<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

/**
 * Template constructions filter
 */
namespace Magento\Framework\Filter;

use Magento\Framework\Model\AbstractExtensibleModel;
use Magento\Framework\Model\AbstractModel;

/**
 * @api
 */
class Template implements \Zend_Filter_Interface
{
    /**
     * Construction regular expression
     */
    const CONSTRUCTION_PATTERN = '/{{([a-z]{0,10})(.*?)}}/si';

    /**#@+
     * Construction logic regular expression
     */
    const CONSTRUCTION_DEPEND_PATTERN = '/{{depend\s*(.*?)}}(.*?){{\\/depend\s*}}/si';

    const CONSTRUCTION_IF_PATTERN = '/{{if\s*(.*?)}}(.*?)({{else}}(.*?))?{{\\/if\s*}}/si';

    const CONSTRUCTION_TEMPLATE_PATTERN = '/{{(template)(.*?)}}/si';

    /**#@-*/

    /**#@-*/
    private $afterFilterCallbacks = [];

    /**
     * Assigned template variables
     *
     * @var array
     */
    protected $templateVars = [];

    /**
     * Template processor
     *
     * @var callable|null
     */
    protected $templateProcessor = null;

    /**
     * @var \Magento\Framework\Stdlib\StringUtils
     */
    protected $string;

    /**
     * @var string[]
     */
    private $restrictedMethods = [
        'addafterfiltercallback',
        'getresourcecollection',
        'load',
        'save',
        'getcollection',
        'getresource',
        'getconfig',
        'getresource',
        'setvariables',
        'settemplateprocessor',
        'gettemplateprocessor',
        'vardirective',
        'delete',
    ];

    /**
     * @param \Magento\Framework\Stdlib\StringUtils $string
     * @param array $variables
     */
    public function __construct(\Magento\Framework\Stdlib\StringUtils $string, $variables = [])
    {
        $this->string = $string;
        $this->setVariables($variables);
    }

    /**
     * Sets template variables that's can be called through {var ...} statement
     *
     * @param array $variables
     * @return \Magento\Framework\Filter\Template
     */
    public function setVariables(array $variables)
    {
        foreach ($variables as $name => $value) {
            $this->templateVars[$name] = $value;
        }
        return $this;
    }

    /**
     * Sets the processor for template directive.
     *
     * @param callable $callback it must return string
     * @return $this
     */
    public function setTemplateProcessor(callable $callback)
    {
        $this->templateProcessor = $callback;
        return $this;
    }

    /**
     * Sets the processor for template directive.
     *
     * @return callable|null
     */
    public function getTemplateProcessor()
    {
        return is_callable($this->templateProcessor) ? $this->templateProcessor : null;
    }

    /**
     * Filter the string as template.
     *
     * @param string $value
     * @return string
     * @throws \Exception
     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
     */
    public function filter($value)
    {
        // "depend", "if", and "template" directives should be first
        foreach ([
                     self::CONSTRUCTION_DEPEND_PATTERN => 'dependDirective',
                     self::CONSTRUCTION_IF_PATTERN => 'ifDirective',
                     self::CONSTRUCTION_TEMPLATE_PATTERN => 'templateDirective',
                 ] as $pattern => $directive) {
            if (preg_match_all($pattern, $value, $constructions, PREG_SET_ORDER)) {
                foreach ($constructions as $construction) {
                    $callback = [$this, $directive];
                    if (!is_callable($callback)) {
                        continue;
                    }
                    try {
                        $replacedValue = call_user_func($callback, $construction);
                    } catch (\Exception $e) {
                        throw $e;
                    }
                    $value = str_replace($construction[0], $replacedValue, $value);
                }
            }
        }

        if (preg_match_all(self::CONSTRUCTION_PATTERN, $value, $constructions, PREG_SET_ORDER)) {
            foreach ($constructions as $construction) {
                $callback = [$this, $construction[1] . 'Directive'];
                if (!is_callable($callback)) {
                    continue;
                }
                try {
                    $replacedValue = call_user_func($callback, $construction);
                } catch (\Exception $e) {
                    throw $e;
                }
                $value = str_replace($construction[0], $replacedValue, $value);
            }
        }

