Ollama: added method to delete a model (langchain4j#1557)

## Change
Added a new method to `OllamaModels.deleteModel(...)`. It is now possible to delete an
Ollama model through the API.


## General checklist
<!-- Please double-check the following points and mark them like this:
[X] -->
- [X] There are no breaking changes
- [X] I have added unit and integration tests for my change
- [X] I have manually run all the unit and integration tests in the
module I have added/changed, and they are all green
- [X] I have manually run all the unit and integration tests in the
[core](https://github.com/langchain4j/langchain4j/tree/main/langchain4j-core)
and
[main](https://github.com/langchain4j/langchain4j/tree/main/langchain4j)
modules, and they are all green
<!-- Before adding documentation and example(s) (below), please wait
until the PR is reviewed and approved. -->
- [ ] I have added/updated the
[documentation](https://github.com/langchain4j/langchain4j/tree/main/docs/docs)
- [ ] I have added an example in the [examples
repo](https://github.com/langchain4j/langchain4j-examples) (only for
"big" features)
- [ ] I have added/updated [Spring Boot
starter(s)](https://github.com/langchain4j/langchain4j-spring) (if
applicable)

langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/DeleteModelRequest.java

@@ -0,0 +1,15 @@
+package dev.langchain4j.model.ollama;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+class DeleteModelRequest {
+
+    private String name;
+}

langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaApi.java

@@ -35,4 +35,8 @@ interface OllamaApi {
     @POST("api/show")
     @Headers({"Content-Type: application/json"})
     Call<OllamaModelCard> showInformation(@Body ShowModelInformationRequest modelDetailsRequest);
+
+    @HTTP(method = "DELETE", path = "/api/delete", hasBody = true)
+    @Headers({"Content-Type: application/json"})
+    Call<Void> deleteModel(@Body DeleteModelRequest deleteModelRequest);
 }

langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaClient.java

@@ -229,6 +229,19 @@ public OllamaModelCard showInformation(ShowModelInformationRequest showInformati
         }
     }
 
+    public Void deleteModel(DeleteModelRequest deleteModelRequest) {
+        try {
+            retrofit2.Response<Void> retrofitResponse = ollamaApi.deleteModel(deleteModelRequest).execute();
+            if (retrofitResponse.isSuccessful()) {
+                return retrofitResponse.body();
+            } else {
+                throw toException(retrofitResponse);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     private RuntimeException toException(retrofit2.Response<?> response) throws IOException {
         int code = response.code();
         String body = response.errorBody().string();

langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaModels.java

@@ -47,4 +47,16 @@ public Response<OllamaModelCard> modelCard(String modelName) {
         ), maxRetries);
         return Response.from(response);
     }
+
+    public void deleteModel(OllamaModel ollamaModel) {
+        deleteModel(ollamaModel.getName());
+    }
+
+    public void deleteModel(String ollamaModelName) {
+        withRetry(() -> client.deleteModel(
+                DeleteModelRequest.builder()
+                        .name(ollamaModelName)
+                        .build()
+        ), maxRetries);
+    }
 }

langchain4j-ollama/src/test/java/dev/langchain4j/model/ollama/OllamaClientIT.java

@@ -48,4 +48,28 @@ void should_respond_with_model_information() {
         assertThat(modelDetailsResponse.getDetails().getFormat()).isEqualTo("gguf");
         assertThat(modelDetailsResponse.getDetails().getFamily()).isEqualTo("llama");
     }
+
+    @Test
+    void should_delete_model() {
+        // given AbstractOllamaInfrastructure
+
+        OllamaClient ollamaClient = OllamaClient.builder()
+                .baseUrl(ollama.getEndpoint())
+                .logRequests(true)
+                .logResponses(true)
+                .timeout(Duration.ofMinutes(1))
+                .build();
+
+        ModelsListResponse beforeDeleteModelList = ollamaClient.listModels();
+        assertThat(beforeDeleteModelList.getModels().size()).isPositive();
+
+        // when
+        ollamaClient.deleteModel(DeleteModelRequest.builder()
+                .name("tinydolphin")
+                .build());
+
+        // then
+        ModelsListResponse afterDeleteModelList = ollamaClient.listModels();
+        assertThat(afterDeleteModelList.getModels().size()).isZero();
+    }
 }