<?php
/**
 * Checks for unused function parameters.
 *
 * This sniff checks that all function parameters are used in the function body.
 * One exception is made for empty function bodies or function bodies that only
 * contain comments. This could be useful for the classes that implement an
 * interface that defines multiple methods but the implementation only needs some
 * of them.
 *
 * @author    Manuel Pichler <mapi@manuel-pichler.de>
 * @author    Greg Sherwood <gsherwood@squiz.net>
 * @copyright 2007-2014 Manuel Pichler. All rights reserved.
 * @copyright 2023 PHPCSStandards and contributors
 * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/HEAD/licence.txt BSD Licence
 */

namespace PHP_CodeSniffer\Standards\Generic\Sniffs\CodeAnalysis;

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

class UnusedFunctionParameterSniff implements Sniff
{

    /**
     * A list of all PHP magic methods with fixed method signatures.
     *
     * Note: `__construct()` and `__invoke()` are excluded on purpose
     * as their method signature is not fixed.
     *
     * @var array<string, true>
     */
    private const MAGIC_METHODS = [
        '__destruct'    => true,
        '__call'        => true,
        '__callstatic'  => true,
        '__get'         => true,
        '__set'         => true,
        '__isset'       => true,
        '__unset'       => true,
        '__sleep'       => true,
        '__wakeup'      => true,
        '__serialize'   => true,
        '__unserialize' => true,
        '__tostring'    => true,
        '__set_state'   => true,
        '__clone'       => true,
        '__debuginfo'   => true,
    ];

    /**
     * The list of class type hints which will be ignored.
     *
     * @var array
     */
    public $ignoreTypeHints = [];


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


    /**
     * 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();
        $token  = $tokens[$stackPtr];

        // Skip broken function declarations.
        if (isset($token['scope_opener']) === false || isset($token['parenthesis_opener']) === false) {
            return;
        }

        $errorCode  = 'Found';
        $implements = false;

        if ($token['code'] === T_FUNCTION) {
            $classPtr = $phpcsFile->getCondition($stackPtr, T_CLASS);
            if ($classPtr !== false) {
                // Check for magic methods and ignore these as the method signature cannot be changed.
                $methodName   = $phpcsFile->getDeclarationName($stackPtr);
                $methodNameLc = strtolower($methodName);
                if (isset(self::MAGIC_METHODS[$methodNameLc]) === true) {
                    return;
                }

                // Check for extends/implements and adjust the error code when found.
                $implements = $phpcsFile->findImplementedInterfaceNames($classPtr);
                $extends    = $phpcsFile->findExtendedClassName($classPtr);
                if ($extends !== false) {
                    $errorCode .= 'InExtendedClass';
                } elseif ($implements !== false) {
                    $errorCode .= 'InImplementedInterface';
                }
            }
        }

        $params       = [];
        $methodParams = $phpcsFile->getMethodParameters($stackPtr);

        // Skip when no parameters found.
        $methodParamsCount = count($methodParams);
        if ($methodParamsCount === 0) {
            return;
        }

        foreach ($methodParams as $param) {
            if (isset($param['property_visibility']) === true) {
                // Ignore constructor property promotion.
                continue;
            }

            $params[$param['name']] = $stackPtr;
        }

        $next = ++$token['scope_opener'];
        $end  = --$token['scope_closer'];

        // Check the end token for arrow functions as
        // they can end at a content token due to not having
        // a clearly defined closing token.
        if ($token['code'] === T_FN) {
            ++$end;
        }

        $foundContent = false;
        $validTokens  = [
            T_HEREDOC              => T_HEREDOC,
            T_NOWDOC               => T_NOWDOC,
            T_END_HEREDOC          => T_END_HEREDOC,
            T_END_NOWDOC           => T_END_NOWDOC,
            T_DOUBLE_QUOTED_STRING => T_DOUBLE_QUOTED_STRING,
        ];
        $validTokens += Tokens::EMPTY_TOKENS;

        for (; $next <= $end; ++$next) {
            $token = $tokens[$next];
            $code  = $token['code'];

            // Ignorable tokens.
            if (isset(Tokens::EMPTY_TOKENS[$code]) === true) {
                continue;
            }

            if ($foundContent === false) {
                // A throw statement as the first content indicates an interface method.
                if ($code === T_THROW && $implements !== false) {
                    return;
                }

                // A return statement as the first content indicates an interface method.
                if ($code === T_RETURN) {
                    $firstNonEmptyTokenAfterReturn = $phpcsFile->findNext(Tokens::EMPTY_TOKENS, ($next + 1), null, true);
                    if ($tokens[$firstNonEmptyTokenAfterReturn]['code'] === T_SEMICOLON && $implements !== false) {
                        return;
                    }

