Storage.cs

using System.Text.Json;

namespace FMPReceiptPrinter;

public static class Storage
{
    private static readonly JsonSerializerOptions JsonOptions = new() { WriteIndented = true };
    public static string Root => Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "ARCWorksSimpleReceiptPrinter");
    public static string TemplateFolder => Path.Combine(Root, "Templates");
    public static string ReceiptFolder => Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "ARCWorks Simple Receipt Printer", "Receipts");
    public static string SignatureFolder => Path.Combine(Root, "Signatures");
    private static string StatePath => Path.Combine(Root, "state.json");

    public static void Initialize()
    {
        Directory.CreateDirectory(Root);
        Directory.CreateDirectory(TemplateFolder);
        Directory.CreateDirectory(ReceiptFolder);
        Directory.CreateDirectory(SignatureFolder);
        var bundled = Path.Combine(AppContext.BaseDirectory, "Templates");
        if (Directory.Exists(bundled))
        {
            foreach (var file in Directory.GetFiles(bundled, "*.json"))
            {
                var destination = Path.Combine(TemplateFolder, Path.GetFileName(file));
                if (!File.Exists(destination)) File.Copy(file, destination);
            }
        }
    }

    public static List<ReceiptTemplate> LoadTemplates() => LoadTemplatesFrom(TemplateFolder);

    public static List<ReceiptTemplate> LoadTemplatesFrom(string folder)
    {
        var templates = new List<ReceiptTemplate>();
        if (!Directory.Exists(folder)) return templates;

        foreach (var path in Directory.GetFiles(folder, "*.json"))
        {
            try
            {
                var template = JsonSerializer.Deserialize<ReceiptTemplate>(File.ReadAllText(path), JsonOptions);
                if (template is not null) templates.Add(template);
            }
            catch (JsonException) { /* Skip malformed user templates without blocking startup. */ }
            catch (IOException) { /* Skip templates that are temporarily unreadable. */ }
            catch (UnauthorizedAccessException) { /* Skip inaccessible templates. */ }
        }

        return templates.OrderBy(x => x.Name).ToList();
    }

    public static AppState LoadState()
    {
        try { return File.Exists(StatePath) ? JsonSerializer.Deserialize<AppState>(File.ReadAllText(StatePath), JsonOptions) ?? new() : new(); }
        catch { return new(); }
    }

    public static void SaveState(AppState state) => File.WriteAllText(StatePath, JsonSerializer.Serialize(state, JsonOptions));

    public static string SaveReceipt(ReceiptData receipt)
    {
        Directory.CreateDirectory(ReceiptFolder);
        var safeCustomer = string.Concat(receipt.Customer.Select(c => Path.GetInvalidFileNameChars().Contains(c) ? '_' : c)).Trim();
        if (string.IsNullOrWhiteSpace(safeCustomer)) safeCustomer = "Customer";
        var path = Path.Combine(ReceiptFolder, $"DR-{receipt.ReceiptNumber:00000}_{receipt.Date:yyyy-MM-dd}_{safeCustomer}.json");
        File.WriteAllText(path, JsonSerializer.Serialize(receipt, JsonOptions));
        return path;
    }

    public static string ImportTemplate(string source)
    {
        Directory.CreateDirectory(TemplateFolder);
        _ = JsonSerializer.Deserialize<ReceiptTemplate>(File.ReadAllText(source), JsonOptions)
            ?? throw new InvalidDataException("Template JSON is empty or invalid.");
        var destination = Path.Combine(TemplateFolder, Path.GetFileName(source));
        File.Copy(source, destination, true);
        return destination;
    }

    public static string ImportSignature(string source)
    {
        Directory.CreateDirectory(SignatureFolder);
        var extension = Path.GetExtension(source).ToLowerInvariant();
        if (extension is not ".png" and not ".jpg" and not ".jpeg" and not ".bmp") throw new InvalidDataException("Signature must be a PNG, JPG, JPEG, or BMP image.");
        var destination = Path.Combine(SignatureFolder, $"signature{extension}");
        File.Copy(source, destination, true);
        return destination;
    }
}