#include "common.hh"

#include "htmlutil.hh"

namespace html {

namespace {

constexpr const std::string_view kBodyChars = "&<>";
constexpr const std::string_view kAttributeChars = "&<>\"'";

}  // namespace

std::string escape(std::string_view in, EscapeTarget target) {
  std::string out;
  escape(in, &out, target);
  return out;
}

void escape(std::string_view in, std::string* out, EscapeTarget target) {
  std::string_view chars;
  switch (target) {
  case EscapeTarget::BODY:
    chars = kBodyChars;
    break;
  case EscapeTarget::ATTRIBUTE:
    chars = kAttributeChars;
    break;
  }
  size_t last = 0;
  while (true) {
    auto next = in.find_first_of(chars, last);
    if (next == std::string::npos) {
      out->append(in, last);
      break;
    }
    out->append(in, last, next - last);
    switch (in[next]) {
    case '&':
      out->append("&amp;");
      break;
    case '<':
      out->append("&lt;");
      break;
    case '>':
      out->append("&gt;");
      break;
    case '"':
      out->append("&quot;");
      break;
    case '\'':
      out->append("&apos;");
      break;
    }
    last = next + 1;
  }
}

}  // namespace html