<?php
/**
 * Session, Visitor and License management for Agentorie Chat.
 *
 * @package    Agentorie_Chat
 * @subpackage Agentorie_Chat/includes
 * @since      1.0.0
 */

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

/**
 * Session class.
 *
 * @since 1.0.0
 */
class Agentorie_Session {

	/**
	 * Singleton instance.
	 *
	 * @var Agentorie_Session|null
	 */
	private static $instance = null;

	/**
	 * Current session ID.
	 *
	 * @var string
	 */
	private $session_id = '';

	/**
	 * Session data array.
	 *
	 * @var array
	 */
	private $data = array();

	/**
	 * Transient key for license cache.
	 *
	 * @var string
	 */
	const LICENSE_CACHE_KEY = 'agentorie_chat_license_data';

	/**
	 * Get singleton instance.
	 *
	 * @since 1.0.0
	 * @return Agentorie_Session
	 */
	public static function get_instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Private constructor to enforce singleton.
	 *
	 * @since 1.0.0
	 */
	private function __construct() {
	}

	/**
	 * Load session data.
	 *
	 * @since 1.0.0
	 * @param string $session_id Optional session ID.
	 * @return Agentorie_Session
	 */
	public function load( $session_id = '' ) {
		if ( empty( $session_id ) ) {
			$session_id = self::generate_session_id();
		}

		$this->session_id = $session_id;
		$data             = get_transient( 'agentorie_chat_session_' . $this->session_id );

		if ( false !== $data && is_array( $data ) ) {
			$this->data = $data;
		} else {
			$this->data = $this->get_default_data();
		}

		return $this;
	}

	/**
	 * Generate a unique session ID.
	 *
	 * @since 1.0.0
	 * @return string Generated session ID.
	 */
	public static function generate_session_id() {
		return time() . '000_' . wp_generate_password( 9, false, false );
	}

	/**
	 * Validate session ID format.
	 *
	 * @since 1.0.0
	 * @param string $session_id Session ID to validate.
	 * @return bool True if valid.
	 */
	public static function validate_session_id( $session_id ) {
		if ( preg_match( '/^[0-9]{13}_[a-z0-9]{9}$/i', $session_id ) ) {
			return true;
		}
		if ( preg_match( '/^[a-f0-9]{32}$/i', $session_id ) ) {
			return true;
		}
		if ( preg_match( '/^[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}$/i', $session_id ) ) {
			return true;
		}
		return false;
	}

	/**
	 * Get default session data.
	 *
	 * @since 1.0.0
	 * @return array Default data array.
	 */
	private function get_default_data() {
		return array(
			'session_id'         => $this->session_id,
			'visitor_id'         => '',
			'visitor_ip'         => self::get_client_ip(),
			'visitor_country'    => '',
			'current_url'        => '',
			'page_title'         => '',
			'referrer'           => '',
			'user_agent'         => self::get_user_agent(),
			'is_active'          => true,
			'admin_takeover'     => false,
			'admin_user_id'      => null,
			'human_requested'    => false,
			'negotiate_detected' => false,
			'unread_count'       => 0,
			'messages_count'     => 0,
			'last_message'       => '',
			'last_activity'      => current_time( 'mysql' ),
			'created_at'         => current_time( 'mysql' ),
		);
	}

	/**
	 * Save session data to transient.
	 *
	 * @since 1.0.0
	 * @return bool True on success.
	 */
	public function save() {
		$this->data['last_activity'] = current_time( 'mysql' );
		$retention_hours             = agentorie_chat_get_setting( 'conversation_retention_hours', 6 );
		$expiration                  = $retention_hours * HOUR_IN_SECONDS;
		return set_transient( 'agentorie_chat_session_' . $this->session_id, $this->data, $expiration );
	}

	/**
	 * Get current session ID.
	 *
	 * @since 1.0.0
	 * @return string Session ID.
	 */
	public function get_session_id() {
		return $this->session_id;
	}

	/**
	 * Get a session data value.
	 *
	 * @since 1.0.0
	 * @param string $key     Data key.
	 * @param mixed  $default_value Default value.
	 * @return mixed Value or default.
	 */
	public function get( $key, $default_value = null ) {
		return isset( $this->data[ $key ] ) ? $this->data[ $key ] : $default_value;
	}

	/**
	 * Set a session data value.
	 *
	 * @since 1.0.0
	 * @param string $key   Data key.
	 * @param mixed  $value Value to set.
	 * @return void
	 */
	public function set( $key, $value ) {
		$this->data[ $key ] = $value;
	}

	/**
	 * Get all session data.
	 *
	 * @since 1.0.0
	 * @return array Session data.
	 */
	public function get_all() {
		return $this->data;
	}

