<?php

namespace InstagramAPI\Settings;

use Fbns\Client\Auth\DeviceAuth;
use Fbns\Client\AuthInterface;
use InstagramAPI\Exception\SettingsException;
use InstagramAPI\Utils;

/**
 * Advanced, modular settings storage engine.
 *
 * Connects to a StorageInterface and transfers data to/from the application,
 * with intelligent caching and data translation.
 *
 * @author SteveJobzniak (https://github.com/SteveJobzniak)
 */
class StorageHandler
{
    /**
     * Complete list of all settings that will be stored/retrieved persistently.
     *
     * This key list WILL be changed whenever we need to support new features,
     * so do NOT assume that it will stay the same forever.
     *
     * @var array
     */
    const PERSISTENT_KEYS = [
        'account_id', // The numerical UserPK ID of the account.
        'devicestring', // Which Android device they're identifying as.
        'device_id', // Hardware identifier.
        'phone_id', // Hardware identifier.
        'uuid', // Universally unique identifier.
        'advertising_id', // Google Play advertising ID.
        'session_id', // The user's current application session ID.
        'experiments', // Interesting experiment variables for this account.
        'fbns_auth', // Serialized auth credentials for FBNS.
        'fbns_token', // Serialized FBNS token.
        'last_fbns_token', // Tracks time elapsed since our last FBNS token refresh.
        'last_login', // Tracks time elapsed since our last login state refresh.
        'last_experiments', // Tracks time elapsed since our last experiments refresh.
        'datacenter', // Preferred data center (region-based).
        'presence_disabled', // Whether the presence feature has been disabled by user.
    ];

    /**
     * List of important settings to keep when erasing device-specific settings.
     *
     * Whenever we are told to erase all device-specific settings, we will clear
     * the values of all settings EXCEPT the keys listed here. It is therefore
     * VERY important to list ALL important NON-DEVICE specific settings here!
     *
     * @var array
     *
     * @see StorageHandler::eraseDeviceSettings()
     */
    const KEEP_KEYS_WHEN_ERASING_DEVICE = [
        'account_id', // We don't really need to keep this, but it's a good example.
    ];

    /**
     * Whitelist for experiments.
     *
     * We will save ONLY the experiments mentioned in this list.
     *
     * @var array
     */
    const EXPERIMENT_KEYS = [
        'ig_android_2fac',
        'ig_android_realtime_iris',
        'ig_android_skywalker_live_event_start_end',
        'ig_android_gqls_typing_indicator',
        'ig_android_upload_reliability_universe',
        'ig_android_photo_fbupload_universe',
        'ig_android_video_segmented_upload_universe',
        'ig_android_direct_video_segmented_upload_universe',
        'ig_android_reel_raven_video_segmented_upload_universe',
        'ig_android_ad_async_ads_universe',
        'ig_android_direct_inbox_presence',
        'ig_android_direct_thread_presence',
        'ig_android_mqtt_region_hint_universe',
        'ig_android_rtc_reshare',
    ];

    /**
     * Complete list of all supported callbacks.
     *
     * - "onCloseUser": Triggered before closing a user's storage (at script
     *   end or when switching to a different user). Can be used for bulk-saving
     *   data at the end of a user's session, to avoid constant micro-updates.
     */
    const SUPPORTED_CALLBACKS = [
        'onCloseUser',
    ];

    /** @var StorageInterface The active storage backend. */
    private $_storage;

    /** @var array Optional callback functions. */
    private $_callbacks;

    /** @var string Current Instagram username that all settings belong to. */
    private $_username;

    /** @var array Cache for the current user's key-value settings pairs. */
    private $_userSettings;

    /** @var string|null Location of the cookiefile if file-based jar wanted. */
    private $_cookiesFilePath;

