<?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\Fixer\ExperimentalFixerInterface;
use PhpCsFixer\FixerDefinition\CodeSample;
use PhpCsFixer\FixerDefinition\FixerDefinition;
use PhpCsFixer\FixerDefinition\FixerDefinitionInterface;
use PhpCsFixer\FixerDefinition\VersionSpecification;
use PhpCsFixer\FixerDefinition\VersionSpecificCodeSample;
use PhpCsFixer\Tokenizer\CT;
use PhpCsFixer\Tokenizer\Token;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Filippo Tessarotto <zoeslam@gmail.com>
 */
final class PhpdocToReturnTypeFixer extends AbstractPhpdocToTypeDeclarationFixer implements ExperimentalFixerInterface
{
    private const TYPE_CHECK_TEMPLATE = '<?php function f(): %s {}';

    /**
     * @var array<int, array<int, int|string>>
     */
    private array $excludeFuncNames = [
        [T_STRING, '__construct'],
        [T_STRING, '__destruct'],
        [T_STRING, '__clone'],
    ];

    /**
     * @var array<string, true>
     */
    private array $skippedTypes = [
        'resource' => true,
        'null' => true,
    ];

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

/** @return \My\Bar */
function f1()
{}

/** @return void */
function f2()
{}

/** @return object */
function my_foo()
{}
',
                ),
                new CodeSample(
                    '<?php

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

/** @return Foo */
function foo() {}
/** @return int|string */
function bar() {}
',
                    ['union_types' => false]
                ),
                new VersionSpecificCodeSample(
                    '<?php
final class Foo {
    /**
     * @return static
     */
    public function create($prototype) {
        return new static($prototype);
    }
}
',
                    new VersionSpecification(8_00_00)
                ),
            ],
            null,
            'The `@return` 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 FullyQualifiedStrictTypesFixer, NoSuperfluousPhpdocTagsFixer, PhpdocAlignFixer, ReturnToYieldFromFixer, ReturnTypeDeclarationFixer.
     * Must run after AlignMultilineCommentFixer, CommentToPhpdocFixer, PhpdocIndentFixer, PhpdocScalarFixer, PhpdocToCommentFixer, PhpdocTypesFixer.
     */
    public function getPriority(): int
    {
        return 13;
    }

    protected function isSkippedType(string $type): bool
    {
        return isset($this->skippedTypes[$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($this->excludeFuncNames, false)) {
                continue;
            }

            $docCommentIndex = $this->findFunctionDocComment($tokens, $index);
            if (null === $docCommentIndex) {
                continue;
            }

            $returnTypeAnnotations = $this->getAnnotationsFromDocComment('return', $tokens, $docCommentIndex);
            if (1 !== \count($returnTypeAnnotations)) {
                continue;
            }

            $returnTypeAnnotation = $returnTypeAnnotations[0];

            $typesExpression = $returnTypeAnnotation->getTypeExpression();

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

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

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

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

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

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

            $paramsStartIndex = $tokens->getNextTokenOfKind($index, ['(']);
            $paramsEndIndex = $tokens->findBlockEnd(Tokens::BLOCK_TYPE_PARENTHESIS_BRACE, $paramsStartIndex);

            $bodyStartIndex = $tokens->getNextTokenOfKind($paramsEndIndex, ['{', ';', [T_DOUBLE_ARROW]]);

            if ($this->hasReturnTypeHint($tokens, $bodyStartIndex)) {
                continue;
            }

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

            $tokens->insertAt(
                $paramsEndIndex + 1,
                array_merge(
                    [
                        new Token([CT::T_TYPE_COLON, ':']),
                        new Token([T_WHITESPACE, ' ']),
                    ],
                    $this->createTypeDeclarationTokens($returnType, $isNullable)
                )
            );
        }
    }

    protected function createTokensFromRawType(string $type): Tokens
    {
        $typeTokens = Tokens::fromCode(sprintf(self::TYPE_CHECK_TEMPLATE, $type));
        $typeTokens->clearRange(0, 7);
        $typeTokens->clearRange(\count($typeTokens) - 3, \count($typeTokens) - 1);
        $typeTokens->clearEmptyTokens();

        return $typeTokens;
    }

    /**
     * Determine whether the function already has a return type hint.
     *
     * @param int $index The index of the end of the function definition line, EG at { or ;
     */
    private function hasReturnTypeHint(Tokens $tokens, int $index): bool
    {
        $endFuncIndex = $tokens->getPrevTokenOfKind($index, [')']);
        $nextIndex = $tokens->getNextMeaningfulToken($endFuncIndex);

        return $tokens[$nextIndex]->isGivenKind(CT::T_TYPE_COLON);
    }
}