                    $secondNonEmptyTokenAfterReturn = $phpcsFile->findNext(
                        Tokens::EMPTY_TOKENS,
                        ($firstNonEmptyTokenAfterReturn + 1),
                        null,
                        true
                    );

                    if ($secondNonEmptyTokenAfterReturn !== false
                        && $tokens[$secondNonEmptyTokenAfterReturn]['code'] === T_SEMICOLON
                        && $implements !== false
                    ) {
                        // There is a return <token>.
                        return;
                    }
                }
            }

            $foundContent = true;

            if ($code === T_VARIABLE && isset($params[$token['content']]) === true) {
                unset($params[$token['content']]);
            } elseif ($code === T_DOLLAR) {
                $nextToken = $phpcsFile->findNext(T_WHITESPACE, ($next + 1), null, true);
                if ($tokens[$nextToken]['code'] === T_OPEN_CURLY_BRACKET) {
                    $nextToken = $phpcsFile->findNext(T_WHITESPACE, ($nextToken + 1), null, true);
                    if ($tokens[$nextToken]['code'] === T_STRING) {
                        $varContent = '$' . $tokens[$nextToken]['content'];
                        if (isset($params[$varContent]) === true) {
                            unset($params[$varContent]);
                        }
                    }
                }
            } elseif ($code === T_DOUBLE_QUOTED_STRING
                || $code === T_START_HEREDOC
                || $code === T_START_NOWDOC
            ) {
                // Tokenize strings that can contain variables.
                // Make sure the string is re-joined if it occurs over multiple lines.
                $content = $token['content'];
                for ($i = ($next + 1); $i <= $end; $i++) {
                    if (isset($validTokens[$tokens[$i]['code']]) === true) {
                        $content .= $tokens[$i]['content'];
                        $next++;
                    } else {
                        break;
                    }
                }

                $stringTokens = token_get_all(sprintf('<?php %s;?>', $content));
                foreach ($stringTokens as $stringPtr => $stringToken) {
                    if (is_array($stringToken) === false) {
                        continue;
                    }

                    $varContent = '';
                    if ($stringToken[0] === T_DOLLAR_OPEN_CURLY_BRACES) {
                        $varContent = '$' . $stringTokens[($stringPtr + 1)][1];
                    } elseif ($stringToken[0] === T_VARIABLE) {
                        $varContent = $stringToken[1];
                    }

                    if ($varContent !== '' && isset($params[$varContent]) === true) {
                        unset($params[$varContent]);
                    }
                }
            }
        }

        if ($foundContent === true && count($params) > 0) {
            $error = 'The method parameter %s is never used';

            // If there is only one parameter and it is unused, no need for additional errorcode toggling logic.
            if ($methodParamsCount === 1) {
                foreach ($params as $paramName => $position) {
                    if (in_array($methodParams[0]['type_hint'], $this->ignoreTypeHints, true) === true) {
                        continue;
                    }

                    $data = [$paramName];
                    $phpcsFile->addWarning($error, $position, $errorCode, $data);
                }

                return;
            }

            $foundLastUsed = false;
            $lastIndex     = ($methodParamsCount - 1);
            $errorInfo     = [];
            for ($i = $lastIndex; $i >= 0; --$i) {
                if ($foundLastUsed !== false) {
                    if (isset($params[$methodParams[$i]['name']]) === true) {
                        $errorInfo[$methodParams[$i]['name']] = [
                            'position'  => $params[$methodParams[$i]['name']],
                            'errorcode' => $errorCode . 'BeforeLastUsed',
                            'typehint'  => $methodParams[$i]['type_hint'],
                        ];
                    }
                } else {
                    if (isset($params[$methodParams[$i]['name']]) === false) {
                        $foundLastUsed = true;
                    } else {
                        $errorInfo[$methodParams[$i]['name']] = [
                            'position'  => $params[$methodParams[$i]['name']],
                            'errorcode' => $errorCode . 'AfterLastUsed',
                            'typehint'  => $methodParams[$i]['type_hint'],
                        ];
                    }
                }
            }

            if (count($errorInfo) > 0) {
                $errorInfo = array_reverse($errorInfo);
                foreach ($errorInfo as $paramName => $info) {
                    if (in_array($info['typehint'], $this->ignoreTypeHints, true) === true) {
                        continue;
                    }

                    $data = [$paramName];
                    $phpcsFile->addWarning($error, $info['position'], $info['errorcode'], $data);
                }
            }
        }
    }
}