    /**
     * Constructor.
     *
     * @param StorageInterface $storageInstance An instance of desired Storage.
     * @param array            $locationConfig  Configuration parameters for
     *                                          the storage backend location.
     * @param array            $callbacks       Optional callback functions.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function __construct(
        $storageInstance,
        array $locationConfig = [],
        array $callbacks = [])
    {
        if (!$storageInstance instanceof StorageInterface) {
            throw new SettingsException(
                'You must provide an instance of a StorageInterface class.'
            );
        }
        if (!is_array($locationConfig)) {
            throw new SettingsException(
                'The storage location configuration must be an array.'
            );
        }

        // Store any user-provided callbacks.
        $this->_callbacks = $callbacks;

        // Connect the storage instance to the user's desired storage location.
        $this->_storage = $storageInstance;
        $this->_storage->openLocation($locationConfig);
    }

    /**
     * Destructor.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function __destruct()
    {
        // The storage handler is being killed, so tell the location to close.
        if ($this->_username !== null) {
            $this->_triggerCallback('onCloseUser');
            $this->_storage->closeUser();
            $this->_username = null;
        }
        $this->_storage->closeLocation();
    }

    /**
     * Whether the storage backend contains a specific user.
     *
     * @param string $username The Instagram username.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return bool TRUE if user exists, otherwise FALSE.
     */
    public function hasUser(
        $username)
    {
        $this->_throwIfEmptyValue($username);

        return $this->_storage->hasUser($username);
    }

    /**
     * Move the internal data for a username to a new username.
     *
     * This function is important because of the fact that all per-user settings
     * in all Storage implementations are retrieved and stored via its Instagram
     * username, since their NAME is literally the ONLY thing we know about a
     * user before we have loaded their settings or logged in! So if you later
     * rename that Instagram account, it means that your old device settings
     * WON'T follow along automatically, since the new login username is seen
     * as a brand new user that isn't in the settings storage.
     *
     * This function conveniently tells your chosen Storage backend to move a
     * user's settings to a new name, so that they WILL be found again when you
     * later look for settings for your new name.
     *
     * Bonus guide for easily confused people: YOU must manually rename your
     * user on Instagram.com before you call this function. We don't do that.
     *
     * @param string $oldUsername The old name that settings are stored as.
     * @param string $newUsername The new name to move the settings to.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function moveUser(
        $oldUsername,
        $newUsername)
    {
        $this->_throwIfEmptyValue($oldUsername);
        $this->_throwIfEmptyValue($newUsername);

        if ($oldUsername === $this->_username
            || $newUsername === $this->_username) {
            throw new SettingsException(
                'Attempted to move settings to/from the currently active user.'
            );
        }

        $this->_storage->moveUser($oldUsername, $newUsername);
    }

    /**
     * Delete all internal data for a given username.
     *
     * @param string $username The Instagram username.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function deleteUser(
        $username)
    {
        $this->_throwIfEmptyValue($username);

        if ($username === $this->_username) {
            throw new SettingsException(
                'Attempted to delete the currently active user.'
            );
        }

        $this->_storage->deleteUser($username);
    }

    /**
     * Load all settings for a user from the storage and mark as current user.
     *
     * @param string $username The Instagram username.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function setActiveUser(
        $username)
    {
        $this->_throwIfEmptyValue($username);

        // If that user is already loaded, there's no need to do anything.
        if ($username === $this->_username) {
            return;
        }

        // If we're switching away from a user, tell the backend to close the
        // current user's storage (if it needs to do any special processing).
        if ($this->_username !== null) {
            $this->_triggerCallback('onCloseUser');
            $this->_storage->closeUser();
        }

        // Set the new user as the current user for this storage instance.
        $this->_username = $username;
        $this->_userSettings = [];
        $this->_storage->openUser($username);

        // Retrieve any existing settings for the user from the backend.
        $loadedSettings = $this->_storage->loadUserSettings();
        foreach ($loadedSettings as $key => $value) {
            // Map renamed old-school keys to new key names.
            if ($key == 'username_id') {
                $key = 'account_id';
            } elseif ($key == 'adid') {
                $key = 'advertising_id';
            }

