<?php

/*
 * 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\Token;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Kuba Werłos <werlos@gmail.com>
 * @author SpacePossum
 *
 * @internal
 */
final class CommentsAnalyzer
{
    const TYPE_HASH = 1;
    const TYPE_DOUBLE_SLASH = 2;
    const TYPE_SLASH_ASTERISK = 3;

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

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

        return $tokens[$prevIndex]->isGivenKind(T_OPEN_TAG) && null !== $tokens->getNextMeaningfulToken($index);
    }

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

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

        $nextIndex = $index;
        do {
            $nextIndex = $tokens->getNextMeaningfulToken($nextIndex);
        } while (null !== $nextIndex && $tokens[$nextIndex]->equals('('));

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

        $nextToken = $tokens[$nextIndex];

        if ($this->isStructuralElement($nextToken)) {
            return true;
        }

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

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

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

        return false;
    }

    /**
     * Return array of indices that are part of a comment started at given index.
     *
     * @param Tokens $tokens
     * @param int    $index  T_COMMENT index
     *
     * @return null|array
     */
    public function getCommentBlockIndices(Tokens $tokens, $index)
    {
        if (!$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
     *
     * @param Token $token
     *
     * @return bool
     */
    private function isStructuralElement(Token $token)
    {
        static $skip = [
            T_PRIVATE,
            T_PROTECTED,
            T_PUBLIC,
            T_VAR,
            T_FUNCTION,
            T_ABSTRACT,
            T_CONST,
            T_NAMESPACE,
            T_REQUIRE,
            T_REQUIRE_ONCE,
            T_INCLUDE,
            T_INCLUDE_ONCE,
            T_FINAL,
            T_STATIC,
        ];

        return $token->isClassy() || $token->isGivenKind($skip);
    }

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

        if (!$tokens[$controlIndex]->isGivenKind($controlStructures)) {
            return false;
        }

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

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

            if (
                $token->isGivenKind(T_VARIABLE) &&
                false !== strpos($docsContent, $token->getContent())
            ) {
                return true;
            }
        }

        return false;
    }

    /**
     * Checks variable assignments through `list()`, `print()` etc. calls for correct docblock usage.
     *
     * @param Tokens $tokens
     * @param Token  $docsToken              docs Token
     * @param int    $languageConstructIndex index of variable Token
     *
     * @return bool
     */
    private function isValidLanguageConstruct(Tokens $tokens, Token $docsToken, $languageConstructIndex)
    {
        static $languageStructures = [
            T_LIST,
            T_PRINT,
            T_ECHO,
            CT::T_DESTRUCTURING_SQUARE_BRACE_OPEN,
        ];

        if (!$tokens[$languageConstructIndex]->isGivenKind($languageStructures)) {
            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 ($token->isGivenKind(T_VARIABLE) && false !== strpos($docsContent, $token->getContent())) {
                return true;
            }
        }

        return false;
    }

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

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

        return $tokens[$nextIndex]->equals('=');
    }

    /**
     * @param string $content
     *
     * @return int
     */
    private function getCommentType($content)
    {
        if ('#' === $content[0]) {
            return self::TYPE_HASH;
        }

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

        return self::TYPE_DOUBLE_SLASH;
    }

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

        return $lineCount;
    }
}