<?php
declare(strict_types=1);

namespace Gatecraft;

if (!defined('ABSPATH')) exit;

/*
 * Languages.
 *
 * Pages are written in English. When another language is active, the finished HTML is translated on its way out:
 * text between tags and the readable attributes (placeholder, title, aria-label, alt, button values, confirm texts)
 * are looked up in a dictionary of exact phrases, then in a short list of patterns for phrases with a value inside
 * them. Anything not found stays in English, so a missing phrase never breaks a page. Text that people type
 * (event titles, descriptions, venue names) is left alone unless it happens to be an exact dictionary phrase;
 * anything inside an element marked translate="no" is never touched.
 *
 * Which language a page uses, first match wins:
 *   1. ?lang=xx in the address (also remembered, see 2 and 3)
 *   2. the signed-in person's own choice
 *   3. the visitor's choice, remembered in a cookie
 *   4. on public pages for one event or booking: that event's language
 *   5. the site's default language
 */

const GATECRAFT_LANGUAGES = ['en' => 'English', 'ja' => '日本語'];

add_filter('gatecraft_setting_defaults', fn(array $d) => $d + ['language_default' => 'en', 'language_ja' => '0', 'language_switcher' => '1']);
add_filter('gatecraft_setting_rules', function (array $r, string $tab) {
    if ($tab !== 'regional') return $r;
    return $r + ['language_default' => ['enum', array_keys(GATECRAFT_LANGUAGES)], 'language_ja' => ['bool'], 'language_switcher' => ['bool']];
}, 10, 2);

/** The file with the phrases of a language that ships with the plugin, or '' when there is none. */
function language_file(string $lang): string
{
    if (!preg_match('/^[a-z]{2}$/', $lang)) return '';
    $f = GATECRAFT_DIR . 'languages/' . $lang . '.php';
    return is_file($f) ? $f : '';
}

/**
 * True when the phrases for a language are installed. English is built in and Japanese ships in languages/ja.php.
 * Add-ons can supply more languages through the gatecraft_language_installed and gatecraft_dictionary filters.
 */
function language_installed(string $lang): bool
{
    return $lang === 'en' || language_file($lang) !== '' || (bool)apply_filters('gatecraft_language_installed', false, $lang);
}

/** Languages people can choose on this site. English is always available. */
function languages_enabled(): array
{
    $out = ['en' => GATECRAFT_LANGUAGES['en']];
    if (setting_on('language_ja') && language_installed('ja')) $out['ja'] = GATECRAFT_LANGUAGES['ja'];
    return $out;
}

function language_valid($l): bool
{
    return is_string($l) && isset(languages_enabled()[$l]);
}

/** The site default, falling back to English when the default language is switched off. */
function language_default(): string
{
    $d = setting('language_default');
    return language_valid($d) ? $d : 'en';
}

/** Set by a public page about one event or booking, so its language applies when the visitor has not chosen one. */
function language_context($lang = null, bool $set = false): ?string
{
    static $ctx = null;
    if ($set) $ctx = language_valid($lang) ? $lang : null;
    return $ctx;
}

/** A forced language for work done outside a page (emails to a buyer or a staff member). */
function language_force(?string $lang = null, bool $set = false): ?string
{
    static $f = null;
    if ($set) $f = $lang !== null && isset(GATECRAFT_LANGUAGES[$lang]) ? $lang : null;
    return $f;
}

/** Run $fn with a language active, for example to build an email in the recipient's language. */
function with_language(?string $lang, callable $fn)
{
    $before = language_force();
    language_force(language_valid($lang) ? $lang : language_default(), true);
    try {
        return $fn();
    } finally {
        language_force($before, true);
    }
}

function current_language(): string
{
    if (($f = language_force()) !== null) return $f;
    if (count(languages_enabled()) < 2) return 'en';
    static $chosen = false;
    if ($chosen === false) {
        $chosen = null;
        // ?lang= is a display choice for this browser, compared with the enabled languages (language_valid()). It is saved
        // on the signed-in account only when the link carries our nonce (language_save_from_link()).
        $q = isset($_GET['lang']) && is_string($_GET['lang']) ? strtolower(substr(sanitize_key(wp_unslash($_GET['lang'])), 0, 5)) : null; // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- display choice for this browser; the account is only changed after the nonce check in language_save_from_link()
        if (language_valid($q)) {
            $chosen = $q;
            language_remember($q);
            language_save_from_link($q);
        } else {
            $u = PHP_SAPI === 'cli' ? null : current_user();
            $pref = $u ? user_language((int)$u['id']) : null;
            $cookie = $GLOBALS['gatecraft_lang_chosen'] ?? (isset($_COOKIE['gc_lang']) && is_string($_COOKIE['gc_lang']) ? sanitize_key(wp_unslash($_COOKIE['gc_lang'])) : null);
            if (language_valid($pref)) $chosen = $pref;
            elseif (language_valid($cookie)) $chosen = $cookie;
        }
    }
    if ($chosen !== null) return $chosen;
    $ctx = language_context();
    return $ctx ?? language_default();
}

