using Qrakhen.Qamp.Core.Collections;
using Qrakhen.Qamp.Core.Values;
using String = Qrakhen.Qamp.Core.Values.Objects.String;

namespace Qrakhen.Qamp.Core.Execution;

public class InstructionPtr : Pointer<Instruction>
{
    public Segment Segment;

    public Instruction Instruction => Segment.Instructions[Ptr];

    public InstructionPtr(Segment segment, int position = 0) : base(segment.Instructions, position)
    {
        Segment = segment;
    }

    public long NextLong()
    {
        long value = Segment.ReadLong(Ptr);
        Ptr += sizeof(long);
        return value;
    }

    public Value NextConstant()
    {
        return Segment.Constants[NextDynamic()];
    }

    public String NextString()
    {
        Value value = NextConstant();
        if (value.IsString)
            return value.Ptr.As<String>()!;
        throw new Exception($"Expected string, got {value}");
    }

    public long NextDynamic()
    {
        var result = Segment.ReadDynamic(Ptr, out int read);
        Ptr += read;
        return result;
    }

    public String? GetStringConstant(long offset) 
        => Segment.Constants[offset].Ptr.Value as String;

    public static Instruction operator +(InstructionPtr ptr, int value) 
        => ptr.Segment.Instructions[ptr.Ptr + value];

    public static Instruction operator -(InstructionPtr ptr, int value) 
        => ptr.Segment.Instructions[ptr.Ptr - value];

    public static InstructionPtr operator ++(InstructionPtr ptr)
    {
        ptr.Ptr++;
        return ptr;
    }

    public static InstructionPtr operator --(InstructionPtr ptr)
    {
        ptr.Ptr--;
        return ptr;
    }
}