<?php namespace BookStack\Services;

use BookStack\Book;
use BookStack\Chapter;
use BookStack\Page;
use BookStack\Repos\EntityRepo;

class ExportService
{

    const VIDEO_REGEX = "/\<video.*?\>\<source.*?\ src\=(\")(.*?)(\").*?><\/video>/";
    const YOUTUBE_REGEX = "/\<iframe.*src\=(\'|\")(\/\/www\.youtube\.com.*?)(\'|\").*?><\/iframe>/";
    const VIMEO_REGEX = "/\<iframe.*src\=(\'|\")(\/\/player\.vimeo\.com.*?)(\'|\").*?><\/iframe>/";
    const GOOGLE_MAP_REGEX = "/\<iframe.*src\=(\'|\")(\/\/maps\.google\.com.*?)(\'|\").*?><\/iframe>/";
    const DAILYMOTION_REGEX = "/\<iframe.*src\=(\'|\")(\/\/www\.dailymotion\.com.*?)(\'|\").*?><\/iframe>/";

    protected $entityRepo;
    protected $imageService;

    /**
     * ExportService constructor.
     * @param $entityRepo
     */
    public function __construct(EntityRepo $entityRepo, ImageService $imageService)
    {
        $this->entityRepo = $entityRepo;
        $this->imageService = $imageService;
    }

    /**
     * Convert a page to a self-contained HTML file.
     * Includes required CSS & image content. Images are base64 encoded into the HTML.
     * @param Page $page
     * @return mixed|string
     * @throws \Throwable
     */
    public function pageToContainedHtml(Page $page)
    {
        $this->entityRepo->renderPage($page);
        $pageHtml = view('pages/export', [
            'page' => $page
        ])->render();
        return $this->containHtml($pageHtml);
    }

    /**
     * Convert a chapter to a self-contained HTML file.
     * @param Chapter $chapter
     * @return mixed|string
     * @throws \Throwable
     */
    public function chapterToContainedHtml(Chapter $chapter)
    {
        $pages = $this->entityRepo->getChapterChildren($chapter);
        $pages->each(function ($page) {
            $page->html = $this->entityRepo->renderPage($page);
        });
        $html = view('chapters/export', [
            'chapter' => $chapter,
            'pages' => $pages
        ])->render();
        return $this->containHtml($html);
    }

    /**
     * Convert a book to a self-contained HTML file.
     * @param Book $book
     * @return mixed|string
     * @throws \Throwable
     */
    public function bookToContainedHtml(Book $book)
    {
        $bookTree = $this->entityRepo->getBookChildren($book, true, true);
        $html = view('books/export', [
            'book' => $book,
            'bookChildren' => $bookTree
        ])->render();
        return $this->containHtml($html);
    }

    /**
     * Convert a page to a PDF file.
     * @param Page $page
     * @return mixed|string
     * @throws \Throwable
     */
    public function pageToPdf(Page $page)
    {
        $this->entityRepo->renderPage($page);
        $html = view('pages/pdf', [
            'page' => $page
        ])->render();
        return $this->htmlToPdf($html);
    }

    /**
     * Convert a chapter to a PDF file.
     * @param Chapter $chapter
     * @return mixed|string
     * @throws \Throwable
     */
    public function chapterToPdf(Chapter $chapter)
    {
        $pages = $this->entityRepo->getChapterChildren($chapter);
        $pages->each(function ($page) {
            $page->html = $this->entityRepo->renderPage($page);
        });
        $html = view('chapters/export', [
            'chapter' => $chapter,
            'pages' => $pages
        ])->render();
        return $this->htmlToPdf($html);
    }

    /**
     * Convert a book to a PDF file
     * @param Book $book
     * @return string
     * @throws \Throwable
     */
    public function bookToPdf(Book $book)
    {
        $bookTree = $this->entityRepo->getBookChildren($book, true, true);
        $html = view('books/export', [
            'book' => $book,
            'bookChildren' => $bookTree
        ])->render();
        return $this->htmlToPdf($html);
    }