/** Remember a visitor's choice in a cookie in their browser. */
function language_remember(string $lang): void
{
    if (PHP_SAPI !== 'cli' && !headers_sent()) {
        setcookie('gc_lang', $lang, ['expires' => time() + 365 * 86400, 'path' => '/', 'secure' => is_https(), 'httponly' => false, 'samesite' => 'Lax']);
    }
    $GLOBALS['gatecraft_lang_chosen'] = $lang;
}

/** Save a language chosen from a language link on the signed-in account. The link must carry a valid nonce. */
function language_save_from_link(string $lang): void
{
    if (PHP_SAPI === 'cli' || !is_user_logged_in()) return;
    // 1. The nonce, on its own. Without it the account is not changed.
    $nonce = isset($_GET['_gclang']) ? sanitize_text_field(wp_unslash($_GET['_gclang'])) : '';
    if (!wp_verify_nonce($nonce, 'gatecraft_lang')) return;
    // 2. Then the change, for the person's own account only.
    $u = current_user();
    if ($u && language_valid($lang) && user_language((int)$u['id']) !== $lang) user_language_set((int)$u['id'], $lang);
}

function is_https_request(): bool
{
    return is_ssl();
}

/** The language a person chose for themselves, or null. */
function user_language(int $userId): ?string
{
    try {
        $v = qv('SELECT language FROM {' . user_language_table() . '} WHERE ' . user_language_key() . ' = ?', [$userId]);
    } catch (\Throwable $e) {
        return null; // before the upgrade that adds the column
    }
    return is_string($v) && $v !== '' ? $v : null;
}

function user_language_set(int $userId, ?string $lang): void
{
    $lang = $lang !== null && isset(GATECRAFT_LANGUAGES[$lang]) ? $lang : null;
    try {
        q('UPDATE {' . user_language_table() . '} SET language = ? WHERE ' . user_language_key() . ' = ?', [$lang, $userId]);
    } catch (\Throwable $e) {
        // The column arrives with the database upgrade; nothing to remember until then.
    }
}

/** The language a staff member or buyer chose, looked up by email, else the site default. */
function user_language_by_email(string $email): string
{
    try {
        $v = qv('SELECT a.language FROM {accounts} a JOIN {wpusers} u ON u.ID = a.user_id WHERE u.user_email = ?', [$email]);
    } catch (\Throwable $e) {
        $v = null;
    }
    return is_string($v) && language_valid($v) ? $v : language_default();
}

function user_language_table(): string
{
    return 'accounts';
}

function user_language_key(): string
{
    return 'user_id';
}

/**
 * The language menu: in the page header for visitors (when the switcher is on), and on the account page and in the
 * admin for signed-in people ($force). Empty on a one-language site.
 */
function language_menu(bool $force = false): string
{
    return (string)apply_filters('gatecraft_language_menu', language_menu_html($force), $force);
}

/** A link to the current page in another language. */
function language_link_url(string $lang): string
{
    $q = get_all();
    unset($q['lang'], $q['_gclang']);
    $q['lang'] = $lang;
    // Signed in: the link may also save the choice on the account, so it carries a nonce (checked in language_save_from_link()).
    if (is_user_logged_in()) $q['_gclang'] = wp_create_nonce('gatecraft_lang');
    return gatecraft_current_path() . '?' . http_build_query($q);
}

function language_menu_html(bool $force = false): string
{
    $langs = languages_enabled();
    if (count($langs) < 2 || (!$force && !setting_on('language_switcher'))) return '';
    $cur = current_language();
    $out = '<nav class="lang-switch" aria-label="Language" translate="no">';
    foreach ($langs as $k => $name) {
        $label = '<span class="ls-long">' . e($name) . '</span><span class="ls-short" aria-hidden="true">' . e(strtoupper($k)) . '</span>';
        $out .= $k === $cur ? '<span class="lang-on" lang="' . e($k) . '" aria-current="true" aria-label="' . e($name) . '">' . $label . '</span>'
            : '<a href="' . e(language_link_url($k)) . '" lang="' . e($k) . '" hreflang="' . e($k) . '" rel="nofollow" aria-label="' . e($name) . '">' . $label . '</a>';
    }
    return $out . '</nav>';
}

/** Choices for a language select. $inherit adds an empty "use the default" option. */
function language_options(string $inherit = ''): array
{
    $o = $inherit !== '' ? ['' => $inherit] : [];
    return $o + GATECRAFT_LANGUAGES;
}

