<?php
/**
 * Forbidden Functions
 *
 * @package   CodeIgniter4-Standard
 * @author    Louis Linehan <louis.linehan@gmail.com>
 * @copyright 2017 British Columbia Institute of Technology
 * @license   https://github.com/bcit-ci/CodeIgniter4-Standard/blob/master/LICENSE MIT License
 */

namespace CodeIgniter4\Sniffs\PHP;

use PHP_CodeSniffer\Sniffs\Sniff;
use PHP_CodeSniffer\Files\File;

/**
 * Forbidden Functions Sniff
 *
 * Discourages the use of alias functions that are kept in PHP for compatibility
 * with older versions. Can be used to forbid the use of any function.
 *
 * @author Louis Linehan <louis.linehan@gmail.com>
 */
class ForbiddenFunctionsSniff implements Sniff
{

    /**
     * A list of forbidden functions with their alternatives.
     *
     * The value is NULL if no alternative exists. IE, the
     * function should just not be used.
     *
     * @var array|null)
     */
    public $forbiddenFunctions = ['sizeof' => 'count'];

    /**
     * A cache of forbidden function names, for faster lookups.
     *
     * @var array(string)
     */
    protected $forbiddenFunctionNames = [];

    /**
     * If true, forbidden functions will be considered regular expressions.
     *
     * @var boolean
     */
    protected $patternMatch = false;

    /**
     * If true, an error will be thrown; otherwise a warning.
     *
     * @var boolean
     */
    public $error = true;


    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array
     */
    public function register()
    {
        // Everyone has had a chance to figure out what forbidden functions
        // they want to check for, so now we can cache out the list.
        $this->forbiddenFunctionNames = array_keys($this->forbiddenFunctions);

        if ($this->patternMatch === true) {
            foreach ($this->forbiddenFunctionNames as $i => $name) {
                $this->forbiddenFunctionNames[$i] = '/'.$name.'/i';
            }

            return [T_STRING];
        }

        // If we are not pattern matching, we need to work out what
        // tokens to listen for.
        $string = '<?php ';
        foreach ($this->forbiddenFunctionNames as $name) {
            $string .= $name.'();';
        }

        $register = [];

        $tokens = token_get_all($string);
        array_shift($tokens);
        foreach ($tokens as $token) {
            if (is_array($token) === true) {
                $register[] = $token[0];
            }
        }

        return array_unique($register);

    }//end register()


    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param File $phpcsFile The file being scanned.
     * @param int  $stackPtr  The position of the current token in
     *                        the stack passed in $tokens.
     *
     * @return void
     */
    public function process(File $phpcsFile, $stackPtr)
    {
        $tokens = $phpcsFile->getTokens();

        $ignore = [
            T_DOUBLE_COLON => true,
            T_FUNCTION     => true,
            T_CONST        => true,
            T_PUBLIC       => true,
            T_PRIVATE      => true,
            T_PROTECTED    => true,
            T_AS           => true,
            T_NEW          => true,
            T_INSTEADOF    => true,
            T_NS_SEPARATOR => true,
            T_IMPLEMENTS   => true,
        ];

        $prevToken = $phpcsFile->findPrevious(T_WHITESPACE, ($stackPtr - 1), null, true);

        // If function call is directly preceded by a NS_SEPARATOR it points to the
        // global namespace, so we should still catch it.
        if ($tokens[$prevToken]['code'] === T_NS_SEPARATOR) {
            $prevToken = $phpcsFile->findPrevious(T_WHITESPACE, ($prevToken - 1), null, true);
            if ($tokens[$prevToken]['code'] === T_STRING) {
                // Not in the global namespace.
                return;
            }
        }

        if (isset($ignore[$tokens[$prevToken]['code']]) === true) {
            // Not a call to a PHP function.
            return;
        }

        $nextToken = $phpcsFile->findNext(T_WHITESPACE, ($stackPtr + 1), null, true);
        if (isset($ignore[$tokens[$nextToken]['code']]) === true) {
            // Not a call to a PHP function.
            return;
        }

        if ($tokens[$stackPtr]['code'] === T_STRING && $tokens[$nextToken]['code'] !== T_OPEN_PARENTHESIS) {
            // Not a call to a PHP function.
            return;
        }

        $function = strtolower($tokens[$stackPtr]['content']);
        $pattern  = null;

        if ($this->patternMatch === true) {
            $count   = 0;
            $pattern = preg_replace(
                $this->forbiddenFunctionNames,
                $this->forbiddenFunctionNames,
                $function,
                1,
                $count
            );

            if ($count === 0) {
                return;
            }

            // Remove the pattern delimiters and modifier.
            $pattern = substr($pattern, 1, -2);
        } else {
            if (in_array($function, $this->forbiddenFunctionNames) === false) {
                return;
            }
        }//end if

        $this->addError($phpcsFile, $stackPtr, $function, $pattern);

    }//end process()


    /**
     * Generates the error or warning for this sniff.
     *
     * @param File   $phpcsFile The file being scanned.
     * @param int    $stackPtr  The position of the forbidden function
     *                          in the token array.
     * @param string $function  The name of the forbidden function.
     * @param string $pattern   The pattern used for the match.
     *
     * @return void
     */
    protected function addError($phpcsFile, $stackPtr, $function, $pattern=null)
    {
        $data  = [$function];
        $error = 'The use of function %s() is ';
        if ($this->error === true) {
            $type   = 'Found';
            $error .= 'forbidden';
        } else {
            $type   = 'Discouraged';
            $error .= 'discouraged';
        }

        if ($pattern === null) {
            $pattern = $function;
        }

        if ($this->forbiddenFunctions[$pattern] !== null
            && $this->forbiddenFunctions[$pattern] !== 'null'
        ) {
            $type  .= 'WithAlternative';
            $data[] = $this->forbiddenFunctions[$pattern];
            $error .= '; use %s() instead';
        }

        if ($this->error === true) {
            $phpcsFile->addError($error, $stackPtr, $type, $data);
        } else {
            $phpcsFile->addWarning($error, $stackPtr, $type, $data);
        }

    }//end addError()


}//end class