        $value = $this->afterFilter($value);
        return $value;
    }

    /**
     * Runs callbacks that have been added to filter content after directive processing is finished.
     *
     * @param string $value
     * @return string
     */
    protected function afterFilter($value)
    {
        foreach ($this->afterFilterCallbacks as $callback) {
            $value = call_user_func($callback, $value);
        }
        // Since a single instance of this class can be used to filter content multiple times, reset callbacks to
        // prevent callbacks running for unrelated content (e.g., email subject and email body)
        $this->resetAfterFilterCallbacks();
        return $value;
    }

    /**
     * Adds a callback to run after main filtering has happened. Callback must accept a single argument and return
     * a string of the processed value.
     *
     * @param callable $afterFilterCallback
     * @return $this
     */
    public function addAfterFilterCallback(callable $afterFilterCallback)
    {
        // Only add callback if it doesn't already exist
        if (in_array($afterFilterCallback, $this->afterFilterCallbacks)) {
            return $this;
        }

        $this->afterFilterCallbacks[] = $afterFilterCallback;
        return $this;
    }

    /**
     * Resets the after filter callbacks
     *
     * @return $this
     */
    protected function resetAfterFilterCallbacks()
    {
        $this->afterFilterCallbacks = [];
        return $this;
    }

    /**
     * @param string[] $construction
     * @return string
     */
    public function varDirective($construction)
    {
        if (count($this->templateVars) == 0) {
            // If template prepossessing
            return $construction[0];
        }

        $replacedValue = $this->getVariable($construction[2], '');
        return $replacedValue;
    }

    /**
     * Allows templates to be included inside other templates
     *
     * Usage:
     *
     *     {{template config_path="<PATH>"}}
     *
     * <PATH> equals the XPATH to the system configuration value that contains the value of the template.
     * This directive is useful to include things like a global header/footer.
     *
     * @param string[] $construction
     * @return mixed
     */
    public function templateDirective($construction)
    {
        // Processing of {template config_path=... [...]} statement
        $templateParameters = $this->getParameters($construction[2]);
        if (!isset($templateParameters['config_path']) || !$this->getTemplateProcessor()) {
            // Not specified template or not set include processor
            $replacedValue = '{Error in template processing}';
        } else {
            // Including of template
            $configPath = $templateParameters['config_path'];
            unset($templateParameters['config_path']);
            $templateParameters = array_merge_recursive($templateParameters, $this->templateVars);
            $replacedValue = call_user_func($this->getTemplateProcessor(), $configPath, $templateParameters);
        }
        return $replacedValue;
    }

    /**
     * @param string[] $construction
     * @return string
     */
    public function dependDirective($construction)
    {
        if (count($this->templateVars) == 0) {
            // If template processing
            return $construction[0];
        }

        if ($this->getVariable($construction[1], '') == '') {
            return '';
        } else {
            return $construction[2];
        }
    }

    /**
     * @param string[] $construction
     * @return string
     */
    public function ifDirective($construction)
    {
        if (count($this->templateVars) == 0) {
            return $construction[0];
        }

        if ($this->getVariable($construction[1], '') == '') {
            if (isset($construction[3]) && isset($construction[4])) {
                return $construction[4];
            }
            return '';
        } else {
            return $construction[2];
        }
    }

    /**
     * Return associative array of parameters.
     *
     * @param string $value raw parameters
     * @return array
     */
    protected function getParameters($value)
    {
        $tokenizer = new Template\Tokenizer\Parameter();
        $tokenizer->setString($value);
        $params = $tokenizer->tokenize();
        foreach ($params as $key => $value) {
            if (substr($value, 0, 1) === '$') {
                $params[$key] = $this->getVariable(substr($value, 1), null);
            }
        }
        return $params;
    }

    /**
     * Validate method call initiated in a template.
     *
     * Deny calls for methods that may disrupt template processing.
     *
     * @param object $object
     * @param string $method
     * @return void
     * @throws \InvalidArgumentException
     */
    private function validateVariableMethodCall($object, string $method)
    {
        if ($object === $this) {
            if (in_array(mb_strtolower($method), $this->restrictedMethods)) {
                throw new \InvalidArgumentException("Method $method cannot be called from template.");
            }
        }
    }

