feat(model-client): implement createBranch(…) properly

Author: abstraktor

model-client/src/commonMain/kotlin/org/modelix/model/client2/IModelClientV2.kt

@@ -84,6 +84,17 @@ interface IModelClientV2 {
     suspend fun push(branch: BranchReference, version: IVersion, baseVersion: IVersion?, force: Boolean = false): IVersion
     suspend fun push(branch: BranchReference, version: IVersion, baseVersions: List<IVersion>, force: Boolean = false): IVersion
 
+    /**
+     * The pushed version is merged automatically by the server with the current head.
+     *
+     * If [failIfExists] is true, the push fails if the version already exists on the server.
+     * @return The resulting version on the server or null iff the version already exists and [failIfExists] is true.
+     * @param baseVersion Some version that is known to exist on the server.
+     *                    Is used for optimizing the amount of data sent to the server.
+     */
+    suspend fun push(branch: BranchReference, version: IVersion, baseVersion: IVersion?, force: Boolean = false, failIfExists: Boolean): IVersion?
+    suspend fun push(branch: BranchReference, version: IVersion, baseVersions: List<IVersion>, force: Boolean = false, failIfExists: Boolean): IVersion?
+
     suspend fun pull(
         branch: BranchReference,
         lastKnownVersion: IVersion?,

model-client/src/commonMain/kotlin/org/modelix/model/client2/ModelClientV2.kt

@@ -518,10 +518,20 @@ class ModelClientV2(
     }
 
     override suspend fun push(branch: BranchReference, version: IVersion, baseVersion: IVersion?, force: Boolean): IVersion {
-        return push(branch, version, listOfNotNull(baseVersion), force)
+        // safe to ignore null, because push may only return null if failIfExists is true
+        return push(branch, version, baseVersion, force, failIfExists = false)!!
     }
 
     override suspend fun push(branch: BranchReference, version: IVersion, knownVersions: List<IVersion>, force: Boolean): IVersion {
+        // safe to ignore null, because push may only return null if failIfExists is true
+        return push(branch, version, knownVersions, force, failIfExists = false)!!
+    }
+
+    override suspend fun push(branch: BranchReference, version: IVersion, baseVersion: IVersion?, force: Boolean, failIfExists: Boolean): IVersion? {
+        return push(branch, version, listOfNotNull(baseVersion), force)
+    }
+
+    override suspend fun push(branch: BranchReference, version: IVersion, knownVersions: List<IVersion>, force: Boolean, failIfExists: Boolean): IVersion? {
         LOG.debug { "${clientId.toString(16)}.push($branch, $version, ${knownVersions.joinToString(", ").take(200)})" }
         require(version is CLVersion)
         val delta = if (knownVersions.map { it.getObjectHash() }.contains(version.getObjectHash())) {
@@ -546,12 +556,19 @@ class ModelClientV2(
                 if (force) {
                     parameters["force"] = force.toString()
                 }
+                if (failIfExists) {
+                    parameters["failIfExists"] = failIfExists.toString()
+                }
             }
             useVersionStreamFormat()
             contentType(ContentType.Application.Json)
             setBody(delta)
         }.execute { response ->
-            createVersion(branch.repositoryId, version, response.readVersionDelta())
+            if (response.status == HttpStatusCode.Conflict) {
+                null
+            } else {
+                createVersion(branch.repositoryId, version, response.readVersionDelta())
+            }
         }
     }
 

model-client/src/jsMain/kotlin/org/modelix/model/client2/ClientJS.kt

@@ -31,6 +31,7 @@ import org.modelix.model.mutable.withAutoTransactions
 import org.modelix.model.persistent.MapBasedStore
 import org.modelix.model.server.api.BranchInfo
 import org.modelix.mps.multiplatform.model.MPSIdGenerator
+import kotlin.coroutines.cancellation.CancellationException
 import kotlin.js.Date
 import kotlin.js.Promise
 import kotlin.time.Duration.Companion.seconds
@@ -150,8 +151,26 @@ interface ClientJS {
         repositoryId: String,
     ): Promise<Array<BranchInfo>>
 
-    fun createBranch(repositoryId: String, branchId: String, versionHash: String, failIfExists: Boolean = false): Promise<Boolean>
+    /**
+     * Create a new branch in the given repository on the model server.
+     * The new branch will point to the given version.
+     * If the branch already exists, the promise will be rejected.
+     * See also [deleteBranch] to delete an existing branch.
+     * @param repositoryId Repository ID to create the branch in.
+     * @param branchId ID of the new branch to create.
+     * @param versionHash Hash of the version the new branch should point to.
+     */
+    fun createBranch(repositoryId: String, branchId: String, versionHash: String): Promise<Unit>
 
+    /**
+     * Delete an existing branch from the given repository on the model server.
+     * If the branch does not exist, the promise will be resolved with `false`.
+     * See also [createBranch] to create a new branch.
+     *
+     * @param repositoryId Repository ID to delete the branch from.
+     * @param branchId ID of the branch to delete.
+     * @return Promise that resolves to `true` if the branch existed and was deleted, else `false`.
+     */
     fun deleteBranch(
         repositoryId: String,
         branchId: String,
@@ -217,19 +236,14 @@ internal class ClientJSImpl(private val modelClient: ModelClientV2) : ClientJS {
         repositoryId: String,
         branchId: String,
         versionHash: String,
-        failIfExists: Boolean,
-    ): Promise<Boolean> {
+    ): Promise<Unit> {
         return GlobalScope.promise {
             RepositoryId(repositoryId).let { repositoryId ->
                 val branchReference = repositoryId.getBranchReference(branchId)
 
-                if (failIfExists) {
-                    throw TODO("implement server endpoint for this")
-                } else {
-                    val version = modelClient.lazyLoadVersion(repositoryId, versionHash)
-                    modelClient.push(branchReference, version, version, true)
-                    return@promise true
-                }
+                val version = modelClient.lazyLoadVersion(repositoryId, versionHash)
+                modelClient.push(branchReference, version, version, force = false, failIfExists = true)
+                    ?: throw CancellationException("Branch $branchId already exists in repository $repositoryId")
             }
         }
     }