using System;

using System.Collections.Generic;

using System.IO;

using JavaResolver.Class.Constants;

using JavaResolver.Class.Metadata;

namespace JavaResolver.Class

{

/// <summary>

/// Represents a file containing a class targeting the Java runtime.

/// </summary>

public class JavaClassFile : FileSegment, IAttributeProvider

{

/// <summary>

/// The signature every class file starts with.

/// </summary>

public const uint Magic = 0xCAFEBABE;

public static JavaClassFile FromFile(string path)

{

var reader = new MemoryBigEndianReader(File.ReadAllBytes(path));

return FromReader(reader);

}

/// <summary>

/// Parses a class file from a binary reader.

/// </summary>

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

/// <returns>The parsed class file.</returns>

/// <exception cref="BadImageFormatException">Occurs when the file does not provide a valid signature of

/// a class file.</exception>

public static JavaClassFile FromReader(IBigEndianReader reader)

{

uint magic = reader.ReadUInt32();

if (magic != Magic)

throw new BadImageFormatException("Image does not contain a valid class file.");

var file = new JavaClassFile

{

MinorVersion = reader.ReadUInt16(),

MajorVersion = reader.ReadUInt16(),

ConstantPool = ConstantPool.FromReader(reader),

AccessFlags = (ClassAccessFlags) reader.ReadUInt16(),

ThisClass = reader.ReadUInt16(),

SuperClass = reader.ReadUInt16(),

};

ushort interfaceCount = reader.ReadUInt16();

for (int i = 0; i < interfaceCount; i++)

file.Interfaces.Add(reader.ReadUInt16());

ushort fieldCount = reader.ReadUInt16();

for (int i = 0; i < fieldCount; i++)

file.Fields.Add(FieldInfo.FromReader(reader));

ushort methodCount = reader.ReadUInt16();

for (int i = 0; i < methodCount; i++)

file.Methods.Add(MethodInfo.FromReader(reader));

ushort attributeCount = reader.ReadUInt16();

for (int i = 0; i < attributeCount; i++)

file.Attributes.Add(AttributeInfo.FromReader(reader));

return file;

}

/// <summary>

/// Gets or sets the minor version the class file format is build for.

/// </summary>

public ushort MinorVersion

{

get;

set;

}

/// <summary>

/// Gets or sets the major version the class file format is build for.

/// </summary>

public ushort MajorVersion

{

get;

set;

}

/// <summary>

/// Gets the constant pool of the class file, containing all the literals

/// and references to external members.

/// </summary>

public ConstantPool ConstantPool

{

get;

internal set;

}

/// <summary>

/// Gets or sets the accessibility attributes for the class stored in the file.

/// </summary>

public ClassAccessFlags AccessFlags

{

get;

set;

}

/// <summary>

/// Gets or sets an index into the constant pool that references a <see cref="ClassInfo"/>

/// representing the class defined in the file.

/// </summary>

public ushort ThisClass

{

get;

set;

}

/// <summary>

/// Gets or sets an index into the constant pool that references a <see cref="ClassInfo"/>

/// representing the direct super class of the class defined in the file.

/// </summary>

public ushort SuperClass

{

get;

set;

}

/// <summary>

/// Gets a collection of indices into the constant pool referencing interfaces that the class implements.

/// </summary>

public IList<ushort> Interfaces

{

get;

} = new List<ushort>();

/// <summary>

/// Gets a collection of fields defined by the class.

/// </summary>

public IList<FieldInfo> Fields

{

get;

} = new List<FieldInfo>();

/// <summary>

/// Gets a collection of methods defined by the class.

/// </summary>

public IList<MethodInfo> Methods

{

get;

} = new List<MethodInfo>();

/// <summary>

/// Gets a collection of attributes defined by the class.

/// </summary>

public IList<AttributeInfo> Attributes

{

get;

} = new List<AttributeInfo>();

/// <summary>

/// Saves the Java class file to the disk.

/// </summary>

/// <param name="path">The path of the new file to create.</param>

public void Write(string path)

{

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

{

Write(fs);

}

}

/// <summary>

/// Saves the Java class file to an output stream.

/// </summary>

/// <param name="outputStream">The stream to write to.</param>

public void Write(Stream outputStream)

{

Write(new BigEndianStreamWriter(outputStream));

}

/// <summary>

/// Writes the Java class file to a specified binary writer.

/// </summary>

/// <param name="writer">The writer to use.</param>

public void Write(IBigEndianWriter writer)

{

Write(new WritingContext(writer));

}

public override void Write(WritingContext context)

{

var writer = context.Writer;

writer.Write(Magic);

writer.Write(MinorVersion);

writer.Write(MajorVersion);

ConstantPool.Write(context);

writer.Write((ushort) AccessFlags);

writer.Write(ThisClass);

writer.Write(SuperClass);

writer.Write((ushort) Interfaces.Count);

foreach (var @interface in Interfaces)

writer.Write(@interface);

writer.Write((ushort) Fields.Count);

foreach (var field in Fields)

field.Write(context);

writer.Write((ushort) Methods.Count);

foreach (var method in Methods)

method.Write(context);

writer.Write((ushort) Attributes.Count);

foreach (var attribute in Attributes)

attribute.Write(context);

}

}

}