class DisallowYodaConditionsSniff

class DisallowYodaConditionsSniff implements Sniff {
    
    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        $tokens = Tokens::$comparisonTokens;
        unset($tokens[T_COALESCE]);
        return $tokens;
    }
    
    //end register()
    
    /**
     * 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, $stackPtr) {
        $tokens = $phpcsFile->getTokens();
        $previousIndex = $phpcsFile->findPrevious(Tokens::$emptyTokens, $stackPtr - 1, null, true);
        $relevantTokens = [
            T_CLOSE_SHORT_ARRAY,
            T_CLOSE_PARENTHESIS,
            T_TRUE,
            T_FALSE,
            T_NULL,
            T_LNUMBER,
            T_DNUMBER,
            T_CONSTANT_ENCAPSED_STRING,
        ];
        if (in_array($tokens[$previousIndex]['code'], $relevantTokens, true) === false) {
            return;
        }
        if ($tokens[$previousIndex]['code'] === T_CLOSE_SHORT_ARRAY) {
            $previousIndex = $tokens[$previousIndex]['bracket_opener'];
            if ($this->isArrayStatic($phpcsFile, $previousIndex) === false) {
                return;
            }
        }
        $prevIndex = $phpcsFile->findPrevious(Tokens::$emptyTokens, $previousIndex - 1, null, true);
        if (in_array($tokens[$prevIndex]['code'], Tokens::$arithmeticTokens, true) === true) {
            return;
        }
        if ($tokens[$prevIndex]['code'] === T_STRING_CONCAT) {
            return;
        }
        // Is it a parenthesis.
        if ($tokens[$previousIndex]['code'] === T_CLOSE_PARENTHESIS) {
            $beforeOpeningParenthesisIndex = $phpcsFile->findPrevious(Tokens::$emptyTokens, $tokens[$previousIndex]['parenthesis_opener'] - 1, null, true);
            if ($beforeOpeningParenthesisIndex === false || $tokens[$beforeOpeningParenthesisIndex]['code'] !== T_ARRAY) {
                if ($tokens[$beforeOpeningParenthesisIndex]['code'] === T_STRING) {
                    return;
                }
                // If it is not an array check what is inside.
                $found = $phpcsFile->findPrevious(T_VARIABLE, $previousIndex - 1, $tokens[$previousIndex]['parenthesis_opener']);
                // If a variable exists, it is not Yoda.
                if ($found !== false) {
                    return;
                }
                // If there is nothing inside the parenthesis, it is not a Yoda condition.
                $opener = $tokens[$previousIndex]['parenthesis_opener'];
                $prev = $phpcsFile->findPrevious(Tokens::$emptyTokens, $previousIndex - 1, $opener + 1, true);
                if ($prev === false) {
                    return;
                }
            }
            else {
                if ($tokens[$beforeOpeningParenthesisIndex]['code'] === T_ARRAY && $this->isArrayStatic($phpcsFile, $beforeOpeningParenthesisIndex) === false) {
                    return;
                }
            }
            
            //end if
        }
        
        //end if
        $phpcsFile->addError('Usage of Yoda conditions is not allowed; switch the expression order', $stackPtr, 'Found');
    }
    
    //end process()
    
    /**
     * Determines if an array is a static definition.
     *
     * @param \PHP_CodeSniffer\Files\File $phpcsFile  The file being scanned.
     * @param int                         $arrayToken The position of the array token.
     *
     * @return bool
     */
    public function isArrayStatic(File $phpcsFile, $arrayToken) {
        $tokens = $phpcsFile->getTokens();
        if ($tokens[$arrayToken]['code'] === T_OPEN_SHORT_ARRAY) {
            $start = $arrayToken;
            $end = $tokens[$arrayToken]['bracket_closer'];
        }
        else {
            if ($tokens[$arrayToken]['code'] === T_ARRAY) {
                $start = $tokens[$arrayToken]['parenthesis_opener'];
                $end = $tokens[$arrayToken]['parenthesis_closer'];
            }
            else {
                // Shouldn't be possible but may happen if external sniffs are using this method.
                return true;
                // @codeCoverageIgnore
            }
        }
        $staticTokens = Tokens::$emptyTokens;
        $staticTokens += Tokens::$textStringTokens;
        $staticTokens += Tokens::$assignmentTokens;
        $staticTokens += Tokens::$equalityTokens;
        $staticTokens += Tokens::$comparisonTokens;
        $staticTokens += Tokens::$arithmeticTokens;
        $staticTokens += Tokens::$operators;
        $staticTokens += Tokens::$booleanOperators;
        $staticTokens += Tokens::$castTokens;
        $staticTokens += Tokens::$bracketTokens;
        $staticTokens += [
            T_DOUBLE_ARROW => T_DOUBLE_ARROW,
            T_COMMA => T_COMMA,
            T_TRUE => T_TRUE,
            T_FALSE => T_FALSE,
        ];
        for ($i = $start + 1; $i < $end; $i++) {
            if (isset($tokens[$i]['scope_closer']) === true) {
                $i = $tokens[$i]['scope_closer'];
                continue;
            }
            if (isset($staticTokens[$tokens[$i]['code']]) === false) {
                return false;
            }
        }
        return true;
    }
    
    //end isArrayStatic()

}