<?php
/*
 * languagestore.php
 *
 * Small SQLite-backed translation module.
 *
 * Database:
 *   data/racket-sandbox.sqlite
 */

class LanguageStoreException extends Exception
{
}

class LanguageStore
{
    private $db;
    private $fallbackLanguage;

    public function __construct($dbFile, $fallbackLanguage = 'en')
    {
        $dir = dirname($dbFile);

        if (!is_dir($dir)) {
            if (!mkdir($dir, 0700, true)) {
                throw new LanguageStoreException('Could not create database directory: ' . $dir);
            }
        }

        $this->fallbackLanguage = $this->safeLanguage($fallbackLanguage);

        $this->db = new PDO('sqlite:' . $dbFile);
        $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->db->exec('PRAGMA journal_mode = WAL');
        $this->db->exec('PRAGMA busy_timeout = 5000');

        $this->init();
    }

    private function init()
    {
        $this->db->exec(
            'CREATE TABLE IF NOT EXISTS app_translations (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                translation_key TEXT NOT NULL,
                language TEXT NOT NULL,
                text TEXT NOT NULL,
                created_at INTEGER NOT NULL,
                updated_at INTEGER NOT NULL,
                UNIQUE(translation_key, language)
            )'
        );

        $this->db->exec(
            'CREATE INDEX IF NOT EXISTS idx_app_translations_language
             ON app_translations(language, translation_key)'
        );
    }

    public function translate($key, $language, $fallback = null)
    {
        $key = $this->safeKey($key);
        $language = $this->safeLanguage($language);

        $text = $this->findText($key, $language);

        if ($text !== null) {
            return $text;
        }

        if ($language !== $this->fallbackLanguage) {
            $text = $this->findText($key, $this->fallbackLanguage);

            if ($text !== null) {
                return $text;
            }
        }

        return $fallback !== null ? (string)$fallback : $key;
    }

    public function setTranslation($key, $language, $text)
    {
        $key = $this->safeKey($key);
        $language = $this->safeLanguage($language);
        $text = (string)$text;
        $now = time();

        $stmt = $this->db->prepare(
            'INSERT INTO app_translations
             (translation_key, language, text, created_at, updated_at)
             VALUES
             (:translation_key, :language, :text, :created_at, :updated_at)
             ON CONFLICT(translation_key, language)
             DO UPDATE SET text = excluded.text, updated_at = excluded.updated_at'
        );

        $stmt->execute(array(
            ':translation_key' => $key,
            ':language' => $language,
            ':text' => $text,
            ':created_at' => $now,
            ':updated_at' => $now,
        ));
    }

    public function seedDefaults($translations)
    {
        foreach ($translations as $key => $byLanguage) {
            foreach ($byLanguage as $language => $text) {
                if (!$this->hasTranslation($key, $language)) {
                    $this->setTranslation($key, $language, $text);
                }
            }
        }
    }

    public function listTranslations($language = null)
    {
        if ($language !== null && $language !== '') {
            $stmt = $this->db->prepare(
                'SELECT translation_key, language, text, created_at, updated_at
                 FROM app_translations
                 WHERE language = :language
                 ORDER BY translation_key'
            );
            $stmt->execute(array(':language' => $this->safeLanguage($language)));
        } else {
            $stmt = $this->db->query(
                'SELECT translation_key, language, text, created_at, updated_at
                 FROM app_translations
                 ORDER BY translation_key, language'
            );
        }

        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    public function supportedLanguages()
    {
        return array('en', 'nl');
    }

    public function languageLabel($language)
    {
        if ($language === 'nl') {
            return 'Nederlands';
        }

        if ($language === 'en') {
            return 'English';
        }

        return $language;
    }

    private function findText($key, $language)
    {
        $stmt = $this->db->prepare(
            'SELECT text
             FROM app_translations
             WHERE translation_key = :translation_key
               AND language = :language'
        );
        $stmt->execute(array(
            ':translation_key' => $key,
            ':language' => $language,
        ));

        $row = $stmt->fetch(PDO::FETCH_ASSOC);

        return $row ? (string)$row['text'] : null;
    }

    private function hasTranslation($key, $language)
    {
        return $this->findText($this->safeKey($key), $this->safeLanguage($language)) !== null;
    }

    private function safeKey($key)
    {
        $key = trim((string)$key);

        if ($key === '') {
            throw new LanguageStoreException('Translation key is required.');
        }

        if (strlen($key) > 160) {
            throw new LanguageStoreException('Translation key is too long.');
        }

        return $key;
    }

    private function safeLanguage($language)
    {
        $language = strtolower(trim((string)$language));

        if (!preg_match('/^[a-z][a-z0-9_-]{1,15}$/', $language)) {
            throw new LanguageStoreException('Invalid language code.');
        }

        return $language;
    }
}