<?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\Tokenizer\Analyzer;

use PhpCsFixer\Tokenizer\Analyzer\Analysis\NamespaceAnalysis;
use PhpCsFixer\Tokenizer\Analyzer\Analysis\NamespaceUseAnalysis;
use PhpCsFixer\Tokenizer\CT;
use PhpCsFixer\Tokenizer\Tokens;
use PhpCsFixer\Tokenizer\TokensAnalyzer;

/**
 * @author VeeWee <toonverwerft@gmail.com>
 * @author Greg Korba <greg@codito.dev>
 *
 * @internal
 *
 * @TODO Drop `allowMultiUses` opt-in flag when all fixers are updated and can handle multi-use statements.
 */
final class NamespaceUsesAnalyzer
{
    /**
     * @return list<NamespaceUseAnalysis>
     */
    public function getDeclarationsFromTokens(Tokens $tokens, bool $allowMultiUses = false): array
    {
        $tokenAnalyzer = new TokensAnalyzer($tokens);
        $useIndices = $tokenAnalyzer->getImportUseIndexes();

        return $this->getDeclarations($tokens, $useIndices, $allowMultiUses);
    }

    /**
     * @return list<NamespaceUseAnalysis>
     */
    public function getDeclarationsInNamespace(Tokens $tokens, NamespaceAnalysis $namespace, bool $allowMultiUses = false): array
    {
        $namespaceUses = [];

        foreach ($this->getDeclarationsFromTokens($tokens, $allowMultiUses) as $namespaceUse) {
            if ($namespaceUse->getStartIndex() >= $namespace->getScopeStartIndex() && $namespaceUse->getStartIndex() <= $namespace->getScopeEndIndex()) {
                $namespaceUses[] = $namespaceUse;
            }
        }

        return $namespaceUses;
    }

    /**
     * @param list<int> $useIndices
     *
     * @return list<NamespaceUseAnalysis>
     */
    private function getDeclarations(Tokens $tokens, array $useIndices, bool $allowMultiUses = false): array
    {
        $uses = [];

        foreach ($useIndices as $index) {
            $endIndex = $tokens->getNextTokenOfKind($index, [';', [T_CLOSE_TAG]]);

            $declarations = $this->parseDeclarations($index, $endIndex, $tokens);
            if (false === $allowMultiUses) {
                $declarations = array_filter($declarations, static fn (NamespaceUseAnalysis $declaration) => !$declaration->isInMulti());
            }

            if ([] !== $declarations) {
                $uses = array_merge($uses, $declarations);
            }
        }

        return $uses;
    }

    /**
     * @return list<NamespaceUseAnalysis>
     */
    private function parseDeclarations(int $startIndex, int $endIndex, Tokens $tokens): array
    {
        $type = $this->determineImportType($tokens, $startIndex);
        $potentialMulti = $tokens->getNextTokenOfKind($startIndex, [',', [CT::T_GROUP_IMPORT_BRACE_OPEN]]);
        $multi = null !== $potentialMulti && $potentialMulti < $endIndex;
        $index = $tokens->getNextTokenOfKind($startIndex, [[T_STRING], [T_NS_SEPARATOR]]);
        $imports = [];

        while (null !== $index && $index <= $endIndex) {
            $qualifiedName = $this->getNearestQualifiedName($tokens, $index);
            $token = $tokens[$qualifiedName['afterIndex']];

            if ($token->isGivenKind(CT::T_GROUP_IMPORT_BRACE_OPEN)) {
                $groupStart = $groupIndex = $qualifiedName['afterIndex'];
                $groupEnd = $tokens->findBlockEnd(Tokens::BLOCK_TYPE_GROUP_IMPORT_BRACE, $groupStart);

                while ($groupIndex < $groupEnd) {
                    $chunkStart = $tokens->getNextMeaningfulToken($groupIndex);

                    // Finish parsing on trailing comma (no more chunks there)
                    if ($tokens[$chunkStart]->isGivenKind(CT::T_GROUP_IMPORT_BRACE_CLOSE)) {
                        break;
                    }

                    $groupQualifiedName = $this->getNearestQualifiedName($tokens, $chunkStart);
                    $imports[] = new NamespaceUseAnalysis(
                        $type,
                        $qualifiedName['fullName'].$groupQualifiedName['fullName'],
                        $groupQualifiedName['shortName'],
                        $groupQualifiedName['aliased'],
                        true,
                        $startIndex,
                        $endIndex,
                        $chunkStart,
                        $tokens->getPrevMeaningfulToken($groupQualifiedName['afterIndex'])
                    );

                    $groupIndex = $groupQualifiedName['afterIndex'];
                }

                $index = $groupIndex;
            } elseif ($token->equalsAny([',', ';', [T_CLOSE_TAG]])) {
                $previousToken = $tokens->getPrevMeaningfulToken($qualifiedName['afterIndex']);

                if (!$tokens[$previousToken]->isGivenKind(CT::T_GROUP_IMPORT_BRACE_CLOSE)) {
                    $imports[] = new NamespaceUseAnalysis(
                        $type,
                        $qualifiedName['fullName'],
                        $qualifiedName['shortName'],
                        $qualifiedName['aliased'],
                        $multi,
                        $startIndex,
                        $endIndex,
                        $multi ? $index : null,
                        $multi ? $previousToken : null
                    );
                }

                $index = $qualifiedName['afterIndex'];
            }

            $index = $tokens->getNextMeaningfulToken($index);
        }

        return $imports;
    }

    /**
     * @return NamespaceUseAnalysis::TYPE_*
     */
    private function determineImportType(Tokens $tokens, int $startIndex): int
    {
        $potentialType = $tokens[$tokens->getNextMeaningfulToken($startIndex)];

        if ($potentialType->isGivenKind(CT::T_FUNCTION_IMPORT)) {
            return NamespaceUseAnalysis::TYPE_FUNCTION;
        }

        if ($potentialType->isGivenKind(CT::T_CONST_IMPORT)) {
            return NamespaceUseAnalysis::TYPE_CONSTANT;
        }

        return NamespaceUseAnalysis::TYPE_CLASS;
    }

    /**
     * @return array{fullName: string, shortName: string, aliased: bool, afterIndex: int}
     */
    private function getNearestQualifiedName(Tokens $tokens, int $index): array
    {
        $fullName = $shortName = '';
        $aliased = false;

        while (null !== $index) {
            $token = $tokens[$index];

            if ($token->isGivenKind(T_STRING)) {
                $shortName = $token->getContent();
                if (!$aliased) {
                    $fullName .= $shortName;
                }
            } elseif ($token->isGivenKind(T_NS_SEPARATOR)) {
                $fullName .= $token->getContent();
            } elseif ($token->isGivenKind(T_AS)) {
                $aliased = true;
            } elseif ($token->equalsAny([
                ',',
                ';',
                [CT::T_GROUP_IMPORT_BRACE_OPEN],
                [CT::T_GROUP_IMPORT_BRACE_CLOSE],
                [T_CLOSE_TAG],
            ])) {
                break;
            }

            $index = $tokens->getNextMeaningfulToken($index);
        }

        return [
            'fullName' => $fullName,
            'shortName' => $shortName,
            'aliased' => $aliased,
            'afterIndex' => $index,
        ];
    }
}