<?php
/**
 * WordPress Coding Standard.
 *
 * @package WPCS\WordPressCodingStandards
 * @link    https://github.com/WordPress/WordPress-Coding-Standards
 * @license https://opensource.org/licenses/MIT MIT
 */

namespace WordPressCS\WordPress\Sniffs\Security;

use PHP_CodeSniffer\Files\File;
use PHP_CodeSniffer\Util\Tokens;
use PHPCSUtils\Utils\Context;
use PHPCSUtils\Utils\TextStrings;
use PHPCSUtils\Utils\Variables;
use WordPressCS\WordPress\Helpers\ContextHelper;
use WordPressCS\WordPress\Helpers\SanitizationHelperTrait;
use WordPressCS\WordPress\Helpers\ValidationHelper;
use WordPressCS\WordPress\Helpers\VariableHelper;
use WordPressCS\WordPress\Sniff;

/**
 * Flag any non-validated/sanitized input ( _GET / _POST / etc. ).
 *
 * @link https://github.com/WordPress/WordPress-Coding-Standards/issues/69
 *
 * @since 0.3.0
 * @since 0.4.0  This class now extends the WordPressCS native `Sniff` class.
 * @since 0.5.0  Method getArrayIndexKey() has been moved to the WordPressCS native `Sniff` class.
 * @since 0.13.0 Class name changed: this class is now namespaced.
 * @since 1.0.0  This sniff has been moved from the `VIP` category to the `Security` category.
 *
 * @uses \WordPressCS\WordPress\Helpers\SanitizationHelperTrait::$customSanitizingFunctions
 * @uses \WordPressCS\WordPress\Helpers\SanitizationHelperTrait::$customUnslashingSanitizingFunctions
 */
class ValidatedSanitizedInputSniff extends Sniff {

    use SanitizationHelperTrait;

    /**
     * Check for validation functions for a variable within its own parenthesis only.
     *
     * @var boolean
     */
    public $check_validation_in_scope_only = false;

    /**
     * Superglobals for which the values will be slashed by WP.
     *
     * @link https://developer.wordpress.org/reference/functions/wp_magic_quotes/
     *
     * @since 3.0.0
     *
     * @var array<string, true>
     */
    private $slashed_superglobals = array(
        '$_COOKIE'  => true,
        '$_GET'     => true,
        '$_POST'    => true,
        '$_REQUEST' => true,
        '$_SERVER'  => true,
    );

    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array
     */
    public function register() {
        return array(
            \T_VARIABLE,
            \T_DOUBLE_QUOTED_STRING,
            \T_HEREDOC,
        );
    }

    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param int $stackPtr The position of the current token in the stack.
     *
     * @return void
     */
    public function process_token( $stackPtr ) {

        // Handling string interpolation.
        if ( \T_DOUBLE_QUOTED_STRING === $this->tokens[ $stackPtr ]['code']
            || \T_HEREDOC === $this->tokens[ $stackPtr ]['code']
        ) {
            // Retrieve all embeds, but use only the initial variable name part.
            $interpolated_variables = array_map(
                static function ( $embed ) {
                    return preg_replace( '`^(\{?\$\{?\(?)([a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*)(.*)$`', '$2', $embed );
                },
                TextStrings::getEmbeds( $this->tokens[ $stackPtr ]['content'] )
            );

            // Filter the embeds down to superglobals only.
            $interpolated_superglobals = array_filter(
                $interpolated_variables,
                static function ( $var_name ) {
                    return ( 'GLOBALS' !== $var_name && Variables::isSuperglobalName( $var_name ) );
                }
            );

            foreach ( $interpolated_superglobals as $bad_variable ) {
                $this->phpcsFile->addError( 'Detected usage of a non-sanitized, non-validated input variable %s: %s', $stackPtr, 'InputNotValidatedNotSanitized', array( $bad_variable, $this->tokens[ $stackPtr ]['content'] ) );
            }

            return;
        }

        /* Handle variables */

        // Check if this is a superglobal we want to examine.
        if ( '$GLOBALS' === $this->tokens[ $stackPtr ]['content']
            || Variables::isSuperglobalName( $this->tokens[ $stackPtr ]['content'] ) === false
        ) {
            return;
        }

