Properly parse attachment file names

app/src/main/kotlin/com/simplemobiletools/smsmessenger/helpers/AttachmentUtils.kt

@@ -0,0 +1,72 @@
+package com.simplemobiletools.smsmessenger.helpers
+
+import android.util.Xml
+import org.xmlpull.v1.XmlPullParser
+
+object AttachmentUtils {
+
+    fun parseAttachmentNames(text: String): List<String> {
+        val parser = Xml.newPullParser()
+        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false)
+        parser.setInput(text.reader())
+        parser.nextTag()
+
+        return readSmil(parser)
+    }
+
+    private fun readSmil(parser: XmlPullParser): List<String> {
+        parser.require(XmlPullParser.START_TAG, null, "smil")
+        while (parser.next() != XmlPullParser.END_TAG) {
+            if (parser.eventType != XmlPullParser.START_TAG) {
+                continue
+            }
+            if (parser.name == "body") {
+                return readBody(parser)
+            } else {
+                skip(parser)
+            }
+        }
+
+        return emptyList()
+    }
+
+    private fun readBody(parser: XmlPullParser): List<String> {
+        val names = mutableListOf<String>()
+        parser.require(XmlPullParser.START_TAG, null, "body")
+        while (parser.next() != XmlPullParser.END_TAG) {
+            if (parser.eventType != XmlPullParser.START_TAG) {
+                continue
+            }
+            if (parser.name == "par") {
+                parser.require(XmlPullParser.START_TAG, null, "par")
+                while (parser.next() != XmlPullParser.END_TAG) {
+                    if (parser.eventType != XmlPullParser.START_TAG) {
+                        continue
+                    }
+                    if (parser.name == "ref") {
+                        val value = parser.getAttributeValue(null, "src")
+                        names.add(value)
+                        parser.nextTag()
+                    }
+                }
+            } else {
+                skip(parser)
+            }
+        }
+        return names
+    }
+
+    private fun skip(parser: XmlPullParser) {
+        if (parser.eventType != XmlPullParser.START_TAG) {
+            throw IllegalStateException()
+        }
+        var depth = 1
+        while (depth != 0) {
+            when (parser.next()) {
+                XmlPullParser.END_TAG -> depth--
+                XmlPullParser.START_TAG -> depth++
+            }
+        }
+    }
+
+}