alpha version of requirement checker basic plugin info

https://trello.com/c/B7ovwoMv/2068-wp-loader

src/Basic_Requirement_Checker.php

+<?php
+
+/**
+ * Checks requirements for plugin
+ * have to be compatible with PHP 5.2.x
+ */
+class WPDesk_Basic_Requirement_Checker {
+    /** @var string */
+    private $plugin_name = '';
+
+    /** @var string */
+    private $plugin_file = '';
+
+    /** @var string */
+    private $min_php_version;
+
+    /** @var string */
+    private $min_wp_version;
+
+    /** @var array */
+    private $plugin_require;
+
+    /** @var array */
+    private $module_require;
+
+    /** @var array */
+    private $setting_require;
+
+    /** @var array */
+    private $notices;
+
+    /**
+     * @param string $plugin_file
+     * @param string $plugin_name
+     * @param string $php_version
+     * @param string $wp_version
+     */
+    public function __construct( $plugin_file, $plugin_name, $php_version, $wp_version ) {
+        $this->plugin_file = $plugin_file;
+        $this->plugin_name = $plugin_name;
+        $this->set_min_php_require( $php_version );
+        $this->set_min_wp_require( $wp_version );
+
+        $this->plugin_require  = array();
+        $this->module_require  = array();
+        $this->setting_require = array();
+        $this->notices         = array();
+    }
+
+    /**
+     * @param string $version
+     *
+     * @return $this
+     */
+    public function set_min_php_require( $version ) {
+        $this->min_php_version = $version;
+
+        return $this;
+    }
+
+    /**
+     * @param string $version
+     *
+     * @return $this
+     */
+    public function set_min_wp_require( $version ) {
+        $this->min_wp_version = $version;
+
+        return $this;
+    }
+
+    /**
+     * @param string $version
+     *
+     * @return $this
+     */
+    public function set_min_wc_require( $version ) {
+        $this->min_wc_version = $version;
+
+        return $this;
+    }
+
+    /**
+     * @param string $plugin_name
+     * @param string $nice_plugin_name Nice plugin name for better looks in notice
+     *
+     * @return $this
+     */
+    public function add_plugin_require( $plugin_name, $nice_plugin_name = null ) {
+        if ( is_null( $nice_plugin_name ) ) {
+            $this->plugin_require[ $plugin_name ] = $plugin_name;
+        } else {
+            $this->plugin_require[ $plugin_name ] = $nice_plugin_name;
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param string $module_name
+     * @param string $nice_name Nice module name for better looks in notice
+     *
+     * @return $this
+     */
+    public function add_php_module_require( $module_name, $nice_name = null ) {
+        if ( is_null( $nice_name ) ) {
+            $this->module_require[ $module_name ] = $module_name;
+        } else {
+            $this->module_require[ $module_name ] = $nice_name;
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param string $setting
+     * @param mixed $value
+     *
+     * @return $this
+     */
+    public function add_php_setting_require( $setting, $value ) {
+        $this->setting_require[ $setting ] = $value;
+
+        return $this;
+    }
+
+    /**
+     * @return bool
+     */
+    public function are_requirements_met() {
+        $this->notices = $this->prepare_requirement_notices();
+
+        return count( $this->notices ) === 0;
+    }
+
+    /**
+     * @return array
+     */
+    private function prepare_requirement_notices() {
+        $notices = array();
+        if ( ! $this->is_php_at_least( $this->min_php_version ) ) {
+            $notices[] = $this->prepare_notice_message( sprintf( __( 'The &#8220;%s&#8221; plugin cannot run on PHP versions older than %s. Please contact your host and ask them to upgrade.', 'wpdesk-plugin' ), esc_html( $this->plugin_name ), $this->min_php_version ) );
+        }
+        if ( ! $this->is_wp_at_least( $this->min_wp_version ) ) {
+            $notices[] = $this->prepare_notice_message( sprintf( __( 'The &#8220;%s&#8221; plugin cannot run on WordPress versions older than %s. Please update WordPress.', 'wpdesk-plugin' ), esc_html( $this->plugin_name ), $this->min_wp_version ) );
+        }
+        $notices = $this->append_plugin_require_notices( $notices );
+        $notices = $this->append_module_require_notices( $notices );
+        $notices = $this->append_settings_require_notices( $notices );
+
+        return $notices;
+    }
+
+    /**
+     * @param array $notices
+     *
+     * @return array
+     */
+    private function append_module_require_notices( $notices ) {
