/*
 * Copyright (C) 2015 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.
 */

/**
 * An implementation of Liang's hyphenation algorithm.
 */

#include "unicode/locid.h"
#include <memory>
#include <unordered_map>

#ifndef MINIKIN_HYPHENATOR_H
#define MINIKIN_HYPHENATOR_H

namespace minikin {

enum class HyphenationType : uint8_t {
    // Note: There are implicit assumptions scattered in the code that DONT_BREAK is 0.

    // Do not break.
    DONT_BREAK = 0,
    // Break the line and insert a normal hyphen.
    BREAK_AND_INSERT_HYPHEN = 1,
    // Break the line and insert an Armenian hyphen (U+058A).
    BREAK_AND_INSERT_ARMENIAN_HYPHEN = 2,
    // Break the line and insert a maqaf (Hebrew hyphen, U+05BE).
    BREAK_AND_INSERT_MAQAF = 3,
    // Break the line and insert a Canadian Syllabics hyphen (U+1400).
    BREAK_AND_INSERT_UCAS_HYPHEN = 4,
    // Break the line, but don't insert a hyphen. Used for cases when there is already a hyphen
    // present or the script does not use a hyphen (e.g. in Malayalam).
    BREAK_AND_DONT_INSERT_HYPHEN = 5,
    // Break and replace the last code unit with hyphen. Used for Catalan "l·l" which hyphenates
    // as "l-/l".
    BREAK_AND_REPLACE_WITH_HYPHEN = 6,
    // Break the line, and repeat the hyphen (which is the last character) at the beginning of the
    // next line. Used in Polish, where "czerwono-niebieska" should hyphenate as
    // "czerwono-/-niebieska".
    BREAK_AND_INSERT_HYPHEN_AT_NEXT_LINE = 7,
    // Break the line, insert a ZWJ and hyphen at the first line, and a ZWJ at the second line.
    // This is used in Arabic script, mostly for writing systems of Central Asia. It's our default
    // behavior when a soft hyphen is used in Arabic script.
    BREAK_AND_INSERT_HYPHEN_AND_ZWJ = 8
};

// The hyphen edit represents an edit to the string when a word is
// hyphenated. The most common hyphen edit is adding a "-" at the end
// of a syllable, but nonstandard hyphenation allows for more choices.
// Note that a HyphenEdit can hold two types of edits at the same time,
// One at the beginning of the string/line and one at the end.
class HyphenEdit {
public:
    static const uint32_t NO_EDIT = 0x00;

    static const uint32_t INSERT_HYPHEN_AT_END = 0x01;
    static const uint32_t INSERT_ARMENIAN_HYPHEN_AT_END = 0x02;
    static const uint32_t INSERT_MAQAF_AT_END = 0x03;
    static const uint32_t INSERT_UCAS_HYPHEN_AT_END = 0x04;
    static const uint32_t INSERT_ZWJ_AND_HYPHEN_AT_END = 0x05;
    static const uint32_t REPLACE_WITH_HYPHEN_AT_END = 0x06;
    static const uint32_t BREAK_AT_END = 0x07;

    static const uint32_t INSERT_HYPHEN_AT_START = 0x01 << 3;
    static const uint32_t INSERT_ZWJ_AT_START = 0x02 << 3;
    static const uint32_t BREAK_AT_START = 0x03 << 3;

    // Keep in sync with the definitions in the Java code at:
    // frameworks/base/graphics/java/android/graphics/Paint.java
    static const uint32_t MASK_END_OF_LINE = 0x07;
    static const uint32_t MASK_START_OF_LINE = 0x03 << 3;

    inline static bool isReplacement(uint32_t hyph) {
        return hyph == REPLACE_WITH_HYPHEN_AT_END;
    }

    inline static bool isInsertion(uint32_t hyph) {
        return (hyph == INSERT_HYPHEN_AT_END
                || hyph == INSERT_ARMENIAN_HYPHEN_AT_END
                || hyph == INSERT_MAQAF_AT_END
                || hyph == INSERT_UCAS_HYPHEN_AT_END
                || hyph == INSERT_ZWJ_AND_HYPHEN_AT_END
                || hyph == INSERT_HYPHEN_AT_START
                || hyph == INSERT_ZWJ_AT_START);
    }

    const static uint32_t* getHyphenString(uint32_t hyph);
    static uint32_t editForThisLine(HyphenationType type);
    static uint32_t editForNextLine(HyphenationType type);

