using EnvelopeGenerator.Domain.Interfaces;
using GdPicture14;

#if NETFRAMEWORK
using System;
using System.IO;
using System.Threading.Tasks;
using System.Collections.Generic;
#endif

namespace EnvelopeGenerator.PdfEditor
{
    public static class Pdf
    {
        private const string LicenseKey = "kG1Qf9PwmqgR8aDmIW2zI_ebj48RzqAJegRxcystEmkbTGQqfkNBdFOXIb6C_A00Ra8zZkrHdfjqzOPXK7kgkF2YDhvrqKfqh4WDug2vOt0qO31IommzkANSuLjZ4zmraoubyEVd25rE3veQ2h_j7tGIoH_LyIHmy24GaXsxdG0yCzIBMdiLbMMMDwcPY-809KeZ83Grv76OVhFvcbBWyYc251vou1N-kGg5_ZlHDgfWoY85gTLRxafjD3KS_i9ARW4BMiy36y8n7UP2jN8kGRnW_04ubpFtfjJqvtsrP_J9D0x7bqV8xtVtT5JI6dpKsVTiMgDCrIcoFSo5gCC1fw9oUopX4TDCkBQttO4-WHBlOeq9dG5Yb0otonVmJKaQA2tP6sMR-lZDs3ql_WI9t91yPWgpssrJUxSHDd27_LMTH_owJIqkF3NOJd9mYQuAv22oNKFYbH8e41pVKb8cT33Y9CgcQ_sy6YDA5PTuIRi67mjKge_nD9rd0IN213Ir9M_EFWqg9e4haWzIdHXQUo0md70kVhPX4UIH_BKJnxEEnFfoFRNMh77bB0N4jkcBEHPl-ghOERv8dOztf4vCnNpzzWvcLD2cqWIm6THy8XGGq9h4hp8aEreRleSMwv9QQAC7mjLwhQ1rBYkpUHlpTjhTLnMwHknl6HH0Z6zzmsgkRKVyfquv94Pd7QbQfZrRka0ss_48pf9p8hAywEn81Q==";

        private static bool _initialized = false;
        private static readonly object _initLock = new object();

        internal static void EnsureInitialized()
        {
            if (_initialized) return;
            lock (_initLock)
            {
                if (_initialized) return;
                var licenseManager = new LicenseManager();
                licenseManager.RegisterKEY(LicenseKey);
                _initialized = true;
            }
        }

        public static Pdf<MemoryStream, MemoryStream> FromMemory(byte[] documentBytes)
        {
            EnsureInitialized();
            return new Pdf<MemoryStream, MemoryStream>(new MemoryStream(documentBytes), new MemoryStream());
        }

        public static Pdf<MemoryStream, MemoryStream> FromMemory(MemoryStream stream, MemoryStream
#if NET
            ?
#endif
            outputStream = null)
        {
            EnsureInitialized();
            return new Pdf<MemoryStream, MemoryStream>(stream, outputStream ?? new MemoryStream(), disposeInputStream: false, disposeOutputStream: outputStream is null);
        }
    }

    public class Pdf<TInputStream, TOutputStream> : IDisposable, IAsyncDisposable
        where TInputStream : Stream
        where TOutputStream : Stream
    {
        private readonly TInputStream _inputStream;
        private readonly TOutputStream _outputStream;
        private readonly bool _disposeInputStream;
        private readonly bool _disposeOutputStream;

        // Holds the current PDF bytes; replaced after each Background() call
        private byte[] _pdfBytes;

        public Pdf(TInputStream inputStream, TOutputStream outputStream, bool disposeInputStream = true, bool disposeOutputStream = true)
        {
            _inputStream = inputStream;
            _outputStream = outputStream;
            _disposeInputStream = disposeInputStream;
            _disposeOutputStream = disposeOutputStream;
            _pdfBytes = ReadAllBytes(inputStream);
        }

        private static byte[] ReadAllBytes(Stream stream)
        {
            if (stream is MemoryStream ms)
                return ms.ToArray();

            using (var buf = new MemoryStream())
            {
                stream.CopyTo(buf);
                return buf.ToArray();
            }
        }