            // Only keep values for keys that are still in use. Discard others.
            if (in_array($key, self::PERSISTENT_KEYS)) {
                // Cast all values to strings to ensure we only use strings!
                // NOTE: THIS CAST IS EXTREMELY IMPORTANT AND *MUST* BE DONE!
                $this->_userSettings[$key] = (string) $value;
            }
        }

        // Determine what type of cookie storage the backend wants for the user.
        // NOTE: Do NOT validate file existence, since we'll create if missing.
        $cookiesFilePath = $this->_storage->getUserCookiesFilePath();
        if ($cookiesFilePath !== null && (!is_string($cookiesFilePath) || !strlen($cookiesFilePath))) {
            $cookiesFilePath = null; // Disable since it isn't a non-empty string.
        }
        $this->_cookiesFilePath = $cookiesFilePath;
    }

    /**
     * Does a preliminary guess about whether the current user is logged in.
     *
     * Can only be executed after setActiveUser(). And the session it looks
     * for may be expired, so there's no guarantee that we are still logged in.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return bool TRUE if possibly logged in, otherwise FALSE.
     */
    public function isMaybeLoggedIn()
    {
        $this->_throwIfNoActiveUser();

        return $this->_storage->hasUserCookies()
                && !empty($this->get('account_id'));
    }

    /**
     * Erase all device-specific settings and all cookies.
     *
     * This is useful when assigning a new Android device to the account, upon
     * which it's very important that we erase all previous, device-specific
     * settings so that our account still looks natural to Instagram.
     *
     * Note that ALL cookies will be erased too, to clear out the old session.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function eraseDeviceSettings()
    {
        foreach (self::PERSISTENT_KEYS as $key) {
            if (!in_array($key, self::KEEP_KEYS_WHEN_ERASING_DEVICE)) {
                $this->set($key, ''); // Erase the setting.
            }
        }

        $this->setCookies(''); // Erase all cookies.
    }

    /**
     * Retrieve the value of a setting from the current user's memory cache.
     *
     * Can only be executed after setActiveUser().
     *
     * @param string $key Name of the setting.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return string|null The value as a string IF the setting exists AND is
     *                     a NON-EMPTY string. Otherwise NULL.
     */
    public function get(
        $key)
    {
        $this->_throwIfNoActiveUser();

        // Reject anything that isn't in our list of VALID persistent keys.
        if (!in_array($key, self::PERSISTENT_KEYS)) {
            throw new SettingsException(sprintf(
                'The settings key "%s" is not a valid persistent key name.',
                $key
            ));
        }

        // Return value if it's a NON-EMPTY string, otherwise return NULL.
        // NOTE: All values are cached as strings so no casting is needed.
        return (isset($this->_userSettings[$key])
                 && $this->_userSettings[$key] !== '')
                ? $this->_userSettings[$key]
                : null;
    }

    /**
     * Store a setting's value for the current user.
     *
     * Can only be executed after setActiveUser(). To clear the value of a
     * setting, simply pass in an empty string as value.
     *
     * @param string       $key   Name of the setting.
     * @param string|mixed $value The data to store. MUST be castable to string.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function set(
        $key,
        $value)
    {
        $this->_throwIfNoActiveUser();

        // Reject anything that isn't in our list of VALID persistent keys.
        if (!in_array($key, self::PERSISTENT_KEYS)) {
            throw new SettingsException(sprintf(
                'The settings key "%s" is not a valid persistent key name.',
                $key
            ));
        }

        // Reject null values, since they may be accidental. To unset a setting,
        // the caller must explicitly pass in an empty string instead.
        if ($value === null) {
            throw new SettingsException(
                'Illegal attempt to store null value in settings storage.'
            );
        }

        // Cast the value to string to ensure we don't try writing non-strings.
        // NOTE: THIS CAST IS EXTREMELY IMPORTANT AND *MUST* ALWAYS BE DONE!
        $value = (string) $value;

        // Check if the value differs from our storage (cached representation).
        // NOTE: This optimizes writes by only writing when values change!
        if (!array_key_exists($key, $this->_userSettings)
            || $this->_userSettings[$key] !== $value) {
            // The value differs, so save to memory cache and write to storage.
            $this->_userSettings[$key] = $value;
            $this->_storage->saveUserSettings($this->_userSettings, $key);
        }
    }

