<?php
/**
 * Checks the cyclomatic complexity (McCabe) for functions.
 *
 * The cyclomatic complexity (also called McCabe code metrics)
 * indicates the complexity within a function by counting
 * the different paths the function includes.
 *
 * @author    Johann-Peter Hartmann <hartmann@mayflower.de>
 * @author    Greg Sherwood <gsherwood@squiz.net>
 * @copyright 2007-2014 Mayflower GmbH
 * @copyright 2023 PHPCSStandards and contributors
 * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/HEAD/licence.txt BSD Licence
 */

namespace PHP_CodeSniffer\Standards\Generic\Sniffs\Metrics;

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

class CyclomaticComplexitySniff implements Sniff
{

    /**
     * Predicate nodes for PHP.
     *
     * @var array<int|string, true>
     */
    private const PREDICATE_NODES = [
        T_CASE                     => true,
        T_DEFAULT                  => true,
        T_CATCH                    => true,
        T_IF                       => true,
        T_FOR                      => true,
        T_FOREACH                  => true,
        T_WHILE                    => true,
        T_ELSEIF                   => true,
        T_INLINE_THEN              => true,
        T_COALESCE                 => true,
        T_COALESCE_EQUAL           => true,
        T_MATCH_ARROW              => true,
        T_NULLSAFE_OBJECT_OPERATOR => true,
    ];

    /**
     * A complexity higher than this value will throw a warning.
     *
     * @var integer
     */
    public $complexity = 10;

    /**
     * A complexity higher than this value will throw an error.
     *
     * @var integer
     */
    public $absoluteComplexity = 20;


    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register()
    {
        return [T_FUNCTION];
    }


    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param \PHP_CodeSniffer\Files\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, int $stackPtr)
    {
        $tokens = $phpcsFile->getTokens();

        // Ignore abstract and interface methods. Bail early when live coding.
        if (isset($tokens[$stackPtr]['scope_opener'], $tokens[$stackPtr]['scope_closer']) === false) {
            return;
        }

        // Detect start and end of this function definition.
        $start = $tokens[$stackPtr]['scope_opener'];
        $end   = $tokens[$stackPtr]['scope_closer'];

        $complexity = 1;

        // Iterate from start to end and count predicate nodes.
        for ($i = ($start + 1); $i < $end; $i++) {
            if (isset(self::PREDICATE_NODES[$tokens[$i]['code']]) === true) {
                $complexity++;
            }
        }

        if ($complexity > $this->absoluteComplexity) {
            $error = 'Function\'s cyclomatic complexity (%s) exceeds allowed maximum of %s';
            $data  = [
                $complexity,
                $this->absoluteComplexity,
            ];
            $phpcsFile->addError($error, $stackPtr, 'MaxExceeded', $data);
        } elseif ($complexity > $this->complexity) {
            $warning = 'Function\'s cyclomatic complexity (%s) exceeds %s; consider refactoring the function';
            $data    = [
                $complexity,
                $this->complexity,
            ];
            $phpcsFile->addWarning($warning, $stackPtr, 'TooHigh', $data);
        }
    }
}
