/* -------------------------------------------

  Copyright (C) 2024-2025 Amlal EL Mahrouss, all rights reserved

------------------------------------------- */

/////////////////////////////////////////////////////////////////////////////////////////

/// @file AssemblerARM64.cc
/// @author EL Mahrouss Amlal
/// @brief 'ACORN' Assembler.

/// REMINDER: when dealing with an undefined symbol use (string
/// size):LinkerFindSymbol:(string) so that li will look for it.

/////////////////////////////////////////////////////////////////////////////////////////

#ifndef __ASM_NEED_ARM64__
#define __ASM_NEED_ARM64__ 1
#endif

#include <CompilerKit/AE.h>
#include <CompilerKit/ErrorID.h>
#include <CompilerKit/Frontend.h>
#include <CompilerKit/PEF.h>
#include <CompilerKit/Version.h>
#include <CompilerKit/impl/Aarch64.h>
#include <CompilerKit/utils/AsmUtils.h>
#include <algorithm>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <vector>

/////////////////////

// ANSI ESCAPE CODES

/////////////////////

#define kBlank "\e[0;30m"
#define kRed "\e[0;31m"
#define kWhite "\e[0;97m"
#define kYellow "\e[0;33m"

constexpr auto cPowerIPAlignment = 0x1U;

static Char kOutputArch = CompilerKit::kPefArchARM64;

static std::size_t kCounter = 1UL;

static std::uintptr_t                                      kOrigin = kPefBaseOrigin;
static std::vector<std::pair<std::string, std::uintptr_t>> kOriginLabel;

static std::vector<uint8_t> kBytes;

static CompilerKit::AERecordHeader kCurrentRecord{
    .fName = "", .fKind = CompilerKit::kPefCode, .fSize = 0, .fOffset = 0};

static std::vector<CompilerKit::AERecordHeader> kRecords;
static std::vector<std::string>                 kUndefinedSymbols;

static const std::string kUndefinedSymbol = ":UndefinedSymbol:";
static const std::string kRelocSymbol     = ":RuntimeSymbol:";

// \brief forward decl.
static bool asm_read_attributes(std::string line);

/////////////////////////////////////////////////////////////////////////////////////////

/// @brief POWER assembler entrypoint, the program/module starts here.

/////////////////////////////////////////////////////////////////////////////////////////

NECTI_MODULE(AssemblerMainARM64) {
  CompilerKit::install_signal(SIGSEGV, Detail::drvi_crash_handler);

  for (size_t i = 1; i < argc; ++i) {
    if (argv[i][0] == '-') {
      if (strcmp(argv[i], "--ver") == 0 || strcmp(argv[i], "--v") == 0) {
        kStdOut << "AssemblerPower: AARCH64 Assembler Driver.\nAssemblerPower: " << kDistVersion
                << "\nAssemblerPower: "
                   "Copyright (c) "
                   "Amlal El Mahrouss\n";
        return 0;
      } else if (strcmp(argv[i], "--h") == 0) {
        kStdOut << "AssemblerPower: AARCH64 Assembler Driver.\nAssemblerPower: Copyright (c) 2024 "
                   "Amlal El Mahrouss\n";
        kStdOut << "--version,/v: print program version.\n";
        kStdOut << "--verbose: print verbose output.\n";
        kStdOut << "--binary: output as flat binary.\n";

        return 0;
      } else if (strcmp(argv[i], "--binary") == 0) {
        kOutputAsBinary = true;
        continue;
      } else if (strcmp(argv[i], "--verbose") == 0) {
        kVerbose = true;
        continue;
      }

      kStdOut << "AssemblerPower: ignore " << argv[i] << "\n";
      continue;
    }

    if (!std::filesystem::exists(argv[i])) {
      kStdOut << "AssemblerPower: can't open: " << argv[i] << std::endl;
      goto asm_fail_exit;
    }

    std::string object_output(argv[i]);

    for (auto& ext : kAsmFileExts) {
      if (object_output.find(ext) != std::string::npos) {
        object_output.erase(object_output.find(ext), std::strlen(ext));
      }
    }

    object_output += kOutputAsBinary ? kBinaryFileExt : kObjectFileExt;

    std::ifstream file_ptr(argv[i]);
    std::ofstream file_ptr_out(object_output, std::ofstream::binary);

    if (file_ptr_out.bad()) {
      if (kVerbose) {
        kStdOut << "AssemblerPower: error: " << strerror(errno) << "\n";
      }
    }

    std::string line;

