using WhiteMagic;
using WhiteMagic.Discovery;

namespace WhiteMagicTest.Discovery;

/// <summary>
/// Tests for <see cref="PeHeaderParser"/>.
/// </summary>
public class PeHeaderParserTests
{
    private static InProcessReader CreateReader()
    {
        return new InProcessReader();
    }

    [Fact]
    public void EntryPoint_returns_nonzero_for_current_module()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);
        IntPtr entryPoint = parser.EntryPoint;

        // Entry point should be a valid RVA (non-zero for a valid PE)
        Assert.NotEqual(IntPtr.Zero, entryPoint);

        // Entry point should be less than module size
        Assert.True((nint)entryPoint < mainModule.ModuleMemorySize);
    }

    [Fact]
    public void Sections_enumerates_at_least_text_section()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);
        var sections = parser.Sections.ToList();

        Assert.NotEmpty(sections);

        // Every PE file should have a .text section (or similar)
        var textSection = sections.FirstOrDefault(s =>
            s.Name.Equals(".text", StringComparison.OrdinalIgnoreCase) ||
            s.Name.Equals("TEXT", StringComparison.OrdinalIgnoreCase));

        // May not find ".text" exactly, but should have at least some sections
        Assert.True(sections.Count >= 1);
    }

    [Fact]
    public void Sections_have_valid_properties()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);
        var sections = parser.Sections.ToList();

        foreach (var section in sections)
        {
            // Name should not be empty
            Assert.False(string.IsNullOrWhiteSpace(section.Name));

            // Virtual address should be within module bounds
            Assert.True((nint)section.VirtualAddress < mainModule.ModuleMemorySize);

            // Virtual size should be positive
            Assert.True(section.VirtualSize > 0);
        }
    }

    [Fact]
    public void Sections_have_common_names()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);
        var sections = parser.Sections.Select(s => s.Name).ToList();

        // At least some common section names should be present
        var commonNames = new[] { ".text", ".data", ".rdata", ".bss" };
        bool hasCommonSection = commonNames.Any(name =>
            sections.Contains(name, StringComparer.OrdinalIgnoreCase));

        // This might not always be true, but for managed EXEs it usually is
        // We'll just verify sections were enumerated
        Assert.NotEmpty(sections);
    }

    [Fact]
    public void EntryPoint_is_consistent_across_calls()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);

        IntPtr first = parser.EntryPoint;
        IntPtr second = parser.EntryPoint;

        Assert.Equal(first, second);
    }

    [Fact]
    public void Sections_are_consistent_across_calls()
    {
        using var reader = CreateReader();

        var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
        var mainModule = currentProcess.MainModule;
        Assert.NotNull(mainModule);

        var parser = new PeHeaderParser(reader, mainModule.BaseAddress);

        var first = parser.Sections.ToList();
        var second = parser.Sections.ToList();

        Assert.Equal(first.Count, second.Count);

        for (int i = 0; i < first.Count; i++)
        {
            Assert.Equal(first[i].Name, second[i].Name);
            Assert.Equal(first[i].VirtualAddress, second[i].VirtualAddress);
            Assert.Equal(first[i].VirtualSize, second[i].VirtualSize);
        }
    }

    [Fact]
    public void Constructor_throws_on_zero_base_address()
    {
        using var reader = CreateReader();

        var ex = Assert.Throws<ArgumentException>(() =>
            new PeHeaderParser(reader, IntPtr.Zero));

        Assert.Contains("Base address cannot be zero", ex.Message);
    }
}