<?php

use Twig\Error\LoaderError;

const RESOURCE_INTEGRITY_HASHES = ['sha256', 'sha384', 'sha512'];

class skin {

    public array $lang = [];
    protected array $vars = [];
    protected array $globalVars = [];
    protected bool $globalsApplied = false;
    public string $title = 'title';
    /** @var (\Closure(string $title):string)[] */
    protected array $titleModifiers = [];
    public array $meta = [];
    protected array $js = [];
    public array $options = [
        'full_width' => false,
        'wide' => false,
        'logo_path_map' => [],
        'logo_link_map' => [],
        'is_index' => false,
        'head_section' => null,
        'articles_lang' => null,
        'inside_admin_interface' => false,
    ];
    public array $static = [];
    protected array $styleNames = [];
    protected array $svgDefs = [];

    public \Twig\Environment $twig;

    protected static ?skin $instance = null;

    public static function getInstance(): skin {
        if (self::$instance === null)
            self::$instance = new skin();
        return self::$instance;
    }

    /**
     * @throws LoaderError
     */
    protected function __construct() {
        global $config;
        $cache_dir = $config['skin_cache_'.(isDev() ? 'dev' : 'prod').'_dir'];
        if (!file_exists($cache_dir)) {
            if (mkdir($cache_dir, $config['dirs_mode'], true))
                setperm($cache_dir);
        }

        // must specify a second argument ($rootPath) here
        // otherwise it will be getcwd() and it's www-prod/htdocs/ for apache and www-prod/ for cli code
        // this is bad for templates rebuilding
        $twig_loader = new \Twig\Loader\FilesystemLoader(APP_ROOT.'/skin', APP_ROOT);
        // $twig_loader->addPath(APP_ROOT.'/htdocs/svg', 'svg');

        $env_options = [];
        if (!is_null($cache_dir)) {
            $env_options += [
                'cache' => $cache_dir,
                'auto_reload' => isDev()
            ];
        }
        $twig = new \Twig\Environment($twig_loader, $env_options);
        $twig->addExtension(new \TwigAddons\MyExtension());

        $this->twig = $twig;
    }

    public function addMeta(array $data) {
        static $twitter_limits = [
            'title' => 70,
            'description' => 200
        ];
        $real_meta = [];
        $add_og_twitter = function($key, $value) use (&$real_meta, $twitter_limits) {
            foreach (['og', 'twitter'] as $social) {
                if ($social == 'twitter' && isset($twitter_limits[$key])) {
                    if (mb_strlen($value) > $twitter_limits[$key])
                        $value = mb_substr($value, 0, $twitter_limits[$key]-3).'...';
                }
                $real_meta[] = [
                    $social == 'twitter' ? 'name' : 'property' => $social.':'.$key,
                    'content' => $value
                ];
            }
        };
        foreach ($data as $key => $value) {
            if (str_starts_with($value, '@'))
                $value = lang(substr($value, 1));
            switch ($key) {
                case '@url':
                case '@title':
                case '@image':
                    $add_og_twitter(substr($key, 1), $value);
                    break;

                case '@description':
                case '@keywords':
                    $real_name = substr($key, 1);
                    $add_og_twitter($real_name, $value);
                    $real_meta[] = ['name' => $real_name, 'content' => $value];
                    break;

                default:
                    if (str_starts_with($key, 'og:')) {
                        $real_meta[] = ['property' => $key, 'content' => $value];
                    } else {
                        logWarning("unsupported meta: $key => $value");
                    }
                    break;
            }
        }
        $this->meta = array_merge($this->meta, $real_meta);
    }

    public function exportStrings(array|string $keys): void {
        global $__lang;
        $this->lang = array_merge($this->lang, is_string($keys) ? $__lang->search($keys) : $keys);
    }

    public function setTitle(string $title): void {
        if (str_starts_with($title, '$'))
            $title = lang(substr($title, 1));
        else if (str_starts_with($title, '\\$'))
            $title = substr($title, 1);
        $this->title = $title;
    }

    public function addPageTitleModifier(callable $callable): void {
        if (!is_callable($callable)) {
            trigger_error(__METHOD__.': argument is not callable');
        } else {
            $this->titleModifiers[] = $callable;
        }
    }

    protected function getTitle(): string {
        $title = $this->title != '' ? $this->title : lang('site_title');
        if (!empty($this->titleModifiers)) {
            foreach ($this->titleModifiers as $modifier)
                $title = $modifier($title);
        }
        return $title;
    }

    public function set($arg1, $arg2 = null) {
        if (is_array($arg1)) {
            foreach ($arg1 as $key => $value)
                $this->vars[$key] = $value;
        } elseif ($arg2 !== null) {
            $this->vars[$arg1] = $arg2;
        }
    }