    CompilerKit::AEHeader hdr{0};

    memset(hdr.fPad, kAENullType, kAEPad);

    hdr.fMagic[0] = kAEMag0;
    hdr.fMagic[1] = kAEMag1;
    hdr.fSize     = sizeof(CompilerKit::AEHeader);
    hdr.fArch     = kOutputArch;

    /////////////////////////////////////////////////////////////////////////////////////////

    // COMPILATION LOOP

    /////////////////////////////////////////////////////////////////////////////////////////

    CompilerKit::EncoderARM64 asm64;

    while (std::getline(file_ptr, line)) {
      if (auto ln = asm64.CheckLine(line, argv[i]); !ln.empty()) {
        Detail::print_error(ln, argv[i]);
        continue;
      }

      try {
        asm_read_attributes(line);
        asm64.WriteLine(line, argv[i]);
      } catch (const std::exception& e) {
        if (kVerbose) {
          std::string what = e.what();
          Detail::print_warning("exit because of: " + what, "CompilerKit");
        }

        std::filesystem::remove(object_output);
        goto asm_fail_exit;
      }
    }

    if (!kOutputAsBinary) {
      if (kVerbose) {
        kStdOut << "AssemblerARM64: Writing object file...\n";
      }

      // this is the final step, write everything to the file.

      auto pos = file_ptr_out.tellp();

      hdr.fCount = kRecords.size() + kUndefinedSymbols.size();

      file_ptr_out << hdr;

      if (kRecords.empty()) {
        kStdErr << "AssemblerARM64: At least one record is needed to write an object "
                   "file.\nAssemblerARM64: Make one using `public_segment .code64 foo_bar`.\n";

        std::filesystem::remove(object_output);
        return 1;
      }

      kRecords[kRecords.size() - 1].fSize = kBytes.size();

      std::size_t record_count = 0UL;

      for (auto& record_hdr : kRecords) {
        record_hdr.fFlags |= CompilerKit::kKindRelocationAtRuntime;
        record_hdr.fOffset = record_count;
        ++record_count;

        file_ptr_out << record_hdr;

        if (kVerbose) kStdOut << "AssemblerARM64: Wrote record " << record_hdr.fName << "...\n";
      }

      // increment once again, so that we won't lie about the kUndefinedSymbols.
      ++record_count;

      for (auto& sym : kUndefinedSymbols) {
        CompilerKit::AERecordHeader undefined_sym{0};

        if (kVerbose) kStdOut << "AssemblerARM64: Wrote symbol " << sym << " to file...\n";

        undefined_sym.fKind   = kAENullType;
        undefined_sym.fSize   = sym.size();
        undefined_sym.fOffset = record_count;

        ++record_count;

        memset(undefined_sym.fPad, kAENullType, kAEPad);
        memcpy(undefined_sym.fName, sym.c_str(), sym.size());

        file_ptr_out << undefined_sym;

        ++kCounter;
      }

      auto pos_end = file_ptr_out.tellp();

      file_ptr_out.seekp(pos);

      hdr.fStartCode = pos_end;
      hdr.fCodeSize  = kBytes.size();

      file_ptr_out << hdr;

      file_ptr_out.seekp(pos_end);
    } else {
      if (kVerbose) {
        kStdOut << "AssemblerARM64: Write raw binary...\n";
      }
    }

    // byte from byte, we write this.
    for (auto& byte : kBytes) {
      file_ptr_out.write(reinterpret_cast<const char*>(&byte), sizeof(byte));
    }

    if (kVerbose) kStdOut << "AssemblerARM64: Wrote file with program in it.\n";

    file_ptr_out.flush();
    file_ptr_out.close();

    if (kVerbose) kStdOut << "AssemblerARM64: Exit succeeded.\n";

    return 0;
  }

asm_fail_exit:

  if (kVerbose) kStdOut << "AssemblerARM64: Exit failed.\n";

  return NECTI_EXEC_ERROR;
}

/////////////////////////////////////////////////////////////////////////////////////////

// @brief Check for attributes
// returns true if any was found.

/////////////////////////////////////////////////////////////////////////////////////////

static bool asm_read_attributes(std::string line) {
  // extern_segment is the opposite of public_segment, it signals to the li
  // that we need this symbol.
  if (CompilerKit::find_word(line, "extern_segment")) {
    if (kOutputAsBinary) {
      Detail::print_error("Invalid extern_segment directive in flat binary mode.", "CompilerKit");
      throw std::runtime_error("invalid_extern_segment_bin");
    }

    auto name = line.substr(line.find("extern_segment") + strlen("extern_segment") + 1);

    if (name.size() == 0) {
      Detail::print_error("Invalid extern_segment", "CompilerKit");
      throw std::runtime_error("invalid_extern_segment");
    }

    std::string result = std::to_string(name.size());
    result += kUndefinedSymbol;

