<?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\Preg;
use PhpCsFixer\Tokenizer\CT;
use PhpCsFixer\Tokenizer\FCT;
use PhpCsFixer\Tokenizer\Token;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Kuba Werłos <werlos@gmail.com>
 *
 * @internal
 */
final class CommentsAnalyzer
{
    private const TYPE_HASH = 1;
    private const TYPE_DOUBLE_SLASH = 2;
    private const TYPE_SLASH_ASTERISK = 3;
    private const SKIP_TYPES = [
        \T_PRIVATE,
        \T_PROTECTED,
        \T_PUBLIC,
        \T_VAR,
        \T_FUNCTION,
        \T_FN,
        \T_ABSTRACT,
        \T_CONST,
        \T_NAMESPACE,
        \T_REQUIRE,
        \T_REQUIRE_ONCE,
        \T_INCLUDE,
        \T_INCLUDE_ONCE,
        \T_FINAL,
        CT::T_CONSTRUCTOR_PROPERTY_PROMOTION_PUBLIC,
        CT::T_CONSTRUCTOR_PROPERTY_PROMOTION_PROTECTED,
        CT::T_CONSTRUCTOR_PROPERTY_PROMOTION_PRIVATE,
        FCT::T_READONLY,
        FCT::T_PUBLIC_SET,
        FCT::T_PROTECTED_SET,
        FCT::T_PRIVATE_SET,
    ];

    public function isHeaderComment(Tokens $tokens, int $index): bool
    {
        if (!$tokens[$index]->isGivenKind([\T_COMMENT, \T_DOC_COMMENT])) {
            throw new \InvalidArgumentException('Given index must point to a comment.');
        }

        if (null === $tokens->getNextMeaningfulToken($index)) {
            return false;
        }

        $prevIndex = $tokens->getPrevNonWhitespace($index);

        if ($tokens[$prevIndex]->equals(';')) {
            $braceCloseIndex = $tokens->getPrevMeaningfulToken($prevIndex);
            if (!$tokens[$braceCloseIndex]->equals(')')) {
                return false;
            }

            $braceOpenIndex = $tokens->findBlockStart(Tokens::BLOCK_TYPE_PARENTHESIS_BRACE, $braceCloseIndex);
            $declareIndex = $tokens->getPrevMeaningfulToken($braceOpenIndex);
            if (!$tokens[$declareIndex]->isGivenKind(\T_DECLARE)) {
                return false;
            }

            $prevIndex = $tokens->getPrevNonWhitespace($declareIndex);
        }

        return $tokens[$prevIndex]->isGivenKind(\T_OPEN_TAG);
    }

    /**
     * Check if comment at given index precedes structural element.
     *
     * @see https://github.com/php-fig/fig-standards/blob/master/proposed/phpdoc.md#3-definitions
     */
    public function isBeforeStructuralElement(Tokens $tokens, int $index): bool
    {
        $token = $tokens[$index];

        if (!$token->isGivenKind([\T_COMMENT, \T_DOC_COMMENT])) {
            throw new \InvalidArgumentException('Given index must point to a comment.');
        }

        $nextIndex = $this->getNextTokenIndex($tokens, $index);

        if (null === $nextIndex || $tokens[$nextIndex]->equals('}')) {
            return false;
        }

        if ($this->isStructuralElement($tokens, $nextIndex)) {
            return true;
        }

        if ($this->isValidControl($tokens, $token, $nextIndex)) {
            return true;
        }

        if ($this->isValidVariable($tokens, $nextIndex)) {
            return true;
        }

        if ($this->isValidVariableAssignment($tokens, $token, $nextIndex)) {
            return true;
        }

        if ($tokens[$nextIndex]->isGivenKind(CT::T_USE_TRAIT)) {
            return true;
        }

        return false;
    }

    /**
     * Check if comment at given index precedes return statement.
     */
    public function isBeforeReturn(Tokens $tokens, int $index): bool
    {
        if (!$tokens[$index]->isGivenKind([\T_COMMENT, \T_DOC_COMMENT])) {
            throw new \InvalidArgumentException('Given index must point to a comment.');
        }

        $nextIndex = $this->getNextTokenIndex($tokens, $index);

        if (null === $nextIndex || $tokens[$nextIndex]->equals('}')) {
            return false;
        }

        return $tokens[$nextIndex]->isGivenKind(\T_RETURN);
    }

    /**
     * Return array of indices that are part of a comment started at given index.
     *
     * @param int $index T_COMMENT index
     *
     * @return non-empty-list<int>
     */
    public function getCommentBlockIndices(Tokens $tokens, int $index): array
    {
        if (!$tokens[$index]->isGivenKind(\T_COMMENT)) {
            throw new \InvalidArgumentException('Given index must point to a comment.');
        }

        $commentType = $this->getCommentType($tokens[$index]->getContent());
        $indices = [$index];

        if (self::TYPE_SLASH_ASTERISK === $commentType) {
            return $indices;
        }

