/**

* Jooby https://jooby.io

* Apache License Version 2.0 https://jooby.io/LICENSE.txt

* Copyright 2014 Edgar Espina

*/

package io.jooby;

import javax.annotation.Nonnull;

import java.nio.charset.StandardCharsets;

import java.util.Collections;

import java.util.List;

/**

* Template engine renderer. This class renderer instances of {@link ModelAndView} objects.

* Template engine rendering is done by checking view name and supported file {@link #extensions()}.

*

* @since 2.0.0

* @author edgar

*/

public interface TemplateEngine extends MessageEncoder {

/** Name of application property that defines the template path. */

String TEMPLATE_PATH = "templates.path";

/** Default template path. */

String PATH = "views";

/**

* Render a model and view instance as String.

*

* @param ctx Web context.

* @param modelAndView Model and view.

* @return Rendered template.

* @throws Exception If something goes wrong.

*/

String render(Context ctx, ModelAndView modelAndView) throws Exception;

@Override default byte[] encode(@Nonnull Context ctx, @Nonnull Object value) throws Exception {

// initialize flash and session attributes (if any)

ctx.flash();

ctx.sessionOrNull();

ctx.setDefaultResponseType(MediaType.html);

String output = render(ctx, (ModelAndView) value);

return output.getBytes(StandardCharsets.UTF_8);

}

/**

* True if the template engine is able to render the given view. This method checks if the view

* name matches one of the {@link #extensions()}.

*

* @param modelAndView View to check.

* @return True when view is supported.

*/

default boolean supports(@Nonnull ModelAndView modelAndView) {

String view = modelAndView.getView();

for (String extension : extensions()) {

if (view.endsWith(extension)) {

return true;

}

}

return false;

}

/**

* Number of file extensions supported by the template engine. Default is <code>.html</code>.

*

* @return Number of file extensions supported by the template engine.

* Default is <code>.html</code>.

*/

default @Nonnull List<String> extensions() {

return Collections.singletonList(".html");

}

/**

* Normalize a template path by removing the leading `/` when present.

*

* @param templatesPath Template path.

* @return Normalized path.

*/

static @Nonnull String normalizePath(@Nonnull String templatesPath) {

if (templatesPath == null) {

return null;

}

return templatesPath.startsWith("/") ? templatesPath.substring(1) : templatesPath;

}

}