sftp as individual arguments.
			flag = strings.ReplaceAll(flag, "\"", "")
			repo.Flags[i] = flag
		}
	}
}