/*
 * Copyright (c) 2017, Daniel Gultsch All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation and/or
 * other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package eu.siacs.conversations.utils;

import android.support.annotation.NonNull;
import android.util.LruCache;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.regex.Pattern;

public class Emoticons {

    private static final UnicodeRange MISC_SYMBOLS_AND_PICTOGRAPHS = new UnicodeRange(0x1F300, 0x1F5FF);
    private static final UnicodeRange SUPPLEMENTAL_SYMBOLS = new UnicodeRange(0x1F900, 0x1F9FF);
    private static final UnicodeRange EMOTICONS = new UnicodeRange(0x1F600, 0x1F64F);
    private static final UnicodeRange TRANSPORT_SYMBOLS = new UnicodeRange(0x1F680, 0x1F6FF);
    private static final UnicodeRange MISC_SYMBOLS = new UnicodeRange(0x2600, 0x26FF);
    private static final UnicodeRange DINGBATS = new UnicodeRange(0x2700, 0x27BF);
    private static final UnicodeRange ENCLOSED_ALPHANUMERIC_SUPPLEMENT = new UnicodeRange(0x1F100, 0x1F1FF);
    private static final UnicodeRange ENCLOSED_IDEOGRAPHIC_SUPPLEMENT = new UnicodeRange(0x1F200, 0x1F2FF);
    private static final UnicodeRange REGIONAL_INDICATORS = new UnicodeRange(0x1F1E6, 0x1F1FF);
    private static final UnicodeRange GEOMETRIC_SHAPES = new UnicodeRange(0x25A0, 0x25FF);
    private static final UnicodeRange LATIN_SUPPLEMENT = new UnicodeRange(0x80, 0xFF);
    private static final UnicodeRange MISC_TECHNICAL = new UnicodeRange(0x2300, 0x23FF);
    private static final UnicodeRange TAGS = new UnicodeRange(0xE0020, 0xE007F);
    private static final UnicodeList CYK_SYMBOLS_AND_PUNCTUATION = new UnicodeList(0x3030, 0x303D);
    private static final UnicodeList LETTERLIKE_SYMBOLS = new UnicodeList(0x2122, 0x2139);

    private static final UnicodeBlocks KEYCAP_COMBINEABLE = new UnicodeBlocks(new UnicodeList(0x23), new UnicodeList(0x2A), new UnicodeRange(0x30, 0x39));

    private static final UnicodeBlocks SYMBOLIZE = new UnicodeBlocks(
            GEOMETRIC_SHAPES,
            LATIN_SUPPLEMENT,
            CYK_SYMBOLS_AND_PUNCTUATION,
            LETTERLIKE_SYMBOLS,
            KEYCAP_COMBINEABLE);
    private static final UnicodeBlocks EMOJIS = new UnicodeBlocks(
            MISC_SYMBOLS_AND_PICTOGRAPHS,
            SUPPLEMENTAL_SYMBOLS,
            EMOTICONS,
            TRANSPORT_SYMBOLS,
            MISC_SYMBOLS,
            DINGBATS,
            ENCLOSED_ALPHANUMERIC_SUPPLEMENT,
            ENCLOSED_IDEOGRAPHIC_SUPPLEMENT,
            MISC_TECHNICAL);

    private static final int MAX_EMOIJS = 42;

    private static final int ZWJ = 0x200D;
    private static final int VARIATION_16 = 0xFE0F;
    private static final int COMBINING_ENCLOSING_KEYCAP = 0x20E3;
    private static final int BLACK_FLAG = 0x1F3F4;
    private static final UnicodeRange FITZPATRICK = new UnicodeRange(0x1F3FB, 0x1F3FF);

    private static final LruCache<CharSequence, Pattern> CACHE = new LruCache<>(256);

    private static List<Symbol> parse(String input) {
        List<Symbol> symbols = new ArrayList<>();
        Builder builder = new Builder();
        boolean needsFinalBuild = false;
        for (int cp, i = 0; i < input.length(); i += Character.charCount(cp)) {
            cp = input.codePointAt(i);
            if (builder.offer(cp)) {
                needsFinalBuild = true;
            } else {
                symbols.add(builder.build());
                builder = new Builder();
                if (builder.offer(cp)) {
                    needsFinalBuild = true;
                }
            }
        }
        if (needsFinalBuild) {
            symbols.add(builder.build());
        }
        return symbols;
    }

    public static Pattern getEmojiPattern(final CharSequence input) {
        Pattern pattern = CACHE.get(input);
        if (pattern == null) {
            pattern = generatePattern(input);
            CACHE.put(input, pattern);
        }
        return pattern;
    }

    private static Pattern generatePattern(CharSequence input) {
        final HashSet<String> emojis = new HashSet<>();
        int i = 0;
        for (final Symbol symbol : parse(input.toString())) {
            if (symbol instanceof Emoji) {
                emojis.add(symbol.toString());
                if (++i >= MAX_EMOIJS) {
                    return Pattern.compile("");
                }
            }
        }
        final StringBuilder pattern = new StringBuilder();
        for (String emoji : emojis) {
            if (pattern.length() != 0) {
                pattern.append('|');
            }
            pattern.append(Pattern.quote(emoji));
        }
        return Pattern.compile(pattern.toString());
    }

    public static boolean isEmoji(String input) {
        List<Symbol> symbols = parse(input);
        return symbols.size() == 1 && symbols.get(0).isEmoji();
    }

    public static boolean isOnlyEmoji(String input) {
        List<Symbol> symbols = parse(input);
        for (Symbol symbol : symbols) {
            if (!symbol.isEmoji()) {
                return false;
            }
        }
        return symbols.size() > 0;
    }

    private static abstract class Symbol {

        private final String value;