    // mangle this
    for (char& j : name) {
      if (j == ' ' || j == ',') j = '$';
    }

    result += name;

    if (name.find(".code64") != std::string::npos) {
      // data is treated as code.
      kCurrentRecord.fKind = CompilerKit::kPefCode;
    } else if (name.find(".data64") != std::string::npos) {
      // no code will be executed from here.
      kCurrentRecord.fKind = CompilerKit::kPefData;
    } else if (name.find(".zero64") != std::string::npos) {
      // this is a bss section.
      kCurrentRecord.fKind = CompilerKit::kPefZero;
    }

    // this is a special case for the start stub.
    // we want this so that li can find it.

    if (name == kPefStart) {
      kCurrentRecord.fKind = CompilerKit::kPefCode;
    }

    // now we can tell the code size of the previous kCurrentRecord.

    if (!kRecords.empty()) kRecords[kRecords.size() - 1].fSize = kBytes.size();

    memset(kCurrentRecord.fName, 0, kAESymbolLen);
    memcpy(kCurrentRecord.fName, result.c_str(), result.size());

    ++kCounter;

    memset(kCurrentRecord.fPad, kAENullType, kAEPad);

    kRecords.emplace_back(kCurrentRecord);

    return true;
  }
  // public_segment is a special keyword used by Assembler to tell the AE output stage to
  // mark this section as a header. it currently supports .code64, .data64.,
  // .zero64
  else if (CompilerKit::find_word(line, "public_segment")) {
    if (kOutputAsBinary) {
      Detail::print_error("Invalid public_segment directive in flat binary mode.", "CompilerKit");
      throw std::runtime_error("invalid_public_segment_bin");
    }

    auto name = line.substr(line.find("public_segment") + strlen("public_segment"));

    std::string name_copy = name;

    for (char& j : name) {
      if (j == ' ') j = '$';
    }

    if (name.find(".code64") != std::string::npos) {
      // data is treated as code.

      name_copy.erase(name_copy.find(".code64"), strlen(".code64"));
      kCurrentRecord.fKind = CompilerKit::kPefCode;
    } else if (name.find(".data64") != std::string::npos) {
      // no code will be executed from here.

      name_copy.erase(name_copy.find(".data64"), strlen(".data64"));
      kCurrentRecord.fKind = CompilerKit::kPefData;
    } else if (name.find(".zero64") != std::string::npos) {
      // this is a bss section.

      name_copy.erase(name_copy.find(".zero64"), strlen(".zero64"));
      kCurrentRecord.fKind = CompilerKit::kPefZero;
    }

    // this is a special case for the start stub.
    // we want this so that li can find it.

    if (name == kPefStart) {
      kCurrentRecord.fKind = CompilerKit::kPefCode;
    }

    while (name_copy.find(" ") != std::string::npos) name_copy.erase(name_copy.find(" "), 1);

    kOriginLabel.push_back(std::make_pair(name_copy, kOrigin));
    ++kOrigin;

    // now we can tell the code size of the previous kCurrentRecord.

    if (!kRecords.empty()) kRecords[kRecords.size() - 1].fSize = kBytes.size();

    memset(kCurrentRecord.fName, 0, kAESymbolLen);
    memcpy(kCurrentRecord.fName, name.c_str(), name.size());

    ++kCounter;

    memset(kCurrentRecord.fPad, kAENullType, kAEPad);

    kRecords.emplace_back(kCurrentRecord);

    return true;
  }

  return false;
}

// \brief algorithms and helpers.

namespace Detail::algorithm {
// \brief authorize a brief set of characters.
static inline bool is_not_alnum_space(char c) {
  return !(isalpha(c) || isdigit(c) || (c == ' ') || (c == '\t') || (c == ',') || (c == '(') ||
           (c == ')') || (c == '"') || (c == '\'') || (c == '[') || (c == ']') || (c == '+') ||
           (c == '_') || (c == ':') || (c == '@') || (c == '.'));
}

bool is_valid_arm64(std::string str) {
  return std::find_if(str.begin(), str.end(), is_not_alnum_space) == str.end();
}
}  // namespace Detail::algorithm

/////////////////////////////////////////////////////////////////////////////////////////

// @brief Check for line (syntax check)

