package app

import (
	"encoding/json"
	"fmt"
	"os"
	"strings"
	"time"

	"gitea.maximumdirect.net/eric/narratio/internal/artifacts"
	"gitea.maximumdirect.net/eric/narratio/internal/fileops"
)

type restoreMarker struct {
	StartedAt time.Time `json:"started_at"`
}

func writeRestoreMarker(paths artifacts.SessionPaths) error {
	marker := restoreMarker{StartedAt: nowUTC()}
	data, err := json.Marshal(marker)
	if err != nil {
		return fmt.Errorf("encode recovery marker: %w", err)
	}
	if err := fileops.WriteFileAtomic(paths.RestoreMarkerPath, data, fileops.WorkspaceFileMode); err != nil {
		return fmt.Errorf("write recovery marker: %w", err)
	}
	return nil
}

func clearRestoreMarker(paths artifacts.SessionPaths) error {
	if strings.TrimSpace(paths.RestoreMarkerPath) == "" {
		return fmt.Errorf("recovery marker path is required")
	}
	if err := os.Remove(paths.RestoreMarkerPath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("remove recovery marker: %w", err)
	}
	return nil
}

func requireCompleteRestore(paths artifacts.SessionPaths) error {
	if strings.TrimSpace(paths.RestoreMarkerPath) == "" {
		return fmt.Errorf("restore recovery marker path is required")
	}
	info, err := os.Lstat(paths.RestoreMarkerPath)
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		return fmt.Errorf("check restore recovery marker: %w", err)
	}
	if !info.Mode().IsRegular() {
		return fmt.Errorf("restore recovery marker is not a regular file; rerun session restore")
	}
	data, err := os.ReadFile(paths.RestoreMarkerPath)
	if err != nil {
		return fmt.Errorf("read restore recovery marker: %w", err)
	}
	var marker restoreMarker
	if err := json.Unmarshal(data, &marker); err != nil || marker.StartedAt.IsZero() {
		return fmt.Errorf("restore recovery marker is invalid; rerun session restore")
	}
	return fmt.Errorf("restore is incomplete; rerun session restore before running pipeline stages")
}