using System.Text;

using System.Text.RegularExpressions;

namespace QuantumConcepts.Formats.StereoLithography

{

/// <summary>The outer-most STL object which contains the <see cref="Facets"/> that make up the model.</summary>

public class STLDocument : IEquatable<STLDocument>, IEnumerable<Facet>

{

/// <summary>Defines the buffer size to use when reading from a <see cref="StreamReader"/>.</summary>

private const int DefaultBufferSize = 1024;

/// <summary>The name of the solid.</summary>

/// <remarks>This property is not used for binary STLs.</remarks>

public string? Name { get; set; } = null;

/// <summary>The list of <see cref="Facet"/>s within this solid.</summary>

public IList<Facet> Facets { get; set; } = new List<Facet>();

/// <summary>Creates a new, empty <see cref="STLDocument"/>.</summary>

public STLDocument() { }

/// <summary>Creates a new <see cref="STLDocument"/> with the given <paramref name="name"/> and populated with the given <paramref name="facets"/>.</summary>

/// <param name="name">

/// The name of the solid.

/// <remarks>This property is not used for binary STLs.</remarks>

/// </param>

/// <param name="facets">The facets with which to populate this solid.</param>

public STLDocument(string name, IEnumerable<Facet> facets) : this()

{

Name = name;

Facets = facets.ToList();

}

/// <summary>Writes the <see cref="STLDocument"/> as text to the provided <paramref name="stream"/>.</summary>

/// <param name="stream">The stream to which the <see cref="STLDocument"/> will be written.</param>

public void WriteText(Stream stream)

{

if (stream == null) throw new NullReferenceException(nameof(stream));

using (var writer = new StreamWriter(stream, Encoding.ASCII, DefaultBufferSize, true))

{

// Write the header.

writer.WriteLine(this);

// Write each facet.

Facets.ForEach(o => o.Write(writer));

// Write the footer.

writer.Write($"end{this}");

}

}

/// <summary>Writes the <see cref="STLDocument"/> as binary to the provided <paramref name="stream"/>.</summary>

/// <param name="stream">The stream to which the <see cref="STLDocument"/> will be written.</param>

public void WriteBinary(Stream stream)

{

if (stream == null) throw new NullReferenceException(nameof(stream));

using (var writer = new BinaryWriter(stream, Encoding.ASCII, true))

{

byte[] header = Encoding.ASCII.GetBytes("Binary STL generated by STLdotNET");

byte[] headerFull = new byte[80];

Buffer.BlockCopy(header, 0, headerFull, 0, Math.Min(header.Length, headerFull.Length));

// Write the header and facet count.

writer.Write(headerFull);

writer.Write((UInt32)Facets.Count);

// Write each facet.

Facets.ForEach(o => o.Write(writer));

}

}

/// <summary>Writes the <see cref="STLDocument"/> as text to the provided <paramref name="path"/>.</summary>

/// <param name="path">The absolute path where the <see cref="STLDocument"/> will be written.</param>

public void SaveAsText(string path)

{

CreatePathDirectories(path);

using (var stream = File.Create(path))

{

WriteText(stream);

}

}

/// <summary>Writes the <see cref="STLDocument"/> as binary to the provided <paramref name="path"/>.</summary>

/// <param name="path">The absolute path where the <see cref="STLDocument"/> will be written.</param>

public void SaveAsBinary(string path)

{

CreatePathDirectories(path);

using (var stream = File.Create(path))

{

WriteBinary(stream);

}

}

private void CreatePathDirectories(string path)

{

if (path.IsNullOrEmpty()) throw new ArgumentNullException("path");

var dir = Path.GetDirectoryName(path);

if (dir == null) throw new InvalidOperationException($"Could not determine directory name for path: {path}");

// Create dir(s).

Directory.CreateDirectory(dir);

}

/// <summary>Appends the provided facets to this instance's <see cref="Facets"/>.</summary>

/// <remarks>An entire <see cref="STLDocument"/> can be passed to this method and all of the facets which it contains will be appended to this instance.</remarks>

/// <param name="facets">The facets to append.</param>

public void AppendFacets(IEnumerable<Facet> facets)

{

foreach (var facet in facets)

{

Facets.Add(facet);

}

}

/// <summary>Determines if the <see cref="STLDocument"/> contained within the <paramref name="stream"/> is text-based.</summary>

/// <remarks>The <paramref name="stream"/> will be reset to position 0.</remarks>