/////////////////////////////////////////////////////////////////////////////////////////

std::string CompilerKit::EncoderARM64::CheckLine(std::string line, std::string file) {
  std::string err_str;

  if (line.empty() || CompilerKit::find_word(line, "extern_segment") ||
      CompilerKit::find_word(line, "public_segment") || line.find('#') != std::string::npos ||
      CompilerKit::find_word(line, ";")) {
    if (line.find('#') != std::string::npos) {
      line.erase(line.find('#'));
    } else if (line.find(';') != std::string::npos) {
      line.erase(line.find(';'));
    } else {
      /// does the line contains valid input?
      if (!Detail::algorithm::is_valid_arm64(line)) {
        err_str = "Line contains non alphanumeric characters.\nhere -> ";
        err_str += line;
      }
    }

    return err_str;
  }

  if (!Detail::algorithm::is_valid_arm64(line)) {
    err_str = "Line contains non alphanumeric characters.\nhere -> ";
    err_str += line;

    return err_str;
  }

  // check for a valid instruction format.

  if (line.find(',') != std::string::npos) {
    if (line.find(',') + 1 == line.size()) {
      err_str += "\nInstruction lacks right register, here -> ";
      err_str += line.substr(line.find(','));

      return err_str;
    } else {
      bool nothing_on_right = true;

      if (line.find(',') + 1 > line.size()) {
        err_str += "\nInstruction not complete, here -> ";
        err_str += line;

        return err_str;
      }

      auto substr = line.substr(line.find(',') + 1);

      for (auto& ch : substr) {
        if (ch != ' ' && ch != '\t') {
          nothing_on_right = false;
        }
      }

      // this means we found nothing after that ',' .
      if (nothing_on_right) {
        err_str += "\nInstruction not complete, here -> ";
        err_str += line;

        return err_str;
      }
    }
  }

  return err_str;
}

bool CompilerKit::EncoderARM64::WriteNumber(const std::size_t& pos, std::string& jump_label) {
  if (!isdigit(jump_label[pos])) return false;

  switch (jump_label[pos + 1]) {
    case 'x': {
      if (auto res = strtol(jump_label.substr(pos + 2).c_str(), nullptr, 16); !res) {
        if (errno != 0) {
          Detail::print_error("invalid hex number: " + jump_label, "CompilerKit");
          throw std::runtime_error("invalid_hex");
        }
      }

      CompilerKit::NumberCast64 num(strtol(jump_label.substr(pos + 2).c_str(), nullptr, 16));

      for (char& i : num.number) {
        kBytes.push_back(i);
      }

      if (kVerbose) {
        kStdOut << "AssemblerARM64: found a base 16 number here: " << jump_label.substr(pos)
                << "\n";
      }

      return true;
    }
    case 'b': {
      if (auto res = strtol(jump_label.substr(pos + 2).c_str(), nullptr, 2); !res) {
        if (errno != 0) {
          Detail::print_error("invalid binary number: " + jump_label, "CompilerKit");
          throw std::runtime_error("invalid_bin");
        }
      }

      CompilerKit::NumberCast64 num(strtol(jump_label.substr(pos + 2).c_str(), nullptr, 2));

      if (kVerbose) {
        kStdOut << "AssemblerARM64: found a base 2 number here: " << jump_label.substr(pos) << "\n";
      }

      for (char& i : num.number) {
        kBytes.push_back(i);
      }

      return true;
    }
    case 'o': {
      if (auto res = strtol(jump_label.substr(pos + 2).c_str(), nullptr, 7); !res) {
        if (errno != 0) {
          Detail::print_error("invalid octal number: " + jump_label, "CompilerKit");
          throw std::runtime_error("invalid_octal");
        }
      }

      CompilerKit::NumberCast64 num(strtol(jump_label.substr(pos + 2).c_str(), nullptr, 7));

      if (kVerbose) {
        kStdOut << "AssemblerARM64: found a base 8 number here: " << jump_label.substr(pos) << "\n";
      }

      for (char& i : num.number) {
        kBytes.push_back(i);
      }

      return true;
    }
    default: {
      break;
    }
  }

  /* check for errno and stuff like that */
  if (auto res = strtol(jump_label.substr(pos).c_str(), nullptr, 10); !res) {
    if (errno != 0) {
      return false;
    }
  }

  CompilerKit::NumberCast64 num(strtol(jump_label.substr(pos).c_str(), nullptr, 10));

  for (char& i : num.number) {
    kBytes.push_back(i);
  }

  if (kVerbose) {
    kStdOut << "AssemblerARM64: found a base 10 number here: " << jump_label.substr(pos) << "\n";
  }

  return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

/// @brief Read and write an instruction to the output array.

/////////////////////////////////////////////////////////////////////////////////////////

bool CompilerKit::EncoderARM64::WriteLine(std::string line, std::string file) {
  if (CompilerKit::find_word(line, "public_segment")) return false;

  if (!Detail::algorithm::is_valid_arm64(line)) return false;

  return true;
}

// Last rev 13-1-24