    HyphenEdit() : hyphen(NO_EDIT) { }
    HyphenEdit(uint32_t hyphenInt) : hyphen(hyphenInt) { }  // NOLINT(implicit)
    uint32_t getHyphen() const { return hyphen; }
    bool operator==(const HyphenEdit &other) const { return hyphen == other.hyphen; }

    uint32_t getEnd() const { return hyphen & MASK_END_OF_LINE; }
    uint32_t getStart() const { return hyphen & MASK_START_OF_LINE; }

private:
    uint32_t hyphen;
};

// hyb file header; implementation details are in the .cpp file
struct Header;

class Hyphenator {
public:
    // Compute the hyphenation of a word, storing the hyphenation in result vector. Each entry in
    // the vector is a "hyphenation type" for a potential hyphenation that can be applied at the
    // corresponding code unit offset in the word.
    //
    // Example: word is "hyphen", result is the following, corresponding to "hy-phen":
    // [DONT_BREAK, DONT_BREAK, BREAK_AND_INSERT_HYPHEN, DONT_BREAK, DONT_BREAK, DONT_BREAK]
    void hyphenate(std::vector<HyphenationType>* result, const uint16_t* word, size_t len,
            const icu::Locale& locale);

    // Returns true if the codepoint is like U+2010 HYPHEN in line breaking and usage: a character
    // immediately after which line breaks are allowed, but words containing it should not be
    // automatically hyphenated.
    static bool isLineBreakingHyphen(uint32_t cp);

    // pattern data is in binary format, as described in doc/hyb_file_format.md. Note:
    // the caller is responsible for ensuring that the lifetime of the pattern data is
    // at least as long as the Hyphenator object.

    // Note: nullptr is valid input, in which case the hyphenator only processes soft hyphens.
    static Hyphenator* loadBinary(const uint8_t* patternData, size_t minPrefix, size_t minSuffix);

private:
    // apply various hyphenation rules including hard and soft hyphens, ignoring patterns
    void hyphenateWithNoPatterns(HyphenationType* result, const uint16_t* word, size_t len,
            const icu::Locale& locale);

    // Try looking up word in alphabet table, return DONT_BREAK if any code units fail to map.
    // Otherwise, returns BREAK_AND_INSERT_HYPHEN, BREAK_AND_INSERT_ARMENIAN_HYPHEN, or
    // BREAK_AND_DONT_INSERT_HYPHEN based on the the script of the characters seen.
    // Note that this method writes len+2 entries into alpha_codes (including start and stop)
    HyphenationType alphabetLookup(uint16_t* alpha_codes, const uint16_t* word, size_t len);

    // calculate hyphenation from patterns, assuming alphabet lookup has already been done
    void hyphenateFromCodes(HyphenationType* result, const uint16_t* codes, size_t len,
            HyphenationType hyphenValue);

    // See also LONGEST_HYPHENATED_WORD in LineBreaker.cpp. Here the constant is used so
    // that temporary buffers can be stack-allocated without waste, which is a slightly
    // different use case. It measures UTF-16 code units.
    static const size_t MAX_HYPHENATED_SIZE = 64;

    const uint8_t* patternData;
    size_t minPrefix, minSuffix;

    // accessors for binary data
    const Header* getHeader() const {
        return reinterpret_cast<const Header*>(patternData);
    }

};

}  // namespace minikin

#endif   // MINIKIN_HYPHENATOR_H