content: /*
   * Copyright (C) 2013 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.amnesica.kryptey.inputmethod.latin.utils;
  
  import android.text.InputType;
  import android.text.TextUtils;
  
  import com.amnesica.kryptey.inputmethod.latin.common.Constants;
  import com.amnesica.kryptey.inputmethod.latin.settings.SpacingAndPunctuations;
  
  import java.util.ArrayList;
  
  public final class CapsModeUtils {
    private CapsModeUtils() {
      // This utility class is not publicly instantiable.
    }
  
    /**
     * Helper method to find out if a code point is starting punctuation.
     * <p>
     * This include the Unicode START_PUNCTUATION category, but also some other symbols that are
     * starting, like the inverted question mark or the double quote.
     *
     * @param codePoint the code point
     * @return true if it's starting punctuation, false otherwise.
     */
    private static boolean isStartPunctuation(final int codePoint) {
      return (codePoint == Constants.CODE_DOUBLE_QUOTE || codePoint == Constants.CODE_SINGLE_QUOTE
          || codePoint == Constants.CODE_INVERTED_QUESTION_MARK
          || codePoint == Constants.CODE_INVERTED_EXCLAMATION_MARK
          || Character.getType(codePoint) == Character.START_PUNCTUATION);
    }
  
    /**
     * Determine what caps mode should be in effect at the current offset in
     * the text. Only the mode bits set in <var>reqModes</var> will be
     * checked. Note that the caps mode flags here are explicitly defined
     * to match those in {@link InputType}.
     * <p>
     * This code is a straight copy of TextUtils.getCapsMode (modulo namespace and formatting
     * issues). This will change in the future as we simplify the code for our use and fix bugs.
     *
     * @param cs                     The text that should be checked for caps modes.
     * @param reqModes               The modes to be checked: may be any combination of
     *                               {@link TextUtils#CAP_MODE_CHARACTERS}, {@link TextUtils#CAP_MODE_WORDS}, and
     *                               {@link TextUtils#CAP_MODE_SENTENCES}.
     * @param spacingAndPunctuations The current spacing and punctuations settings.
     * @return Returns the actual capitalization modes that can be in effect
     * at the current position, which is any combination of
     * {@link TextUtils#CAP_MODE_CHARACTERS}, {@link TextUtils#CAP_MODE_WORDS}, and
     * {@link TextUtils#CAP_MODE_SENTENCES}.
     */
    public static int getCapsMode(final CharSequence cs, final int reqModes,
                                  final SpacingAndPunctuations spacingAndPunctuations) {
      // Quick description of what we want to do:
      // CAP_MODE_CHARACTERS is always on.
      // CAP_MODE_WORDS is on if there is some whitespace before the cursor.
      // CAP_MODE_SENTENCES is on if there is some whitespace before the cursor, and the end
      //   of a sentence just before that.
      // We ignore opening parentheses and the like just before the cursor for purposes of
      // finding whitespace for WORDS and SENTENCES modes.
      // The end of a sentence ends with a period, question mark or exclamation mark. If it's
      // a period, it also needs not to be an abbreviation, which means it also needs to either
      // be immediately preceded by punctuation, or by a string of only letters with single
      // periods interleaved.
  
      // Step 1 : check for cap MODE_CHARACTERS. If it's looked for, it's always on.
      if ((reqModes & (TextUtils.CAP_MODE_WORDS | TextUtils.CAP_MODE_SENTENCES)) == 0) {
        // Here we are not looking for MODE_WORDS or MODE_SENTENCES, so since we already
        // evaluated MODE_CHARACTERS, we can return.
        return TextUtils.CAP_MODE_CHARACTERS & reqModes;
      }
  
      // Step 2 : Skip (ignore at the end of input) any opening punctuation. This includes
      // opening parentheses, brackets, opening quotes, everything that *opens* a span of
      // text in the linguistic sense. In RTL languages, this is still an opening sign, although
      // it may look like a right parenthesis for example. We also include double quote and
      // single quote since they aren't start punctuation in the unicode sense, but should still
      // be skipped for English. TODO: does this depend on the language?
      int i;
      for (i = cs.length(); i > 0; i--) {
        final char c = cs.charAt(i - 1);
        if (!isStartPunctuation(c)) {
          break;
        }
      }
      final int newCapIndex = i;
  
      // We are now on the character that precedes any starting punctuation, so in the most
      // frequent case this will be whitespace or a letter, although it may occasionally be a
      // start of line, or some symbol.
  
