#include "utils.hh"

#include "decoder.hh"
#include "sax_decoder.hh"
#include "sax_decoder_factory.hh"

namespace modxml {
namespace sax {

namespace {

std::string cleanup_encoding(std::string_view str) {
  std::string ret;
  ret.reserve(str.size());
  for (auto c : str) {
    if (c >= 'A' && c <= 'Z') {
      ret.push_back(c | 0x20);
    } else if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')) {
      ret.push_back(c);
    } else if (c == '.' || c == '_' || c == '-') {
      ret.push_back('-');
    }
  }
  return ret;
}

}  // namespace

// Names inspired by:
// https://www.iana.org/assignments/character-sets/character-sets.xhtml
std::unique_ptr<Decoder> pick_decoder_for_encoding(
    std::string_view encoding, DecoderFactory* factory) {
  auto clean_enc = cleanup_encoding(encoding);
  if (clean_enc == "utf-8" || clean_enc == "utf8")
    return create_utf8_decoder();

  if (clean_enc == "utf-16" || clean_enc == "utf16")
    return create_utf16_decoder();

  if (clean_enc == "utf-16be" || clean_enc == "utf16be")
    return create_utf16be_decoder();

  if (clean_enc == "utf-16le" || clean_enc == "utf16le")
    return create_utf16le_decoder();

  if (clean_enc == "utf-32" || clean_enc == "utf32")
    return create_utf32_decoder();

  if (clean_enc == "utf-32be" || clean_enc == "utf32be")
    return create_utf32be_decoder();

  if (clean_enc == "utf-32le" || clean_enc == "utf32le")
    return create_utf32le_decoder();

  if (clean_enc == "ascii" || clean_enc == "us-ascii" ||
      clean_enc == "usascii" || clean_enc == "iso-ir-6" ||
      clean_enc == "ansi-x3-4-1968" || clean_enc == "ansi-x3-4-1986" ||
      clean_enc == "iso-646-irv1991" || clean_enc == "iso646-us" ||
      clean_enc == "us" || clean_enc == "ibm367" || clean_enc == "cp367") {
    return create_ascii_decoder();
  }

  if (factory)
    return factory->create(encoding);

  return nullptr;
}

}  // namespace sax

}  // namespace modxml