Use native git in GitArchiver if possible (#193)

orx-jvm/orx-git-archiver/src/main/kotlin/NativeGit.kt

@@ -0,0 +1,49 @@
+package org.openrndr.extra.gitarchiver
+
+import java.io.File
+import java.io.IOException
+import java.util.concurrent.TimeUnit
+
+private val dir = File(".")
+
+class NativeGit : GitProvider {
+    override fun commitChanges(commitMessage: String) {
+        val gitStatus = "git status --porcelain".runCommand(dir)!!
+        if (gitStatus.first.isNotBlank()){
+            if (gitStatus.first.contains("Not a git repository")){
+                logger.error { "Can't commit changes because the working directory is not a git repository" }
+            } else {
+                "git add .".runCommand(dir)
+                "git commit -m \"${commitMessage}\"".runCommand(dir)
+                logger.info { "git repository is now at ${headReference()}" }
+            }
+        } else {
+            logger.info { "no changes" }
+        }
+    }
+
+    override fun headReference(): String {
+        return "git rev-parse --short HEAD".runCommand(dir)!!.first
+    }
+}
+
+internal fun nativeGitInstalled(): Boolean {
+    return "git --version".runCommand(dir) != null
+}
+
+// Adapted from https://stackoverflow.com/questions/35421699/how-to-invoke-external-command-from-within-kotlin-code
+private fun String.runCommand(workingDir: File): Pair<String, String>? {
+    try {
+        val parts = this.split("\\s".toRegex())
+        val proc = ProcessBuilder(*parts.toTypedArray())
+            .directory(workingDir)
+            .redirectOutput(ProcessBuilder.Redirect.PIPE)
+            .redirectError(ProcessBuilder.Redirect.PIPE)
+            .start()
+
+        proc.waitFor(60, TimeUnit.MINUTES)
+        return Pair(proc.inputStream.bufferedReader().readText(), proc.errorStream.bufferedReader().readText())
+    } catch(e: IOException) {
+        return null
+    }
+}