/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.maven.plugin;
   
   import org.apache.maven.plugin.MojoExecutionException;
   import org.apache.maven.plugins.annotations.LifecyclePhase;
  import org.apache.maven.plugins.annotations.Mojo;
  import org.apache.maven.plugins.annotations.Parameter;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.Writer;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  import java.util.EnumSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Locale;
  import java.util.Set;
  
  import dev.metaschema.core.configuration.DefaultConfiguration;
  import dev.metaschema.core.configuration.IConfiguration;
  import dev.metaschema.core.configuration.IMutableConfiguration;
  import dev.metaschema.core.model.IModule;
  import dev.metaschema.core.util.CollectionUtil;
  import dev.metaschema.core.util.ObjectUtils;
  import dev.metaschema.schemagen.ISchemaGenerator;
  import dev.metaschema.schemagen.SchemaGenerationFeature;
  import dev.metaschema.schemagen.json.JsonSchemaGenerator;
  import dev.metaschema.schemagen.xml.XmlSchemaGenerator;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * Goal which generates XML and JSON schemas for a given set of Metaschema
   * modules.
   */
  @Mojo(name = "generate-schemas", defaultPhase = LifecyclePhase.GENERATE_RESOURCES)
  public class GenerateSchemaMojo
      extends AbstractMetaschemaMojo {
    /**
     * Supported schema output formats for generation.
     */
    public enum SchemaFormat {
      /**
       * XML Schema Definition (XSD) format.
       */
      XSD,
      /**
       * JSON Schema format.
       */
      JSON_SCHEMA;
    }
  
    @NonNull
    private static final String STALE_FILE_NAME = "generateSschemaStaleFile";
  
    @NonNull
    private static final XmlSchemaGenerator XML_SCHEMA_GENERATOR = new XmlSchemaGenerator();
    @NonNull
    private static final JsonSchemaGenerator JSON_SCHEMA_GENERATOR = new JsonSchemaGenerator();
  
    /**
     * Specifies the formats of the schemas to generate. Multiple formats can be
     * supplied and this plugin will generate a schema for each of the desired
     * formats.
     * <p>
     * A format is specified by supplying one of the following values in a
     * &lt;format&gt; subelement:
     * <ul>
     * <li><em>json</em> - Creates a JSON Schema
     * <li><em>xsd</em> - Creates an XML Schema Definition
     * </ul>
     */
    @Parameter
    private List<String> formats;
  
    /**
     * If enabled, definitions that are defined inline will be generated as inline
     * types. If disabled, definitions will always be generated as global types.
     */
    @Parameter(defaultValue = "true")
    @SuppressWarnings("PMD.ImmutableField")
    private boolean inlineDefinitions = true;
  
    /**
     * If enabled, child definitions of a choice that are defined inline will be
     * generated as inline types. If disabled, child definitions of a choice will
     * always be generated as global types. This option will only be used if
     * <code>inlineDefinitions</code> is also enabled.
     */
    @Parameter(defaultValue = "false")
    private boolean inlineChoiceDefinitions; // false;
  
    /**
    * Determine if inlining definitions is required.
    *
    * @return {@code true} if inlining definitions is required, or {@code false}
    *         otherwise
    */
   protected boolean isInlineDefinitions() {
     return inlineDefinitions;
   }
 
   /**
    * Determine if inlining choice definitions is required.
    *
    * @return {@code true} if inlining choice definitions is required, or
    *         {@code false} otherwise
    */
   protected boolean isInlineChoiceDefinitions() {
     return inlineChoiceDefinitions;
   }
 
   /**
    * <p>
    * Gets the last part of the stale filename.
    * </p>
    * <p>
    * The full stale filename will be generated by pre-pending
    * {@code "." + getExecution().getExecutionId()} to this staleFileName.
    *
    * @return the stale filename postfix
    */
   @Override
   protected String getStaleFileName() {
     return STALE_FILE_NAME;
   }
 