    public function isSet($key): bool {
        return isset($this->vars[$key]);
    }

    public function setGlobal($arg1, $arg2 = null): void {
        if ($this->globalsApplied)
            logError(__METHOD__.': WARNING: globals were already applied, your change will not be visible');

        if (is_array($arg1)) {
            foreach ($arg1 as $key => $value)
                $this->globalVars[$key] = $value;
        } elseif ($arg2 !== null) {
            $this->globalVars[$arg1] = $arg2;
        }
    }

    public function isGlobalSet($key): bool {
        return isset($this->globalVars[$key]);
    }

    public function getGlobal($key) {
        return $this->isGlobalSet($key) ? $this->globalVars[$key] : null;
    }

    public function applyGlobals(): void {
        if (!empty($this->globalVars) && !$this->globalsApplied) {
            foreach ($this->globalVars as $key => $value)
                $this->twig->addGlobal($key, $value);
            $this->globalsApplied = true;
        }
    }

    public function addStatic(string ...$files): void {
        foreach ($files as $file)
            $this->static[] = $file;
    }

    public function addJS(string $js): void {
        if ($js != '')
            $this->js[] = $js;
    }

    protected function getJS(): string {
        if (empty($this->js))
            return '';
        return implode("\n", $this->js);
    }

    public function preloadSVG(string $name): void {
        if (isset($this->svgDefs[$name]))
            return;

        if (!preg_match_all('/\d+/', $name, $matches))
            throw new InvalidArgumentException('icon name '.$name.' is invalid, it should follow following pattern: $name_$size[_$size]');

        $size = array_slice($matches[0], -2);
        $this->svgDefs[$name] = [
            'width' => $size[0],
            'height' => $size[1] ?? $size[0]
        ];
    }

    public function getSVG(string $name, bool $in_place = false): ?string {
        $this->preloadSVG($name);
        $w = $this->svgDefs[$name]['width'];
        $h = $this->svgDefs[$name]['height'];
        if ($in_place) {
            $svg = '<svg id="svgicon_'.$name.'" width="'.$w.'" height="'.$h.'" fill="currentColor" viewBox="0 0 '.$w.' '.$h.'">';
            $svg .= file_get_contents(APP_ROOT.'/skin/svg/'.$name.'.svg');
            $svg .= '</svg>';
            return $svg;
        } else {
            return '<svg width="'.$w.'" height="'.$h.'"><use xlink:href="#svgicon_'.$name.'"></use></svg>';
        }
    }

    public function renderBreadCrumbs(array $items, ?string $style = null, bool $mt = false): string {
        static $chevron = '<svg width="20" height="20" viewBox="0 0 20 20" fill="none" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" clip-rule="evenodd" d="M7.47 4.217a.75.75 0 0 0 0 1.06L12.185 10 7.469 14.72a.75.75 0 1 0 1.062 1.06l5.245-5.25a.75.75 0 0 0 0-1.061L8.531 4.218a.75.75 0 0 0-1.061-.001z" fill="currentColor"/></svg>';
        $buf = implode(array_map(function(array $i) use ($chevron): string {
            $buf = '';
            $has_url = array_key_exists('url', $i);

            if ($has_url)
                $buf .= '<a class="bc-item" href="'.htmlescape($i['url']).'">';
            else
                $buf .= '<span class="bc-item">';
            $buf .= htmlescape($i['text']);

            if ($has_url)
                $buf .= ' <span class="bc-arrow">'.$chevron.'</span></a>';
            else
                $buf .= '</span>';

            return $buf;
        }, $items));
        $class = 'bc';
        if ($mt)
            $class .= ' mt';
        return '<div class="'.$class.'"'.($style ? ' style="'.$style.'"' : '').'>'.$buf.'</div>';
    }

    public function renderPageNav(int $page, int $pages, string $link_template, ?array $opts = null): string {
        if ($opts === null) {
            $count = 0;
        } else {
            $opts = array_merge(['count' => 0], $opts);
            $count = $opts['count'];
        }

        $min_page = max(1, $page-2);
        $max_page = min($pages, $page+2);

        $pages_html = '';
        $base_class = 'pn-button no-hover no-select no-drag is-page';
        for ($p = $min_page; $p <= $max_page; $p++) {
            $class = $base_class;
            if ($p == $page)
                $class .= ' is-page-cur';
            $pages_html .= '<a class="'.$class.'" href="'.htmlescape(self::pageNavGetLink($p, $link_template)).'" data-page="'.$p.'" draggable="false">'.$p.'</a>';
        }

        if ($min_page > 2) {
            $pages_html = '<div class="pn-button-sep no-select no-drag">&nbsp;</div>'.$pages_html;
        }
        if ($min_page > 1) {
            $pages_html = '<a class="'.$base_class.'" href="'.htmlescape(self::pageNavGetLink(1, $link_template)).'" data-page="1" draggable="false">1</a>'.$pages_html;
        }

        if ($max_page < $pages-1) {
            $pages_html .= '<div class="pn-button-sep no-select no-drag">&nbsp;</div>';
        }
        if ($max_page < $pages) {
            $pages_html .= '<a class="'.$base_class.'" href="'.htmlescape(self::pageNavGetLink($pages, $link_template)).'" data-page="'.$pages.'" draggable="false">'.$pages.'</a>';
        }

