Introduce bal openapi flatten sub command

openapi-cli/src/main/java/io/ballerina/openapi/cmd/CmdConstants.java

@@ -206,6 +206,7 @@ public String getValue() {
             List.of("2.0", "3.0.0", "3.0.1", "3.0.2", "3.0.3", "3.1.0");
     public static final String DEFAULT_CLIENT_ID = "oas_%s_%s";
     public static final String OPENAPI_ADD_CMD = "add";
+    public static final String OPENAPI_FLATTEN_CMD = "flatten";
 
     public enum Mode {
         SERVICE,

openapi-cli/src/main/java/io/ballerina/openapi/cmd/Flatten.java

@@ -0,0 +1,359 @@
+/*
+ * Copyright (c) 2024, WSO2 LLC. (http://www.wso2.com).
+ *
+ * WSO2 Inc. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package io.ballerina.openapi.cmd;
+
+import io.ballerina.cli.BLauncherCmd;
+import io.ballerina.openapi.core.generators.common.OASModifier;
+import io.ballerina.openapi.core.generators.common.model.Filter;
+import io.ballerina.openapi.service.mapper.utils.CodegenUtils;
+import io.swagger.parser.OpenAPIParser;
+import io.swagger.v3.core.util.Json;
+import io.swagger.v3.core.util.Yaml;
+import io.swagger.v3.oas.models.Components;
+import io.swagger.v3.oas.models.OpenAPI;
+import io.swagger.v3.oas.models.media.Schema;
+import io.swagger.v3.parser.core.models.ParseOptions;
+import io.swagger.v3.parser.core.models.SwaggerParseResult;
+import io.swagger.v3.parser.util.InlineModelResolver;
+import picocli.CommandLine;
+
+import java.io.IOException;
+import java.io.PrintStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+
+import static io.ballerina.openapi.cmd.CmdConstants.JSON_EXTENSION;
+import static io.ballerina.openapi.cmd.CmdConstants.OPENAPI_FLATTEN_CMD;
+import static io.ballerina.openapi.cmd.CmdConstants.YAML_EXTENSION;
+import static io.ballerina.openapi.cmd.CmdConstants.YML_EXTENSION;
+import static io.ballerina.openapi.core.generators.common.GeneratorConstants.UNSUPPORTED_OPENAPI_VERSION_PARSER_MESSAGE;
+import static io.ballerina.openapi.core.generators.common.OASModifier.getResolvedNameMapping;
+import static io.ballerina.openapi.core.generators.common.OASModifier.getValidNameForType;
+import static io.ballerina.openapi.service.mapper.utils.CodegenUtils.resolveContractFileName;
+
+/**
+ * Main class to implement "flatten" subcommand which is used to flatten the OpenAPI definition
+ * by moving all the inline schemas to the "#/components/schemas" section.
+ *
+ * @since 1.9.0
+ */
+@CommandLine.Command(
+        name = "flatten",
+        description = "Flatten the OpenAPI definition by moving all the inline schemas to the " +
+                "\"#/components/schemas\" section."
+)
+public class Flatten implements BLauncherCmd {
+    private static final String COMMAND_IDENTIFIER = "openapi-flatten";
+    private static final String COMMA = ",";
+
+    private static final String INFO_OUTPUT_WRITTEN_MSG = "INFO: flattened OpenAPI definition file was successfully" +
+            " written to: %s%n";
+    private static final String WARNING_INVALID_OUTPUT_FORMAT = "WARNING: invalid output format. The output format" +
+            " should be either \"json\" or \"yaml\".Defaulting to format of the input file.";
+    private static final String ERROR_INPUT_PATH_IS_REQUIRED = "ERROR: an OpenAPI definition path is required to " +
+            "flatten the OpenAPI definition.";
+    private static final String ERROR_INVALID_INPUT_FILE_EXTENSION = "ERROR: invalid input OpenAPI definition file " +
+            "extension. The OpenAPI definition file should be in YAML or JSON format.";
+    private static final String ERROR_OCCURRED_WHILE_READING_THE_INPUT_FILE = "ERROR: error occurred while reading " +
+            "the OpenAPI definition file.";
+    private static final String ERROR_UNSUPPORTED_OPENAPI_VERSION = "ERROR: provided OpenAPI contract version is " +
