File View.php | ICanBoogie/View v0.5.0

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<?php

/*
 * This file is part of the ICanBoogie package.
 *
 * (c) Olivier Laviale <olivier.laviale@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace ICanBoogie\View;

use ICanBoogie\Events;
use ICanBoogie\OffsetNotDefined;
use ICanBoogie\PropertyNotDefined;
use ICanBoogie\PrototypeTrait;
use ICanBoogie\Render\TemplateName;
use ICanBoogie\Render\TemplateNotFound;
use ICanBoogie\Routing\Controller;

/**
 * A view.
 *
 * @property-read Controller $controller The controller invoking the view.
 * @property-read array $variables The variables to pass to the template.
 * @property mixed $content The content of the view.
 * @property string $layout The name of the layout that should decorate the content.
 * @property string $template The name of the template that should render the content.
 * @property-read callable[] $layout_resolvers @internal
 * @property-read callable[] $template_resolvers @internal
 */
class View implements \ArrayAccess
{
    const TEMPLATE_TYPE_VIEW = 1;
    const TEMPLATE_TYPE_LAYOUT = 2;
    const TEMPLATE_TYPE_PARTIAL = 3;

    const TEMPLATE_PREFIX_VIEW = '';
    const TEMPLATE_PREFIX_LAYOUT = '@';
    const TEMPLATE_PREFIX_PARTIAL = '_';

    static private $template_type_name = [

        self::TEMPLATE_TYPE_VIEW => "template",
        self::TEMPLATE_TYPE_LAYOUT => "layout",
        self::TEMPLATE_TYPE_PARTIAL=> "partial"

    ];

    static private $template_prefix = [

        self::TEMPLATE_TYPE_VIEW => self::TEMPLATE_PREFIX_VIEW,
        self::TEMPLATE_TYPE_LAYOUT => self::TEMPLATE_PREFIX_LAYOUT,
        self::TEMPLATE_TYPE_PARTIAL=> self::TEMPLATE_PREFIX_PARTIAL

    ];

    use PrototypeTrait;
    use ViewBindings;

    /**
     * @var Controller
     */
    private $controller;

    /**
     * @see $controller
     *
     * @return Controller
     */
    protected function get_controller()
    {
        return $this->controller;
    }

    /**
     * View's variables.
     *
     * @var array
     */
    private $variables = [];

    /**
     * @see $variables
     *
     * @return array
     */
    protected function get_variables()
    {
        return $this->variables;
    }

    /**
     * @see $content
     *
     * @return mixed
     */
    protected function get_content()
    {
        return isset($this->variables['content']) ? $this->variables['content'] : null;
    }

    /**
     * @see $content
     *
     * @param mixed $content
     */
    protected function set_content($content)
    {
        $this->variables['content'] = $content;
    }

    private $decorators = [];

    /**
     * Return the name of the template.
     *
     * The template name is resolved as follows:
     *
     * - The `template` property of the route.
     * - The `template` property of the controller.
     * - The `{$controller->name}/{$controller->action}`, if the controller has an `action`
     * property.
     *
     * @return string|null
     */
    protected function lazy_get_template()
    {
        $controller = $this->controller;

        foreach ($this->template_resolvers as $provider)
        {
            try
            {
                return $provider($controller);
            }
            catch (PropertyNotDefined $e)
            {
                #
                # Resolver failed, we continue with the next.
                #
            }

        }

        return null;
    }

    /**
     * Returns an array of callable used to resolve the {@link $template} property.
     *
     * @return callable[]
     *
     * @internal
     */
    protected function get_template_resolvers()
    {
        return [

            function ($controller) {

                return $controller->route->template;

            },

            function ($controller) {

                return $controller->template;

            },

            function ($controller) {

                return $controller->name . "/" . $controller->action;

            }

        ];
    }

    /**
     * Returns the name of the layout.
     *
     * The layout name is resolved as follows:
     *
     * - The `layout` property of the route.
     * - The `layout` property of the controller.
     * - If the identifier of the route starts with "admin:", "admin" is returned.
     * - If the route pattern is "/" and a "home" layout template is available, "home" is returned.
     * - If the "@page" template is available, "page" is returned.
     * - "default" is returned.
     *
     * @return string
     */
    protected function lazy_get_layout()
    {
        $controller = $this->controller;

        foreach ($this->layout_resolvers as $resolver)
        {
            try
            {
                return $resolver($controller);
            }
            catch (PropertyNotDefined $e)
            {
                #
                # Resolver failed, we continue with the next.
                #
            }

        }

        if (strpos($controller->route->id, "admin:") === 0)
        {
            return 'admin';
        }

        if ($controller->route->pattern == "/" && $this->resolve_template('home', self::TEMPLATE_PREFIX_LAYOUT))
        {
            return 'home';
        }

        if ($this->resolve_template('page', self::TEMPLATE_PREFIX_LAYOUT))
        {
            return 'page';
        }

        return 'default';
    }

    /**
     * Returns an array of callable used to resolve the {@link $template} property.
     *
     * @return callable[]
     *
     * @internal
     */
    protected function get_layout_resolvers()
    {
        return [

            function ($controller) {

                return $controller->route->layout;