      // Step 3 : Search for the start of a paragraph. From the starting point computed in step 2,
      // we go back over any space or tab char sitting there. We find the start of a paragraph
      // if the first char that's not a space or tab is a start of line (as in \n, start of text,
      // or some other similar characters).
      char prevChar = Constants.CODE_SPACE;
      while (i > 0) {
        prevChar = cs.charAt(i - 1);
        if (!Character.isSpaceChar(prevChar) && prevChar != Constants.CODE_TAB) {
          break;
        }
        i--;
      }
      if (i <= 0 || Character.isWhitespace(prevChar)) {
        if (spacingAndPunctuations.mUsesGermanRules) {
          // In German typography rules, there is a specific case that the first character
          // of a new line should not be capitalized if the previous line ends in a comma.
          boolean hasNewLine = false;
          while (--i >= 0 && Character.isWhitespace(prevChar)) {
            if (Constants.CODE_ENTER == prevChar) {
              hasNewLine = true;
            }
            prevChar = cs.charAt(i);
          }
          if (Constants.CODE_COMMA == prevChar && hasNewLine) {
            return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & reqModes;
          }
        }
        // There are only spacing chars between the start of the paragraph and the cursor,
        // defined as a isWhitespace() char that is neither a isSpaceChar() nor a tab. Both
        // MODE_WORDS and MODE_SENTENCES should be active.
        return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS
            | TextUtils.CAP_MODE_SENTENCES) & reqModes;
      }
      if (newCapIndex == i) {
        // The last character is all that really needs to be checked to determine if a new word
        // is being started.
        if (spacingAndPunctuations.isWordSeparator(cs.charAt(cs.length() - 1))) {
          return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & reqModes;
        }
        // If we don't have whitespace before newCapIndex, it means neither MODE_WORDS
        // nor mode sentences should be on so we can return right away.
        return TextUtils.CAP_MODE_CHARACTERS & reqModes;
      }
      if ((reqModes & TextUtils.CAP_MODE_SENTENCES) == 0) {
        // Here we know we have whitespace before the cursor (if not, we returned in the above
        // if newCapIndex == i clause), so we need MODE_WORDS to be on. And we don't need to
        // evaluate MODE_SENTENCES so we can return right away.
        return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & reqModes;
      }
      // Please note that because of the reqModes & CAP_MODE_SENTENCES test a few lines above,
      // we know that MODE_SENTENCES is being requested.
  
      // Step 4 : Search for MODE_SENTENCES.
      // English is a special case in that "American typography" rules, which are the most common
      // in English, state that a sentence terminator immediately following a quotation mark
      // should be swapped with it and de-duplicated (included in the quotation mark),
      // e.g. <<Did he say, "let's go home?">>
      // No other language has such a rule as far as I know, instead putting inside the quotation
      // mark as the exact thing quoted and handling the surrounding punctuation independently,
      // e.g. <<Did he say, "let's go home"?>>
      if (spacingAndPunctuations.mUsesAmericanTypography) {
        for (; i > 0; i--) {
          // Here we look to go over any closing punctuation. This is because in dominant
          // variants of English, the final period is placed within double quotes and maybe
          // other closing punctuation signs. This is generally not true in other languages.
          final char c = cs.charAt(i - 1);
          if (c != Constants.CODE_DOUBLE_QUOTE && c != Constants.CODE_SINGLE_QUOTE
              && Character.getType(c) != Character.END_PUNCTUATION) {
            break;
          }
        }
      }
  
      if (i <= 0) {
        return TextUtils.CAP_MODE_CHARACTERS & reqModes;
      }
      char c = cs.charAt(--i);
  
      // We found the next interesting chunk of text ; next we need to determine if it's the
      // end of a sentence. If we have a sentence terminator (typically a question mark or an
      // exclamation mark), then it's the end of a sentence; however, we treat the abbreviation
      // marker specially because usually is the same char as the sentence separator (the
      // period in most languages) and in this case we need to apply a heuristic to determine
      // in which of these senses it's used.
      if (spacingAndPunctuations.isSentenceTerminator(c)
          && !spacingAndPunctuations.isAbbreviationMarker(c)) {
        return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS
            | TextUtils.CAP_MODE_SENTENCES) & reqModes;
      }
      // If we reach here, we know we have whitespace before the cursor and before that there
      // is something that either does not terminate the sentence, or a symbol preceded by the
      // start of the text, or it's the sentence separator AND it happens to be the same code
      // point as the abbreviation marker.
      // If it's a symbol or something that does not terminate the sentence, then we need to
      // return caps for MODE_CHARACTERS and MODE_WORDS, but not for MODE_SENTENCES.
      if (!spacingAndPunctuations.isSentenceSeparator(c) || i <= 0) {
        return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & reqModes;
      }
  