        Symbol(List<Integer> codepoints) {
            final StringBuilder builder = new StringBuilder();
            for (final Integer codepoint : codepoints) {
                builder.appendCodePoint(codepoint);
            }
            this.value = builder.toString();
        }

        abstract boolean isEmoji();

        @NonNull
        @Override
        public String toString() {
            return value;
        }
    }

    public static class Emoji extends Symbol {

        Emoji(List<Integer> codepoints) {
            super(codepoints);
        }

        @Override
        boolean isEmoji() {
            return true;
        }
    }

    public static class Other extends Symbol {

        public Other(List<Integer> codepoints) {
            super(codepoints);
        }

        @Override
        boolean isEmoji() {
            return false;
        }
    }

    private static class Builder {
        private final List<Integer> codepoints = new ArrayList<>();


        public boolean offer(int codepoint) {
            boolean add = false;
            if (this.codepoints.size() == 0) {
                if (SYMBOLIZE.contains(codepoint)) {
                    add = true;
                } else if (REGIONAL_INDICATORS.contains(codepoint)) {
                    add = true;
                } else if (EMOJIS.contains(codepoint) && !FITZPATRICK.contains(codepoint) && codepoint != ZWJ) {
                    add = true;
                }
            } else {
                int previous = codepoints.get(codepoints.size() - 1);
                if (codepoints.get(0) == BLACK_FLAG) {
                    add = TAGS.contains(codepoint);
                } else if (COMBINING_ENCLOSING_KEYCAP == codepoint) {
                    add = KEYCAP_COMBINEABLE.contains(previous) || previous == VARIATION_16;
                } else if (SYMBOLIZE.contains(previous)) {
                    add = codepoint == VARIATION_16;
                } else if (REGIONAL_INDICATORS.contains(previous) && REGIONAL_INDICATORS.contains(codepoint)) {
                    add = codepoints.size() == 1;
                } else if (previous == VARIATION_16) {
                    add = isMerger(codepoint) || codepoint == VARIATION_16;
                } else if (FITZPATRICK.contains(previous)) {
                    add = codepoint == ZWJ;
                } else if (ZWJ == previous) {
                    add = EMOJIS.contains(codepoint);
                } else if (isMerger(codepoint)) {
                    add = true;
                } else if (codepoint == VARIATION_16 && EMOJIS.contains(previous)) {
                    add = true;
                }
            }
            if (add) {
                codepoints.add(codepoint);
                return true;
            } else {
                return false;
            }
        }

        private static boolean isMerger(int codepoint) {
            return codepoint == ZWJ || FITZPATRICK.contains(codepoint);
        }

        public Symbol build() {
            if (codepoints.size() > 0 && SYMBOLIZE.contains(codepoints.get(codepoints.size() - 1))) {
                return new Other(codepoints);
            } else if (codepoints.size() > 1 && KEYCAP_COMBINEABLE.contains(codepoints.get(0)) && codepoints.get(codepoints.size() - 1) != COMBINING_ENCLOSING_KEYCAP) {
                return new Other(codepoints);
            }
            return codepoints.size() == 0 ? new Other(codepoints) : new Emoji(codepoints);
        }
    }

    public static class UnicodeBlocks implements UnicodeSet {
        final UnicodeSet[] unicodeSets;

        UnicodeBlocks(final UnicodeSet... sets) {
            this.unicodeSets = sets;
        }

        @Override
        public boolean contains(int codepoint) {
            for (UnicodeSet unicodeSet : unicodeSets) {
                if (unicodeSet.contains(codepoint)) {
                    return true;
                }
            }
            return false;
        }
    }

    public interface UnicodeSet {
        boolean contains(int codepoint);
    }

    public static class UnicodeList implements UnicodeSet {

        private final List<Integer> list;

        UnicodeList(final Integer... codes) {
            this.list = Arrays.asList(codes);
        }

        @Override
        public boolean contains(int codepoint) {
            return this.list.contains(codepoint);
        }
    }


    public static class UnicodeRange implements UnicodeSet {

        private final int lower;
        private final int upper;

        UnicodeRange(int lower, int upper) {
            this.lower = lower;
            this.upper = upper;
        }

        public boolean contains(int codePoint) {
            return codePoint >= lower && codePoint <= upper;
        }
    }
}