using BMDevs.Runtime;
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using dnlib.PE;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BMDevs.Mutations
{
    public class NumbersToModuleReference : IObfuscation
    {
        public ModuleDef Module { get; set; }

        public Dictionary<int, FieldDef> Numbers { get; set; }

        public void Execute(ModuleDefMD md)
        {
            Numbers = new Dictionary<int, FieldDef>();
            Module = md;
            foreach (var type in md.Types.Where(x => x != md.GlobalType))
                foreach (var method in type.Methods.Where(x => !x.IsConstructor && x.HasBody && x.Body.HasInstructions))
                    ExecuteMethod(method);
        }

        public FieldDef AddNumberField(int num)
        {
            var cstype = RuntimeHelper.GetRuntimeType("BMDevs.Runtime.NumbersToModule");
            FieldDef field = cstype.FindField("val");
            Renamer.Rename(field, Renamer.RenameMode.Invalid2, 2);
            //Renamer.Rename(field, Renamer.RenameMode.Base64, 2);
            field.DeclaringType = null;
            Module.GlobalType.Fields.Add(field);

            var method = Module.GlobalType.FindOrCreateStaticConstructor();
            method.Body.Instructions.Insert(0, new Instruction(OpCodes.Ldc_I4, num));
            method.Body.Instructions.Insert(1, new Instruction(OpCodes.Stsfld, field));
            return field;
        }

        //thanks to mighty
        public void ExecuteMethod(MethodDef method)
        {
            for (int i = 0; i < method.Body.Instructions.Count; i++)
            {
                var instr = method.Body.Instructions[i];
                if (instr.IsLdcI4())
                {
                    if (Module.GlobalType.Fields.Count < 65000)
                    {
                        var val = instr.GetLdcI4Value();
                        FieldDef fld;
                        if (!Numbers.TryGetValue(val, out fld))
                        {
                            fld = AddNumberField(val);
                            Numbers.Add(val, fld);
                            //Console.WriteLine("NumberModule: " + val);
                        }
                        instr.OpCode = OpCodes.Ldsfld;
                        instr.Operand = fld;
                    }
                }
            }
        }
    }
}