<?php
namespace Psalm\Checker;

use Psalm\Context;
use Psalm\Exception\TypeParseTreeException;
use Psalm\Exception\DocblockParseException;
use Psalm\FunctionDocblockComment;
use Psalm\StatementsSource;
use Psalm\Type;

class CommentChecker
{
    const TYPE_REGEX =
        '(\\\?[A-Za-z0-9_\<,\>\[\]\-\{\}:|\\\]+[A-Za-z0-9_\<,\>\[\]-\{\}:]|\$[a-zA-Z_0-9_\<,\>\|\[\]-\{\}:]+)';

    /**
     * @param  string           $comment
     * @param  Context|null     $context
     * @param  StatementsSource $source
     * @param  string           $var_id
     * @return Type\Union|null
     * @throws DocblockParseException If there was a problem parsing the docblock.
     * @psalm-suppress MixedArrayAccess
     */
    public static function getTypeFromComment(
        $comment,
        Context $context = null,
        StatementsSource $source,
        $var_id = null
    ) {
        $type_in_comments_var_id = null;

        $type_in_comments = null;

        $comments = self::parseDocComment($comment);

        if ($comments && isset($comments['specials']['var'][0]) && trim((string)$comments['specials']['var'][0])) {
            try {
                $line_parts = self::splitDocLine(trim((string)$comments['specials']['var'][0]));
            } catch (DocblockParseException $e) {
                throw $e;
            }

            if ($line_parts && $line_parts[0]) {
                $type_in_comments = FunctionLikeChecker::fixUpLocalType(
                    $line_parts[0],
                    $source->getFQCLN(),
                    $source->getNamespace(),
                    $source->getAliasedClasses()
                );

                // support PHPStorm-style docblocks like
                // @var Type $variable
                if (count($line_parts) > 1 && $line_parts[1][0] === '$') {
                    $type_in_comments_var_id = $line_parts[1];
                }
            }
        }

        if (!$type_in_comments) {
            return null;
        }

        try {
            $defined_type = Type::parseString($type_in_comments);
        } catch (TypeParseTreeException $e) {
            throw new DocblockParseException($type_in_comments . ' is not a valid type');
        }

        if ($context && $type_in_comments_var_id && $type_in_comments_var_id !== $var_id) {
            $context->vars_in_scope[$type_in_comments_var_id] = $defined_type;

            return null;
        }

        return $defined_type;
    }

    /**
     * @param  string  $comment
     * @param  int     $line_number
     * @return FunctionDocblockComment
     * @throws DocblockParseException If there was a problem parsing the docblock.
     * @psalm-suppress MixedArrayAccess
     */
    public static function extractDocblockInfo($comment, $line_number)
    {
        $comments = self::parseDocComment($comment, $line_number);

        $info = new FunctionDocblockComment();

        if (isset($comments['specials']['return']) || isset($comments['specials']['psalm-return'])) {
            /** @var array<int, string> */
            $return_specials = isset($comments['specials']['psalm-return'])
                ? $comments['specials']['psalm-return']
                : $comments['specials']['return'];

            $return_block = trim((string)reset($return_specials));

            try {
                $line_parts = self::splitDocLine($return_block);
            } catch (DocblockParseException $e) {
                throw $e;
            }

            if (preg_match('/^' . self::TYPE_REGEX . '$/', $line_parts[0])
                && !preg_match('/\[[^\]]+\]/', $line_parts[0])
                && !strpos($line_parts[0], '::')
            ) {
                $info->return_type = $line_parts[0];
                $info->return_type_line_number = array_keys($return_specials)[0];
            }
        }

        if (isset($comments['specials']['param'])) {
            /** @var string $param */
            foreach ($comments['specials']['param'] as $line_number => $param) {
                try {
                    $line_parts = self::splitDocLine($param);
                } catch (DocblockParseException $e) {
                    throw $e;
                }

                if (count($line_parts) > 1) {
                    if (preg_match('/^' . self::TYPE_REGEX . '$/', $line_parts[0])
                        && !preg_match('/\[[^\]]+\]/', $line_parts[0])
                        && preg_match('/^&?\$[A-Za-z0-9_]+$/', $line_parts[1])
                        && !strpos($line_parts[0], '::')
                    ) {
                        if ($line_parts[1][0] === '&') {
                            $line_parts[1] = substr($line_parts[1], 1);
                        }

                        $info->params[] = [
                            'name' => substr($line_parts[1], 1),
                            'type' => $line_parts[0],
                            'line_number' => $line_number
                        ];
                    }
                } else {
                    throw new DocblockParseException('Badly-formatted @param');
                }
            }
        }

        if (isset($comments['specials']['deprecated'])) {
            $info->deprecated = true;
        }

        if (isset($comments['specials']['psalm-suppress'])) {
            /** @var string $suppress_entry */
            foreach ($comments['specials']['psalm-suppress'] as $suppress_entry) {
                $info->suppress[] = preg_split('/[\s]+/', $suppress_entry)[0];
            }
        }

        $info->variadic = isset($comments['specials']['psalm-variadic']);

        return $info;
    }

    /**
     * @param  string $return_block
     * @return array<string>
     * @throws DocblockParseException If an invalid string is found.
     */
    protected static function splitDocLine($return_block)
    {
        $brackets = '';