	/**
	 * Update multiple session data values.
	 *
	 * @since 1.0.0
	 * @param array $data Data to update.
	 * @return void
	 */
	public function update( $data ) {
		foreach ( $data as $key => $value ) {
			$this->data[ $key ] = $value;
		}
	}

	/**
	 * Update visitor information.
	 *
	 * @since 1.0.0
	 * @param string|null $visitor_id  Visitor ID.
	 * @param string|null $current_url Current page URL.
	 * @param string|null $page_title  Page title.
	 * @return void
	 */
	public function update_visitor_info( $visitor_id, $current_url, $page_title ) {
		if ( null !== $visitor_id && self::validate_visitor_id( $visitor_id ) ) {
			$this->data['visitor_id'] = sanitize_text_field( $visitor_id );
		}
		if ( null !== $current_url ) {
			$this->data['current_url'] = esc_url_raw( substr( $current_url, 0, 500 ) );
		}
		if ( null !== $page_title ) {
			$this->data['page_title'] = sanitize_text_field( substr( $page_title, 0, 255 ) );
		}
	}

	/**
	 * Set admin takeover status.
	 *
	 * @since 1.0.0
	 * @param bool     $takeover Whether admin has taken over.
	 * @param int|null $admin_id Admin user ID.
	 * @return void
	 */
	public function set_admin_takeover( $takeover, $admin_id = null ) {
		$this->data['admin_takeover'] = $takeover;
		$this->data['admin_user_id']  = $takeover ? $admin_id : null;
		if ( $takeover ) {
			$this->data['human_requested']    = false;
			$this->data['negotiate_detected'] = false;
		}
	}

	/**
	 * Check if admin has taken over.
	 *
	 * @since 1.0.0
	 * @return bool True if admin takeover is active.
	 */
	public function is_admin_takeover() {
		return (bool) ( isset( $this->data['admin_takeover'] ) ? $this->data['admin_takeover'] : false );
	}

	/**
	 * Get admin user ID.
	 *
	 * @since 1.0.0
	 * @return int|null Admin ID or null.
	 */
	public function get_admin_id() {
		return isset( $this->data['admin_user_id'] ) ? $this->data['admin_user_id'] : null;
	}

	/**
	 * Set human requested flag.
	 *
	 * @since 1.0.0
	 * @param bool $requested Whether human was requested.
	 * @return void
	 */
	public function set_human_requested( $requested ) {
		$this->data['human_requested'] = $requested;
	}

	/**
	 * Set negotiate detected flag.
	 *
	 * @since 1.0.0
	 * @param bool $detected Whether negotiation was detected.
	 * @return void
	 */
	public function set_negotiate_detected( $detected ) {
		$this->data['negotiate_detected'] = $detected;
	}

	/**
	 * Increment message count.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public function increment_messages() {
		$current                      = isset( $this->data['messages_count'] ) ? $this->data['messages_count'] : 0;
		$this->data['messages_count'] = $current + 1;
	}

	/**
	 * Set last message preview.
	 *
	 * @since 1.0.0
	 * @param string $message Message content.
	 * @return void
	 */
	public function set_last_message( $message ) {
		$this->data['last_message'] = sanitize_text_field( substr( $message, 0, 255 ) );
	}

	/**
	 * Destroy the session.
	 *
	 * @since 1.0.0
	 * @return bool True on success.
	 */
	public function destroy() {
		return delete_transient( 'agentorie_chat_session_' . $this->session_id );
	}

	/**
	 * Sync session data to database.
	 *
	 * @since 1.0.0
	 * @return bool True on success.
	 */
	public function sync_to_database() {
		return Agentorie_Database::update_session( $this->session_id, $this->data );
	}

	/**
	 * Get or create a session.
	 *
	 * @since 1.0.0
	 * @param string $session_id Session ID.
	 * @return Agentorie_Session Session instance.
	 */
	public static function get_or_create( $session_id ) {
		if ( ! self::validate_session_id( $session_id ) ) {
			$session_id = self::generate_session_id();
		}

		$instance   = self::get_instance()->load( $session_id );
		$db_session = Agentorie_Database::get_or_create_session( $session_id, $instance->get_all() );

		// Synchronize critical flags from database to transient.
		// Database is source of truth for admin_takeover (set by LiveChat admin).
		if ( $db_session && is_array( $db_session ) ) {
			$sync_fields = array( 'admin_takeover', 'admin_user_id', 'human_requested', 'negotiate_detected' );
			$needs_save  = false;

			foreach ( $sync_fields as $field ) {
				if ( isset( $db_session[ $field ] ) ) {
					$db_value      = $db_session[ $field ];
					$current_value = $instance->get( $field );

