using QuestPDF.Drawing;

namespace Oms.Application.Labeling.Hiprint;

/// <summary>
/// 面单 PDF 中文字体：QuestPDF 默认字体无 CJK，不注册会显示 □ / ?。
/// </summary>
public static class LabelPdfFontRegistrar
{
    public const string FamilyName = "OmsLabelSans";

    private static int _state; // 0=未试 1=成功 2=失败
    private static string? _sourcePath;

    /// <summary>
    /// 确保已注册可用中文字体；成功返回 <see cref="FamilyName"/>，否则 null（仅西文）。
    /// </summary>
    public static string? EnsureRegistered()
    {
        var state = Volatile.Read(ref _state);
        if (state == 1)
        {
            return FamilyName;
        }

        if (state == 2)
        {
            return null;
        }

        foreach (var path in EnumerateCandidates())
        {
            if (string.IsNullOrWhiteSpace(path) || !File.Exists(path))
            {
                continue;
            }

            try
            {
                using var stream = File.OpenRead(path);
                FontManager.RegisterFontWithCustomName(FamilyName, stream);
                _sourcePath = path;
                Interlocked.Exchange(ref _state, 1);
                return FamilyName;
            }
            catch
            {
                // 试下一个候选
            }
        }

        Interlocked.Exchange(ref _state, 2);
        return null;
    }

    /// <summary>已成功注册时的字体文件路径（诊断用）。</summary>
    public static string? RegisteredSourcePath => _sourcePath;

    private static IEnumerable<string> EnumerateCandidates()
    {
        var fromEnv = Environment.GetEnvironmentVariable("OMS_LABEL_FONT");
        if (!string.IsNullOrWhiteSpace(fromEnv))
        {
            yield return fromEnv.Trim();
        }

        var baseDir = AppContext.BaseDirectory;
        yield return Path.Combine(baseDir, "Fonts", "NotoSansSC-Regular.otf");
        yield return Path.Combine(baseDir, "Fonts", "NotoSansSC-Regular.ttf");
        yield return Path.Combine(baseDir, "Fonts", "NotoSansCJKsc-Regular.otf");

        // Windows
        var winFonts = Environment.GetFolderPath(Environment.SpecialFolder.Fonts);
        if (!string.IsNullOrWhiteSpace(winFonts))
        {
            yield return Path.Combine(winFonts, "msyh.ttc");
            yield return Path.Combine(winFonts, "msyhbd.ttc");
            yield return Path.Combine(winFonts, "simhei.ttf");
            yield return Path.Combine(winFonts, "simsun.ttc");
        }

        // Debian/Ubuntu（Dockerfile 安装 fonts-noto-cjk）
        yield return "/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc";
        yield return "/usr/share/fonts/opentype/noto/NotoSansCJKsc-Regular.otf";
        yield return "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc";
        yield return "/usr/share/fonts/truetype/wqy/wqy-microhei.ttc";
    }
}