        // If the variable is being unset, we don't care about it.
        if ( Context::inUnset( $this->phpcsFile, $stackPtr ) ) {
            return;
        }

        // If we're overriding a superglobal with an assignment, no need to test.
        if ( VariableHelper::is_assignment( $this->phpcsFile, $stackPtr ) ) {
            return;
        }

        // This superglobal is being validated.
        if ( ContextHelper::is_in_isset_or_empty( $this->phpcsFile, $stackPtr ) ) {
            return;
        }

        $array_keys = VariableHelper::get_array_access_keys( $this->phpcsFile, $stackPtr );

        if ( empty( $array_keys ) ) {
            return;
        }

        $error_data = array( $this->tokens[ $stackPtr ]['content'] . '[' . implode( '][', $array_keys ) . ']' );

        /*
         * Check for validation first.
         */
        $validated = false;

        for ( $i = ( $stackPtr + 1 ); $i < $this->phpcsFile->numTokens; $i++ ) {
            if ( isset( Tokens::$emptyTokens[ $this->tokens[ $i ]['code'] ] ) ) {
                continue;
            }

            if ( \T_OPEN_SQUARE_BRACKET === $this->tokens[ $i ]['code']
                && isset( $this->tokens[ $i ]['bracket_closer'] )
            ) {
                // Skip over array keys.
                $i = $this->tokens[ $i ]['bracket_closer'];
                continue;
            }

            if ( \T_COALESCE === $this->tokens[ $i ]['code'] ) {
                $validated = true;
            }

            // Anything else means this is not a validation coalesce.
            break;
        }

        if ( false === $validated ) {
            $validated = ValidationHelper::is_validated( $this->phpcsFile, $stackPtr, $array_keys, $this->check_validation_in_scope_only );
        }

        if ( false === $validated ) {
            $this->phpcsFile->addError(
                'Detected usage of a possibly undefined superglobal array index: %s. Use isset() or empty() to check the index exists before using it',
                $stackPtr,
                'InputNotValidated',
                $error_data
            );
        }

        // If this variable is being tested with one of the `is_..()` functions, sanitization isn't needed.
        if ( ContextHelper::is_in_type_test( $this->phpcsFile, $stackPtr ) ) {
            return;
        }

        // If this is a comparison ('a' == $_POST['foo']), sanitization isn't needed.
        if ( VariableHelper::is_comparison( $this->phpcsFile, $stackPtr, false ) ) {
            return;
        }

        // If this is a comparison using the array comparison functions, sanitization isn't needed.
        if ( ContextHelper::is_in_array_comparison( $this->phpcsFile, $stackPtr ) ) {
            return;
        }

        // Now look for sanitizing functions.
        if ( ! $this->is_sanitized( $this->phpcsFile, $stackPtr, array( $this, 'add_unslash_error' ) ) ) {
            $this->phpcsFile->addError(
                'Detected usage of a non-sanitized input variable: %s',
                $stackPtr,
                'InputNotSanitized',
                $error_data
            );
        }
    }

    /**
     * Add an error for missing use of unslashing.
     *
     * @since 0.5.0
     * @since 3.0.0 - Moved from the `Sniff` class to this class.
     *              - The `$phpcsFile` parameter was added.
     *
     * @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
     * @param int                         $stackPtr  The index of the token in the stack
     *                                               which is missing unslashing.
     *
     * @return void
     */
    public function add_unslash_error( File $phpcsFile, $stackPtr ) {
        $tokens   = $phpcsFile->getTokens();
        $var_name = $tokens[ $stackPtr ]['content'];

        if ( isset( $this->slashed_superglobals[ $var_name ] ) === false ) {
            // WP doesn't slash these, so they don't need unslashing.
            return;
        }

        // We know there will be array keys as that's checked in the process_token() method.
        $array_keys = VariableHelper::get_array_access_keys( $phpcsFile, $stackPtr );
        $error_data = array( $var_name . '[' . implode( '][', $array_keys ) . ']' );

        $phpcsFile->addError(
            '%s not unslashed before sanitization. Use wp_unslash() or similar',
            $stackPtr,
            'MissingUnslash',
            $error_data
        );
    }
}