<?php

declare(strict_types=1);

/*
 * This file is part of PHP CS Fixer.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

namespace PhpCsFixer\Fixer\FunctionNotation;

use PhpCsFixer\AbstractPhpdocToTypeDeclarationFixer;
use PhpCsFixer\DocBlock\Annotation;
use PhpCsFixer\Fixer\ExperimentalFixerInterface;
use PhpCsFixer\FixerDefinition\CodeSample;
use PhpCsFixer\FixerDefinition\FixerDefinition;
use PhpCsFixer\FixerDefinition\FixerDefinitionInterface;
use PhpCsFixer\Tokenizer\Token;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Jan Gantzert <jan@familie-gantzert.de>
 */
final class PhpdocToParamTypeFixer extends AbstractPhpdocToTypeDeclarationFixer implements ExperimentalFixerInterface
{
    private const TYPE_CHECK_TEMPLATE = '<?php function f(%s $x) {}';

    /**
     * @var array{int, string}[]
     */
    private const EXCLUDE_FUNC_NAMES = [
        [T_STRING, '__clone'],
        [T_STRING, '__destruct'],
    ];

    /**
     * @var array<string, true>
     */
    private const SKIPPED_TYPES = [
        'resource' => true,
        'static' => true,
        'void' => true,
    ];

    public function getDefinition(): FixerDefinitionInterface
    {
        return new FixerDefinition(
            'Takes `@param` annotations of non-mixed types and adjusts accordingly the function signature. Requires PHP >= 7.0.',
            [
                new CodeSample(
                    '<?php

/**
 * @param string $foo
 * @param string|null $bar
 */
function f($foo, $bar)
{}
'
                ),
                new CodeSample(
                    '<?php

/** @param Foo $foo */
function foo($foo) {}
/** @param string $foo */
function bar($foo) {}
',
                    ['scalar_types' => false]
                ),
                new CodeSample(
                    '<?php

/** @param Foo $foo */
function foo($foo) {}
/** @param int|string $foo */
function bar($foo) {}
',
                    ['union_types' => false]
                ),
            ],
            null,
            'The `@param` annotation is mandatory for the fixer to make changes, signatures of methods without it (no docblock, inheritdocs) will not be fixed. Manual actions are required if inherited signatures are not properly documented.'
        );
    }

    public function isCandidate(Tokens $tokens): bool
    {
        return $tokens->isAnyTokenKindsFound([T_FUNCTION, T_FN]);
    }

    /**
     * {@inheritdoc}
     *
     * Must run before NoSuperfluousPhpdocTagsFixer, PhpdocAlignFixer.
     * Must run after AlignMultilineCommentFixer, CommentToPhpdocFixer, PhpdocIndentFixer, PhpdocScalarFixer, PhpdocToCommentFixer, PhpdocTypesFixer.
     */
    public function getPriority(): int
    {
        return 8;
    }

    protected function isSkippedType(string $type): bool
    {
        return isset(self::SKIPPED_TYPES[$type]);
    }

    protected function applyFix(\SplFileInfo $file, Tokens $tokens): void
    {
        for ($index = $tokens->count() - 1; 0 < $index; --$index) {
            if (!$tokens[$index]->isGivenKind([T_FUNCTION, T_FN])) {
                continue;
            }

            $funcName = $tokens->getNextMeaningfulToken($index);
            if ($tokens[$funcName]->equalsAny(self::EXCLUDE_FUNC_NAMES, false)) {
                continue;
            }

            $docCommentIndex = $this->findFunctionDocComment($tokens, $index);

            if (null === $docCommentIndex) {
                continue;
            }

            foreach ($this->getAnnotationsFromDocComment('param', $tokens, $docCommentIndex) as $paramTypeAnnotation) {
                $typesExpression = $paramTypeAnnotation->getTypeExpression();

                if (null === $typesExpression) {
                    continue;
                }

                $typeInfo = $this->getCommonTypeInfo($typesExpression, false);
                $unionTypes = null;

                if (null === $typeInfo) {
                    $unionTypes = $this->getUnionTypes($typesExpression, false);
                }

                if (null === $typeInfo && null === $unionTypes) {
                    continue;
                }

                if (null !== $typeInfo) {
                    $paramType = $typeInfo['commonType'];
                    $isNullable = $typeInfo['isNullable'];
                } elseif (null !== $unionTypes) {
                    $paramType = $unionTypes;
                    $isNullable = false;
                }

                if (!isset($paramType, $isNullable)) {
                    continue;
                }

                $startIndex = $tokens->getNextTokenOfKind($index, ['(']);
                $variableIndex = $this->findCorrectVariable($tokens, $startIndex, $paramTypeAnnotation);

                if (null === $variableIndex) {
                    continue;
                }

                $byRefIndex = $tokens->getPrevMeaningfulToken($variableIndex);

                if ($tokens[$byRefIndex]->equals('&')) {
                    $variableIndex = $byRefIndex;
                }

                if ($this->hasParamTypeHint($tokens, $variableIndex)) {
                    continue;
                }

                if (!$this->isValidSyntax(sprintf(self::TYPE_CHECK_TEMPLATE, $paramType))) {
                    continue;
                }

                $tokens->insertAt($variableIndex, array_merge(
                    $this->createTypeDeclarationTokens($paramType, $isNullable),
                    [new Token([T_WHITESPACE, ' '])]
                ));
            }
        }
    }

    protected function createTokensFromRawType(string $type): Tokens
    {
        $typeTokens = Tokens::fromCode(sprintf(self::TYPE_CHECK_TEMPLATE, $type));
        $typeTokens->clearRange(0, 4);
        $typeTokens->clearRange(\count($typeTokens) - 6, \count($typeTokens) - 1);
        $typeTokens->clearEmptyTokens();

        return $typeTokens;
    }

    private function findCorrectVariable(Tokens $tokens, int $startIndex, Annotation $paramTypeAnnotation): ?int
    {
        $endIndex = $tokens->findBlockEnd(Tokens::BLOCK_TYPE_PARENTHESIS_BRACE, $startIndex);

        for ($index = $startIndex + 1; $index < $endIndex; ++$index) {
            if (!$tokens[$index]->isGivenKind(T_VARIABLE)) {
                continue;
            }

            $variableName = $tokens[$index]->getContent();

            if ($paramTypeAnnotation->getVariableName() === $variableName) {
                return $index;
            }
        }

        return null;
    }

    /**
     * Determine whether the function already has a param type hint.
     *
     * @param int $index The index of the end of the function definition line, EG at { or ;
     */
    private function hasParamTypeHint(Tokens $tokens, int $index): bool
    {
        $prevIndex = $tokens->getPrevMeaningfulToken($index);

        return !$tokens[$prevIndex]->equalsAny([',', '(']);
    }
}