            },

            function ($controller) {

                return $controller->layout;

            }

        ];
    }

    /**
     * An event hook is attached to the `action` event of the controller for late rendering,
     * which only happens if the response is `null`.
     *
     * @param Controller $controller The controller that invoked the view.
     */
    public function __construct(Controller $controller)
    {
        $this->controller = $controller;

        Events::get()->attach_to($controller, function (Controller\ActionEvent $event, Controller $target) {

            $this->on_action($event);

        });
    }

    /**
     * @inheritdoc
     */
    public function offsetExists($offset)
    {
        return array_key_exists($offset, $this->variables);
    }

    /**
     * @inheritdoc
     *
     * @throws OffsetNotDefined if the offset is not defined.
     */
    public function offsetGet($offset)
    {
        if (!$this->offsetExists($offset))
        {
            throw new OffsetNotDefined([ $offset, $this ]);
        }

        return $this->variables[$offset];
    }

    /**
     * @inheritdoc
     */
    public function offsetSet($offset, $value)
    {
        $this->variables[$offset] = $value;
    }

    /**
     * @inheritdoc
     */
    public function offsetUnset($offset)
    {
        unset($this->variables[$offset]);
    }

    /**
     * Add a path to search for templates.
     *
     * @param string $path
     * @param int $weight
     */
    public function add_path($path, $weight=0)
    {
        $this->template_resolver->add_path($path, $weight);
    }

    /**
     * Resolve a template pathname from its name and type.
     *
     * @param string $name Name of the template.
     * @param string $prefix Template prefix.
     * @param array $tries Reference to an array where tried path are collected.
     *
     * @return string|false
     */
    protected function resolve_template($name, $prefix, &$tries = [])
    {
        $tries = $tries ?: [];

        if ($prefix)
        {
            $name = TemplateName::from($name);
            $name = $name->with_prefix($prefix);
        }

        $resolver = $this->template_resolver;

        return $resolver->resolve($name, $this->engines->extensions, $tries);
    }

    /**
     * Add a template to decorate the content with.
     *
     * @param string $template Name of the template.
     */
    public function decorate_with($template)
    {
        $this->decorators[] = $template;
    }

    /**
     * Decorate the content.
     *
     * @param mixed $content The content to decorate.
     *
     * @return mixed
     */
    protected function decorate($content)
    {
        $decorators = array_reverse($this->decorators);

        foreach ($decorators as $template)
        {
            $content = $this->render_with_template($content, $template, self::TEMPLATE_TYPE_LAYOUT);
        }

        return $content;
    }

    /**
     * Render the view.
     *
     * @return string
     */
    public function render()
    {
        $steps = [

            [ $this->template, self::TEMPLATE_TYPE_VIEW ],
            [ $this->layout, self::TEMPLATE_TYPE_LAYOUT ]

        ];

        $content = $this->content;

        foreach ($steps as list($template, $type))
        {
            if (!$template)
            {
                continue;
            }

            $content = $this->render_with_template($content, $template, $type);
        }

        return $this->decorate($content);
    }

    /**
     * Renders the content using a template.
     *
     * @param mixed $content The content to render.
     * @param string $template Name of the template.
     * @param string $type Type of the template.
     *
     * @return string
     */
    protected function render_with_template($content, $template, $type)
    {
        $pathname = $this->resolve_template($template, self::$template_prefix[$type], $tries);

        if (!$pathname)
        {
            $type_name = self::$template_type_name[$type];

            throw new TemplateNotFound("There is no $type_name matching <q>$template</q>.", $tries);
        }

        list($thisArg, $variables) = $this->prepare_engine_args($content, $type);

        return $this->engines->render($pathname, $thisArg, $variables);
    }

    /**
     * Prepares engine arguments.
     *
     * @param mixed $content
     * @param string $type
     *
     * @return array
     */
    protected function prepare_engine_args($content, $type)
    {
        $variables = $this->variables;

        if ($type == self::TEMPLATE_TYPE_LAYOUT)
        {
            $variables['content'] = $content;

            return [ $this, $variables ];
        }

        $variables['view'] = $this;

        return [ $content, $variables ];
    }

    /**
     * Renders the view on `Controller::action` event.
     *
     * **Note:** The view is not rendered if the event's response is defined, which is the case
     * when the controller obtained a result after its execution.
     *
     * @param Controller\ActionEvent $event
     */
    protected function on_action(Controller\ActionEvent $event)
    {
        if ($event->result !== null)
        {
            return;
        }

        new View\BeforeRender($this);

        $event->result = $this->render();
    }
}

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