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// Simple word patterns matcher which will be used in composer objects
// for auto swtiching input mode.

#include "composer/internal/mode_switching_handler.h"

#include <string>

#include "base/logging.h"
#include "base/singleton.h"
#include "absl/container/flat_hash_map.h"
#include "absl/strings/ascii.h"
#include "absl/strings/string_view.h"

namespace mozc {
namespace composer {

ModeSwitchingHandler::ModeSwitchingHandler() {
  // Default patterns are fixed right now.
  // AddRule(key, {display_mode, input_mode});
  AddRule("google", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("Google", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("Chrome", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("chrome", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("Android", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("android", {PREFERRED_ALPHANUMERIC, REVERT_TO_PREVIOUS_MODE});
  AddRule("http", {HALF_ALPHANUMERIC, HALF_ALPHANUMERIC});
  AddRule("www.", {HALF_ALPHANUMERIC, HALF_ALPHANUMERIC});
  AddRule("\\\\", {HALF_ALPHANUMERIC, HALF_ALPHANUMERIC});
}

ModeSwitchingHandler::Rule ModeSwitchingHandler::GetModeSwitchingRule(
    absl::string_view key) const {
  const auto it = patterns_.find(key);
  if (it != patterns_.end()) {
    return it->second;
  }

  if (IsDriveLetter(key)) {
    return {HALF_ALPHANUMERIC, HALF_ALPHANUMERIC};
  }

  return {NO_CHANGE, NO_CHANGE};
}

bool ModeSwitchingHandler::IsDriveLetter(absl::string_view key) {
  return key.size() == 3 && absl::ascii_isalpha(key[0]) && key[1] == ':' &&
         key[2] == '\\';
}

void ModeSwitchingHandler::AddRule(absl::string_view key, const Rule rule) {
  patterns_.emplace(key, rule);
}

ModeSwitchingHandler *ModeSwitchingHandler::GetModeSwitchingHandler() {
  return Singleton<ModeSwitchingHandler>::get();
}

}  // namespace composer
}  // namespace mozc