      // We found out that we have a period. We need to determine if this is a full stop or
      // otherwise sentence-ending period, or an abbreviation like "e.g.". An abbreviation
      // looks like (\w\.){2,}. Moreover, in German, you put periods after digits for dates
      // and some other things, and in German specifically we need to not go into autocaps after
      // a whitespace-digits-period sequence.
      // To find out, we will have a simple state machine with the following states :
      // START, WORD, PERIOD, ABBREVIATION, NUMBER
      // On START : (just before the first period)
      //           letter => WORD
      //           digit => NUMBER if German; end with caps otherwise
      //           whitespace => end with no caps (it was a stand-alone period)
      //           otherwise => end with caps (several periods/symbols in a row)
      // On WORD : (within the word just before the first period)
      //           letter => WORD
      //           period => PERIOD
      //           otherwise => end with caps (it was a word with a full stop at the end)
      // On PERIOD : (period within a potential abbreviation)
      //           letter => LETTER
      //           otherwise => end with caps (it was not an abbreviation)
      // On LETTER : (letter within a potential abbreviation)
      //           letter => LETTER
      //           period => PERIOD
      //           otherwise => end with no caps (it was an abbreviation)
      // On NUMBER : (period immediately preceded by one or more digits)
      //           digit => NUMBER
      //           letter => LETTER (promote to word)
      //           otherwise => end with no caps (it was a whitespace-digits-period sequence,
      //            or a punctuation-digits-period sequence like "11.11.")
      // "Not an abbreviation" in the above chart essentially covers cases like "...yes.". This
      // should capitalize.
  
      final int START = 0;
      final int WORD = 1;
      final int PERIOD = 2;
      final int LETTER = 3;
      final int NUMBER = 4;
      final int caps = (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS
          | TextUtils.CAP_MODE_SENTENCES) & reqModes;
      final int noCaps = (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & reqModes;
      int state = START;
      while (i > 0) {
        c = cs.charAt(--i);
        switch (state) {
          case START:
            if (Character.isLetter(c)) {
              state = WORD;
            } else if (Character.isWhitespace(c)) {
              return noCaps;
            } else if (Character.isDigit(c) && spacingAndPunctuations.mUsesGermanRules) {
              state = NUMBER;
            } else {
              return caps;
            }
            break;
          case WORD:
            if (Character.isLetter(c)) {
              state = WORD;
            } else if (spacingAndPunctuations.isSentenceSeparator(c)) {
              state = PERIOD;
            } else {
              return caps;
            }
            break;
          case PERIOD:
            if (Character.isLetter(c)) {
              state = LETTER;
            } else {
              return caps;
            }
            break;
          case LETTER:
            if (Character.isLetter(c)) {
              state = LETTER;
            } else if (spacingAndPunctuations.isSentenceSeparator(c)) {
              state = PERIOD;
            } else {
              return noCaps;
            }
            break;
          case NUMBER:
            if (Character.isLetter(c)) {
              state = WORD;
            } else if (Character.isDigit(c)) {
              state = NUMBER;
            } else {
              return noCaps;
            }
        }
      }
      // Here we arrived at the start of the line. This should behave exactly like whitespace.
      return (START == state || LETTER == state) ? noCaps : caps;
    }
  
    /**
     * Convert capitalize mode flags into human readable text.
     *
     * @param capsFlags The modes flags to be converted. It may be any combination of
     *                  {@link TextUtils#CAP_MODE_CHARACTERS}, {@link TextUtils#CAP_MODE_WORDS}, and
     *                  {@link TextUtils#CAP_MODE_SENTENCES}.
     * @return the text that describe the <code>capsMode</code>.
     */
    public static String flagsToString(final int capsFlags) {
      final int capsFlagsMask = TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS
          | TextUtils.CAP_MODE_SENTENCES;
      if ((capsFlags & ~capsFlagsMask) != 0) {
        return "unknown<0x" + Integer.toHexString(capsFlags) + ">";
      }
      final ArrayList<String> builder = new ArrayList<>();
      if ((capsFlags & android.text.TextUtils.CAP_MODE_CHARACTERS) != 0) {
        builder.add("characters");
      }
      if ((capsFlags & android.text.TextUtils.CAP_MODE_WORDS) != 0) {
        builder.add("words");
      }
      if ((capsFlags & android.text.TextUtils.CAP_MODE_SENTENCES) != 0) {
        builder.add("sentences");
      }
      return builder.isEmpty() ? "none" : TextUtils.join("|", builder);
    }
  }
  