    /**
     * Convert normal webpage HTML to a PDF.
     * @param $html
     * @return string
     * @throws \Exception
     */
    protected function htmlToPdf($html)
    {
        $containedHtml = $this->containHtml($html, true);
        $useWKHTML = config('snappy.pdf.binary') !== false;
        if ($useWKHTML) {
            $pdf = \SnappyPDF::loadHTML($containedHtml);
            $pdf->setOption('print-media-type', true);
        } else {
            $pdf = \DomPDF::loadHTML($containedHtml);
        }
        return $pdf->output();
    }

    /**
     * Bundle of the contents of a html file to be self-contained.
     * @param $htmlContent
     * @param bool $isPDF
     * @return mixed|string
     * @throws \Illuminate\Contracts\Filesystem\FileNotFoundException
     */
    protected function containHtml($htmlContent, $isPDF = false)
    {
        $imageTagsOutput = [];
        preg_match_all("/\<img.*src\=(\'|\")(.*?)(\'|\").*?\>/i", $htmlContent, $imageTagsOutput);

        // Replace image src with base64 encoded image strings
        if (isset($imageTagsOutput[0]) && count($imageTagsOutput[0]) > 0) {
            foreach ($imageTagsOutput[0] as $index => $imgMatch) {
                $oldImgTagString = $imgMatch;
                $srcString = $imageTagsOutput[2][$index];
                $imageEncoded = $this->imageService->imageUriToBase64($srcString);
                if ($imageEncoded === null) {
                    $imageEncoded = $srcString;
                }
                $newImgTagString = str_replace($srcString, $imageEncoded, $oldImgTagString);
                $htmlContent = str_replace($oldImgTagString, $newImgTagString, $htmlContent);
            }
        }

        $linksOutput = [];
        preg_match_all("/\<a.*href\=(\'|\")(.*?)(\'|\").*?\>/i", $htmlContent, $linksOutput);

        // Replace image src with base64 encoded image strings
        if (isset($linksOutput[0]) && count($linksOutput[0]) > 0) {
            foreach ($linksOutput[0] as $index => $linkMatch) {
                $oldLinkString = $linkMatch;
                $srcString = $linksOutput[2][$index];
                if (strpos(trim($srcString), 'http') !== 0) {
                    $newSrcString = url($srcString);
                    $newLinkString = str_replace($srcString, $newSrcString, $oldLinkString);
                    $htmlContent = str_replace($oldLinkString, $newLinkString, $htmlContent);
                }
            }
        }

        // Replace problems caused by TinyMCE removing the protocol for YouTube, Google Maps, DailyMotion and Vimeo
        if ($isPDF) {
            $callback = [$this, 'replaceContentPDF'];
            $htmlContent = $this->replaceLinkedTags(self::VIDEO_REGEX, $htmlContent, $callback, 'Video');
        } else {
            $callback = [$this, 'replaceContentHtml'];
        }
        $htmlContent = $this->replaceLinkedTags(self::YOUTUBE_REGEX, $htmlContent, $callback, 'Video');
        $htmlContent = $this->replaceLinkedTags(self::GOOGLE_MAP_REGEX, $htmlContent, $callback, 'Map');
        $htmlContent = $this->replaceLinkedTags(self::DAILYMOTION_REGEX, $htmlContent, $callback, 'Video');
        $htmlContent = $this->replaceLinkedTags(self::VIMEO_REGEX, $htmlContent, $callback, 'Video');

        return $htmlContent;
    }

    /**
     * Converts the page contents into simple plain text.
     * This method filters any bad looking content to provide a nice final output.
     * @param Page $page
     * @return mixed
     */
    public function pageToPlainText(Page $page)
    {
        $html = $this->entityRepo->renderPage($page);

        $callback = [$this, 'replaceContentText'];
        // Replace video tag in PDF
        $html = $this->replaceLinkedTags(self::VIDEO_REGEX, $html, $callback, 'Video');
        // Replace problems caused by TinyMCE removing the protocol for YouTube, Google Maps, DailyMotion and Vimeo
        $html = $this->replaceLinkedTags(self::YOUTUBE_REGEX, $html, $callback, 'Video');
        $html = $this->replaceLinkedTags(self::GOOGLE_MAP_REGEX, $html, $callback, 'Map');
        $html = $this->replaceLinkedTags(self::DAILYMOTION_REGEX, $html, $callback, 'Video');
        $html = $this->replaceLinkedTags(self::VIMEO_REGEX, $html, $callback, 'Video');

