using System.Runtime.InteropServices;
using System.Text;

namespace GeoSigmaDrawLib
{
    public enum StreamError
    {
        STREAM_OK = 0,
        STREAM_INVALID_HANDLE = 1,
        STREAM_WRITE_FAILED = 2,
        STREAM_ALREADY_CLOSED = 3,
        STREAM_UNKNOWN_TYPE = 4
    }

    public enum StreamImportType
    {
        Points = 1,
        XyzPoints = 2,
        Curves = 3
    }

    public sealed class StreamImporter : IDisposable
    {
        private const string DllName = "GeoSigmaDraw.dll"; // 或实际 DLL 名
        private long _handle;
        private bool _disposed;
        private nint pView;
        private int importType;

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        private static extern long Stream_Open(IntPtr pView, int importType, out int outError);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        private static extern int Stream_Write(long handle, byte[] data, int size);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        private static extern int Stream_Close(long handle);

        /// <summary>
        /// 创建流式表格导入器。Open 时即绑定视图与导入类型，后续 Write 会边解析边导入。
        /// </summary>
        /// <param name="pVeiw">CSigmaView*（例如从 CreateView 得到的 IntPtr）</param>
        /// <param name="importType">点 / 散点 / 曲线</param>
        /// <exception cref="InvalidOperationException">Open 失败时抛出</exception>
        public StreamImporter(IntPtr pView, StreamImportType importType)
        {
            _handle = Stream_Open(pView, (int)importType, out int err);
            if (_handle == 0 || err != (int)StreamError.STREAM_OK)
            {
                throw new InvalidOperationException($"Stream_Open failed: error={err}");
            }
        }

        public StreamImporter(nint pView, int importType)
        {
            this.pView = pView;
            this.importType = importType;
        }

        /// <summary>
        /// 写入一块 TSV 数据（UTF-8）。内部会边解析边导入，无需攒整表。
        /// </summary>
        public void Write(byte[] buffer, int length)
        {
            ArgumentNullException.ThrowIfNull(buffer);
            ArgumentOutOfRangeException.ThrowIfLessThan(length, 0, nameof(length));
            ArgumentOutOfRangeException.ThrowIfGreaterThan(length, buffer.Length, nameof(length));
            ObjectDisposedException.ThrowIf(_disposed, nameof(StreamImporter));

            int ret = Stream_Write(_handle, buffer, length);
            if (ret != (int)StreamError.STREAM_OK)
            {
                throw new InvalidOperationException($"Stream_Write failed: error={ret}");
            }
        }

        public void Write(byte[] buffer)
        {
            Write(buffer, buffer.Length);
        }

        /// <summary>
        /// 写入一段 TSV 文本（按 GB2312 编码后写入）。
        /// </summary>
        public void WriteString(string tsvText)
        {
            ArgumentNullException.ThrowIfNull(tsvText);

            byte[] bytes = Encoding.GetEncoding("GB2312").GetBytes(tsvText);
            Write(bytes, bytes.Length);
        }

        public void Close()
        {
            if (_disposed)
            {
                return;
            }

            if (_handle != 0)
            {
                _ = Stream_Close(_handle);
                _handle = 0;
            }
            _disposed = true;
        }

        public void Dispose()
        {
            Close();
        }
    }
}