   /**
    * Performs schema generation using the provided Metaschema modules.
    *
    * @param modules
    *          the Metaschema modules to generate the schema for
    * @return the list of generated schema files
    * @throws MojoExecutionException
    *           if an error occurred during generation
    */
   @Override
   @NonNull
   protected List<File> generate(@NonNull Set<IModule> modules) throws MojoExecutionException {
     IMutableConfiguration<SchemaGenerationFeature<?>> schemaGenerationConfig
         = new DefaultConfiguration<>();
 
     if (isInlineDefinitions()) {
       schemaGenerationConfig.enableFeature(SchemaGenerationFeature.INLINE_DEFINITIONS);
     } else {
       schemaGenerationConfig.disableFeature(SchemaGenerationFeature.INLINE_DEFINITIONS);
     }
 
     if (isInlineChoiceDefinitions()) {
       schemaGenerationConfig.enableFeature(SchemaGenerationFeature.INLINE_CHOICE_DEFINITIONS);
     } else {
       schemaGenerationConfig.disableFeature(SchemaGenerationFeature.INLINE_CHOICE_DEFINITIONS);
     }
 
     Set<SchemaFormat> schemaFormats;
     if (formats != null) {
       schemaFormats = ObjectUtils.notNull(EnumSet.noneOf(SchemaFormat.class));
       for (String format : formats) {
         switch (format.toLowerCase(Locale.ROOT)) {
         case "xsd":
           schemaFormats.add(SchemaFormat.XSD);
           break;
         case "json":
           schemaFormats.add(SchemaFormat.JSON_SCHEMA);
           break;
         default:
           throw new IllegalStateException("Unsupported schema format: " + format);
         }
       }
     } else {
       schemaFormats = ObjectUtils.notNull(EnumSet.allOf(SchemaFormat.class));
     }
 
     Path outputDirectory = ObjectUtils.notNull(getOutputDirectory().toPath());
     List<File> generatedSchemas = new LinkedList<>();
     for (IModule module : modules) {
       if (getLog().isInfoEnabled()) {
         getLog().info(String.format("Processing metaschema: %s", module.getLocation()));
       }
       if (module.getExportedRootAssemblyDefinitions().isEmpty()) {
         continue;
       }
       generatedSchemas.addAll(generateSchemas(module, schemaGenerationConfig, outputDirectory, schemaFormats));
     }
     return CollectionUtil.unmodifiableList(generatedSchemas);
   }
 
   @SuppressWarnings("PMD.AvoidCatchingGenericException")
   @NonNull
   private static List<File> generateSchemas(
       @NonNull IModule module,
       @NonNull IConfiguration<SchemaGenerationFeature<?>> schemaGenerationConfig,
       @NonNull Path outputDirectory,
       @NonNull Set<SchemaFormat> schemaFormats) throws MojoExecutionException {
 
     String shortName = module.getShortName();
 
     List<File> generatedSchemas = new LinkedList<>();
     if (schemaFormats.contains(SchemaFormat.XSD)) {
       try { // XML Schema
         String filename = String.format("%s_schema.xsd", shortName);
         Path xmlSchema = ObjectUtils.notNull(outputDirectory.resolve(filename));
         generateSchema(module, schemaGenerationConfig, xmlSchema, XML_SCHEMA_GENERATOR);
         generatedSchemas.add(xmlSchema.toFile());
       } catch (Exception ex) {
         throw new MojoExecutionException("Unable to generate XML schema.", ex);
       }
     }
 
     if (schemaFormats.contains(SchemaFormat.JSON_SCHEMA)) {
       try { // JSON Schema
         String filename = String.format("%s_schema.json", shortName);
         Path jsonSchema = ObjectUtils.notNull(outputDirectory.resolve(filename));
         generateSchema(module, schemaGenerationConfig, jsonSchema, JSON_SCHEMA_GENERATOR);
         generatedSchemas.add(jsonSchema.toFile());
       } catch (Exception ex) {
         throw new MojoExecutionException("Unable to generate JSON schema.", ex);
       }
     }
     return CollectionUtil.unmodifiableList(generatedSchemas);
   }
 
   private static void generateSchema(
       @NonNull IModule module,
       @NonNull IConfiguration<SchemaGenerationFeature<?>> schemaGenerationConfig,
       @NonNull Path schemaPath,
       @NonNull ISchemaGenerator generator) throws IOException {
     try (@SuppressWarnings("resource")
     Writer writer = ObjectUtils.notNull(Files.newBufferedWriter(
         schemaPath,
         StandardCharsets.UTF_8,
         StandardOpenOption.CREATE,
         StandardOpenOption.WRITE,
         StandardOpenOption.TRUNCATE_EXISTING))) {
       generator.generateFromModule(module, writer, schemaGenerationConfig);
     }
   }
 }