Step 22 C: the repository registry

RepoRegistry opens one RepoContext per entry of the home configuration, or the
current directory without one. An entry that is no git repository or a name
used twice aborts the start naming the home file; a repository whose config
must not be read is skipped with an error and the others are served. The
current-repo bean now comes from the registry (the cwd when served, else the
first entry), and the pre-rename state-dir migration runs per opened repository.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/werkator/WerkatorApplication.kt

@@ -10,7 +10,6 @@ import org.springframework.context.annotation.Profile
 import org.springframework.stereotype.Component
 import picocli.CommandLine
 import picocli.CommandLine.IFactory
-import java.nio.file.Paths
 import kotlin.system.exitProcess
 
 @SpringBootApplication
@@ -27,8 +26,6 @@ class CliRunner(
     private var exitCode = 0
 
     override fun run(vararg args: String) {
-        // before any command resolves a path under it, and once per process
-        StateDirMigration.migrateIfNeeded(Paths.get("."))
         exitCode =
             CommandLine(rootCommand, factory)
                 .setExecutionExceptionHandler { exception, commandLine, _ ->

src/main/kotlin/de/hoennig/werkator/repo/RepoConfiguration.kt

@@ -2,15 +2,14 @@ package de.hoennig.werkator.repo
 
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
-import java.nio.file.Paths
 
 @Configuration
 class RepoConfiguration {
     /**
-     * The single-repository case: the current working directory, which is how every
-     * CLI command and the server resolve their files. Only paths are computed here, so
-     * the bean is safe outside a git repository.
+     * The repository the unscoped code paths mean — the current working directory
+     * when it is served, see [RepoRegistry.current]. Without a registry only paths are
+     * computed here, so the bean is safe outside a git repository.
      */
     @Bean
-    fun currentRepo(repoContexts: RepoContexts): RepoContext = repoContexts.open(Paths.get("."))
+    fun currentRepo(registry: RepoRegistry): RepoContext = registry.current()
 }

src/main/kotlin/de/hoennig/werkator/repo/RepoContexts.kt

@@ -1,12 +1,17 @@
 package de.hoennig.werkator.repo
 
+import de.hoennig.werkator.StateDirMigration
 import de.hoennig.werkator.artifacts.FileArtifactStore
 import de.hoennig.werkator.build.FileBuildResultRepository
 import de.hoennig.werkator.config.ConfigLoader
 import org.springframework.stereotype.Component
 import java.nio.file.Path
 
-/** Opens a [RepoContext] over a repository directory; nothing is touched until the first build. */
+/**
+ * Opens a [RepoContext] over a repository directory. Nothing is created until the first
+ * build; only a pre-rename state directory is moved to its current name on the way, per
+ * repository, before any path under it is resolved.
+ */
 @Component
 class RepoContexts(
     private val configLoader: ConfigLoader,
@@ -14,13 +19,15 @@ class RepoContexts(
     fun open(
         workingDir: Path,
         name: String = defaultName(workingDir),
-    ): RepoContext =
-        RepoContext(
+    ): RepoContext {
+        StateDirMigration.migrateIfNeeded(workingDir)
+        return RepoContext(
             name = name,
             workingDir = workingDir,
             results = FileBuildResultRepository(workingDir.resolve(RESULTS_FILE)),
             artifactStore = FileArtifactStore(configLoader, workingDir),
         )
+    }
 
     companion object {
         /** Results file relative to the repository, next to the machine config in `.git/werkator/`. */

src/main/kotlin/de/hoennig/werkator/repo/RepoRegistry.kt

@@ -0,0 +1,100 @@
+package de.hoennig.werkator.repo
+
+import de.hoennig.werkator.config.ConfigException
+import de.hoennig.werkator.config.ConfigLoader
+import de.hoennig.werkator.config.RepositoryEntry
+import org.slf4j.LoggerFactory
+import org.springframework.stereotype.Component
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.Paths
+
+/**
+ * The repositories this instance serves (ADR 0009): one [RepoContext] per entry of the
+ * home configuration's `repositories`, or — without a home config or with an empty
+ * registry — the current working directory, exactly as before.
+ *
+ * Opened once, on first use, and loudly: an entry that is no git repository or a name
+ * used twice aborts the start with a message naming the home file, because an instance
+ * serving the wrong set is worse than one that does not come up. A repository whose
+ * configuration Werkator must not read (version or format violation) is the exception:
+ * it is skipped with an error, like a branch config violation fails only that branch —
+ * the other repositories keep building.
+ */
+@Component
+class RepoRegistry(
+    private val configLoader: ConfigLoader,
+    private val repoContexts: RepoContexts,
+) {
+    private val log = LoggerFactory.getLogger(RepoRegistry::class.java)
+
+    private val contexts: List<RepoContext> by lazy { open() }
+
+    /** Every served repository, in registry order. */
+    fun all(): List<RepoContext> = contexts
+
+    /** The repository registered under [name], or null. */
+    fun byName(name: String): RepoContext? = contexts.firstOrNull { it.name == name }
+
+    /**
+     * The repository a command without a selector means: the current working directory
+     * when it is served (so `werkator status` inside a repository behaves as today),
+     * otherwise the first registered one.
+     */
+    fun current(): RepoContext {
+        val cwd = Paths.get(".").toAbsolutePath().normalize()
+        return contexts.firstOrNull { it.workingDir.toAbsolutePath().normalize() == cwd } ?: contexts.first()
+    }
+
+    private fun open(): List<RepoContext> {
+        val entries = configLoader.loadInstance()?.repositories.orEmpty()
+        if (entries.isEmpty()) {
+            return listOf(repoContexts.open(Paths.get(".")))
+        }
+        val home = configLoader.instanceFile()
+        val opened = entries.mapNotNull { openEntry(it, home) }
+        val duplicates = opened.groupBy { it.name }.filterValues { it.size > 1 }
+        if (duplicates.isNotEmpty()) {
+            val listed =
+                duplicates.entries.joinToString(
+                    "; ",
+                ) { (name, repos) -> "$name: ${repos.joinToString(", ") { it.workingDir.toString() }}" }
+            throw IllegalStateException("$home registers the same repository name more than once ($listed); set a distinct name per entry")
+        }
+        check(opened.isNotEmpty()) { "$home registers no readable repository" }
+        return opened
+    }
+
+    private fun openEntry(
+        entry: RepositoryEntry,
+        home: Path,
+    ): RepoContext? {
+        val dir = resolve(entry.path)
+        if (!Files.isDirectory(dir) || !Files.exists(dir.resolve(".git"))) {
+            throw IllegalStateException(
+                "$home registers ${entry.path.ifBlank { "an entry without a path" }}, which is not a git repository ($dir)",
+            )
+        }
+        val name = entry.name.trim().ifEmpty { RepoContexts.defaultName(dir) }
+        try {
+            // the configuration is read here only to find out whether Werkator may read it at all
+            configLoader.load(dir)
+        } catch (e: ConfigException) {
+            log.error("not serving repository {} ({}): {}", name, dir, e.message)
+            return null
+        }
+        return repoContexts.open(dir, name)
+    }
+
+    /** `~` expands to the home directory; a relative path is relative to the home directory, not the cwd. */
+    private fun resolve(path: String): Path {
+        val home = configLoader.homeDir
+        val expanded =
+            when {
+                path == "~" -> home
+                path.startsWith("~/") -> home.resolve(path.removePrefix("~/"))
+                else -> home.resolve(path)
+            }
+        return expanded.toAbsolutePath().normalize()
+    }
+}