<?php
/**
 * TMDO_Monthly_Summary — 30-day rollup report (v2.4.0 M11).
 *
 * Generates a monthly executive summary covering：
 *   - Health success / fail / rate-limit ratios over last 30 days
 *   - Zone size growth (deltas from 30 days ago snapshot if available)
 *   - Per-module FSM trajectory (who promoted, who rolled back)
 *   - Snapshot retention overview (count, oldest, newest)
 *
 * Hooks the existing `wpdo_health_snapshot_monthly` action (Core line ~489)
 * so it runs once per month at 03:00 UTC on the 1st. Output：
 *   1. Persisted to wp_wpdo_audit (op='monthly_summary').
 *   2. Stored as wp_options.wpdo_monthly_summary_latest (autoload=no).
 *   3. Rendered on the admin Doctor tab "📅 Monthly Summary" sub-section.
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

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

/**
 * Monthly summary aggregator.
 */
class TMDO_Monthly_Summary {

	public const OPTION_LATEST = 'wpdo_monthly_summary_latest';

	/**
	 * Hook into Core's existing monthly cron.
	 *
	 * @return void
	 */
	public static function register(): void {
		add_action( 'wpdo_health_snapshot_monthly', array( __CLASS__, 'generate' ), 20 );
	}

	/**
	 * Build + persist the monthly summary.
	 *
	 * @return array Summary structure.
	 */
	public static function generate(): array {
		$started_at             = microtime( true );
		$summary                = array(
			'period_start'   => gmdate( 'Y-m-d H:i:s', strtotime( '-30 days' ) ),
			'period_end'     => gmdate( 'Y-m-d H:i:s' ),
			'health'         => self::aggregate_health(),
			'fsm_trajectory' => self::aggregate_fsm(),
			'snapshots'      => self::aggregate_snapshots(),
			'zone_growth'    => self::aggregate_zone_growth(),
			'autoload_size'  => self::measure_autoload(),
			'duration_ms'    => 0,
			'generated_at'   => gmdate( 'Y-m-d H:i:s' ),
		);
		$summary['duration_ms'] = (int) round( ( microtime( true ) - $started_at ) * 1000 );

		update_option( self::OPTION_LATEST, $summary, false );

		// v2.5.0 M14: archive into history (max 12 entries).
		$history = (array) get_option( 'wpdo_monthly_summary_history', array() );
		array_unshift( $history, $summary );
		$history = array_slice( $history, 0, 12 );
		update_option( 'wpdo_monthly_summary_history', $history, false );

		if ( class_exists( 'TMDO_Logger' ) ) {
			TMDO_Logger::info(
				'monthly_summary',
				array(
					'health_success'  => (int) ( $summary['health']['success'] ?? 0 ),
					'health_critical' => (int) ( $summary['health']['critical'] ?? 0 ),
					'fsm_promotions'  => count( $summary['fsm_trajectory']['promotions'] ?? array() ),
					'fsm_rollbacks'   => count( $summary['fsm_trajectory']['rollbacks'] ?? array() ),
					'snapshots_total' => (int) ( $summary['snapshots']['total'] ?? 0 ),
					'autoload_kb'     => (int) round( ( $summary['autoload_size'] ?? 0 ) / 1024 ),
				)
			);
		}

		do_action( 'wpdo/monthly_summary_generated', $summary );
		return $summary;
	}

	/**
	 * Read the latest summary (from wp_options).
	 *
	 * @return array|null
	 */
	public static function get_latest(): ?array {
		$v = get_option( self::OPTION_LATEST );
		return is_array( $v ) ? $v : null;
	}

	// ─── private ────────────────────────────────────────────────────

	/**
	 * Aggregate health-check audit log entries from last 30 days.
	 *
	 * @return array {success:int, recommended:int, critical:int, total:int}
	 */
	private static function aggregate_health(): array {
		global $wpdb;
		$out = array(
			'success'     => 0,
			'recommended' => 0,
			'critical'    => 0,
			'total'       => 0,
		);

		// wp_wpdo_audit may not exist on early v1.x installs; check first.
		$audit  = $wpdb->prefix . 'wpdo_audit';
		$exists = (int) $wpdb->get_var(
			$wpdb->prepare( // phpcs:ignore WordPress.DB
				'SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = %s',
				$audit
			)
		);
		if ( 0 === $exists ) {
			return $out;
		}
		// Health check audit rows have op='health_check_daily'.
		$rows = (array) $wpdb->get_results( "SELECT * FROM `{$audit}` WHERE op = 'health_check_daily' AND ts >= DATE_SUB(UTC_TIMESTAMP(), INTERVAL 30 DAY)", ARRAY_A ); // phpcs:ignore WordPress.DB
		foreach ( $rows as $r ) {
			$ctx = isset( $r['value_after'] ) ? json_decode( (string) $r['value_after'], true ) : null;
			if ( ! is_array( $ctx ) ) {
				continue;
			}
			$crit = (int) ( $ctx['critical'] ?? 0 );
			$rec  = (int) ( $ctx['recommended'] ?? 0 );
			++$out['total'];
			if ( $crit > 0 ) {
				++$out['critical'];
			} elseif ( $rec > 0 ) {
				++$out['recommended'];
			} else {
				++$out['success'];
			}
		}
		return $out;
	}

