#include "FsHelpers.h"

#include <cctype>
#include <cstring>

namespace FsHelpers {

// Process a finalised component in-place, appending it to `out` (preceded by
// '/' if `out` is non-empty) or popping the last component for "..". Used by
// both normalisePath overloads so the parsing rules stay in one place.
static void appendOrPopComponent(std::string& out, const char* compData, size_t compLen) {
  if (compLen == 0) return;
  if (compLen == 2 && compData[0] == '.' && compData[1] == '.') {
    if (out.empty()) return;
    const auto lastSlash = out.find_last_of('/');
    if (lastSlash == std::string::npos) {
      out.clear();
    } else {
      out.resize(lastSlash);
    }
    return;
  }
  if (!out.empty()) {
    out.push_back('/');
  }
  out.append(compData, compLen);
}

void normalisePath(const std::string& path, std::string& out) {
  out.clear();
  size_t componentStart = 0;
  for (size_t i = 0; i < path.size(); i++) {
    if (path[i] == '/') {
      appendOrPopComponent(out, path.data() + componentStart, i - componentStart);
      componentStart = i + 1;
    }
  }
  appendOrPopComponent(out, path.data() + componentStart, path.size() - componentStart);
}

std::string normalisePath(const std::string& path) {
  std::string result;
  normalisePath(path, result);
  return result;
}

bool checkFileExtension(std::string_view fileName, const char* extension) {
  const size_t extLen = strlen(extension);
  if (fileName.length() < extLen) {
    return false;
  }

  const size_t offset = fileName.length() - extLen;
  for (size_t i = 0; i < extLen; i++) {
    if (tolower(static_cast<unsigned char>(fileName[offset + i])) !=
        tolower(static_cast<unsigned char>(extension[i]))) {
      return false;
    }
  }
  return true;
}

bool hasJpgExtension(std::string_view fileName) {
  return checkFileExtension(fileName, ".jpg") || checkFileExtension(fileName, ".jpeg");
}

bool hasPngExtension(std::string_view fileName) { return checkFileExtension(fileName, ".png"); }

bool hasBmpExtension(std::string_view fileName) { return checkFileExtension(fileName, ".bmp"); }

bool hasGifExtension(std::string_view fileName) { return checkFileExtension(fileName, ".gif"); }

bool hasEpubExtension(std::string_view fileName) { return checkFileExtension(fileName, ".epub"); }

bool hasXtcExtension(std::string_view fileName) {
  return checkFileExtension(fileName, ".xtc") || checkFileExtension(fileName, ".xtch");
}

bool hasTxtExtension(std::string_view fileName) { return checkFileExtension(fileName, ".txt"); }

bool hasMarkdownExtension(std::string_view fileName) { return checkFileExtension(fileName, ".md"); }

}  // namespace FsHelpers