        /// <summary>
        /// Flushes the current PDF bytes to the output stream and returns it.
        /// After calling this, the instance should not be modified further.
        /// </summary>
        public TOutputStream ExportStream()
        {
            _outputStream.SetLength(0);
            _outputStream.Position = 0;
            _outputStream.Write(_pdfBytes, 0, _pdfBytes.Length);
            _outputStream.Position = 0;
            return _outputStream;
        }

        /// <summary>
        /// Draws the signature field background rectangles onto the PDF pages.
        ///
        /// Coordinate system: GdPicture SetOrigin(PdfOriginTopLeft) + SetMeasurementUnit(PdfMeasurementUnitInch)
        /// matches the Form app's GdPicture annotation coordinate system exactly.
        /// DB values (X, Y in inches from top-left) are used directly — zero conversion.
        /// </summary>
        public Pdf<TInputStream, TOutputStream> Background<TSignature>(IEnumerable<TSignature> signatures, double widthInch = 1.9500000000000002, double heightInch = 2.52)
            where TSignature : IDocReceiverElement
        {
            using (var gdpdf = new GdPicturePDF())
            {
                GdPictureStatus loadStatus = gdpdf.LoadFromStream(new MemoryStream(_pdfBytes));
                if (loadStatus != GdPictureStatus.OK)
                    throw new InvalidOperationException("GdPicturePDF.LoadFromStream failed: " + loadStatus);

                // Top-left origin + inch units = same coordinate system as GdPicture Form app annotations.
                // DB X and Y (inches from top-left) can be used as-is, no conversion needed.
                gdpdf.SetOrigin(PdfOrigin.PdfOriginTopLeft);
                gdpdf.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitInch);

                // Bottom accent line height: 2.5 PDF points converted to inches (1 inch = 72 pt)
                const float bottomLineHeightInch = 2.5f / 72.0f;

                foreach (var sig in signatures)
                {
                    gdpdf.SelectPage(sig.Page);

                    // sig.Width/Height come from DB (the actual stored dimensions).
                    // Fall back to the method parameters only if the element has no stored size.
                    float w = (float)widthInch; // sig.Width > 0 ? (float)sig.Width : (float)widthInch;
                    float h = (float)heightInch; // sig.Height > 0 ? (float)sig.Height : (float)heightInch;

                    // annotation.Left/Top store the CENTER of the bounding box (GdPicture spec).
                    // DrawRectangle expects the TOP-LEFT corner → subtract half dimensions.
                    float x = (float)sig.X;
                    float y = (float)sig.Y;

                    // Background fill — DeviceRgb(222, 220, 215)
                    // DrawRectangle(Left, Top, Width, Height, Fill, Stroke)
                    gdpdf.SetFillColor(222, 220, 215);
                    gdpdf.DrawRectangle(x, y, w, h, true, false);

                    // Bottom accent line — DeviceRgb(204, 202, 198)
                    gdpdf.SetFillColor(204, 202, 198);
                    gdpdf.DrawRectangle(x, y + h - bottomLineHeightInch, w, bottomLineHeightInch, true, false);
                }

                var outStream = new MemoryStream();
                GdPictureStatus saveStatus = gdpdf.SaveToStream(outStream);
                gdpdf.CloseDocument();

                if (saveStatus != GdPictureStatus.OK)
                    throw new InvalidOperationException("GdPicturePDF.SaveToStream failed: " + saveStatus);

                _pdfBytes = outStream.ToArray();
            }

            return this;
        }

        #region Dispose
        private bool _disposed = false;

        ~Pdf()
        {
            Dispose(false);
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        private void Dispose(bool disposing)
        {
            if (_disposed) return;

            if (disposing)
            {
                if (_disposeInputStream) _inputStream?.Dispose();
                if (_disposeOutputStream) _outputStream?.Dispose();
            }

            _disposed = true;
        }

        public async ValueTask DisposeAsync()
        {
            if (_disposed) return;

            if (_disposeInputStream)
            {
                if (_inputStream is IAsyncDisposable asyncInput)
                    await asyncInput.DisposeAsync();
                else
                    _inputStream?.Dispose();
            }

            if (_disposeOutputStream)
            {
                if (_outputStream is IAsyncDisposable asyncOutput)
                    await asyncOutput.DisposeAsync();
                else
                    _outputStream?.Dispose();
            }

            _disposed = true;
            GC.SuppressFinalize(this);
        }
        #endregion
    }
}