using System;
using System.IO;
using System.Text;
using STCompiler.Common;
using System.Collections.Generic;

class Program {
    static int Main(string[] args) {
        if (args.Length < 1) {
            Console.WriteLine("Usage: StDisasm <file.stbc>");
            return 1;
        }
        var path = args[0];
        if (!File.Exists(path)) { Console.WriteLine("File not found: " + path); return 2; }
        var data = File.ReadAllBytes(path);
        try { Disasm(data); } catch(Exception ex) { Console.WriteLine("Error: " + ex.Message); return 3; }
        return 0;
    }

    static void Disasm(byte[] data) {
        using var ms = new MemoryStream(data);
        using var r = new BinaryReader(ms);

        string magic = Encoding.ASCII.GetString(r.ReadBytes(4));
        Console.WriteLine($"Magic: {magic}");
        ushort ver = r.ReadUInt16();
        Console.WriteLine($"Version: {ver}");
        ushort nConsts = r.ReadUInt16();
        Console.WriteLine($"Consts: {nConsts}");
        var consts = new List<object>();
        for (int i = 0; i < nConsts; i++) {
            byte t = r.ReadByte();
            switch(t) {
                case 1: { long v = r.ReadInt64(); consts.Add(v); Console.WriteLine($"  [{i}] (long) = {v}"); break; }
                case 2: { double v = r.ReadDouble(); consts.Add(v); Console.WriteLine($"  [{i}] (double) = {v}"); break; }
                case 3: { float v = r.ReadSingle(); consts.Add(v); Console.WriteLine($"  [{i}] (float) = {v}"); break; }
                case 4: { int v = r.ReadInt32(); consts.Add(v); Console.WriteLine($"  [{i}] (int) = {v}"); break; }
                default: { Console.WriteLine($"  [{i}] Unknown const type {t}"); break; }
            }
        }

        ushort nVars = r.ReadUInt16();
        Console.WriteLine($"Vars: {nVars}");
        var varTypes = new VarType[nVars];
        for (int i = 0; i < nVars; i++) {
            byte tb = r.ReadByte();
            var vt = (VarType)tb;
            varTypes[i] = vt;
            if (Enum.IsDefined(typeof(VarType), vt))
                Console.WriteLine($"  Var[{i}] type = {vt}");
            else
                Console.WriteLine($"  Var[{i}] type = {tb} (unknown)");
        }

        ushort codeLen = r.ReadUInt16();
        Console.WriteLine($"CodeLen: {codeLen} bytes");
        var code = r.ReadBytes(codeLen);

        Console.WriteLine("\n--- Disassembly ---");
        int ip = 0;
        while (ip < code.Length) {
            int addr = ip;
            byte op = code[ip++];
            Console.Write($"{addr:0000}: 0x{op:X2}  ");
            switch (op) {
                case Bytecode.OpCodes.NOP: Console.WriteLine("NOP"); break;
                case Bytecode.OpCodes.PUSH_CONST: { ushort ci = ReadU16(code, ref ip); Console.WriteLine($"PUSH_CONST {ci} ({consts[ci]})"); break; }
                case Bytecode.OpCodes.PUSH_REAL_CONST: { ushort ci = ReadU16(code, ref ip); Console.WriteLine($"PUSH_REAL_CONST {ci} ({consts[ci]})"); break; }
                case Bytecode.OpCodes.LOAD_VAR: { ushort vi = ReadU16(code, ref ip); Console.WriteLine($"LOAD_VAR {vi}"); break; }
                case Bytecode.OpCodes.STORE_VAR: { ushort vi = ReadU16(code, ref ip); Console.WriteLine($"STORE_VAR {vi}"); break; }
                case Bytecode.OpCodes.JZ: { ushort target = ReadU16(code, ref ip); Console.WriteLine($"JZ addr={target:0000}"); break; }
                case Bytecode.OpCodes.JMP: { ushort target = ReadU16(code, ref ip); Console.WriteLine($"JMP addr={target:0000}"); break; }
                case Bytecode.OpCodes.HALT: Console.WriteLine("HALT"); break;
                default: Console.WriteLine($"{Bytecode.OpName(op)}"); break;
            }
        }
    }

    static ushort ReadU16(byte[] a, ref int ip) {
        ushort v = (ushort)(a[ip] | (a[ip+1] << 8));
        ip += 2;
        return v;
    }
}