<?php

namespace Courseware\ContainerTypes;

use Courseware\CoursewarePlugin;
use Opis\JsonSchema\Validator;

/**
 * This class represents the content of a Courseware container stored in payload.
 *
 * @author  Marcus Eibrink-Lunzenauer <lunzenauer@elan-ev.de>
 * @author  Ron Lucke <lucke@elan-ev.de>
 * @license GPL2 or any later version
 *
 * @SuppressWarnings(PHPMD.StaticAccess)
 *
 * @since   Stud.IP 5.0
 */
abstract class ContainerType
{
    /**
     * Returns the initial payload of every instance of this type of container.
     *
     * @return array<mixed> the initial payload of an instance of this type of container
     */
    abstract public function initialPayload(): array;

    /**
     * Returns the JSON schema which is used to validate the payload of
     * instances of this type of container.
     *
     * @return string the JSON schema to be used
     */
    abstract public static function getJsonSchema(): string;

    /**
     * Returns a short string describing this type of container.
     *
     * @return string the short string describing this type
     */
    abstract public static function getType(): string;

    /**
     * Returns the title of this type of containers suitable to display it to the user.
     *
     * @return string the title of this type of containers
     */
    abstract public static function getTitle(): string;

    /**
     * Returns the description of this type of containers suitable to display it to the user.
     *
     * @return string the description of this type of containers
     */
    abstract public static function getDescription(): string;

    /**
     * Adds a block id to payload of the container
     *
     *  @param /Courseware/Block $block - block to be added to the container
     */
    abstract public function addBlock($block, $sectionIndex): void;

    /**
     * Returns all known types of containers: core types and plugin types as well.
     *
     * @return array<string> a list of all known types of containers;
     *                       each one a fully qualified class name
     */
    public static function getContainerTypes(): array
    {
        $containerTypes = [AccordionContainer::class, ListContainer::class, TabsContainer::class];

        try {
            foreach (\PluginEngine::getPlugins(CoursewarePlugin::class) as $plugin) {
                $containerTypes = $plugin->registerContainerTypes($containerTypes);
            }
        } catch (\Exception $e) {
            // there is nothing we can do here other than absorbing exceptions
        }

        return $containerTypes;
    }

    /**
     * Return all container types that are activated in this Stud.IP installation.
     *
     * @return iterable<string> an iterable of all activated `ContainerType` classes
     */
    public static function getActivatedContainerTypes(): iterable
    {
        return ContainerTypeState::getActivatedContainerTypes();
    }
    /**
     * @param string $containerType a short string describing a type of container; see `getType`
     *
     * @return bool true, if the given type of container is valid; false otherwise
     */
    public static function isContainerType(string $containerType): bool
    {
        return null !== self::findContainerType($containerType);
    }

    /**
     * Returns the classname of a container type whose `type` equals the given one.
     *
     * @param string $containerType a short string describing a type of container; see `getType`
     *
     * @return ?string either the classname if the given type was valid; null otherwise
     */
    public static function findContainerType(string $containerType): ?string
    {
        static $mapping;

        // memorize mapping of types to classes
        if (!$mapping) {
            $mapping = array_reduce(
                self::getContainerTypes(),
                function ($memo, $typeClass) {
                    $memo[$typeClass::getType()] = $typeClass;

                    return $memo;
                },
                []
            );
        }

        foreach ($mapping as $class) {
            if ($class::getType() === $containerType) {
                return $class;
            }
        }

        return null;
    }

    /**
     * Creates an instance of ContainerType for a given container.
     *
     * @param \Courseware\Container $container the container whose ContainerType is returned
     *
     * @return ContainerType the ContainerType associated with the given container
     */
    public static function factory(\Courseware\Container $container): ContainerType
    {
        if (!($class = self::findContainerType($container['container_type']))) {
            // TODO: Hier müsste es eine weniger allgemeine Exception geben.
            throw new \RuntimeException('Invalid `container_type` attribute in database.');
        }

        return new $class($container);
    }

    /**
     * @return bool `true`, if this `ContainerType` is activated, otherwise `false`
     */
    public static function isActivated(): bool
    {
        return in_array(static::class, ContainerTypeState::getActivatedContainerTypes());
    }

    /**
     * Activates a `ContainerType`.
     *
     * @return `true`, if this `ContainerType` was activated, otherwise `false`
     */
    public static function activate(): bool
    {
        $state = static::findContainerTypeStateOrNew();
        return $state->activate();
    }