    /**
     * Check allowed methods for data objects.
     *
     * Deny calls for methods that may disrupt template processing.
     *
     * @param object $object
     * @param string $method
     * @return bool
     * @throws \InvalidArgumentException
     */
    private function isAllowedDataObjectMethod($object, string $method): bool
    {
        if ($object instanceof AbstractExtensibleModel || $object instanceof AbstractModel) {
            if (in_array(mb_strtolower($method), $this->restrictedMethods)) {
                throw new \InvalidArgumentException("Method $method cannot be called from template.");
            }
        }

        return true;
    }

    /**
     * Return variable value for var construction
     *
     * @param string $value raw parameters
     * @param string $default default value
     * @return string
     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
     */
    protected function getVariable($value, $default = '{no_value_defined}')
    {
        \Magento\Framework\Profiler::start('email_template_processing_variables');
        $tokenizer = new Template\Tokenizer\Variable();
        $tokenizer->setString($value);
        $stackVars = $tokenizer->tokenize();
        $result = $default;
        $last = 0;
        $stackVarsCount = count($stackVars);
        for ($i = 0; $i < $stackVarsCount; $i++) {
            if ($i == 0 && isset($this->templateVars[$stackVars[$i]['name']])) {
                // Getting of template value
                $stackVars[$i]['variable'] = & $this->templateVars[$stackVars[$i]['name']];
            } elseif (isset($stackVars[$i - 1]['variable'])
                    && $stackVars[$i - 1]['variable'] instanceof \Magento\Framework\DataObject
            ) {
                // If data object calling methods or getting properties
                if ($stackVars[$i]['type'] == 'property') {
                    $caller = 'get' . $this->string->upperCaseWords($stackVars[$i]['name'], '_', '');
                    $stackVars[$i]['variable'] = method_exists(
                        $stackVars[$i - 1]['variable'],
                        $caller
                    ) ? $stackVars[$i - 1]['variable']->{$caller}() : $stackVars[$i - 1]['variable']->getData(
                        $stackVars[$i]['name']
                    );
                } elseif ($stackVars[$i]['type'] == 'method') {
                    // Calling of data object method
                    if (method_exists($stackVars[$i - 1]['variable'], $stackVars[$i]['name'])
                            || substr($stackVars[$i]['name'], 0, 3) == 'get'
                    ) {
                        $stackVars[$i]['args'] = $this->getStackArgs($stackVars[$i]['args']);

                        if ($this->isAllowedDataObjectMethod($stackVars[$i - 1]['variable'], $stackVars[$i]['name'])) {
                            $stackVars[$i]['variable'] = call_user_func_array(
                                [$stackVars[$i - 1]['variable'], $stackVars[$i]['name']],
                                $stackVars[$i]['args']
                            );
                        }
                    }
                }
                $last = $i;
            } elseif (isset($stackVars[$i - 1]['variable'])
                      && is_object($stackVars[$i - 1]['variable'])
                      && $stackVars[$i]['type'] == 'method'
            ) {
                // Calling object methods
                $object = $stackVars[$i - 1]['variable'];
                $method = $stackVars[$i]['name'];
                if (method_exists($object, $method)) {
                    $args = $this->getStackArgs($stackVars[$i]['args']);
                    $this->validateVariableMethodCall($object, $method);
                    $stackVars[$i]['variable'] = call_user_func_array([$object, $method], $args);
                }
                $last = $i;
            }
        }

        if (isset($stackVars[$last]['variable'])) {
            // If value for construction exists set it
            $result = $stackVars[$last]['variable'];
        }
        \Magento\Framework\Profiler::stop('email_template_processing_variables');
        return $result;
    }

    /**
     * Loops over a set of stack args to process variables into array argument values
     *
     * @param array $stack
     * @return array
     */
    protected function getStackArgs($stack)
    {
        foreach ($stack as $i => $value) {
            if (is_array($value)) {
                $stack[$i] = $this->getStackArgs($value);
            } elseif (substr($value, 0, 1) === '$') {
                $stack[$i] = $this->getVariable(substr($value, 1), null);
            }
        }
        return $stack;
    }
}