// ---------------------------------------------------------------- dates

/** ldate() for dates people read: month and weekday names follow the language. */
function ldate_h(string $format, ?int $ts = null): string
{
    $ts ??= time();
    if (current_language() !== 'ja') return ldate($format, $ts);
    static $map = ['j M Y' => 'Y年n月j日', 'j M' => 'n月j日', 'M' => 'n月', 'F Y' => 'Y年n月', 'g:i a' => 'A g:i'];
    $format = $map[$format] ?? $format;
    $days = ['日', '月', '火', '水', '木', '金', '土'];
    $w = (int)ldate('w', $ts);
    $out = '';
    $len = strlen($format);
    for ($i = 0; $i < $len; $i++) {
        $c = $format[$i];
        if ($c === '\\' && $i + 1 < $len) { $out .= $format[++$i]; continue; }
        $out .= match ($c) {
            'D' => $days[$w],
            'l' => $days[$w] . '曜日',
            'M', 'F' => ldate('n', $ts) . '月',
            'A', 'a' => (int)ldate('G', $ts) < 12 ? '午前' : '午後',
            default => ctype_alpha($c) ? ldate($c, $ts) : $c,
        };
    }
    return $out;
}

// ---------------------------------------------------------------- translation

function i18n_dictionary(string $lang): array
{
    static $cache = [];
    if (isset($cache[$lang])) return $cache[$lang];
    $own = $lang === 'en' ? '' : language_file($lang);
    $d = $lang === 'en' ? [] : (array)apply_filters('gatecraft_dictionary', $own !== '' ? (array)include $own : [], $lang);
    $d += ['phrases' => [], 'patterns' => []];
    // Phrases are matched with their spacing tidied, so a line break in a template does not stop a match.
    $phrases = [];
    foreach ($d['phrases'] as $en => $tr) $phrases[i18n_norm((string)$en)] = (string)$tr;
    return $cache[$lang] = ['phrases' => $phrases, 'patterns' => (array)$d['patterns'], 'js' => (array)($d['js'] ?? [])];
}

function i18n_norm(string $s): string
{
    return trim((string)preg_replace('/\s+/u', ' ', $s));
}

/** Translate one phrase. Returns it unchanged when there is nothing to do. */
function t(string $s, ?string $lang = null): string
{
    $lang ??= current_language();
    if ($lang === 'en' || $s === '') return $s;
    $key = i18n_norm($s);
    if ($key === '' || !preg_match('/[A-Za-z]{2}/', $key)) return $s;
    static $memo = [];
    if (isset($memo[$lang][$key])) return $memo[$lang][$key] === false ? $s : $memo[$lang][$key];
    $d = i18n_dictionary($lang);
    if (isset($d['phrases'][$key])) return $memo[$lang][$key] = $d['phrases'][$key];
    // Patterns: [regex, replacement, a fixed piece of text the phrase must contain]. In the replacement, {n} is the
    // n-th value, itself translated when it is a known phrase (a payment method, a status), and $n is the raw value.
    foreach ($d['patterns'] as $p) {
        [$re, $rep] = $p;
        $needle = $p[2] ?? '';
        if ($needle !== '' && !str_contains($key, $needle)) continue;
        if (!preg_match($re, $key, $m)) continue;
        $out = (string)preg_replace_callback('/\$(\d+)|\{(\d+)\}/', function ($r) use ($m, $lang) {
            if ($r[1] !== '') return $m[(int)$r[1]] ?? '';
            return t($m[(int)$r[2]] ?? '', $lang);
        }, $rep);
        return $memo[$lang][$key] = $out;
    }
    $memo[$lang][$key] = false;
    return $s;
}

/** Translate a text node, keeping its surrounding spaces and HTML entities intact. */
function i18n_text(string $raw, string $lang): string
{
    if (!preg_match('/[A-Za-z]/', $raw)) return $raw;
    $plain = html_entity_decode($raw, ENT_QUOTES | ENT_HTML5, 'UTF-8');
    $tr = t($plain, $lang);
    if ($tr === $plain) return $raw;
    preg_match('/^\s*/u', $plain, $a);
    preg_match('/\s*$/u', $plain, $b);
    return $a[0] . htmlspecialchars($tr, ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML5, 'UTF-8', false) . $b[0];
}

