Implement restore execution for the restore subcommand

internal/app/restore_execute.go

@@ -0,0 +1,173 @@
+package app
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/adapters/storage"
+	"gitea.maximumdirect.net/eric/narratio/internal/artifacts"
+	"gitea.maximumdirect.net/eric/narratio/internal/config"
+	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
+)
+
+// RestoreExecutionResult captures concrete file-install results for one restore execution.
+type RestoreExecutionResult struct {
+	DownloadedCount int
+}
+
+func executeRestorePlan(
+	ctx context.Context,
+	cfg *config.Config,
+	current *RemoteCurrentState,
+	plan *RestorePlan,
+	store storage.ObjectStore,
+) (*RestoreExecutionResult, error) {
+	if cfg == nil || cfg.Pipeline == nil || cfg.Session == nil {
+		return nil, fmt.Errorf("resolved config with pipeline/session is required")
+	}
+	if current == nil {
+		return nil, fmt.Errorf("remote current state is required")
+	}
+	if plan == nil {
+		return nil, fmt.Errorf("restore plan is required")
+	}
+	if store == nil {
+		return nil, fmt.Errorf("remote object store is required")
+	}
+
+	sessionRoot := artifacts.SessionWorkDirForCampaign(cfg.Pipeline.Workspace.Root, cfg.Session.Campaign, cfg.Session.SessionID)
+	manifestActions := make([]RestoreAction, 0, 1)
+	actions := make([]RestoreAction, 0, len(plan.Actions))
+	for _, action := range plan.Actions {
+		if action.Kind != RestoreActionDownload {
+			continue
+		}
+		if action.LocalRelativePath == config.PathManifestFile {
+			manifestActions = append(manifestActions, action)
+			continue
+		}
+		actions = append(actions, action)
+	}
+	if len(manifestActions) > 1 {
+		return nil, fmt.Errorf("restore plan includes multiple manifest download actions")
+	}
+	if len(manifestActions) == 1 {
+		actions = append(actions, manifestActions[0])
+	}
+
+	result := &RestoreExecutionResult{}
+	for _, action := range actions {
+		if err := executeRestoreDownloadAction(ctx, cfg, sessionRoot, current, action, store); err != nil {
+			return nil, fmt.Errorf("install %q from %q: %w", action.LocalRelativePath, action.RemoteKey, err)
+		}
+		result.DownloadedCount++
+	}
+
+	return result, nil
+}
+
+func executeRestoreDownloadAction(
+	ctx context.Context,
+	cfg *config.Config,
+	sessionRoot string,
+	current *RemoteCurrentState,
+	action RestoreAction,
+	store storage.ObjectStore,
+) error {
+	safeLocalPath, err := joinWithinSessionRoot(sessionRoot, action.LocalRelativePath)
+	if err != nil {
+		return fmt.Errorf("resolve safe local path: %w", err)
+	}
+	if strings.TrimSpace(action.LocalPath) != "" && filepath.Clean(action.LocalPath) != safeLocalPath {
+		return fmt.Errorf("restore plan local path mismatch for %q", action.LocalRelativePath)
+	}
+
+	tmpPath, err := downloadObjectToSiblingTemp(ctx, store, action.RemoteKey, safeLocalPath)
+	if err != nil {
+		return fmt.Errorf("download to temp file: %w", err)
+	}
+	removeTmp := true
+	defer func() {
+		if removeTmp {
+			_ = os.Remove(tmpPath)
+		}
+	}()
+
+	if action.LocalRelativePath == config.PathManifestFile {
+		if err := validateRestoredManifest(ctx, cfg, current, tmpPath); err != nil {
+			return err
+		}
+	}
+
+	if err := os.Chmod(tmpPath, 0o644); err != nil {
+		return fmt.Errorf("set file permissions: %w", err)
+	}
+	if err := os.Rename(tmpPath, safeLocalPath); err != nil {
+		return fmt.Errorf("install file atomically: %w", err)
+	}
+	removeTmp = false
+
+	return nil
+}
+
+func downloadObjectToSiblingTemp(ctx context.Context, store storage.ObjectStore, remoteKey, destPath string) (string, error) {
+	if strings.TrimSpace(destPath) == "" {
+		return "", fmt.Errorf("destination path is required")
+	}
+	dir := filepath.Dir(destPath)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return "", fmt.Errorf("create destination directory: %w", err)
+	}
+	base := filepath.Base(destPath)
+	tmp, err := os.CreateTemp(dir, "."+base+".restore-*.tmp")
+	if err != nil {
+		return "", fmt.Errorf("create temp file: %w", err)
+	}
+	tmpPath := tmp.Name()
+	if err := tmp.Close(); err != nil {
+		_ = os.Remove(tmpPath)
+		return "", fmt.Errorf("close temp file: %w", err)
+	}
+
+	if err := store.Download(ctx, remoteKey, tmpPath); err != nil {
+		_ = os.Remove(tmpPath)
+		return "", err
+	}
+
+	return tmpPath, nil
+}
+
+func validateRestoredManifest(ctx context.Context, cfg *config.Config, current *RemoteCurrentState, path string) error {
+	manifestStore := &manifest.LocalStore{}
+	m, err := manifestStore.Load(ctx, path)
+	if err != nil {
+		return fmt.Errorf("validate manifest decode: %w", err)
+	}
+
+	requestedSession := strings.TrimSpace(cfg.Session.SessionID)
+	requestedCampaign := strings.TrimSpace(cfg.Session.Campaign)
+	manifestSession := strings.TrimSpace(m.SessionID)
+	manifestCampaign := strings.TrimSpace(m.Campaign)
+	if manifestSession != requestedSession {
+		return fmt.Errorf("manifest session_id %q does not match requested session_id %q", manifestSession, requestedSession)
+	}
+	if manifestCampaign == "" {
+		return fmt.Errorf("manifest campaign is required")
+	}
+	if manifestCampaign != requestedCampaign {
+		return fmt.Errorf("manifest campaign %q does not match requested campaign %q", manifestCampaign, requestedCampaign)
+	}
+	if current != nil {
+		if expected := strings.TrimSpace(current.SessionID); expected != "" && manifestSession != expected {
+			return fmt.Errorf("manifest session_id %q does not match discovered session_id %q", manifestSession, expected)
+		}
+		if expected := strings.TrimSpace(current.Campaign); expected != "" && manifestCampaign != expected {
+			return fmt.Errorf("manifest campaign %q does not match discovered campaign %q", manifestCampaign, expected)
+		}
+	}
+
+	return nil
+}