using WhiteMagic.Hooking;
using Xunit;

namespace WhiteMagicTest.Hooking;

/// <summary>
/// Tests for <see cref="PrologueDecoder"/> covering the accepted x86/x64 prologue
/// shapes and rejection of opcodes outside the covered set.
/// </summary>
public class PrologueDecoderTests
{
    [Theory]
    [InlineData(false, new byte[] { 0x55 }, 1)] // push rbp
    [InlineData(false, new byte[] { 0x53 }, 1)] // push rbx
    [InlineData(false, new byte[] { 0x8B, 0xFF }, 2)] // mov edi, edi
    [InlineData(false, new byte[] { 0x8B, 0xEC }, 2)] // mov ebp, esp
    [InlineData(false, new byte[] { 0x83, 0xEC, 0x20 }, 3)] // sub esp, 0x20
    [InlineData(false, new byte[] { 0x81, 0xEC, 0x00, 0x01, 0x00, 0x00 }, 6)] // sub esp, 0x100
    [InlineData(true, new byte[] { 0x48, 0x8B, 0xEC }, 3)] // mov rbp, rsp
    [InlineData(true, new byte[] { 0x48, 0x83, 0xEC, 0x28 }, 4)] // sub rsp, 0x28
    [InlineData(true, new byte[] { 0x48, 0x81, 0xEC, 0x78, 0x56, 0x34, 0x12 }, 7)] // sub rsp, 0x12345678
    public void Decodes_covered_prologue_shapes(bool is64Bit, byte[] bytes, int expectedLength)
    {
        int length = PrologueDecoder.GetInstructionLength(bytes, is64Bit);
        Assert.Equal(expectedLength, length);
    }

    [Theory]
    [InlineData(false, new byte[] { 0x83, 0x05, 0x39, 0x00, 0x00, 0x00, 0x01 })] // add [rip+0x39], 1 — wrong modrm
    [InlineData(false, new byte[] { 0x83, 0x3D, 0x00, 0x00, 0x00, 0x00, 0x01 })] // cmp [rip], 1 — wrong modrm
    [InlineData(false, new byte[] { 0x81, 0x05, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00 })] // add [rip], 1 — wrong modrm
    [InlineData(false, new byte[] { 0x0F, 0x05 })] // syscall
    [InlineData(false, new byte[] { 0x90, 0x90 })] // nop
    public void Rejects_unsafe_or_uncovered_shapes(bool is64Bit, byte[] bytes)
    {
        int length = PrologueDecoder.GetInstructionLength(bytes, is64Bit);
        Assert.Equal(-1, length);

        Assert.Throws<InvalidOperationException>(
            () => PrologueDecoder.GetWholeInstructionLength(bytes, requiredBytes: 2, is64Bit));
    }
}