footnotes support (as notes)

shared/src/commonMain/kotlin/net/sergeych/toread/fb2/Fb2Book.kt

@@ -17,6 +17,7 @@ data class Fb2Book(
     val bodyImages: List<Fb2ImageRef> = emptyList(),
     val bodyEpigraphs: List<Fb2Epigraph> = emptyList(),
     val sections: List<Fb2Section> = emptyList(),
+    val notes: Map<String, Fb2Section> = emptyMap(),
     val binaries: List<Fb2Binary> = emptyList(),
 ) {
     fun binaryFor(image: Fb2ImageRef): Fb2Binary? =
@@ -47,6 +48,7 @@ data class Fb2DocumentInfo(
 )
 
 data class Fb2Section(
+    val id: String? = null,
     val title: String? = null,
     val paragraphs: List<String> = emptyList(),
     val images: List<Fb2ImageRef> = emptyList(),
@@ -124,6 +126,8 @@ data class Fb2Text(
 data class Fb2TextSpan(
     val text: String,
     val styles: Set<Fb2TextStyle> = emptySet(),
+    val href: String? = null,
+    val linkType: String? = null,
 )
 
 enum class Fb2TextStyle {

shared/src/commonMain/kotlin/net/sergeych/toread/fb2/Fb2XmlMapper.kt

@@ -13,8 +13,15 @@ internal object Fb2XmlMapper {
             ?: throw Fb2ParseException("FB2 document is missing description/title-info")
         val documentInfo = description.first("document-info")
 
-        val body = root.children("body").firstOrNull { it.attributes["name"] != "notes" }
+        val bodies = root.children("body")
+        val body = bodies.firstOrNull { it.attributes["name"] != "notes" }
             ?: root.first("body")
+        val notes = bodies
+            .filter { it.attributes["name"] == "notes" }
+            .flatMap { it.children("section") }
+            .map(::sectionFrom)
+            .mapNotNull { section -> section.id?.let { it to section } }
+            .toMap()
 
         return Fb2Book(
             title = titleInfo.firstText("book-title")
@@ -34,6 +41,7 @@ internal object Fb2XmlMapper {
             bodyImages = body?.children("image")?.mapNotNull(::imageRefFrom).orEmpty(),
             bodyEpigraphs = body?.children("epigraph")?.map(::epigraphFrom).orEmpty(),
             sections = body?.children("section")?.map(::sectionFrom).orEmpty(),
+            notes = notes,
             binaries = root.children("binary").mapNotNull(::binaryFrom),
         )
     }
@@ -135,6 +143,7 @@ internal object Fb2XmlMapper {
         }
 
         return Fb2Section(
+            id = element.attributes["id"]?.takeIf { it.isNotBlank() },
             title = element.first("title")?.text()?.ifBlank { null },
             paragraphs = blocks.filterIsInstance<Fb2Block.Paragraph>()
                 .mapNotNull { it.content.plainText.ifBlank { null } },
@@ -203,11 +212,23 @@ internal object Fb2XmlMapper {
     private fun textFrom(element: XmlElement): Fb2Text =
         Fb2Text(spansFrom(element.nodes).mergeAdjacent().trimBoundaryWhitespace())
 
-    private fun spansFrom(nodes: List<XmlNode>, styles: Set<Fb2TextStyle> = emptySet()): List<Fb2TextSpan> =
+    private fun spansFrom(
+        nodes: List<XmlNode>,
+        styles: Set<Fb2TextStyle> = emptySet(),
+        href: String? = null,
+        linkType: String? = null,
+    ): List<Fb2TextSpan> =
         nodes.flatMap { node ->
             when (node) {
                 is XmlNode.TextNode -> listOfNotNull(
-                    node.text.takeIf { it.isNotEmpty() }?.let { Fb2TextSpan(it, styles) }
+                    node.text.takeIf { it.isNotEmpty() }?.let {
+                        Fb2TextSpan(
+                            text = it,
+                            styles = styles,
+                            href = href,
+                            linkType = linkType,
+                        )
+                    }
                 )
                 is XmlNode.ElementNode -> {
                     val element = node.element
@@ -220,7 +241,13 @@ internal object Fb2XmlMapper {
                         "sub" -> styles + Fb2TextStyle.Subscript
                         else -> styles
                     }
-                    spansFrom(element.nodes, nestedStyles)
+                    val nestedHref = element.attributeLocal("href")
+                        ?.takeIf { element.localName == "a" && it.isNotBlank() }
+                        ?: href
+                    val nestedLinkType = element.attributes["type"]
+                        ?.takeIf { element.localName == "a" && it.isNotBlank() }
+                        ?: linkType
+                    spansFrom(element.nodes, nestedStyles, nestedHref, nestedLinkType)
                 }
             }
         }
@@ -230,7 +257,11 @@ internal object Fb2XmlMapper {
         val merged = mutableListOf<Fb2TextSpan>()
         forEach { span ->
             val previous = merged.lastOrNull()
-            if (previous != null && previous.styles == span.styles) {
+            if (previous != null &&
+                previous.styles == span.styles &&
+                previous.href == span.href &&
+                previous.linkType == span.linkType
+            ) {
                 merged[merged.lastIndex] = previous.copy(text = previous.text + span.text)
             } else {
                 merged += span