        $pn_class = 'pn';
        if ($pages < 2) {
            $pn_class .= ' no-nav';
            if (!$count) {
                $pn_class .= ' no-results';
            }
        }

        $html = <<<HTML
<div class="{$pn_class}">
    <div class="pn-buttons clearfix">
        {$pages_html}
    </div>
</div>
HTML;

        return $html;
    }

    protected static function pageNavGetLink($page, $link_template) {
        return is_callable($link_template) ? $link_template($page) : str_replace('{page}', $page, $link_template);
    }

    protected function getSVGTags(): string {
        $buf = '<svg style="display: none">';
        foreach ($this->svgDefs as $name => $icon) {
            $content = file_get_contents(APP_ROOT.'/skin/svg/'.$name.'.svg');
            $buf .= "<symbol id=\"svgicon_{$name}\" viewBox=\"0 0 {$icon['width']} {$icon['height']}\" fill=\"currentColor\">$content</symbol>";
        }
        $buf .= '</svg>';
        return $buf;
    }

    public function setRenderOptions(array $options): void {
        $this->options = array_merge($this->options, $options);
    }

    public function render($template, array $vars = []): string {
        $this->applyGlobals();
        return $this->doRender($template, $this->vars + $vars);
    }

    public function renderPage(string $template, array $vars = []): never {
        $this->exportStrings(['4in1']);
        $this->applyGlobals();

        // render body first
        $b = $this->renderBody($template, $vars);

        // then everything else
        $h = $this->renderHeader();
        $f = $this->renderFooter();

        echo $h;
        echo $b;
        echo $f;

        exit;
    }

    protected function renderHeader(): string {
        global $config;

        $body_class = [];
        if ($this->options['full_width'])
            $body_class[] = 'full-width';
        else if ($this->options['wide'])
            $body_class[] = 'wide';

        $title = $this->getTitle();
        if (!$this->options['is_index'])
            $title = lang('4in1').' - '.$title;

        $vars = [
            'title' => $title,
            'meta_html' => $this->getMetaTags(),
            'static_html' => $this->getHeaderStaticTags(),
            'svg_html' => $this->getSVGTags(),
            'render_options' => $this->options,
            'app_config' => [
                'domain' => $config['domain'],
                'devMode' => $config['is_dev'],
                'cookieHost' => $config['cookie_host'],
            ],
            'body_class' => $body_class,
            'theme' => themes::getUserTheme(),
        ];

        return $this->doRender('header.twig', $vars);
    }

    protected function renderBody(string $template, array $vars): string {
        return $this->doRender($template, $this->vars + $vars);
    }

    protected function renderFooter(): string {
        global $config;

        $exec_time = microtime(true) - START_TIME;
        $exec_time = round($exec_time, 4);

        $footer_vars = [
            'exec_time' => $exec_time,
            'render_options' => $this->options,
            'admin_email' => $config['admin_email'],
            // 'lang_json' => json_encode($this->getLangKeys(), JSON_UNESCAPED_UNICODE),
            // 'static_config' => $this->getStaticConfig(),
            'script_html' => $this->getFooterScriptTags(),
            'this_page_url' => $_SERVER['REQUEST_URI'],
            'theme' => themes::getUserTheme(),
        ];
        return $this->doRender('footer.twig', $footer_vars);
    }

    protected function doRender(string $template, array $vars = []): string {
        $s = '';
        try {
            $s = $this->twig->render($template, $vars);
        } catch (\Twig\Error\Error $e) {
            $error = get_class($e).": failed to render";
            $source_ctx = $e->getSourceContext();
            if ($source_ctx) {
                $path = $source_ctx->getPath();
                if (str_starts_with($path, APP_ROOT))
                    $path = substr($path, strlen(APP_ROOT)+1);
                $error .= " ".$source_ctx->getName()." (".$path.") at line ".$e->getTemplateLine();
            }
            $error .= ": ";
            $error .= $e->getMessage();
            logError($error);
            if (isDev())
                $s = $error."\n";
        }
        return $s;
    }

    protected function getMetaTags(): string {
        if (empty($this->meta))
            return '';
        return implode('', array_map(function(array $item): string {
            $s = '<meta';
            foreach ($item as $k => $v)
                $s .= ' '.htmlescape($k).'="'.htmlescape($v).'"';
            $s .= '/>';
            $s .= "\n";
            return $s;
        }, $this->meta));
    }

    protected function getHeaderStaticTags(): string {
        $html = [];
        $theme = themes::getUserTheme();
        $dark = $theme == 'dark' || ($theme == 'auto' && themes::isUserSystemThemeDark());
        $this->styleNames = [];
        foreach ($this->static as $name) {
            // javascript
            if (str_starts_with($name, 'js/'))
                $html[] = $this->jsLink($name);