    /**
     * Deactivates a `ContainerType`.
     *
     * @return `true`, if this `ContainerType` was deactivated, otherwise `false`
     */
    public static function deactivate(): bool
    {
        $state = static::findContainerTypeStateOrNew();
        return $state->deactivate();
    }

    private static function findContainerTypeStateOrNew(): ContainerTypeState
    {
        $state = ContainerTypeState::findOneBySql('container_type = ?', [static::class]);
        if (!$state) {
            $state = new ContainerTypeState();
            $state->container_type = static::class;
        }

        return $state;
    }

    /**
     * Validates a given payload according to the JSON schema of this type of container.
     *
     * @param mixed $payload the payload to be validated
     *
     * @return bool true, if the given payload is valid; false otherwise
     */
    public function validatePayload($payload): bool
    {
        $validator = new Validator();
        $result = $validator->validate($payload, static::getJsonSchema());
        return $result->isValid();
    }

    /** @var \Courseware\Container */
    protected $container;

    /**
     * @param \Courseware\Container $container the container associated to this type
     */
    public function __construct(\Courseware\Container $container)
    {
        $this->container = $container;
    }

    /**
     * Returns the decoded payload of the block associated with this instance.
     *
     * @return mixed the decoded payload
     */
    public function getPayload()
    {
        $decoded = $this->decodePayloadString($this->container['payload']);

        return $decoded;
    }

    /**
     * Encodes the payload and sets it in the associated block.
     *
     * @param mixed $payload the payload to be encoded
     */
    public function setPayload($payload): void
    {
        $this->container['payload'] = null === $payload ? '' : json_encode($payload, true);
    }

    // TODO: (tgloeggl) DocBlock ergänzen
    public function copyPayload(array $block_map = []): array
    {
        $payload = $this->getPayload();

        foreach ($payload['sections'] as &$section) {
            foreach ($section['blocks'] as &$block) {
                $block = (is_string($block) || is_int($block)) ? ($block_map[$block] ?? null) : null;
            }
            $section['blocks'] = array_values(array_filter($section['blocks']));
        }

        return $payload;
    }

    /**
     * Decode a given payload.
     *
     * @param string $payload the payload to be decoded
     *
     * @return mixed the decoded payload
     */
    protected function decodePayloadString(string $payload)
    {
        if ('' === $payload) {
            $decoded = $this->initialPayload();
        } else {
            $decoded = json_decode($payload, true);
            if (JSON_ERROR_NONE !== json_last_error()) {
                throw new \RuntimeException('TODO');
            }
        }

        return $decoded;
    }

    /**
     * Returns a containers width as a description.
     *
     * @return string the description
     */
    public function getContainerWidth(): string
    {
        $width = [
            'full' => _('Volle Breite'),
            'half' => _('Halbe Breite'),
            'half-center' => _('Halbe Breite (zentriert)'),
        ];
        $payload = $this->getPayload();
        if (array_key_exists($payload['colspan'], $width)) {
            return $width[$payload['colspan']];
        } else {
            return _('unbekannter Courseware-Container');
        }
    }

    /**
     * Gets the related container's html template if exists otherwise a default one, to be exported as pdf if exists.
     *
     * It turns the classname into snakecase in order to find the
     * template file in templates/courseware/container_types.
     *
     * @return \Flexi\Template|null the \Flexi\Template instance if exists, otherwise null.
     */
    public function getPdfHtmlTemplate(): ?\Flexi\Template
    {
        if (!$this->isActivated()) {
            return null;
        }

        $template = null;
        try {
            $template_name = strtosnakecase((new \ReflectionClass($this))->getShortName());
            $template_path = $GLOBALS['template_factory']->get_path() . "courseware/container_types/{$template_name}.php";
            if (file_exists($template_path)) {
                $template = $GLOBALS['template_factory']->open("courseware/container_types/{$template_name}");
            } else {
                $template = $GLOBALS['template_factory']->open("courseware/container_types/default");
            }
            $template->set_attributes([
                'title' => $this->getTitle(),
                'payload' => $this->getPayload(),
                'container' => $this->container
            ]);
        } catch (\Exception $e) {
            // it catches the exception mostly because the template file could not be found.
        }
        return $template;
    }
}