        $type = '';

        for ($i = 0; $i < strlen($return_block); $i++) {
            $char = $return_block[$i];

            if ($char === '[' || $char === '{' || $char === '(' || $char === '<') {
                $brackets .= $char;
            } elseif ($char === ']' || $char === '}' || $char === ')' || $char === '>') {
                $last_bracket = substr($brackets, -1);
                $brackets = substr($brackets, 0, -1);

                if (($char === ']' && $last_bracket !== '[')
                    || ($char === '}' && $last_bracket !== '{')
                    || ($char === ')' && $last_bracket !== '(')
                    || ($char === '>' && $last_bracket !== '<')
                ) {
                    throw new DocblockParseException('Invalid string ' . $return_block);
                }
            } elseif ($char === ' ' || $char === "\t") {
                if ($brackets) {
                    continue;
                }

                $remaining = trim(substr($return_block, $i + 1));

                if ($remaining) {
                    return array_merge([$type], preg_split('/[\s\t]+/', $remaining));
                }

                return [$type];
            }

            $type .= $char;
        }

        return [$type];
    }

    /**
     * Parse a docblock comment into its parts.
     *
     * Taken from advanced api docmaker, which was taken from
     * https://github.com/facebook/libphutil/blob/master/src/parser/docblock/PhutilDocblockParser.php
     *
     * @param  string  $docblock
     * @param  int     $line_number
     * @return array Array of the main comment and specials
     */
    public static function parseDocComment($docblock, $line_number = null)
    {
        // Strip off comments.
        $docblock = trim($docblock);
        $docblock = preg_replace('@^/\*\*@', '', $docblock);
        $docblock = preg_replace('@\*/$@', '', $docblock);
        $docblock = preg_replace('@^\s*\*@m', '', $docblock);

        // Normalize multi-line @specials.
        $lines = explode("\n", $docblock);

        $line_map = [];

        if ($line_number) {
            $line_number++;
        }

        /** @var int|false */
        $last = false;
        foreach ($lines as $k => $line) {
            if (preg_match('/^\s?@\w/i', $line)) {
                $last = $k;
            } elseif (preg_match('/^\s*$/', $line)) {
                $last = false;
            } elseif ($last !== false) {
                $lines[$last] = rtrim($lines[$last]).' '.trim($line);
                unset($lines[$k]);
            }

            if ($line_number) {
                $line_map[$line] = $line_number++;
            }
        }

        $docblock = implode("\n", $lines);

        $special = [];

        // Parse @specials.
        $matches = [];
        $have_specials = preg_match_all('/^\s?@([\w\-:]+)\s*([^\n]*)/m', $docblock, $matches, PREG_SET_ORDER);
        if ($have_specials) {
            $docblock = preg_replace('/^\s?@([\w\-:]+)\s*([^\n]*)/m', '', $docblock);
            /** @var string[] $match */
            foreach ($matches as $m => $match) {
                list($_, $type, $data) = $match;

                if (empty($special[$type])) {
                    $special[$type] = [];
                }

                $special[$type][$line_map && isset($line_map[$_]) ? $line_map[$_] : $m] = $data;
            }
        }

        $docblock = str_replace("\t", '  ', $docblock);

        // Smush the whole docblock to the left edge.
        $min_indent = 80;
        $indent = 0;
        foreach (array_filter(explode("\n", $docblock)) as $line) {
            for ($ii = 0; $ii < strlen($line); $ii++) {
                if ($line[$ii] != ' ') {
                    break;
                }
                $indent++;
            }

            /** @var int */
            $min_indent = min($indent, $min_indent);
        }

        $docblock = preg_replace('/^' . str_repeat(' ', $min_indent) . '/m', '', $docblock);
        $docblock = rtrim($docblock);

        // Trim any empty lines off the front, but leave the indent level if there
        // is one.
        $docblock = preg_replace('/^\s*\n/', '', $docblock);

        return [
            'description' => $docblock,
            'specials' => $special
        ];
    }

    /**
     * @param  array{description:string,specials:array<string,array<string>>} $parsed_doc_comment
     * @param  string                                                         $left_padding
     * @return array<int, string>
     */
    public static function renderDocComment(array $parsed_doc_comment, $left_padding)
    {
        $doc_comment_text = [$left_padding . '/**'];

        $description_lines = null;

        $trimmed_description = trim($parsed_doc_comment['description']);

        if (!empty($trimmed_description)) {
            $description_lines = explode(PHP_EOL, $parsed_doc_comment['description']);

            foreach ($description_lines as $line) {
                $doc_comment_text[] = $left_padding . ' * ' . $line;
            }
        }

        if ($description_lines && $parsed_doc_comment['specials']) {
            $doc_comment_text[] = $left_padding . ' *';
        }

        if ($parsed_doc_comment['specials']) {
            $special_type_lengths = array_map('strlen', array_keys($parsed_doc_comment['specials']));
            /** @var int */
            $special_type_width = max($special_type_lengths) + 1;

            foreach ($parsed_doc_comment['specials'] as $type => $lines) {
                foreach ($lines as $line) {
                    $doc_comment_text[] = $left_padding . ' * @' . str_pad($type, $special_type_width) . $line;
                }
            }
        }

        $doc_comment_text[] = $left_padding . ' */';

        return $doc_comment_text;
    }
}