package io.swagger.codegen.cmd;

import ch.lambdaj.function.convert.Converter;
import com.google.common.base.CaseFormat;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.samskivert.mustache.Mustache;
import io.airlift.airline.Command;
import io.airlift.airline.Option;
import io.swagger.codegen.DefaultGenerator;
import io.swagger.codegen.SupportingFile;
import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.util.List;
import java.util.Map;

import static ch.lambdaj.collection.LambdaCollections.with;
import static com.google.common.base.Joiner.on;

/**
 * User: lanwen
 * Date: 24.03.15
 * Time: 20:22
 */

@Command(name = "meta", description = "MetaGenerator. Generator for creating a new template set " +
        "and configuration for Codegen.  The output will be based on the language you " +
        "specify, and includes default templates to include.")
public class Meta implements Runnable {

    private static final Logger LOGGER = LoggerFactory.getLogger(Meta.class);

    private static final String TEMPLATE_DIR_CLASSPATH = "codegen";
    private static final String MUSTACHE_EXTENSION = ".mustache";

    @Option(name = {"-o", "--output"}, title = "output directory",
            description = "where to write the generated files (current dir by default)")
    private String outputFolder = "";

    @Option(name = {"-n", "--name"}, title = "name",
            description = "the human-readable name of the generator")
    private String name = "default";

    @Option(name = {"-p", "--package"}, title = "package",
            description = "the package to put the main class into (defaults to io.swagger.codegen)")
    private String targetPackage = "io.swagger.codegen";

    @Override
    public void run() {
        final File targetDir = new File(outputFolder);
        LOGGER.info("writing to folder [{}]", targetDir.getAbsolutePath());

        String mainClass = CaseFormat.LOWER_HYPHEN.to(CaseFormat.UPPER_CAMEL, name) + "Generator";

        List<SupportingFile> supportingFiles = ImmutableList.of(
                new SupportingFile("pom.mustache", "", "pom.xml"),
                new SupportingFile("generatorClass.mustache",
                        on(File.separator).join("src/main/java", asPath(targetPackage)), mainClass.concat(".java")),
                new SupportingFile("README.mustache", "", "README.md"),
                new SupportingFile("api.template", "src/main/resources" + File.separator + name, "api.mustache"),
                new SupportingFile("model.template", "src/main/resources" + File.separator + name, "model.mustache"),
                new SupportingFile("services.mustache",
                        "src/main/resources/META-INF/services", "io.swagger.codegen.CodegenConfig")
        );

        String swaggerVersion = Version.readVersionFromResources();

        Map<String, Object> data = new ImmutableMap.Builder<String, Object>()
                .put("generatorPackage", targetPackage)
                .put("generatorClass", mainClass)
                .put("name", name)
                .put("fullyQualifiedGeneratorClass", targetPackage + "." + mainClass)
                .put("swaggerCodegenVersion", swaggerVersion).build();


        with(supportingFiles).convert(processFiles(targetDir, data));
    }

    /**
     * Converter method to process supporting files: execute with mustache,
     * or simply copy to destination directory
     *
     * @param targetDir - destination directory
     * @param data      - map with additional params needed to process templates
     * @return converter object to pass to lambdaj
     */
    private static Converter<SupportingFile, File> processFiles(final File targetDir, final Map<String, Object> data) {
        return new Converter<SupportingFile, File>() {
            private DefaultGenerator generator = new DefaultGenerator();

            @Override
            public File convert(SupportingFile support) {
                try {
                    File destinationFolder = new File(new File(targetDir.getAbsolutePath()), support.folder);
                    File outputFile = new File(destinationFolder, support.destinationFilename);

                    String template = generator
                            .readTemplate(new File(TEMPLATE_DIR_CLASSPATH, support.templateFile).getPath());
                    String formatted = template;

                    if (support.templateFile.endsWith(MUSTACHE_EXTENSION)) {
                        LOGGER.info("writing file to {}", outputFile.getAbsolutePath());
                        formatted = Mustache.compiler().withLoader(loader(generator))
                                .defaultValue("")
                                .compile(template)
                                .execute(data);
                    } else {
                        LOGGER.info("copying file to {}", outputFile.getAbsolutePath());
                    }

                    FileUtils.writeStringToFile(outputFile, formatted);
                    return outputFile;

                } catch (IOException e) {
                    throw new RuntimeException("Can't generate project", e);
                }
            }
        };
    }

    /**
     * Creates mustache loader for template using classpath loader
     *
     * @param generator - class with reader getter
     * @return loader for template
     */
    private static Mustache.TemplateLoader loader(final DefaultGenerator generator) {
        return new Mustache.TemplateLoader() {
            @Override
            public Reader getTemplate(String name) {
                return generator.getTemplateReader(TEMPLATE_DIR_CLASSPATH
                        + File.separator + name.concat(MUSTACHE_EXTENSION));
            }
        };
    }

    /**
     * Converts package name to path on file system
     *
     * @param packageName - package name to convert
     * @return relative path
     */
    private static String asPath(String packageName) {
        return packageName.replace(".", File.separator);
    }
}
