add bootstrapping.md

src/main/kotlin/de/hoennig/gittally/git/GitService.kt

@@ -0,0 +1,38 @@
+package de.hoennig.gittally.git
+
+import org.springframework.stereotype.Service
+import java.nio.file.Path
+import java.nio.file.Paths
+
+@Service
+class GitService {
+    fun getTopLevel(workingDir: Path = Paths.get(".")): Path {
+        val process =
+            ProcessBuilder("git", "rev-parse", "--show-toplevel")
+                .directory(workingDir.toFile())
+                .start()
+        if (process.waitFor() != 0) {
+            throw RuntimeException("Not a git repository")
+        }
+        return Paths.get(
+            process.inputStream
+                .bufferedReader()
+                .readText()
+                .trim(),
+        )
+    }
+
+    fun getOriginUrl(workingDir: Path = Paths.get(".")): String? {
+        val process =
+            ProcessBuilder("git", "remote", "get-url", "origin")
+                .directory(workingDir.toFile())
+                .start()
+        if (process.waitFor() != 0) {
+            return null
+        }
+        return process.inputStream
+            .bufferedReader()
+            .readText()
+            .trim()
+    }
+}