            // css
            else if (str_starts_with($name, 'css/')) {
                $html[] = $this->cssLink($name, 'light', $style_name_ptr);
                $this->styleNames[] = $style_name_ptr;

                if ($dark)
                    $html[] = $this->cssLink($name, 'dark', $style_name_ptr);
                else if (!isDev())
                    $html[] = $this->cssPrefetchLink($style_name_ptr.'_dark');
            }
            else
                logError(__FUNCTION__.': unexpected static entry: '.$name);
        }
        return implode("\n", $html);
    }

    protected function getFooterScriptTags(): string {
        global $config;

        $html = '<script type="text/javascript">';

        if (isDev())
            $versions = '{}';
        else {
            $versions = [];
            foreach ($config['static'] as $name => $v) {
                list($type, $bname) = $this->getStaticNameParts($name);
                $versions[$type][$bname] = $v;
            }
            $versions = jsonEncode($versions);
        }
        $html .= 'StaticManager.init('.jsonEncode($this->styleNames).', '.$versions.');';
        $html .= 'ThemeSwitcher.init();';

        if (!empty($this->lang)) {
            $lang = [];
            foreach ($this->lang as $key)
                $lang[$key] = lang($key);
            $html .= 'extend(__lang, '.jsonEncode($lang).');';
        }

        $js = $this->getJS();
        if ($js)
            $html .= '(function(){try{'.$js.'}catch(e){window.console&&console.error("caught exception:",e)}})();';

        $html .= '</script>';
        return $html;
    }

    protected function jsLink(string $name): string {
        list (, $bname) = $this->getStaticNameParts($name);
        if (isDev()) {
            $href = '/js.php?name='.urlencode($bname).'&amp;v='.time();
        } else {
            $href = '/dist-js/'.$bname.'.js?v='.$this->getStaticVersion($name);
        }
        return '<script src="'.$href.'" type="text/javascript"'.$this->getStaticIntegrityAttribute($name).'></script>';
    }

    protected function cssLink(string $name, string $theme, &$bname = null): string {
        list(, $bname) = $this->getStaticNameParts($name);

        $config_name = 'css/'.$bname.($theme == 'dark' ? '_dark' : '').'.css';

        if (isDev()) {
            $href = '/sass.php?name='.urlencode($bname).'&amp;theme='.$theme.'&amp;v='.time();
        } else {
            $version = $this->getStaticVersion($config_name);
            $href = '/dist-css/'.$bname.($theme == 'dark' ? '_dark' : '').'.css?v='.$version;
        }

        $id = 'style_'.$bname;
        if ($theme == 'dark')
            $id .= '_dark';

        return '<link rel="stylesheet" id="'.$id.'" type="text/css" href="'.$href.'"'.$this->getStaticIntegrityAttribute($config_name).'>';
    }

    protected function cssPrefetchLink(string $name): string {
        $url = '/dist-css/'.$name.'.css?v='.$this->getStaticVersion('css/'.$name.'.css');
        $integrity = $this->getStaticIntegrityAttribute('css/'.$name.'.css');
        return '<link rel="prefetch" href="'.$url.'"'.$integrity.' />';
    }

    protected function getStaticNameParts(string $name): array {
        $dname = dirname($name);
        $bname = basename($name);
        if (($pos = strrpos($bname, '.'))) {
            $ext = substr($bname, $pos+1);
            $bname = substr($bname, 0, $pos);
        } else {
            $ext = '';
        }
        return [$dname, $bname, $ext];
    }

    protected function getStaticVersion(string $name): string {
        global $config;
        if (isDev())
            return time();
        if (str_starts_with($name, '/')) {
            logWarning(__FUNCTION__.': '.$name.' starts with /');
            $name = substr($name, 1);
        }
        return $config['static'][$name]['version'] ?? 'notfound';
    }

    protected function getStaticIntegrityAttribute(string $name): string {
        if (isDev())
            return '';
        global $config;
        return ' integrity="'.implode(' ', array_map(fn($hash_type) => $hash_type.'-'.$config['static'][$name]['integrity'][$hash_type], RESOURCE_INTEGRITY_HASHES)).'"';
    }

}