        $count = \count($tokens);
        ++$index;

        for (; $index < $count; ++$index) {
            if ($tokens[$index]->isComment()) {
                if ($commentType === $this->getCommentType($tokens[$index]->getContent())) {
                    $indices[] = $index;

                    continue;
                }

                break;
            }

            if (!$tokens[$index]->isWhitespace() || $this->getLineBreakCount($tokens, $index, $index + 1) > 1) {
                break;
            }
        }

        return $indices;
    }

    /**
     * @see https://github.com/phpDocumentor/fig-standards/blob/master/proposed/phpdoc.md#3-definitions
     */
    private function isStructuralElement(Tokens $tokens, int $index): bool
    {
        $token = $tokens[$index];

        if ($token->isClassy() || $token->isGivenKind(self::SKIP_TYPES)) {
            return true;
        }

        if ($token->isGivenKind(\T_CASE)) {
            $enumParent = $tokens->getPrevTokenOfKind($index, [[FCT::T_ENUM], [\T_SWITCH]]);

            return $tokens[$enumParent]->isGivenKind(FCT::T_ENUM);
        }

        if ($token->isGivenKind(\T_STATIC)) {
            return !$tokens[$tokens->getNextMeaningfulToken($index)]->isGivenKind(\T_DOUBLE_COLON);
        }

        return false;
    }

    /**
     * Checks control structures (for, foreach, if, switch, while) for correct docblock usage.
     *
     * @param Token $docsToken    docs Token
     * @param int   $controlIndex index of control structure Token
     */
    private function isValidControl(Tokens $tokens, Token $docsToken, int $controlIndex): bool
    {
        if (!$tokens[$controlIndex]->isGivenKind([
            \T_FOR,
            \T_FOREACH,
            \T_IF,
            \T_SWITCH,
            \T_WHILE,
        ])) {
            return false;
        }

        $openParenthesisIndex = $tokens->getNextMeaningfulToken($controlIndex);
        $closeParenthesisIndex = $tokens->findBlockEnd(Tokens::BLOCK_TYPE_PARENTHESIS_BRACE, $openParenthesisIndex);
        $docsContent = $docsToken->getContent();

        for ($index = $openParenthesisIndex + 1; $index < $closeParenthesisIndex; ++$index) {
            $token = $tokens[$index];

            if (
                $token->isGivenKind(\T_VARIABLE)
                && str_contains($docsContent, $token->getContent())
            ) {
                return true;
            }
        }

        return false;
    }

    /**
     * Checks variable assignments through `list()`, `print()` etc. calls for correct docblock usage.
     *
     * @param Token $docsToken              docs Token
     * @param int   $languageConstructIndex index of variable Token
     */
    private function isValidVariableAssignment(Tokens $tokens, Token $docsToken, int $languageConstructIndex): bool
    {
        if (!$tokens[$languageConstructIndex]->isGivenKind([
            \T_LIST,
            \T_PRINT,
            \T_ECHO,
            CT::T_DESTRUCTURING_SQUARE_BRACE_OPEN,
        ])) {
            return false;
        }

        $endKind = $tokens[$languageConstructIndex]->isGivenKind(CT::T_DESTRUCTURING_SQUARE_BRACE_OPEN)
            ? [CT::T_DESTRUCTURING_SQUARE_BRACE_CLOSE]
            : ')';

        $endIndex = $tokens->getNextTokenOfKind($languageConstructIndex, [$endKind]);

        $docsContent = $docsToken->getContent();

        for ($index = $languageConstructIndex + 1; $index < $endIndex; ++$index) {
            $token = $tokens[$index];

            if ($token->isGivenKind(\T_VARIABLE) && str_contains($docsContent, $token->getContent())) {
                return true;
            }
        }

        return false;
    }

    /**
     * Checks variable assignments for correct docblock usage.
     *
     * @param int $index index of variable Token
     */
    private function isValidVariable(Tokens $tokens, int $index): bool
    {
        if (!$tokens[$index]->isGivenKind(\T_VARIABLE)) {
            return false;
        }

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

        return $tokens[$nextIndex]->equalsAny([
            '=',
            // arithmetic assignments
            [\T_PLUS_EQUAL, '+='],
            [\T_MINUS_EQUAL, '-='],
            [\T_MUL_EQUAL, '*='],
            [\T_DIV_EQUAL, '/='],
            [\T_MOD_EQUAL, '%='],
            [\T_POW_EQUAL, '**='],
            // bitwise assignments
            [\T_AND_EQUAL, '&='],
            [\T_OR_EQUAL, '|='],
            [\T_XOR_EQUAL, '^='],
            [\T_SL_EQUAL, '<<='],
            [\T_SR_EQUAL, '>>='],
            // other assignments
            [\T_COALESCE_EQUAL, '??='],
            [\T_CONCAT_EQUAL, '.='],
        ]);
    }

    private function getCommentType(string $content): int
    {
        if (str_starts_with($content, '#')) {
            return self::TYPE_HASH;
        }

        if ('*' === $content[1]) {
            return self::TYPE_SLASH_ASTERISK;
        }

        return self::TYPE_DOUBLE_SLASH;
    }

    private function getLineBreakCount(Tokens $tokens, int $whiteStart, int $whiteEnd): int
    {
        $lineCount = 0;
        for ($i = $whiteStart; $i < $whiteEnd; ++$i) {
            $lineCount += Preg::matchAll('/\R/u', $tokens[$i]->getContent());
        }

        return $lineCount;
    }

    private function getNextTokenIndex(Tokens $tokens, int $startIndex): ?int
    {
        $nextIndex = $startIndex;

        do {
            $nextIndex = $tokens->getNextMeaningfulToken($nextIndex);

            while (null !== $nextIndex && $tokens[$nextIndex]->isGivenKind(FCT::T_ATTRIBUTE)) {
                $nextIndex = $tokens->findBlockEnd(Tokens::BLOCK_TYPE_ATTRIBUTE, $nextIndex);
                $nextIndex = $tokens->getNextMeaningfulToken($nextIndex);
            }
        } while (null !== $nextIndex && $tokens[$nextIndex]->equals('('));

        return $nextIndex;
    }
}
