Composable for rendering text with Markdown-style hyperlinks

MarkdownLinkText.kt

import androidx.compose.foundation.text.ClickableText
import androidx.compose.material.LocalContentAlpha
import androidx.compose.material.LocalContentColor
import androidx.compose.material.LocalTextStyle
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.takeOrElse
import androidx.compose.ui.text.ExperimentalTextApi
import androidx.compose.ui.text.SpanStyle
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.buildAnnotatedString
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.text.style.TextDecoration
import androidx.compose.ui.text.withAnnotation
import androidx.compose.ui.text.withStyle

private const val TAG_LINK = "link"

/**
 * Renders text with clickable Markdown-style hyperlinks like `[Description](https://link)`.
 *
 * **Note that no other Markdown formatting is supported!**
 */
@Composable
@OptIn(ExperimentalTextApi::class)
fun MarkdownLinkText(
    text: String,
    onLinkClick: (String) -> Unit,
    modifier: Modifier = Modifier,
    color: Color = Color.Unspecified,
    textAlign: TextAlign? = null,
    style: TextStyle = LocalTextStyle.current,
    linkStyle: SpanStyle = SpanStyle(textDecoration = TextDecoration.Underline),
) {
    val textColor = color.takeOrElse {
        style.color.takeOrElse {
            LocalContentColor.current.copy(alpha = LocalContentAlpha.current)
        }
    }

    val mergedStyle = style.merge(
        TextStyle(
            color = textColor,
            textAlign = textAlign,
        ),
    )

    val annotatedText = remember(text) {
        val linksRegex = Regex("\\[(.*?)]\\((.*?)\\)")
        val results = linksRegex.findAll(text)

        buildAnnotatedString {
            val lastIndex = results.fold(0) { currentIndex, result ->
                val before = text.substring(currentIndex until result.range.first)
                append(before)

                withStyle(linkStyle) {
                    withAnnotation(
                        tag = TAG_LINK,
                        annotation = result.groupValues[2],
                    ) {
                        append(result.groupValues[1])
                    }
                }

                result.range.last + 1
            }

            val after = text.substring(lastIndex)
            append(after)
        }
    }

    ClickableText(
        modifier = modifier,
        text = annotatedText,
        style = mergedStyle,
        onClick = {
            annotatedText.getStringAnnotations(TAG_LINK, it, it).firstOrNull()?.let { annotation ->
                onLinkClick(annotation.item)
            }
        },
    )
}