1 files changed, 105 insertions, 0 deletions
diff --git a/buildSrc/src/main/kotlin/kau/ChangelogGenerator.kt b/buildSrc/src/main/kotlin/kau/ChangelogGenerator.kt
new file mode 100644
index 0000000..20e8eef
--- /dev/null
+++ b/buildSrc/src/main/kotlin/kau/ChangelogGenerator.kt
@@ -0,0 +1,105 @@
+package kau
+
+import groovy.util.Node
+import groovy.util.XmlParser
+import org.gradle.api.GradleException
+import java.io.File
+
+/**
+ * Given an xml of the format
+ *
+ * <?xml version="1.0" encoding="utf-8"?>
+ *  <resources>
+ *  <version title="v0.1" />
+ *  <item text="Initial Changelog" />
+ *  <item text="Bullet point here" />
+ *  <item text="More points" />
+ *  <item text="" /> <!-- this one is empty and therefore ignored -->
+ * </resources>
+ *
+ * Outputs a changelog in markdown format
+ */
+object ChangelogGenerator {
+
+    class ChangelogException(message: String) : GradleException(message)
+
+    private fun fail(message: String): Nothing =
+        throw ChangelogException(message)
+
+    class ChangelogEntry(val version: String, val items: Array<String>)
+
+    private fun Node.forEachNode(action: (Node) -> Unit) {
+        children().forEach {
+            action(it as Node)
+        }
+    }
+
+    @JvmStatic
+    fun read(inputUri: String): List<ChangelogEntry> {
+        val input = File(inputUri)
+        if (!input.exists()) {
+            fail("Could not generate changelog from ${input.absolutePath}")
+        }
+
+        val parser = XmlParser().parse(inputUri)
+
+        val entries: MutableList<ChangelogEntry> = mutableListOf()
+        var version: String? = null
+        val items: MutableList<String> = mutableListOf()
+
+        fun addEntry() {
+            version?.also { v ->
+                entries.add(ChangelogEntry(v, items.toTypedArray()))
+                items.clear()
+            }
+        }
+
+        parser.depthFirst().mapNotNull { it as? Node }.forEach { n ->
+            when (n.name()) {
+                "version" -> {
+                    addEntry()
+                    version = n.attribute("title")?.toString() ?: ""
+                }
+                "item" -> {
+                    n.attribute("text")?.toString()?.takeIf(String::isNotBlank)?.let {
+                        items.add(it)
+                    }
+                }
+            }
+        }
+        addEntry()
+        return entries
+    }
+
+    @JvmStatic
+    fun generate(inputUri: String, outputUri: String): List<ChangelogEntry> {
+        val entries = read(inputUri)
+        val output = File(outputUri)
+        if (output.exists()) {
+            if (output.isDirectory) {
+                fail("Cannot save changelog at directory ${output.absolutePath}")
+            }
+            if (output.isFile && !output.delete()) {
+                fail("Could not delete changelog at ${output.absolutePath}")
+            }
+        } else {
+            output.parentFile.mkdirs()
+        }
+
+        if (!output.createNewFile()) {
+            fail("Could not create changelog file at ${output.absolutePath}")
+        }
+        val markdown = buildString {
+            append("# Changelog\n")
+            entries.forEach { e ->
+                append("\n## ${e.version}\n")
+                e.items.forEach {
+                    append("* $it\n")
+                }
+            }
+        }
+        output.writeText(markdown)
+        println("Generated changelog at ${output.absolutePath}")
+        return entries
+    }
+}
+\ No newline at end of file