/*
 *                     GNU AFFERO GENERAL PUBLIC LICENSE
 *                       Version 3, 19 November 2007
 *  Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 *  Everyone is permitted to copy and distribute verbatim copies
 *  of this license document, but changing it is not allowed.
 */
using System;
using System.IO;
using System.Numerics;
using System.Text;
using UVtools.Core.Extensions;
using UVtools.Core.FileFormats;

namespace UVtools.Core.MeshFormats;

public class STLMeshFile : MeshFile
{
    #region Constants
    public const string DefaultObjectName = "UVTools STL Object";
    #endregion

    #region Properties
    public static FileExtension FileExtension => new(typeof(STLMeshFile), "stl", "Standard Triangle Language");

    public string ObjectName { get; } = DefaultObjectName;
    #endregion

    #region Constructor
    public STLMeshFile(string filePath, FileMode fileMode, MeshFileFormat fileFormat = MeshFileFormat.BINARY, FileFormat? slicerFile = null) : base(filePath, fileMode, fileFormat, slicerFile)
    { }

        
    #endregion

    #region Methods
    public override void BeginWrite()
    {
        if (FileFormat == MeshFileFormat.ASCII)
        {
            MeshStream.WriteLineLF($"solid \"{ObjectName}\"");
        }
        else
        {
            var header = new byte[80];
            var headerText = Encoding.UTF8.GetBytes(HeaderComment);
            Array.Copy(headerText, header, headerText.Length);
            MeshStream.Write(header);
            MeshStream.Seek(4, SeekOrigin.Current);
        }
    }

    public override void WriteTriangle(Vector3 p1, Vector3 p2, Vector3 p3, Vector3 normal)
    {
        if (FileFormat == MeshFileFormat.ASCII)
        {
            MeshStream.WriteLineLF($"  facet normal {normal.X} {normal.Y} {normal.Z}");
            MeshStream.WriteLineLF("    outer loop");
            MeshStream.WriteLineLF($"      vertex {p1.X:E11} {p1.Y:E11} {p1.Z:E11}");
            MeshStream.WriteLineLF($"      vertex {p2.X:E11} {p2.Y:E11} {p2.Z:E11}");
            MeshStream.WriteLineLF($"      vertex {p3.X:E11} {p3.Y:E11} {p3.Z:E11}");
            MeshStream.WriteLineLF("    endloop");
            MeshStream.WriteLineLF("  endfacet");
        } 
        else
        {
            MeshStream.WriteFloatLittleEndian(normal.X);
            MeshStream.WriteFloatLittleEndian(normal.Y);
            MeshStream.WriteFloatLittleEndian(normal.Z);

            MeshStream.WriteFloatLittleEndian(p1.X);
            MeshStream.WriteFloatLittleEndian(p1.Y);
            MeshStream.WriteFloatLittleEndian(p1.Z);

            MeshStream.WriteFloatLittleEndian(p2.X);
            MeshStream.WriteFloatLittleEndian(p2.Y);
            MeshStream.WriteFloatLittleEndian(p2.Z);

            MeshStream.WriteFloatLittleEndian(p3.X);
            MeshStream.WriteFloatLittleEndian(p3.Y);
            MeshStream.WriteFloatLittleEndian(p3.Z);
                
            MeshStream.Write(new byte[2]);
        }

        TriangleCount++;
        VertexCount += 3;
    }

    public override void EndWrite()
    {
        if (FileFormat == MeshFileFormat.ASCII)
        {
            MeshStream.WriteLineLF($"endsolid \"{ObjectName}\"");
        } 
        else
        {
            MeshStream.Seek(80, SeekOrigin.Begin);
            MeshStream.WriteUIntLittleEndian(TriangleCount);
        }
        MeshStream.Flush();
    }

    #endregion
}