	/**
	 * Best-effort FSM trajectory: which modules changed state in the last 30
	 * days. Reads `wpdo_fsm_state_entered` + current state.
	 *
	 * @return array {promotions:array, rollbacks:array, stationary:array}
	 */
	private static function aggregate_fsm(): array {
		$out = array(
			'promotions' => array(),
			'rollbacks'  => array(),
			'stationary' => array(),
		);
		if ( ! class_exists( 'TMDO_Feature_Flags' ) ) {
			return $out;
		}
		$entered = (array) get_option( 'wpdo_fsm_state_entered', array() );
		$now     = time();
		foreach ( TMDO_Feature_Flags::all() as $module => $state ) {
			$ts       = isset( $entered[ $module ]['entered_at'] ) ? strtotime( (string) $entered[ $module ]['entered_at'] . ' UTC' ) : 0;
			$age_days = $ts > 0 ? (int) floor( ( $now - $ts ) / DAY_IN_SECONDS ) : null;

			if ( $ts > 0 && ( $now - $ts ) <= ( 30 * DAY_IN_SECONDS ) ) {
				// Recently changed — bucket by direction.
				if ( 'idle' === $state ) {
					$out['rollbacks'][ $module ] = array(
						'state'         => $state,
						'days_in_state' => $age_days,
					);
				} else {
					$out['promotions'][ $module ] = array(
						'state'         => $state,
						'days_in_state' => $age_days,
					);
				}
			} else {
				$out['stationary'][ $module ] = array(
					'state'         => $state,
					'days_in_state' => $age_days,
				);
			}
		}
		return $out;
	}

	/**
	 * Aggregate snapshot retention stats from the snapshots table.
	 *
	 * @return array {total:int, oldest:string|null, newest:string|null, total_bytes:int}
	 */
	private static function aggregate_snapshots(): array {
		global $wpdb;
		$table  = $wpdb->prefix . 'wpdo_snapshots';
		$exists = (int) $wpdb->get_var(
			$wpdb->prepare( // phpcs:ignore WordPress.DB
				'SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = %s',
				$table
			)
		);
		if ( 0 === $exists ) {
			return array(
				'total'       => 0,
				'oldest'      => null,
				'newest'      => null,
				'total_bytes' => 0,
			);
		}
		$row = $wpdb->get_row( "SELECT COUNT(*) AS c, MIN(created_at) AS oldest, MAX(created_at) AS newest, COALESCE(SUM(size_bytes),0) AS bytes FROM `{$table}`", ARRAY_A ); // phpcs:ignore WordPress.DB
		return array(
			'total'       => (int) ( $row['c'] ?? 0 ),
			'oldest'      => isset( $row['oldest'] ) ? (string) $row['oldest'] : null,
			'newest'      => isset( $row['newest'] ) ? (string) $row['newest'] : null,
			'total_bytes' => (int) ( $row['bytes'] ?? 0 ),
		);
	}

	/**
	 * Per-zone row count snapshot. Compares to previous month's value when
	 * available (delta_rows positive = growth).
	 *
	 * @return array<string,array>
	 */
	private static function aggregate_zone_growth(): array {
		// Use historical site_metrics when available — avoids live COUNT(*) on large tables
		// and provides a 30-day delta (current − oldest snapshot).
		if ( class_exists( 'TMDO_Site_Metrics_Collector' ) ) {
			$latest = TMDO_Site_Metrics_Collector::get_latest_snapshot();
			if ( ! empty( $latest ) ) {
				// Get oldest snapshot within 30 days for delta calculation.
				$keys_of_interest = array( 'eav.postmeta_rows', 'flat.hot_rows', 'flat.cold_rows', 'flat.warm_rows', 'custom_tables.total_rows' );
				$out              = array();
				foreach ( $keys_of_interest as $mk ) {
					if ( ! isset( $latest[ $mk ] ) ) {
						continue;
					}
					$history    = TMDO_Site_Metrics_Collector::get_history( $mk, 30 );
					$oldest     = ! empty( $history ) ? (int) $history[0]['value'] : null;
					$current    = (int) $latest[ $mk ];
					$out[ $mk ] = array(
						'rows'       => $current,
						'delta_rows' => null !== $oldest ? $current - $oldest : null,
					);
				}
				return $out;
			}
		}

		// Fallback: live COUNT(*) for warm + archive tables (pre-v2.6.2 installs).
		global $wpdb;
		$out  = array();
		$keys = array( 'wpdo_warm', 'wpdo_archive' );
		foreach ( $keys as $slug ) {
			$table  = $wpdb->prefix . $slug;
			$exists = (int) $wpdb->get_var(
				$wpdb->prepare( // phpcs:ignore WordPress.DB
					'SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = %s',
					$table
				)
			);
			if ( 0 === $exists ) {
				continue;
			}
			$count        = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$table}`" ); // phpcs:ignore WordPress.DB
			$out[ $slug ] = array(
				'rows'       => $count,
				'delta_rows' => null,
			);
		}
		return $out;
	}

	/**
	 * Return the total byte size of autoloaded options.
	 *
	 * @return int Bytes in autoloaded options.
	 */
	private static function measure_autoload(): int {
		global $wpdb;
		return (int) $wpdb->get_var( "SELECT COALESCE(SUM(LENGTH(option_value)),0) FROM `{$wpdb->options}` WHERE autoload = 'yes'" ); // phpcs:ignore WordPress.DB
	}
}