public class AllApis {
    private final List<InterfaceElement> apis;
    private final Filer filer;
    private final Elements elements;


    public AllApis(List<InterfaceElement> apis, Filer filer, Elements elements) {
        this.apis = apis;
        this.filer = filer;
        this.elements = elements;
    }

    public void generate() {
        TypeSpec.Builder classBuilder = TypeSpec.classBuilder("SynoApi").addModifiers(Modifier.PUBLIC);
        classBuilder.addField(FieldSpec.builder(TypeName.get(Retrofit.class), "retrofit", Modifier.PRIVATE, Modifier.FINAL).build());
        classBuilder.addMethod(MethodSpec.constructorBuilder().addParameter(TypeName.get(Retrofit.class), "retrofit").addModifiers(Modifier.PUBLIC)
                .addStatement("this.$N = $N", "retrofit", "retrofit")
                .build());


        for (InterfaceElement api : apis) {
            classBuilder.addField(createField(api));
            classBuilder.addMethod(createMethod(api));
        }

        saveGeneratedFile(classBuilder.build());
    }

    private FieldSpec createField(InterfaceElement api) {
        return FieldSpec.builder(ClassName.bestGuess(api.IMPL_NAME), "m" + api.IMPL_NAME)
                .addModifiers(Modifier.PRIVATE)
                .build();
    }


    private MethodSpec createMethod(InterfaceElement api) {
        MethodSpec.Builder builder = MethodSpec.methodBuilder(Character.toLowerCase(api.name.charAt(0)) + api.name.substring(1))
                .addModifiers(Modifier.PUBLIC)
                .addStatement("if($N == null) $N = new $N(retrofit)", "m" + api.IMPL_NAME, "m" + api.IMPL_NAME, api.IMPL_NAME)
                .addStatement("return $N", "m" + api.IMPL_NAME)
                .returns(ClassName.bestGuess(api.IMPL_NAME));

        return builder.build();
    }

    private void saveGeneratedFile(TypeSpec typeSpec) {
        if (apis.isEmpty()) return;
        PackageElement pkg = elements.getPackageOf(apis.get(0).typeElement);
        String packageName = pkg.isUnnamed() ? null : pkg.getQualifiedName().toString();

        try {
            JavaFile.builder(getPackageName(), typeSpec).build().writeTo(filer);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String getPackageName() {
        if (apis.isEmpty()) return null;
        PackageElement pkg = elements.getPackageOf(apis.get(0).typeElement);
        return pkg.isUnnamed() ? null : pkg.getQualifiedName().toString();
    }
}