SpannedString.kt

import android.graphics.Typeface
import android.text.Annotation
import android.text.SpannedString
import android.text.style.ForegroundColorSpan
import android.text.style.StrikethroughSpan
import android.text.style.StyleSpan
import android.text.style.UnderlineSpan
import androidx.annotation.StringRes
import androidx.compose.runtime.Composable
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.LinkAnnotation
import androidx.compose.ui.text.SpanStyle
import androidx.compose.ui.text.buildAnnotatedString
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextDecoration
import androidx.core.text.HtmlCompat

@Composable
fun spannedStringResource(
    @StringRes id: Int
): SpannedString {
    val context = LocalContext.current
    return context.getText(id) as SpannedString
}


/**
 * Add string resource as
 * ```
 * <string name="some_text"><annotation clickable="">Clickable part of the text</annotation> the rest of the text</string>
 * ```
 *
 * Use [spannedStringResource] in [Text] composable
 * ```
 * Text(
 *     text = spannedStringResource(R.string.some_text)
 *         .toAnnotatedString { println("Clicked") }
 * )
 * ```
 *
 * @param style The style that will be applied to the annotated string.
 * @param onPartClicked The click action that will be invoked when user clicks on the tagged part of the text.
 */
@Composable
fun SpannedString.toAnnotatedString(
    style: SpanStyle = SpanStyle(),
    onPartClicked: () -> Unit
): AnnotatedString {
    return buildAnnotatedString {
        val spanned = HtmlCompat.fromHtml(
            [email protected](),
            HtmlCompat.FROM_HTML_MODE_LEGACY
        )
        append(spanned)

        val annotations = [email protected](
            0,
            [email protected],
            Annotation::class.java
        )

        annotations.forEach { annotation ->
            if ("clickable" == annotation.key) {
                addLink(
                    LinkAnnotation.Clickable("clickable") { onPartClicked.invoke() },
                    getSpanStart(annotation),
                    getSpanEnd(annotation)
                )
            }
        }

        spanned.getSpans(0, spanned.length, Any::class.java).forEach { span ->
            val start = spanned.getSpanStart(span)
            val end = spanned.getSpanEnd(span)
            addStyle(span, style, start, end)
        }
    }
}

private fun AnnotatedString.Builder.addStyle(
    span: Any,
    style: SpanStyle = SpanStyle(),
    start: Int,
    end: Int
) {
    when (span) {
        is StyleSpan -> when (span.style) {
            Typeface.BOLD -> addStyle(style.copy(fontWeight = FontWeight.Bold), start, end)
            Typeface.ITALIC -> addStyle(
                style.copy(fontStyle = FontStyle.Italic),
                start,
                end
            )

            Typeface.BOLD_ITALIC -> addStyle(
                style.copy(
                    fontWeight = FontWeight.Bold,
                    fontStyle = FontStyle.Italic
                ),
                start,
                end
            )
        }

        is UnderlineSpan -> addStyle(
            style.copy(textDecoration = TextDecoration.Underline),
            start,
            end
        )

        is ForegroundColorSpan -> addStyle(
            style.copy(color = Color(span.foregroundColor)),
            start,
            end
        )

        is StrikethroughSpan -> addStyle(
            style.copy(textDecoration = TextDecoration.LineThrough),
            start,
            end
        )
    }
}