    /**
     * Whether the storage backend has cookies for the currently active user.
     *
     * Can only be executed after setActiveUser().
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return bool TRUE if cookies exist, otherwise FALSE.
     */
    public function hasCookies()
    {
        $this->_throwIfNoActiveUser();

        return $this->_storage->hasUserCookies();
    }

    /**
     * Get all cookies for the currently active user.
     *
     * Can only be executed after setActiveUser().
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return string|null A previously-stored, raw cookie data string
     *                     (non-empty), or NULL if no cookies exist for
     *                     the active user.
     */
    public function getCookies()
    {
        $this->_throwIfNoActiveUser();

        // Read the cookies via the appropriate backend method.
        $userCookies = null;
        if ($this->_cookiesFilePath === null) { // Backend storage.
            $userCookies = $this->_storage->loadUserCookies();
        } else { // Cookiefile on disk.
            if (empty($this->_cookiesFilePath)) { // Just for extra safety.
                throw new SettingsException(
                    'Cookie file format requested, but no file path provided.'
                );
            }

            // Ensure that the cookie file's folder exists and is writable.
            $this->_createCookiesFileDirectory();

            // Read the existing cookie jar file if it already exists.
            if (is_file($this->_cookiesFilePath)) {
                $rawData = file_get_contents($this->_cookiesFilePath);
                if ($rawData !== false) {
                    $userCookies = $rawData;
                }
            }
        }

        // Ensure that we'll always return NULL if no cookies exist.
        if ($userCookies !== null && !strlen($userCookies)) {
            $userCookies = null;
        }

        return $userCookies;
    }

    /**
     * Save all cookies for the currently active user.
     *
     * Can only be executed after setActiveUser(). Note that this function is
     * called frequently!
     *
     * NOTE: It is very important that the owner of this SettingsHandler either
     * continuously calls "setCookies", or better yet listens to the "closeUser"
     * callback to save all cookies in bulk to storage at the end of a session.
     *
     * @param string $rawData An encoded string with all cookie data. Use an
     *                        empty string to erase currently stored cookies.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    public function setCookies(
        $rawData)
    {
        $this->_throwIfNoActiveUser();
        $this->_throwIfNotString($rawData);

        if ($this->_cookiesFilePath === null) { // Backend storage.
            $this->_storage->saveUserCookies($rawData);
        } else { // Cookiefile on disk.
            if (strlen($rawData)) { // Update cookies (new value is non-empty).
                // Perform an atomic diskwrite, which prevents accidental
                // truncation if the script is ever interrupted mid-write.
                $this->_createCookiesFileDirectory(); // Ensures dir exists.
                $written = Utils::atomicWrite($this->_cookiesFilePath, $rawData);
                if ($written === false) {
                    throw new SettingsException(sprintf(
                        'The "%s" cookie file is not writable.',
                        $this->_cookiesFilePath
                    ));
                }
            } else { // Delete cookies (empty string).
                // Delete any existing cookie jar since the new data is empty.
                if (is_file($this->_cookiesFilePath) && !@unlink($this->_cookiesFilePath)) {
                    throw new SettingsException(sprintf(
                        'Unable to delete the "%s" cookie file.',
                        $this->_cookiesFilePath
                    ));
                }
            }
        }
    }

    /**
     * Ensures the whole directory path to the cookie file exists/is writable.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    protected function _createCookiesFileDirectory()
    {
        if ($this->_cookiesFilePath === null) {
            return;
        }

        $cookieDir = dirname($this->_cookiesFilePath); // Can be "." in case of CWD.
        if (!Utils::createFolder($cookieDir)) {
            throw new SettingsException(sprintf(
                'The "%s" cookie folder is not writable.',
                $cookieDir
            ));
        }
    }