+            "not supported in the tool. Use OpenAPI specification version 2 or higher";
+    private static final String ERROR_OCCURRED_WHILE_PARSING_THE_INPUT_OPENAPI_FILE = "ERROR: error occurred while " +
+            "parsing the OpenAPI definition file.";
+    private static final String FOUND_PARSER_DIAGNOSTICS = "found the following parser diagnostic messages:";
+    private static final String ERROR_OCCURRED_WHILE_WRITING_THE_OUTPUT_OPENAPI_FILE = "ERROR: error occurred while " +
+            "writing the flattened OpenAPI definition file";
+    private static final String ERROR_OCCURRED_WHILE_GENERATING_SCHEMA_NAMES = "ERROR: error occurred while " +
+            "generating schema names";
+
+    private PrintStream infoStream = System.out;
+    private PrintStream errorStream = System.err;
+
+    private Path targetPath = Paths.get(System.getProperty("user.dir"));
+    private boolean exitWhenFinish = true;
+
+    @CommandLine.Option(names = {"-h", "--help"}, hidden = true)
+    public boolean helpFlag;
+
+    @CommandLine.Option(names = {"-i", "--input"}, description = "OpenAPI definition file path.")
+    public String inputPath;
+
+    @CommandLine.Option(names = {"-o", "--output"}, description = "Location of the flattened OpenAPI definition.")
+    private String outputPath;
+
+    @CommandLine.Option(names = {"-n", "--name"}, description = "Name of the flattened OpenAPI definition file.")
+    private String fileName;
+
+    @CommandLine.Option(names = {"-f", "--format"}, description = "Output format of the flattened OpenAPI definition.")
+    private String format;
+
+    @CommandLine.Option(names = {"-t", "--tags"}, description = "Tags that need to be considered when flattening.")
+    public String tags;
+
+    @CommandLine.Option(names = {"--operations"}, description = "Operations that need to be included when flattening.")
+    public String operations;
+
+    public Flatten() {
+    }
+
+    public Flatten(PrintStream errorStream, boolean exitWhenFinish) {
+        this.errorStream = errorStream;
+        this.exitWhenFinish = exitWhenFinish;
+    }
+
+    @Override
+    public void execute() {
+        if (helpFlag) {
+            String commandUsageInfo = BLauncherCmd.getCommandUsageInfo(COMMAND_IDENTIFIER);
+            infoStream.println(commandUsageInfo);
+            return;
+        }
+
+        if (Objects.isNull(inputPath) || inputPath.isBlank()) {
+            errorStream.println(ERROR_INPUT_PATH_IS_REQUIRED);
+            exitError();
+            return;
+        }
+
+        if (inputPath.endsWith(YAML_EXTENSION) || inputPath.endsWith(JSON_EXTENSION) ||
+                inputPath.endsWith(YML_EXTENSION)) {
+            populateInputOptions();
+            generateFlattenOpenAPI();
+            return;
+        }
+
+        errorStream.println(ERROR_INVALID_INPUT_FILE_EXTENSION);
+        exitError();
+    }
+
+    private void populateInputOptions() {
+        if (Objects.nonNull(format)) {
+            if (!format.equalsIgnoreCase("json") && !format.equalsIgnoreCase("yaml")) {
+                setDefaultFormat();
+                errorStream.println(WARNING_INVALID_OUTPUT_FORMAT);
+            }
+        } else {
+            setDefaultFormat();
+        }
+
+        if (Objects.isNull(fileName)) {
+            fileName = "flattened_openapi";
+        }
+
+        if (Objects.nonNull(outputPath)) {
+            targetPath = Paths.get(outputPath).isAbsolute() ?
+                    Paths.get(outputPath) : Paths.get(targetPath.toString(), outputPath);
+        }
+    }
+
+    private void setDefaultFormat() {
+        format = inputPath.endsWith(JSON_EXTENSION) ? "json" : "yaml";
+    }
+
+    private void generateFlattenOpenAPI() {
+        String openAPIFileContent;
+        try {
+            openAPIFileContent = Files.readString(Path.of(inputPath));
+        } catch (Exception e) {
