namespace X86Disassembler.PE;

/// <summary>
/// Represents the Optional header of a PE file
/// </summary>
public class OptionalHeader
{
    // Optional Header Magic values
    private const ushort PE32_MAGIC = 0x10B;           // 32-bit executable
    private const ushort PE32PLUS_MAGIC = 0x20B;       // 64-bit executable
        
    // Standard fields
    public ushort Magic;                  // Magic number (PE32 or PE32+)
    public byte MajorLinkerVersion;       // Major linker version
    public byte MinorLinkerVersion;       // Minor linker version
    public uint SizeOfCode;               // Size of code section
    public uint SizeOfInitializedData;    // Size of initialized data section
    public uint SizeOfUninitializedData;  // Size of uninitialized data section
    public uint AddressOfEntryPoint;      // Address of entry point
    public uint BaseOfCode;               // Base of code section
    public uint BaseOfData;               // Base of data section (PE32 only)
        
    // Windows-specific fields
    public ulong ImageBase;              // Image base address (uint for PE32, ulong for PE32+)
    public uint SectionAlignment;         // Section alignment
    public uint FileAlignment;            // File alignment
    public ushort MajorOperatingSystemVersion; // Major OS version
    public ushort MinorOperatingSystemVersion; // Minor OS version
    public ushort MajorImageVersion;      // Major image version
    public ushort MinorImageVersion;      // Minor image version
    public ushort MajorSubsystemVersion;  // Major subsystem version
    public ushort MinorSubsystemVersion;  // Minor subsystem version
    public uint Win32VersionValue;        // Win32 version value
    public uint SizeOfImage;              // Size of image
    public uint SizeOfHeaders;            // Size of headers
    public uint CheckSum;                 // Checksum
    public ushort Subsystem;              // Subsystem
    public ushort DllCharacteristics;     // DLL characteristics
    public ulong SizeOfStackReserve;     // Size of stack reserve (uint for PE32, ulong for PE32+)
    public ulong SizeOfStackCommit;      // Size of stack commit (uint for PE32, ulong for PE32+)
    public ulong SizeOfHeapReserve;      // Size of heap reserve (uint for PE32, ulong for PE32+)
    public ulong SizeOfHeapCommit;       // Size of heap commit (uint for PE32, ulong for PE32+)
    public uint LoaderFlags;              // Loader flags
    public uint NumberOfRvaAndSizes;      // Number of RVA and sizes
        
    public DataDirectory[] DataDirectories; // Data directories
        
    /// <summary>
    /// Initializes a new instance of the OptionalHeader class
    /// </summary>
    public OptionalHeader()
    {
        // Initialize object fields to avoid nullability warnings
        ImageBase = 0u; // Default to 32-bit value
        SizeOfStackReserve = 0u;
        SizeOfStackCommit = 0u;
        SizeOfHeapReserve = 0u;
        SizeOfHeapCommit = 0u;
            
        // Initialize array to avoid nullability warning
        DataDirectories = new DataDirectory[0];
    }
        
    /// <summary>
    /// Determines if the PE file is 64-bit based on the Magic value
    /// </summary>
    /// <returns>True if the PE file is 64-bit, false otherwise</returns>
    public bool Is64Bit()
    {
        return Magic == PE32PLUS_MAGIC;
    }
}