    /**
     * Internal: Ensures that a parameter is a string.
     *
     * @param mixed $value The value to check.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    protected function _throwIfNotString(
        $value)
    {
        if (!is_string($value)) {
            throw new SettingsException('Parameter must be string.');
        }
    }

    /**
     * Internal: Ensures that a parameter is a non-empty string.
     *
     * @param mixed $value The value to check.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    protected function _throwIfEmptyValue(
        $value)
    {
        if (!is_string($value) || $value === '') {
            throw new SettingsException('Parameter must be non-empty string.');
        }
    }

    /**
     * Internal: Ensures that there is an active storage user.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    protected function _throwIfNoActiveUser()
    {
        if ($this->_username === null) {
            throw new SettingsException(
                'Called user-related function before setting the current storage user.'
            );
        }
    }

    /**
     * Internal: Triggers a callback.
     *
     * All callback functions are given the storage handler instance as their
     * one and only argument.
     *
     * @param string $cbName The name of the callback.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     */
    protected function _triggerCallback(
        $cbName)
    {
        // Reject anything that isn't in our list of VALID callbacks.
        if (!in_array($cbName, self::SUPPORTED_CALLBACKS)) {
            throw new SettingsException(sprintf(
                'The string "%s" is not a valid callback name.',
                $cbName
            ));
        }

        // Trigger the callback with a reference to our StorageHandler instance.
        if (isset($this->_callbacks[$cbName])) {
            try {
                $this->_callbacks[$cbName]($this);
            } catch (\Exception $e) {
                // Re-wrap anything that isn't already a SettingsException.
                if (!$e instanceof SettingsException) {
                    $e = new SettingsException($e->getMessage());
                }

                throw $e; // Re-throw;
            }
        }
    }

    /**
     * Process and save experiments.
     *
     * @param array $experiments
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return array A list of "good" experiments.
     */
    public function setExperiments(
        array $experiments)
    {
        $filtered = [];
        foreach (self::EXPERIMENT_KEYS as $key) {
            if (!isset($experiments[$key])) {
                continue;
            }
            $filtered[$key] = $experiments[$key];
        }
        $json = json_encode($filtered);
        $gzipped = base64_encode(zlib_encode($json, ZLIB_ENCODING_DEFLATE, 9));
        // We must compare gzipped with double encoded JSON.
        $doubleJson = json_encode($json);
        if (strlen($gzipped) < strlen($doubleJson)) {
            $serialized = 'Z'.$gzipped;
        } else {
            $serialized = 'J'.$json;
        }
        $this->set('experiments', $serialized);

        return $filtered;
    }

    /**
     * Return saved experiments.
     *
     * @throws \InstagramAPI\Exception\SettingsException
     *
     * @return array
     */
    public function getExperiments()
    {
        $experiments = $this->get('experiments');
        if ($experiments === null || !strlen($experiments)) {
            return [];
        }
        $format = $experiments[0];
        $experiments = substr($experiments, 1);
        switch ($format) {
            case 'Z':
                if (($experiments = base64_decode($experiments)) === false
                    || ($experiments = zlib_decode($experiments)) === false
                    || ($experiments = json_decode($experiments, true)) === null
                    || !is_array($experiments)
                ) {
                    return [];
                }
                break;
            case 'J':
                if (($experiments = json_decode($experiments, true)) === null
                    || !is_array($experiments)
                ) {
                    return [];
                }
                break;
            default:
                $experiments = [];
        }

        return $experiments;
    }

    /**
     * Save FBNS authorization.
     *
     * @param AuthInterface $auth
     */
    public function setFbnsAuth(
        AuthInterface $auth)
    {
        $this->set('fbns_auth', $auth);
    }

    /**
     * Get FBNS authorization.
     *
     * Will restore previously saved auth details if they exist. Otherwise it
     * creates random new authorization details.
     *
     * @return AuthInterface
     */
    public function getFbnsAuth()
    {
        $result = new DeviceAuth();

        try {
            $result->read($this->get('fbns_auth'));
        } catch (\Exception $e) {
        }

        return $result;
    }
}
