using ParsonsMegaDrive.Core;
using ParsonsMegaDrive.Core.Memory;
using Xunit;

namespace ParsonsMegaDrive.Tests
{
    public class CpuTests
    {
        [Fact]
        public void MoveQ_ShouldLoadDataAndSetFlags()
        {
            // 1. Arrange: Boot the machine
            var bus = new MdMemoryBus();
            var cpu = new M68000(bus);

            // 2. Load the opcode for "MOVEQ #5, D1" (0x7205) into memory at PC 0
            bus.Write16(0x000000, 0x7205);

            // 3. Act: Step the CPU exactly once
            int cycles = cpu.Step();

            // 4. Assert: Did it work?
            Assert.Equal(4, cycles);                    // Should take exactly 4 cycles
            Assert.Equal(2u, cpu.PC);                   // PC should advance by 2 bytes
            Assert.Equal(5u, cpu.D[1]);                 // D1 should now contain the number 5

            // Assert Flags (5 is greater than 0, so Z and N should be false)
            Assert.False(cpu.FlagZ);
            Assert.False(cpu.FlagN);
            Assert.False(cpu.FlagV);
            Assert.False(cpu.FlagC);
        }
    }
}