        $text = strip_tags($html);
        // Replace multiple spaces with single spaces
        $text = preg_replace('/\ {2,}/', ' ', $text);
        // Reduce multiple horrid whitespace characters.
        $text = preg_replace('/(\x0A|\xA0|\x0A|\r|\n){2,}/su', "\n\n", $text);
        $text = html_entity_decode($text);
        // Add title
        $text = $page->name . "\n\n" . $text;
        return $text;
    }

    /**
     * Convert a chapter into a plain text string.
     * @param Chapter $chapter
     * @return string
     */
    public function chapterToPlainText(Chapter $chapter)
    {
        $text = $chapter->name . "\n\n";
        $text .= $chapter->description . "\n\n";
        foreach ($chapter->pages as $page) {
            $text .= $this->pageToPlainText($page);
        }
        return $text;
    }

    /**
     * Convert a book into a plain text string.
     * @param Book $book
     * @return string
     */
    public function bookToPlainText(Book $book)
    {
        $bookTree = $this->entityRepo->getBookChildren($book, true, true);
        $text = $book->name . "\n\n";
        foreach ($bookTree as $bookChild) {
            if ($bookChild->isA('chapter')) {
                $text .= $this->chapterToPlainText($bookChild);
            } else {
                $text .= $this->pageToPlainText($bookChild);
            }
        }
        return $text;
    }

    /**
     * Can be used to replace certain tags that cause problems such as the TinyMCE video tag
     * modification that have to be undone.
     * See - https://github.com/tinymce/tinymce/blob/0f7a0f12667bde6eae9377b50b797f4479aa1ac7/src/plugins/media/main/ts/core/UrlPatterns.ts#L22
     * @param String $regex
     * @param String $htmlContent
     * @param array $callback
     * @param String $contentLabel
     * @return String $htmlContent - Modified html content
     */
    protected function replaceLinkedTags($regex, $htmlContent, $callback, $contentLabel = '') {
        $iframeOutput = [];
        preg_match_all($regex, $htmlContent, $iframeOutput);
        if (isset($iframeOutput[0]) && count($iframeOutput[0]) > 0) {
            foreach ($iframeOutput[0] as $index => $iframeMatch) {
                $htmlContent = call_user_func($callback, $htmlContent, $iframeOutput, $index, $contentLabel);
            }
        }
        return $htmlContent;
    }

    protected function replaceContentHtml($htmlContent, $iframeOutput, $index, $contentLabel) {
        $srcString = $iframeOutput[2][$index];
        $newSrcString = $srcString;
        if (strpos($srcString, 'http') !== 0) {
            $newSrcString = 'https:' . $srcString;
        }
        $htmlContent = str_replace($srcString, $newSrcString, $htmlContent);
        return $htmlContent;
    }

    protected function replaceContentPDF($htmlContent, $iframeOutput, $index, $contentLabel) {
        $srcString = $iframeOutput[2][$index];
        $newSrcString = $srcString;
        if (strpos($srcString, 'http') !== 0) {
            $newSrcString = 'https:' . $srcString;
        }
        $finalHtmlString = "$contentLabel: <a href='$newSrcString'>$newSrcString</a>";
        $htmlContent = str_replace($iframeOutput[0][$index], $finalHtmlString, $htmlContent);
        return $htmlContent;
    }

    protected function replaceContentText($htmlContent, $iframeOutput, $index, $contentLabel) {
        $srcString = $iframeOutput[2][$index];
        $newSrcString = $srcString;
        if (strpos($srcString, 'http') !== 0) {
            $newSrcString = 'https:' . $srcString;
        }
        $finalHtmlString = "$contentLabel: $newSrcString";
        $htmlContent = str_replace($iframeOutput[0][$index], $finalHtmlString, $htmlContent);
        return $htmlContent;
    }
}