+            errorStream.println(ERROR_OCCURRED_WHILE_READING_THE_INPUT_FILE);
+            exitError();
+            return;
+        }
+
+        Optional<OpenAPI> openAPIOptional = getFlattenOpenAPI(openAPIFileContent);
+        if (openAPIOptional.isEmpty()) {
+            exitError();
+            return;
+        }
+        writeFlattenOpenAPIFile(openAPIOptional.get());
+    }
+
+    private Optional<OpenAPI> getFlattenOpenAPI(String openAPIFileContent) {
+        // Read the contents of the file with default parser options
+        // Flattening will be done after filtering the operations
+        SwaggerParseResult parserResult = new OpenAPIParser().readContents(openAPIFileContent, null,
+                new ParseOptions());
+        if (!parserResult.getMessages().isEmpty() &&
+                parserResult.getMessages().contains(UNSUPPORTED_OPENAPI_VERSION_PARSER_MESSAGE)) {
+            errorStream.println(ERROR_UNSUPPORTED_OPENAPI_VERSION);
+            return Optional.empty();
+        }
+
+        OpenAPI openAPI = parserResult.getOpenAPI();
+        if (Objects.isNull(openAPI)) {
+            errorStream.println(ERROR_OCCURRED_WHILE_PARSING_THE_INPUT_OPENAPI_FILE);
+            if (!parserResult.getMessages().isEmpty()) {
+                errorStream.println(FOUND_PARSER_DIAGNOSTICS);
+                parserResult.getMessages().forEach(errorStream::println);
+            }
+            return Optional.empty();
+        }
+
+        Components components = openAPI.getComponents();
+        List<String> existingComponentNames = Objects.nonNull(components) && Objects.nonNull(components.getSchemas()) ?
+                new ArrayList<>(components.getSchemas().keySet()) : new ArrayList<>();
+
+        filterOpenAPIOperations(openAPI);
+
+        // Flatten the OpenAPI definition with `flattenComposedSchemas: true` and `camelCaseFlattenNaming: true`
+        InlineModelResolver inlineModelResolver = new InlineModelResolver(true, true);
+        inlineModelResolver.flatten(openAPI);
+
+        return sanitizeOpenAPI(openAPI, existingComponentNames);
+    }
+
+    private void writeFlattenOpenAPIFile(OpenAPI openAPI) {
+        String outputFileNameWithExt = getOutputFileName();
+        try {
+            CodegenUtils.writeFile(targetPath.resolve(outputFileNameWithExt),
+                    outputFileNameWithExt.endsWith(JSON_EXTENSION) ? Json.pretty(openAPI) : Yaml.pretty(openAPI));
+            infoStream.printf(INFO_OUTPUT_WRITTEN_MSG, targetPath.resolve(outputFileNameWithExt));
+        } catch (IOException exception) {
+            errorStream.println(ERROR_OCCURRED_WHILE_WRITING_THE_OUTPUT_OPENAPI_FILE);
+            exitError();
+        }
+    }
+
+    private String getOutputFileName() {
+        return resolveContractFileName(targetPath, fileName + getFileExtension(), format.equals("json"));
+    }
+
+    private String getFileExtension() {
+        return (Objects.nonNull(format) && format.equals("json")) ? JSON_EXTENSION : YAML_EXTENSION;
+    }
+
+    private void filterOpenAPIOperations(OpenAPI openAPI) {
+        Filter filter = getFilter();
+        if (filter.getOperations().isEmpty() && filter.getTags().isEmpty()) {
+            return;
+        }
+
+        // Remove the operations which are not present in the filter
+        openAPI.getPaths().forEach((path, pathItem) -> pathItem.readOperationsMap()
+                .forEach((httpMethod, operation) -> {
+                    if (!filter.getOperations().contains(operation.getOperationId()) &&
+                            operation.getTags().stream().noneMatch(filter.getTags()::contains)) {
+                        pathItem.operation(httpMethod, null);
+                    }
+                })
+        );
+
+        // Remove the paths which do not have any operations after filtering
