using System.ComponentModel;
using WhiteMagic;
using WhiteMagic.Memory;
using WhiteMagic.Native;

namespace WhiteMagicTest.Memory;

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

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

        using var allocated = new AllocatedMemory(reader, 4096);

        Assert.NotEqual(IntPtr.Zero, allocated.BaseAddress);
        Assert.Equal(4096, allocated.Size);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096, MemoryProtectionType.ReadOnly);

        Assert.NotEqual(IntPtr.Zero, allocated.BaseAddress);
    }

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

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            new AllocatedMemory(reader, -1));

        Assert.Equal("size", ex.ParamName);
    }

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

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            new AllocatedMemory(reader, 0));

        Assert.Equal("size", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("test", 100);

        Assert.Equal(100, allocated.AddressOf("test") - allocated.BaseAddress);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("test", 100);

        var ex = Assert.Throws<ArgumentException>(() =>
            allocated.AddRegion("test", 200));

        Assert.Contains("already exists", ex.Message);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.AddRegion("test", -1));

        Assert.Equal("offset", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.AddRegion("test", 4096));

        Assert.Equal("offset", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("region1", 0);
        allocated.AddRegion("region2", 100);
        allocated.AddRegion("region3", 200);

        Assert.Equal(allocated.BaseAddress, allocated.AddressOf("region1"));
        Assert.Equal(allocated.BaseAddress + 100, allocated.AddressOf("region2"));
        Assert.Equal(allocated.BaseAddress + 200, allocated.AddressOf("region3"));
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        var ex = Assert.Throws<ArgumentException>(() =>
            allocated.AddressOf("unknown"));

        Assert.Contains("does not exist", ex.Message);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("value", 0);

        int original = unchecked((int)0xDEADBEEF);
        Assert.True(allocated.Write("value", original));

        int read = allocated.Read<int>("value");
        Assert.Equal(original, read);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("value", 8);

        long original = 0x123456789ABCDEF0;
        Assert.True(allocated.Write("value", original));

        long read = allocated.Read<long>("value");
        Assert.Equal(original, read);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("buffer", 0);

        byte[] original = { 0x01, 0x02, 0x03, 0x04, 0x05 };
        int written = allocated.WriteBytes("buffer", original);
        Assert.Equal(original.Length, written);

        byte[] read = allocated.ReadBytes("buffer", original.Length);
        Assert.Equal(original, read);
    }

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

        var allocated = new AllocatedMemory(reader, 4096);
        IntPtr baseAddr = allocated.BaseAddress;

        Assert.NotEqual(IntPtr.Zero, baseAddr);

        allocated.Dispose();

        // After dispose, accessing properties should throw ObjectDisposedException
        Assert.Throws<ObjectDisposedException>(() =>
            allocated.AddressOf("any"));
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        allocated.AddRegion("a", 0);
        allocated.AddRegion("b", 4);
        allocated.AddRegion("c", 8);

        Assert.True(allocated.Write("a", 0x11111111));
        Assert.True(allocated.Write("b", 0x22222222));
        Assert.True(allocated.Write("c", 0x33333333));

        Assert.Equal(0x11111111, allocated.Read<int>("a"));
        Assert.Equal(0x22222222, allocated.Read<int>("b"));
        Assert.Equal(0x33333333, allocated.Read<int>("c"));
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        var ex = Assert.Throws<ArgumentException>(() =>
            allocated.Write("unknown", 42));

        Assert.Contains("does not exist", ex.Message);
    }

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

        using var allocated = new AllocatedMemory(reader, 4096);

        var ex = Assert.Throws<ArgumentException>(() =>
            allocated.Read<int>("unknown"));

        Assert.Contains("does not exist", ex.Message);
    }

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

        using var allocated = new AllocatedMemory(reader, 100);
        allocated.AddRegion("boundary", 99);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.Read<int>("boundary"));

        Assert.Equal("name", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 100);
        allocated.AddRegion("boundary", 99);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.Write("boundary", 42));

        Assert.Equal("name", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 100);
        allocated.AddRegion("boundary", 99);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.ReadBytes("boundary", 2));

        Assert.Equal("count", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 100);
        allocated.AddRegion("boundary", 99);

        var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
            allocated.WriteBytes("boundary", new byte[2]));

        Assert.Equal("bytes", ex.ParamName);
    }

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

        using var allocated = new AllocatedMemory(reader, 100);
        allocated.AddRegion("boundary", 96);

        const int expected = unchecked((int)0xDEADBEEF);
        Assert.True(allocated.Write("boundary", expected));
        Assert.Equal(expected, allocated.Read<int>("boundary"));
    }
}