/// <param name="stream">The stream which contains the STL data.</param>

/// <returns>True if the <see cref="STLDocument"/> is text-based, otherwise false.</returns>

public static bool IsText(Stream stream)

{

if (stream == null) throw new NullReferenceException(nameof(stream));

const string solid = "solid";

byte[] buffer = new byte[5];

string header;

// Reset the stream to tbe beginning and read the first few bytes, then reset the stream to the beginning again.

stream.Seek(0, SeekOrigin.Begin);

stream.Read(buffer, 0, buffer.Length);

stream.Seek(0, SeekOrigin.Begin);

// Read the header as ASCII.

header = Encoding.ASCII.GetString(buffer);

return solid.Equals(header, StringComparison.InvariantCultureIgnoreCase);

}

/// <summary>Determines if the <see cref="STLDocument"/> contained within the <paramref name="stream"/> is binary-based.</summary>

/// <remarks>The <paramref name="stream"/> will be reset to position 0.</remarks>

/// <param name="stream">The stream which contains the STL data.</param>

/// <returns>True if the <see cref="STLDocument"/> is binary-based, otherwise false.</returns>

public static bool IsBinary(Stream stream)

{

return !IsText(stream);

}

/// <summary>Reads the <see cref="STLDocument"/> contained within the <paramref name="stream"/> into a new <see cref="STLDocument"/>.</summary>

/// <remarks>This method will determine how to read the <see cref="STLDocument"/> (whether to read it as text or binary data).</remarks>

/// <param name="stream">The stream which contains the STL data.</param>

/// <param name="tryBinaryIfTextFailed">Set to true to try read as binary if reading as text results in zero facets</param>

/// <returns>An <see cref="STLDocument"/> representing the data contained in the stream or null if the stream is empty.</returns>

public static STLDocument Read(Stream stream, bool tryBinaryIfTextFailed = false)

{

if (stream == null) throw new NullReferenceException(nameof(stream));

// Determine if the stream contains a text-based or binary-based <see cref="STLDocument"/>, and then read it.

var isText = IsText(stream);

STLDocument? textDoc = null;

STLDocument? binaryDoc = null;

STLDocument? finalDoc = null;

if (isText)

{

using (var reader = new StreamReader(stream, Encoding.ASCII, true, DefaultBufferSize, true))

{

textDoc = Read(reader);

}

if (textDoc.Facets.Count > 0 || !tryBinaryIfTextFailed)

{

return textDoc;

}

}

// Try binary if zero Facets were read and `tryBinaryIfTextFailed == true`.

if (!isText || (textDoc?.Facets.Count == 0 && tryBinaryIfTextFailed))

{

// Make sure we're at the beginning of the stream (in case we tried to read it as text above).

stream.Seek(0, SeekOrigin.Begin);

using (var reader = new BinaryReader(stream, Encoding.ASCII, true))

{

binaryDoc = Read(reader);

}

}

// Use text document if binary reading also failed.

finalDoc = (binaryDoc?.Facets.Count > 0 || !isText) ? binaryDoc : textDoc;

// Make sure we have a text or binary document.

if (finalDoc == null) throw new InvalidOperationException("Could not read stream as text or binary STL document.");

return finalDoc;

}

/// <summary>Reads the STL document contained within the <paramref name="reader"/> into a new <see cref="STLDocument"/>.</summary>

/// <remarks>This method expects a text-based STL document to be contained within the <paramref name="reader"/>.</remarks>

/// <param name="reader">The reader which contains the text-based STL data.</param>

/// <returns>An <see cref="STLDocument"/> representing the data contained in the stream or null if the stream is empty.</returns>

public static STLDocument Read(StreamReader reader)

{

if (reader == null) throw new NullReferenceException(nameof(reader));

const string regexSolid = @"solid\s+(?<Name>[^\r\n]+)?";

string? header = reader.ReadLine();

Match headerMatch;

STLDocument stl;

// Check the header.

if (header == null || !(headerMatch = Regex.Match(header, regexSolid)).Success) throw new FormatException($"Invalid STL header, expected \"solid [name]\" but found: {header}");

// Create the STL and extract the name (optional).

stl = new STLDocument()

{

Name = headerMatch.Groups["Name"].Value

};

// Read each facet until the end of the stream.

while (!reader.EndOfStream)

{

// Peek the next char to make sure it's a facet (e.g. not "endsolid").