+        if ( count( $this->module_require ) > 0 ) {
+            foreach ( $this->module_require as $module_name => $nice_module_name ) {
+                if ( ! $this->is_module_active( $module_name ) ) {
+                    $notices[] = $this->prepare_notice_message( sprintf( __( 'The &#8220;%s&#8221; plugin cannot run without %s php module installed. Please contact your host and ask them to install %s.', 'wpdesk-plugin' ), esc_html( $this->plugin_name ), esc_html( basename( $nice_module_name ) ), esc_html( basename( $nice_module_name ) ) ) );
+                }
+            }
+        }
+
+        return $notices;
+    }
+
+    /**
+     * @param array $notices
+     *
+     * @return array
+     */
+    private function append_settings_require_notices( $notices ) {
+        if ( count( $this->setting_require ) > 0 ) {
+            foreach ( $this->setting_require as $setting => $value ) {
+                if ( ! $this->is_setting_set( $setting, $value ) ) {
+                    $notices[] = $this->prepare_notice_message( sprintf( __( 'The &#8220;%s&#8221; plugin cannot run without %s php setting set to %s. Please contact your host and ask them to set %s.', 'wpdesk-plugin' ), esc_html( $this->plugin_name ), esc_html( basename( $setting ) ), esc_html( basename( $value ) ), esc_html( basename( $setting ) ) ) );
+                }
+            }
+        }
+
+        return $notices;
+    }
+
+    /**
+     * @param array $notices
+     *
+     * @return array
+     */
+    private function append_plugin_require_notices( $notices ) {
+        if ( count( $this->plugin_require ) > 0 ) {
+            foreach ( $this->plugin_require as $plugin_name => $nice_plugin_name ) {
+                if ( ! $this->is_wp_plugin_active( $plugin_name ) ) {
+                    $notices[] = $this->prepare_notice_message( sprintf( __( 'The &#8220;%s&#8221; plugin cannot run without %s active. Please install and activate %s plugin.', 'wpdesk-plugin' ), esc_html( $this->plugin_name ), esc_html( basename( $nice_plugin_name ) ), esc_html( basename( $nice_plugin_name ) ) ) );
+                }
+            }
+        }
+
+        return $notices;
+    }
+
+    /**
+     * @param string $name
+     * @param mixed $value
+     *
+     * @return bool
+     */
+    public static function is_setting_set( $name, $value ) {
+        return ini_get( $name ) === strval( $value );
+    }
+
+    /**
+     * @param string $name
+     *
+     * @return bool
+     */
+    public static function is_module_active( $name ) {
+        return extension_loaded( $name );
+    }
+
+    /**
+     * @return void
+     */
+    public function disable_plugin_render_notice() {
+        add_action( 'admin_notices', array( $this, 'deactivate_action' ) );
+        add_action( 'admin_notices', array( $this, 'render_notices_action' ) );
+    }
+
+    /**
+     * Shoud be called as WordPress action
+     *
+     * @return void
+     */
+    public function render_notices_action() {
+        foreach ( $this->notices as $notice ) {
+            echo $notice;
+        }
+    }
+
+    /**
+     * Prepares message in html format
+     *
+     * @param string $message
+     *
+     * @return string
+     */
+    private function prepare_notice_message( $message ) {
+        return '<div class="error"><p>' . $message . '</p></div>';
+    }
+
+    /**
+     * @return void
+     */
+    public function deactivate_action() {
+        if ( isset( $this->plugin_file ) ) {
+            deactivate_plugins( plugin_basename( $this->plugin_file ) );
+        }
+    }
+
+    /**
+     * @param $min_version
+     *
+     * @return mixed
+     */
+    public static function is_php_at_least( $min_version ) {
+        return version_compare( phpversion(), $min_version, '>=' );
+    }
+
+    /**
+     * @param string $min_version
+     *
+     * @return bool
+     */
+    public static function is_wp_at_least( $min_version ) {
+        return version_compare( get_bloginfo( 'version' ), $min_version, '>=' );
+    }
+
+    /**
+     * Checks if plugin is active. Needs to be enabled in deferred way.
+     *
+     * @param string $plugin_file
+     *
+     * @return bool
+     */
+    public static function is_wp_plugin_active( $plugin_file ) {
+        $active_plugins = (array) get_option( 'active_plugins', array() );
+
+        if ( is_multisite() ) {
+            $active_plugins = array_merge( $active_plugins, get_site_option( 'active_sitewide_plugins', array() ) );
+        }
+
+        return in_array( $plugin_file, $active_plugins ) || array_key_exists( $plugin_file, $active_plugins );
+    }
+}