+        List<String> pathsToRemove = new ArrayList<>();
+        openAPI.getPaths().forEach((path, pathItem) -> {
+            if (pathItem.readOperationsMap().isEmpty()) {
+                pathsToRemove.add(path);
+            }
+        });
+        pathsToRemove.forEach(openAPI.getPaths()::remove);
+    }
+
+    private Optional<OpenAPI> sanitizeOpenAPI(OpenAPI openAPI, List<String> existingComponentNames) {
+        Map<String, String> proposedNameMapping = getProposedNameMapping(openAPI, existingComponentNames);
+        if (proposedNameMapping.isEmpty()) {
+            return Optional.of(openAPI);
+        }
+
+        SwaggerParseResult parserResult = OASModifier.getOASWithSchemaNameModification(openAPI, proposedNameMapping);
+        openAPI = parserResult.getOpenAPI();
+        if (Objects.isNull(openAPI)) {
+            errorStream.println(ERROR_OCCURRED_WHILE_GENERATING_SCHEMA_NAMES);
+            if (!parserResult.getMessages().isEmpty()) {
+                errorStream.println(FOUND_PARSER_DIAGNOSTICS);
+                parserResult.getMessages().forEach(errorStream::println);
+            }
+            return Optional.empty();
+        }
+
+        return Optional.of(openAPI);
+    }
+
+    public Map<String, String> getProposedNameMapping(OpenAPI openapi, List<String> existingComponentNames) {
+        Map<String, String> nameMap = new HashMap<>();
+        if (Objects.isNull(openapi.getComponents())) {
+            return Collections.emptyMap();
+        }
+        Components components = openapi.getComponents();
+        Map<String, Schema> schemas = components.getSchemas();
+        if (Objects.isNull(schemas)) {
+            return Collections.emptyMap();
+        }
+
+        for (Map.Entry<String, Schema> schemaEntry: schemas.entrySet()) {
+            if (existingComponentNames.contains(schemaEntry.getKey())) {
+                continue;
+            }
+            String modifiedName = getValidNameForType(schemaEntry.getKey());
+            if (modifiedName.equals(schemaEntry.getKey())) {
+                continue;
+            }
+            nameMap.put(schemaEntry.getKey(), modifiedName);
+        }
+        return getResolvedNameMapping(nameMap);
+    }
+
+    private Filter getFilter() {
+        List<String> tagList = new ArrayList<>();
+        List<String> operationList = new ArrayList<>();
+
+        if (Objects.nonNull(tags) && !tags.isEmpty()) {
+            tagList.addAll(Arrays.asList(tags.split(COMMA)));
+        }
+
+        if (Objects.nonNull(operations) && !operations.isEmpty()) {
+            operationList.addAll(Arrays.asList(operations.split(COMMA)));
+        }
+
+        return new Filter(tagList, operationList);
+    }
+
+    @Override
+    public String getName() {
+        return OPENAPI_FLATTEN_CMD;
+    }
+
+    @Override
+    public void printLongDesc(StringBuilder stringBuilder) {
+        //This is the long description of the command and all handle within help command
+    }
+
+    @Override
+    public void printUsage(StringBuilder stringBuilder) {
+        //This is the usage description of the command and all handle within help command
+    }
+
+    @Override
+    public void setParentCmdParser(CommandLine commandLine) {
+        //This is not used in this command
+    }
+
+    private void exitError() {
+        if (exitWhenFinish) {
+            Runtime.getRuntime().exit(1);
+        }
+    }
+}

openapi-cli/src/main/java/io/ballerina/openapi/cmd/OpenApiCmd.java

@@ -84,7 +84,7 @@
 @CommandLine.Command(
         name = "openapi",
         description = "Generate the Ballerina sources for a given OpenAPI definition and vice versa.",
-        subcommands = {Add.class}
+        subcommands = {Add.class, Flatten.class}
 )
 public class OpenApiCmd implements BLauncherCmd {
     private static final String CMD_NAME = "openapi";