package chat.rocket.android.emoji

import android.content.Context
import android.graphics.Bitmap
import android.graphics.Typeface
import android.text.Spannable
import android.text.SpannableString
import android.text.Spanned
import android.text.style.ImageSpan
import android.util.Log
import chat.rocket.android.emoji.internal.GlideApp
import com.bumptech.glide.load.engine.DiskCacheStrategy
import com.bumptech.glide.load.resource.gif.GifDrawable
import kotlinx.coroutines.experimental.CommonPool
import kotlinx.coroutines.experimental.Deferred
import kotlinx.coroutines.experimental.async

class EmojiParser {

    companion object {

        private val regex = ":[\\w]+:".toRegex()

        /**
         * Parses a text string containing unicode characters and/or shortnames to a rendered
         * Spannable.
         *
         * @param text The text to parse
         * @param factory Optional. A [Spannable.Factory] instance to reuse when creating [Spannable].
         * @return A rendered Spannable containing any supported emoji.
         */
        fun parse(context: Context, text: CharSequence, factory: Spannable.Factory? = null): CharSequence {
            val unicodedText = EmojiRepository.shortnameToUnicode(text)
            val spannable = factory?.newSpannable(unicodedText)
                ?: SpannableString.valueOf(unicodedText)

            val typeface = try {
                EmojiRepository.cachedTypeface
            } catch (ex: UninitializedPropertyAccessException) {
                // swallow this exception and create typeface now
                Typeface.createFromAsset(context.assets, "fonts/emojione-android.ttf")
            }

            // Look for groups of emojis, set a EmojiTypefaceSpan with the emojione font.
            val length = spannable.length
            var inEmoji = false
            var emojiStart = 0
            var offset = 0
            while (offset < length) {
                val codepoint = unicodedText.codePointAt(offset)
                val count = Character.charCount(codepoint)
                // Skip control characters.
                if (codepoint == 0x2028) {
                    offset += count
                    continue
                }

                if (codepoint >= 0x200) {
                    if (!inEmoji) {
                        emojiStart = offset
                    }
                    inEmoji = true
                } else {
                    if (inEmoji) {
                        spannable.setSpan(EmojiTypefaceSpan("sans-serif", typeface),
                            emojiStart, offset, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                    }
                    inEmoji = false
                }

                offset += count
                if (offset >= length && inEmoji) {
                    spannable.setSpan(EmojiTypefaceSpan("sans-serif", typeface),
                        emojiStart, offset, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                }
            }

            val customEmojis = EmojiRepository.getCustomEmojis()

            val px = context.resources.getDimensionPixelSize(R.dimen.custom_emoji_small)

            return spannable.also { sp ->
                regex.findAll(spannable).iterator().forEach { match ->
                    customEmojis.find { it.shortname.toLowerCase() == match.value.toLowerCase() }?.let { emoji ->
                        emoji.url?.let { url ->
                            try {
                                val glideRequest = if (url.endsWith("gif", true)) {
                                    GlideApp.with(context).asGif()
                                } else {
                                    GlideApp.with(context).asBitmap()
                                }

                                val futureTarget = glideRequest
                                    .diskCacheStrategy(DiskCacheStrategy.ALL)
                                    .load(url)
                                    .submit(px, px)

                                val range = match.range
                                futureTarget.get()?.let { image ->
                                    if (image is Bitmap) {
                                        spannable.setSpan(ImageSpan(context, image), range.start,
                                            range.endInclusive + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                                    } else if (image is GifDrawable) {
                                        image.setBounds(0, 0, image.intrinsicWidth, image.intrinsicHeight)
                                        spannable.setSpan(ImageSpan(image), range.start,
                                            range.endInclusive + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                                    }
                                }
                            } catch (ex: Throwable) {
                                Log.e("EmojiParser", "", ex)
                            }
                        }
                    }
                }
            }
        }

        fun parseAsync(
            context: Context,
            text: CharSequence,
            factory: Spannable.Factory? = null
        ): Deferred<CharSequence> {
            return async(CommonPool) { parse(context, text, factory) }
        }
    }
}
