LibreTube/app/src/main/java/com/github/libretube/util/LinkHandler.kt

package com.github.libretube.util

import android.text.Editable
import android.text.Spanned
import android.text.TextPaint
import android.text.style.ClickableSpan
import android.view.View
import org.xml.sax.Attributes

class LinkHandler(private val clickCallback: ((String) -> Unit)?) {
    private var linkTagStartIndex = -1
    private var link: String? = null
    fun handleTag(
        opening: Boolean,
        tag: String?,
        output: Editable?,
        attributes: Attributes?,
    ): Boolean {
        // if the tag is not an anchor link, ignore for the default handler
        if (output == null || "a" != tag) {
            return false
        }

        if (opening) {
            if (attributes != null) {
                linkTagStartIndex = output.length
                link = attributes.getValue("href")
            }
        } else {
            if (linkTagStartIndex >= 0 && link != null) {
                setLinkSpans(output, linkTagStartIndex, output.length, link!!)

                linkTagStartIndex = -1
                link = null
            }
        }
        return true
    }

    private fun setLinkSpans(output: Editable, start: Int, end: Int, link: String) {
        output.setSpan(
            object : ClickableSpan() {
                override fun onClick(widget: View) {
                    clickCallback?.invoke(link)
                }

                override fun updateDrawState(ds: TextPaint) {
                    super.updateDrawState(ds)
                    ds.isUnderlineText = false
                }
            },
            start,
            end,
            Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
        )
    }
}