if (((char)reader.Peek()) == 'e') break;

stl.Facets.Add(Facet.Read(reader));

}

return stl;

}

/// <summary>Reads the STL document contained within the <paramref name="stl"/> parameter into a new <see cref="STLDocument"/>.</summary>

/// <param name="stl">A string which contains the STL data.</param>

/// <returns>An <see cref="STLDocument"/> representing the data contained in the <paramref name="stl"/> parameter or null if the parameter is empty.</returns>

public static STLDocument Read(string stl)

{

if (stl.IsNullOrEmpty()) return new STLDocument();

using (var stream = new MemoryStream(Encoding.ASCII.GetBytes(stl)))

{

return Read(stream);

}

}

/// <summary>Reads the STL document located at the <paramref name="path"/> into a new <see cref="STLDocument"/>.</summary>

/// <param name="path">A full path to a file which contains the STL data.</param>

/// <returns>An <see cref="STLDocument"/> representing the data contained in the file located at the <paramref name="path"/> specified or null if the parameter is empty.</returns>

public static STLDocument Open(string path)

{

if (path.IsNullOrEmpty())

{

throw new ArgumentNullException("path");

}

using (var stream = File.OpenRead(path))

{

return Read(stream);

}

}

/// <summary>Reads the STL document contained within the <paramref name="reader"/> into a new <see cref="STLDocument"/>.</summary>

/// <remarks>This method will expects a binary-based <see cref="STLDocument"/> to be contained within the <paramref name="reader"/>.</remarks>

/// <param name="reader">The reader which contains the binary-based STL data.</param>

/// <returns>An <see cref="STLDocument"/> representing the data contained in the stream or null if the stream is empty.</returns>

public static STLDocument Read(BinaryReader reader)

{

if (reader == null) throw new NullReferenceException(nameof(reader));

byte[] buffer = new byte[80];

STLDocument stl = new STLDocument();

Facet currentFacet;

// Read (and ignore) the header and number of triangles.

buffer = reader.ReadBytes(80);

reader.ReadBytes(4);

// Read each facet until the end of the stream. Stop when the end of the stream is reached.

while ((reader.BaseStream.Position != reader.BaseStream.Length) && (currentFacet = Facet.Read(reader)) != null)

{

stl.Facets.Add(currentFacet);

}

return stl;

}

/// <summary>Reads the <see cref="STLDocument"/> within the <paramref name="inStream"/> as text into the <paramref name="outStream"/>.</summary>

/// <param name="inStream">The stream to read from.</param>

/// <param name="outStream">The stream to read into.</param>

/// <returns>The <see cref="STLDocument"/> that was copied.</returns>

public static STLDocument CopyAsText(Stream inStream, Stream outStream)

{

STLDocument stl = Read(inStream);

stl.WriteText(outStream);

return stl;

}

/// <summary>Reads the <see cref="STLDocument"/> within the <paramref name="inStream"/> as binary into the <paramref name="outStream"/>.</summary>

/// <param name="inStream">The stream to read from.</param>

/// <param name="outStream">The stream to read into.</param>

/// <returns>The <see cref="STLDocument"/> that was copied.</returns>

public static STLDocument CopyAsBinary(Stream inStream, Stream outStream)

{

STLDocument stl = Read(inStream);

stl.WriteBinary(outStream);

return stl;

}

/// <summary>Returns the header representation of this <see cref="STLDocument"/>.</summary>

public override string ToString()

{

return $"solid {Name}";

}

/// <see cref="Object.GetHashCode"/>

public override int GetHashCode()

{

return this.ToString().GetHashCode();

}

/// <see cref="Equals(STLDocument)"/>

public override bool Equals(object? other)

{

return Equals(other as STLDocument);

}

/// <summary>Determines whether or not this instance is the same as the <paramref name="other"/> instance.</summary>

/// <param name="other">The <see cref="STLDocument"/> to which to compare.</param>

/// <returns>True if this instance is equal to the <paramref name="other"/> instance.</returns>

public bool Equals(STLDocument? other)

{

return

other != null &&

Facets.Count == other.Facets.Count &&

Facets.All((i, o) => o.Equals(other.Facets[i]));

}

/// <summary>Iterates through the <see cref="Facets"/> collection.</summary>

public IEnumerator<Facet> GetEnumerator()

{

return Facets.GetEnumerator();

}

/// <summary>Iterates through the <see cref="Facets"/> collection.</summary>

System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()

{

return GetEnumerator();

}

}

}