TextViewHtmlExtensions.kt

import android.content.Context
import android.os.Build
import android.text.Html
import android.text.SpannableStringBuilder
import android.text.Spanned
import android.text.SpannedString
import android.text.method.LinkMovementMethod
import android.text.style.ClickableSpan
import android.text.style.URLSpan
import android.view.View
import android.widget.TextView
import androidx.annotation.StringRes
import androidx.core.text.TextUtilsCompat

/**
 * Created by Terenfear on 11.02.2019.
 */
fun TextView.setTextFromHtml(html: String, onUrlClick: ((url: String) -> Unit)? = null) {
    val sequence: Spanned = fromHtml(html)
    if (onUrlClick != null) {
        text = processLinks(sequence, onUrlClick)
        movementMethod = LinkMovementMethod.getInstance()
    } else {
        text = sequence
    }
}

fun fromHtml(html: String): Spanned {
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        Html.fromHtml(html, Html.FROM_HTML_MODE_COMPACT)
    } else {
        Html.fromHtml(html)
    }
}

fun toHtml(spanned: Spanned): String {
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        Html.toHtml(spanned, Html.FROM_HTML_MODE_COMPACT)
    } else {
        Html.toHtml(spanned)
    }
}

private fun processLinks(
    sequence: Spanned,
    onUrlClick: ((url: String) -> Unit)?
): Spanned {
    val strBuilder = SpannableStringBuilder(sequence)
    val urls = strBuilder.getSpans(0, sequence.length, URLSpan::class.java)
    for (span in urls) {
        makeLinkClickable(strBuilder, span, onUrlClick)
    }
    return strBuilder
}

private fun makeLinkClickable(
    strBuilder: SpannableStringBuilder,
    span: URLSpan,
    onUrlClick: ((url: String) -> Unit)?
) {
    val start = strBuilder.getSpanStart(span)
    val end = strBuilder.getSpanEnd(span)
    val flags = strBuilder.getSpanFlags(span)
    val clickable = object : ClickableSpan() {
        override fun onClick(view: View) {
            onUrlClick?.invoke(span.url)
        }
    }
    strBuilder.setSpan(clickable, start, end, flags)
    strBuilder.removeSpan(span)
}

fun Context.getText(@StringRes resId: Int, vararg args: Any): CharSequence {
    val formattedArgs = args.map { TextUtilsCompat.htmlEncode(it.toString()) }.toTypedArray()
    return fromHtml(
        String.format(
            toHtml(
                SpannedString(
                    getText(resId)
                )
            ),
            *formattedArgs
        )
    )

}