/** Translate a page of HTML into the current language. */
function i18n_html(string $html, ?string $lang = null): string
{
    $lang ??= current_language();
    if ($lang === 'en' || $html === '') return $html;
    $parts = preg_split('/(<!--.*?-->|<[^>]*>)/s', $html, -1, PREG_SPLIT_DELIM_CAPTURE);
    if ($parts === false) return $html;
    $skip = 0;          // inside script, style, textarea, pre or code
    $skipTag = '';
    $noDepth = [];      // stack of element names opened with translate="no"
    $stack = [];
    static $void = ['area' => 1, 'base' => 1, 'br' => 1, 'col' => 1, 'embed' => 1, 'hr' => 1, 'img' => 1, 'input' => 1, 'link' => 1, 'meta' => 1, 'source' => 1, 'track' => 1, 'wbr' => 1];
    $out = '';
    foreach ($parts as $i => $p) {
        if ($p === '') continue;
        if ($i % 2 === 0) { // text
            $out .= ($skip || $noDepth) ? $p : i18n_text($p, $lang);
            continue;
        }
        if (str_starts_with($p, '<!--')) { $out .= $p; continue; }
        if (!preg_match('#^<(/?)([a-zA-Z][a-zA-Z0-9-]*)#', $p, $m)) { $out .= $p; continue; }
        $close = $m[1] === '/';
        $tag = strtolower($m[2]);
        if ($skip) {
            if ($close && $tag === $skipTag) { $skip = 0; $skipTag = ''; }
            $out .= $p;
            continue;
        }
        if ($close) {
            // Pop to the matching element (tolerates unclosed p, li and similar).
            for ($k = count($stack) - 1; $k >= 0; $k--) {
                if ($stack[$k] === $tag) { $stack = array_slice($stack, 0, $k); break; }
            }
            while ($noDepth && end($noDepth) > count($stack)) array_pop($noDepth);
            $out .= $p;
            continue;
        }
        if ($tag === 'html') $p = (string)preg_replace('/\blang="[^"]*"/', 'lang="' . $lang . '"', $p);
        $selfClose = isset($void[$tag]) || str_ends_with($p, '/>');
        $no = (bool)preg_match('/\btranslate="no"|\bclass="[^"]*\bnotranslate\b/', $p);
        if (!$no && !$noDepth) $p = i18n_attrs($p, $tag, $lang);
        $out .= $p;
        if (in_array($tag, ['script', 'style', 'textarea', 'pre', 'code', 'svg'], true) && !$selfClose) { $skip = 1; $skipTag = $tag; continue; }
        if ($selfClose) continue;
        $stack[] = $tag;
        if ($no) $noDepth[] = count($stack);
    }
    return $out;
}

/** The readable attributes of one tag. */
function i18n_attrs(string $tagHtml, string $tag, string $lang): string
{
    static $attrs = ['placeholder', 'title', 'aria-label', 'alt', 'data-confirm', 'data-confirm-title', 'data-confirm-ok', 'data-confirm-cancel',
        'data-label-pay', 'data-label-approval', 'data-label-free', 'data-label-offline', 'data-busy', 'data-empty', 'data-copied', 'data-hint', 'data-tip', 'label'];
    return (string)preg_replace_callback('/\s(' . implode('|', array_map('preg_quote', $attrs)) . '|value|data-confirm-facts)="([^"]*)"/', function ($m) use ($tag, $tagHtml, $lang) {
        $name = $m[1];
        if ($name === 'value') {
            // Only the words on buttons, never form data.
            if (!($tag === 'input' && preg_match('/\btype="(submit|button|reset)"/i', $tagHtml))) return $m[0];
        }
        $v = html_entity_decode($m[2], ENT_QUOTES | ENT_HTML5, 'UTF-8');
        if ($name === 'data-confirm-facts') {
            // "Label::value||Label::value": translate the labels only.
            $v = implode('||', array_map(function ($pair) use ($lang) {
                $kv = explode('::', $pair, 2);
                return count($kv) === 2 ? t($kv[0], $lang) . '::' . $kv[1] : $pair;
            }, explode('||', $v)));
        } else {
            $v = t($v, $lang);
        }
        return ' ' . $name . '="' . htmlspecialchars($v, ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML5, 'UTF-8', false) . '"';
    }, $tagHtml);
}

/** Translate the readable strings in a JSON reply (errors, labels) before it is sent. */
function i18n_json(array $data): array
{
    if (current_language() === 'en') return $data;
    foreach (['error', 'message', 'tax_label', 'code_error', 'label', 'title', 'status'] as $k) {
        if (isset($data[$k]) && is_string($data[$k])) $data[$k] = t($data[$k]);
    }
    if (($data['total'] ?? null) === 'Free') $data['total'] = t('Free');
    return $data;
}

/** Phrases the browser scripts need, added before the given script with wp_add_inline_script() (window.gcI18n). */
function i18n_attach_script(string $handle): void
{
    $lang = current_language();
    if ($lang === 'en') return;
    $js = i18n_dictionary($lang)['js'] ?? [];
    if (!$js) return;
    $json = wp_json_encode(['lang' => $lang, 'phrases' => (object)($js['phrases'] ?? []), 'patterns' => $js['patterns'] ?? []], JSON_HEX_TAG | JSON_HEX_AMP);
    if ($json) wp_add_inline_script($handle, 'window.gcI18n=' . $json . ';', 'before');
}