<?php

namespace Podlove\Modules;

abstract class Base
{
    /**
     * Stores information about module options.
     *
     * @var array
     */
    protected $options = [];

    protected function __construct()
    {
    }

    private function __clone()
    {
    }

    /**
     * All Modules are singletons.
     */
    public static function instance()
    {
        static $instances = [];

        $calledClass = get_called_class();

        if (!isset($instances[$calledClass])) {
            $instances[$calledClass] = new $calledClass();
        }

        return $instances[$calledClass];
    }

    /**
     * This will be called to load the module.
     *
     * Here hooks can be registered, files be loaded etc.
     * The module must not change any behavior before load() being called!
     */
    abstract public function load();

    /**
     * Fetch module names by iterating over module directories.
     *
     * @return array
     */
    public static function get_all_module_names()
    {
        $modules_dir = \Podlove\PLUGIN_DIR.'lib/modules/';
        $modules = [];

        if ($dhandle = opendir($modules_dir)) {
            while (false !== ($fname = readdir($dhandle))) {
                if (($fname != '.') && ($fname != '..') && is_dir($modules_dir.$fname)) {
                    $modules[] = $fname;
                }
            }
            closedir($dhandle);
        }

        return $modules;
    }

    /**
     * Fetch module names for active modules only.
     *
     * @return array
     */
    public static function get_active_module_names()
    {
        $modules = self::get_all_module_names();

        return array_merge(
            array_filter($modules, function ($module) {
                return Base::is_active($module);
            }),
            self::get_core_module_names()
        );
    }

    /**
     * Fetch module names for core modules only.
     *
     * @return array
     */
    public static function get_core_module_names()
    {
        return array_filter(self::get_all_module_names(), function ($module) {
            $class = self::get_class_by_module_name($module);

            return $class::is_core();
        });
    }

    /**
     * Get full class name for the main module class.
     *
     * @param string $module_name
     *
     * @return string
     */
    public static function get_class_by_module_name($module_name)
    {
        $class_name = podlove_snakecase_to_camelsnakecase($module_name);
        $namespace_name = podlove_camelsnakecase_to_camelcase($class_name);

        return "\\Podlove\\Modules\\{$namespace_name}\\{$class_name}";
    }

    public static function is_active($module_name)
    {
        $options = get_option('podlove_active_modules');

        return isset($options[$module_name]);
    }

    public static function activate($module_name)
    {
        $options = get_option('podlove_active_modules');
        if (!isset($options[$module_name])) {
            $options[$module_name] = 'on';
            update_option('podlove_active_modules', $options);
        }
    }

    /**
     * Is this module core functionality?
     *
     * Core modules are always-on and don't appear in modules list.
     *
     * @return bool
     */
    public static function is_core()
    {
        return false;
    }

    /**
     * Is this module visible in the modules list?
     *
     * Use this method to hide a module even if it's not a core module.
     *
     * @return bool
     */
    public static function is_visible()
    {
        return true;
    }

    public function get_module_url()
    {
        return \Podlove\PLUGIN_URL.'/lib/modules/'.$this->get_module_directory_name();
    }

    public static function deactivate($module_name)
    {
        $options = get_option('podlove_active_modules');
        if (isset($options[$module_name])) {
            unset($options[$module_name]);
            update_option('podlove_active_modules', $options);
        }
    }

    /**
     * Return public module name.
     *
     * @return string
     */
    public function get_module_name()
    {
        return $this->module_name;
    }

    /**
     * Return public module description.
     *
     * @return string
     */
    public function get_module_description()
    {
        return $this->module_description;
    }

    /**
     * Return public module group key.
     *
     * @return string
     */
    public function get_module_group()
    {
        return isset($this->module_group) ? $this->module_group : '';
    }

    /**
     * Return option name of the field where module options are stored.
     *
     * @return string
     */
    public function get_module_options_name()
    {
        return 'podlove_module_'.$this->get_module_directory_name();
    }

    /**
     * Return field of all module options.
     *
     * @return array
     */
    public function get_module_options()
    {
        return get_option($this->get_module_options_name(), []);
    }

    /**
     * Return value for a single module option.
     *
     * @param string $name
     * @param mixed  $default
     *
     * @return mixed
     */
    public function get_module_option($name, $default = null)
    {
        $options = $this->get_module_options();

        return isset($options[$name]) ? $options[$name] : $default;
    }

    /**
     * Set value for a single module option.
     *
     * @param string $name
     * @param mixed  $value
     */
    public function update_module_option($name, $value)
    {
        $options = $this->get_module_options();
        $options[$name] = $value;
        update_option($this->get_module_options_name(), $options);
    }

    public function register_option($name, $input_type, $args)
    {
        $this->options[$name] = [
            'input_type' => $input_type,
            'args' => $args,
        ];
    }

    public function get_registered_options()
    {
        return $this->options;
    }

    public static function is_module_settings_page()
    {
        // If I'm on the module page ...
        if (filter_input(INPUT_GET, 'page') == 'podlove_settings_modules_handle') {
            return true;
        }

        // ... or saving on the module page
        if (\Podlove\is_options_save_page()) {
            return true;
        }

        return false;
    }

    protected function get_module_class_name()
    {
        $fq_class_name = get_class($this);

        return substr($fq_class_name, strrpos($fq_class_name, '\\') + 1);
    }

    protected function get_module_namespace_name()
    {
        return podlove_camelsnakecase_to_camelcase($this->get_module_class_name());
    }

    protected function get_module_directory_name()
    {
        return strtolower($this->get_module_class_name());
    }
}