					// Convert to comparable types.
					if ( is_numeric( $db_value ) ) {
						$db_value = (bool) intval( $db_value );
					}
					if ( is_numeric( $current_value ) ) {
						$current_value = (bool) intval( $current_value );
					}

					// If DB has true and transient has false, sync from DB.
					if ( $db_value && ! $current_value ) {
						$instance->set( $field, $db_value );
						$needs_save = true;
					}
				}
			}

			// Save transient if we synced any fields.
			if ( $needs_save ) {
				$instance->save();
			}
		}

		return $instance;
	}

	/**
	 * Validate visitor ID format.
	 *
	 * @since 1.0.0
	 * @param string $visitor_id Visitor ID to validate.
	 * @return bool True if valid.
	 */
	public static function validate_visitor_id( $visitor_id ) {
		return (bool) preg_match( '/^[A-Za-z0-9]{8,12}$/i', $visitor_id );
	}

	/**
	 * Generate a visitor ID.
	 *
	 * Note: The visitor ID is managed client-side via JavaScript localStorage
	 * and sent with each request. This method provides a server-side fallback.
	 *
	 * @since 1.0.0
	 * @return string Visitor ID.
	 */
	public static function get_or_create_visitor_id() {
		return agentorie_chat_generate_visitor_id();
	}

	/**
	 * Get license data.
	 *
	 * @since 1.0.0
	 * @param bool $force_refresh Force refresh from API.
	 * @return array License data.
	 */
	public static function get_license( $force_refresh = false ) {
		if ( ! $force_refresh ) {
			$license = get_transient( self::LICENSE_CACHE_KEY );
			if ( false !== $license && is_array( $license ) ) {
				return $license;
			}
		}

		$license_key = agentorie_chat_get_setting( 'license_key', '' );

		if ( empty( $license_key ) ) {
			$license = self::get_free_license_data();
			set_transient( self::LICENSE_CACHE_KEY, $license, HOUR_IN_SECONDS );
			return $license;
		}

		if ( class_exists( 'Agentorie_API' ) ) {
			$response = Agentorie_API::check_license( $license_key );
			if ( ! is_wp_error( $response ) && isset( $response['license'] ) ) {
				set_transient( self::LICENSE_CACHE_KEY, $response['license'], HOUR_IN_SECONDS );
				update_option( 'agentorie_chat_license_backup', $response['license'] );
				return $response['license'];
			}
		}

		$cached = get_option( 'agentorie_chat_license_backup', null );
		if ( $cached ) {
			return $cached;
		}

		return self::get_free_license_data();
	}

	/**
	 * Get free license default data.
	 *
	 * @since 1.0.0
	 * @return array Free license data.
	 */
	private static function get_free_license_data() {
		return array(
			'plan'       => 'free',
			'status'     => 'active',
			'features'   => array( 'base_chat' ),
			'limits'     => array(
				'conversations_month' => 100,
				'faq_characters'      => 5000,
			),
			'expires_at' => null,
		);
	}

	/**
	 * Get license status.
	 *
	 * @since 1.0.0
	 * @return string License status.
	 */
	public static function get_license_status() {
		$license = self::get_license();
		return isset( $license['status'] ) ? $license['status'] : 'active';
	}

	/**
	 * Check if license is expired.
	 *
	 * @since 1.0.0
	 * @return bool True if expired.
	 */
	public static function is_license_expired() {
		$license = self::get_license();
		if ( empty( $license['expires_at'] ) ) {
			return false;
		}
		return strtotime( $license['expires_at'] ) < time();
	}

	/**
	 * Clear license cache.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public static function clear_license_cache() {
		delete_transient( self::LICENSE_CACHE_KEY );
	}

	/**
	 * Get client IP address.
	 *
	 * @since 1.0.0
	 * @return string IP address or empty string.
	 */
	public static function get_client_ip() {
		$ip_keys = array( 'HTTP_CF_CONNECTING_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_REAL_IP', 'REMOTE_ADDR' );

		foreach ( $ip_keys as $key ) {
			if ( ! empty( $_SERVER[ $key ] ) ) {
				$ip = sanitize_text_field( wp_unslash( $_SERVER[ $key ] ) );
				if ( false !== strpos( $ip, ',' ) ) {
					$ips = explode( ',', $ip );
					$ip  = trim( $ips[0] );
				}
				if ( filter_var( $ip, FILTER_VALIDATE_IP ) ) {
					return $ip;
				}
			}
		}

		return '';
	}

	/**
	 * Get user agent string.
	 *
	 * @since 1.0.0
	 * @return string User agent or empty string.
	 */
	public static function get_user_agent() {
		if ( isset( $_SERVER['HTTP_USER_AGENT'] ) ) {
			$user_agent = sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) );
			return substr( $user_agent, 0, 255 );
		}
		return '';
	}
}