Twidere-App-Android-Twitter-Mastodon/twidere/src/main/kotlin/org/mariotaku/twidere/extension/EmojiExtensions.kt

/*
 *             Twidere - Twitter client for Android
 *
 *  Copyright (C) 2012-2017 Mariotaku Lee <mariotaku.lee@gmail.com>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.mariotaku.twidere.extension

import android.graphics.drawable.Drawable
import android.text.Spannable
import android.text.Spanned
import android.widget.TextView
import org.mariotaku.commons.text.CodePointArray
import org.mariotaku.commons.text.get
import org.mariotaku.twidere.text.style.EmojiSpan
import org.mariotaku.twidere.text.util.EmojiEditableFactory
import org.mariotaku.twidere.text.util.EmojiSpannableFactory
import org.mariotaku.twidere.util.ExternalThemeManager

/**
 * Created by mariotaku on 2017/5/13.
 */

fun TextView.setupEmojiFactory() {
    if (isInEditMode) return
    setSpannableFactory(EmojiSpannableFactory(this))
    setEditableFactory(EmojiEditableFactory(this))
}

fun ExternalThemeManager.Emoji.applyTo(text: Spannable, textStart: Int = 0, textLength: Int = text.length) {
    if (!isSupported) return
    val array = CodePointArray(text)
    var arrayIdx = array.length() - 1
    while (arrayIdx >= 0) {
        val codePoint = array[arrayIdx]
        if (isEmoji(codePoint)) {
            val arrayEnd = arrayIdx + 1
            var arrayIdxOffset = 0
            val textIdx = array.indexOfText(codePoint, arrayIdx)
            var textIdxOffset = 0
            var skippedIndex = 0
            if (textIdx == -1 || textIdx < textStart) {
                arrayIdx--
                continue
            }
            val textEnd = textIdx + Character.charCount(codePoint)
            if (arrayIdx > 0) {
                val prevCodePoint = array[arrayIdx - 1]
                when {
                    isRegionalIndicatorSymbol(codePoint) -> if (isRegionalIndicatorSymbol(prevCodePoint)) {
                        arrayIdxOffset = -1
                        textIdxOffset = -Character.charCount(prevCodePoint)
                        skippedIndex = -1
                    }
                    isModifier(codePoint) -> if (isEmoji(prevCodePoint)) {
                        arrayIdxOffset = -1
                        textIdxOffset = -Character.charCount(prevCodePoint)
                        skippedIndex = -1
                    }
                    isKeyCap(codePoint) -> if (isPhoneNumberSymbol(prevCodePoint)) {
                        arrayIdxOffset = -1
                        textIdxOffset = -Character.charCount(prevCodePoint)
                        skippedIndex = -1
                    }
                    isZeroWidthJoin(prevCodePoint) -> {
                        var notValidControlCount = 0
                        var charCount = 0
                        for (i in arrayIdx - 1 downTo 0) {
                            val cp = array.get(i)
                            charCount += Character.charCount(cp)
                            if (isZeroWidthJoin(cp) || isVariationSelector(cp)) {
                                // Ignore
                                notValidControlCount = 0
                                continue
                            }
                            notValidControlCount++
                            if (notValidControlCount > 1 || i == 0) {
                                arrayIdxOffset = i - arrayIdx + 1
                                textIdxOffset = -charCount + Character.charCount(cp)
                                skippedIndex = i - arrayIdx + 1
                                break
                            }
                        }
                    }
                }
            }
            if (textEnd > textStart + textLength) {
                arrayIdx--
                continue
            }
            var spans = text.getSpans(textIdx + textIdxOffset, textEnd, EmojiSpan::class.java)
            if (spans.isEmpty()) {
                var drawable: Drawable? = getEmojiDrawableFor(*array[arrayIdx + arrayIdxOffset..arrayEnd])
                if (drawable == null) {
                    // Not emoji combination, just use fallback
                    textIdxOffset = 0
                    arrayIdxOffset = 0
                    skippedIndex = 0
                    spans = text.getSpans(textIdx + textIdxOffset, textEnd, EmojiSpan::class.java)
                    if (spans.isEmpty()) {
                        drawable = getEmojiDrawableFor(*array[arrayIdx + arrayIdxOffset..arrayEnd])
                    }
                }
                if (drawable != null) {
                    text.setSpan(EmojiSpan(drawable), textIdx + textIdxOffset, textEnd,
                            Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                }
            }
            arrayIdx += skippedIndex
        }
        arrayIdx--
    }
}


private fun isVariationSelector(codePoint: Int): Boolean {
    return codePoint == 0xfe0f
}

private fun isZeroWidthJoin(codePoint: Int): Boolean {
    return codePoint == 0x200d
}

private fun isPhoneNumberSymbol(codePoint: Int): Boolean {
    return codePoint == 0x0023 || codePoint == 0x002a || codePoint in 0x0030..0x0039
}

private fun isModifier(codePoint: Int): Boolean {
    return codePoint in 0x1f3fb..0x1f3ff
}

private fun isEmoji(codePoint: Int): Boolean {
    return !Character.isLetterOrDigit(codePoint)
}

private fun isRegionalIndicatorSymbol(codePoint: Int): Boolean {
    return codePoint in 0x1f1e6..0x1f1ff
}

private fun isKeyCap(codePoint: Int): Boolean {
    return codePoint == 0x20e3
}