<?php
/**
 * TMDO_Export — Report export endpoints (v2.5.0 M14).
 *
 * Three export types：
 *   1. health  — wp_wpdo_audit op='health_check_daily' over last N days
 *   2. snapshots — wp_wpdo_snapshots metadata (no inline_blob payload)
 *   3. monthly — wpdo_monthly_summary_history (latest + up to 12 archives)
 *
 * Triggered via admin GET：tools.php?page=wp-data-optimizer&wpdo_export=health&format=csv&days=30
 * Capability: manage_options + nonce.
 *
 * Filenames：wpdo-{type}-{site_slug}-{YYYYMMDD}.{csv|json}
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

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

/**
 * Stateless static export handler.
 */
class TMDO_Export {

	public const NONCE = 'wpdo_export';

	/**
	 * Hook into admin_init to handle export requests.
	 *
	 * @return void
	 */
	public static function register(): void {
		add_action( 'admin_init', array( __CLASS__, 'maybe_handle' ), 1 );
	}

	/**
	 * Detect + serve an export request.
	 *
	 * @return void
	 */
	public static function maybe_handle(): void {
		if ( ! isset( $_GET['wpdo_export'] ) ) {
			return;
		}
		if ( ! TMDO_Capability::current_user_can_admin() ) {
			return;
		}
		if ( ! check_admin_referer( self::NONCE ) ) {
			return;
		}
		$type   = sanitize_key( wp_unslash( (string) $_GET['wpdo_export'] ) );
		$format = sanitize_key( wp_unslash( (string) ( $_GET['format'] ?? 'csv' ) ) );
		$days   = isset( $_GET['days'] ) ? max( 1, min( 365, (int) $_GET['days'] ) ) : 30;
		if ( ! in_array( $format, array( 'csv', 'json' ), true ) ) {
			$format = 'csv';
		}
		switch ( $type ) {
			case 'health':
				self::send_health( $format, $days );
				break;
			case 'snapshots':
				self::send_snapshots( $format );
				break;
			case 'monthly':
				self::send_monthly( $format );
				break;
		}
	}

	/**
	 * Build a download URL with nonce.
	 *
	 * @param string $type   health|snapshots|monthly.
	 * @param string $format csv|json.
	 * @param int    $days   For health only.
	 * @return string
	 */
	public static function url( string $type, string $format = 'csv', int $days = 30 ): string {
		$args = array(
			'page'        => '2meet-data-optimizer',
			'wpdo_export' => $type,
			'format'      => $format,
		);
		if ( 'health' === $type ) {
			$args['days'] = $days;
		}
		return wp_nonce_url( add_query_arg( $args, admin_url( 'tools.php' ) ), self::NONCE );
	}

	// ─── handlers ──────────────────────────────────────────────────────

	/**
	 * Send health export.
	 *
	 * @param string $format csv|json.
	 * @param int    $days   Number of days to include.
	 * @return void
	 */
	private static function send_health( string $format, int $days ): void {
		global $wpdb;
		$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
			)
		);
		$rows   = array();
		if ( 1 === $exists ) {
			$raw = (array) $wpdb->get_results(
				$wpdb->prepare( // phpcs:ignore WordPress.DB
					// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- {$audit} is a trusted table name via $wpdb->prefix
					"SELECT ts, op, value_after FROM `{$audit}` WHERE op = 'health_check_daily' AND ts >= DATE_SUB(UTC_TIMESTAMP(), INTERVAL %d DAY) ORDER BY ts DESC",
					$days
				),
				ARRAY_A
			);
			foreach ( $raw as $r ) {
				$ctx = isset( $r['value_after'] ) ? json_decode( (string) $r['value_after'], true ) : array();
				if ( ! is_array( $ctx ) ) {
					$ctx = array();
				}
				$rows[] = array(
					'ts'                       => (string) $r['ts'],
					'critical'                 => (int) ( $ctx['critical'] ?? 0 ),
					'recommended'              => (int) ( $ctx['recommended'] ?? 0 ),
					'duration_ms'              => (int) ( $ctx['duration_ms'] ?? 0 ),
					'autoload_kb'              => (int) ( $ctx['autoload_kb'] ?? 0 ),
					'conflicts'                => (int) ( $ctx['conflicts'] ?? 0 ),
					'module_suggestions_count' => (int) ( $ctx['module_suggestions_count'] ?? 0 ),
				);
			}
		}
		$headers = array( 'ts', 'critical', 'recommended', 'duration_ms', 'autoload_kb', 'conflicts', 'module_suggestions_count' );
		self::respond( $format, 'health', $headers, $rows );
	}

	/**
	 * Send snapshots export.
	 *
	 * @param string $format csv|json.
	 * @return void
	 */
	private static function send_snapshots( string $format ): void {
		global $wpdb;
		$snap   = $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',
				$snap
			)
		);
		$rows   = array();
		if ( 1 === $exists ) {
			$rows = (array) $wpdb->get_results(
				"SELECT snapshot_id, trigger_type, size_bytes, row_count, storage, file_path, file_sha256, notes, created_at, expires_at FROM `{$snap}` ORDER BY created_at DESC", // phpcs:ignore WordPress.DB
				ARRAY_A
			);
		}
		$headers = array( 'snapshot_id', 'trigger_type', 'size_bytes', 'row_count', 'storage', 'file_path', 'file_sha256', 'notes', 'created_at', 'expires_at' );
		self::respond( $format, 'snapshots', $headers, $rows );
	}

	/**
	 * Send monthly summary export.
	 *
	 * @param string $format csv|json.
	 * @return void
	 */
	private static function send_monthly( string $format ): void {
		$latest  = (array) get_option( 'wpdo_monthly_summary_latest', array() );
		$history = (array) get_option( 'wpdo_monthly_summary_history', array() );
		$all     = array();
		if ( ! empty( $latest ) ) {
			$all[] = $latest;
		}
		foreach ( $history as $h ) {
			if ( is_array( $h ) ) {
				$all[] = $h;
			}
		}
		if ( 'json' === $format ) {
			self::respond_json( 'monthly', $all );
			return;
		}
		// Flatten for CSV — top-level metric only.
		$rows = array();
		foreach ( $all as $row ) {
			$health = (array) ( $row['health'] ?? array() );
			$snap   = (array) ( $row['snapshots'] ?? array() );
			$rows[] = array(
				'period_start'    => (string) ( $row['period_start'] ?? '' ),
				'period_end'      => (string) ( $row['period_end'] ?? '' ),
				'generated_at'    => (string) ( $row['generated_at'] ?? '' ),
				'health_total'    => (int) ( $health['total'] ?? 0 ),
				'health_success'  => (int) ( $health['success'] ?? 0 ),
				'health_critical' => (int) ( $health['critical'] ?? 0 ),
				'snapshots_total' => (int) ( $snap['total'] ?? 0 ),
				'snapshots_bytes' => (int) ( $snap['total_bytes'] ?? 0 ),
				'autoload_size'   => (int) ( $row['autoload_size'] ?? 0 ),
			);
		}
		$headers = array( 'period_start', 'period_end', 'generated_at', 'health_total', 'health_success', 'health_critical', 'snapshots_total', 'snapshots_bytes', 'autoload_size' );
		self::respond_csv( 'monthly', $headers, $rows );
	}

	// ─── output helpers ────────────────────────────────────────────────

	/**
	 * Dispatch to csv or json responder.
	 *
	 * @param string $format  csv|json.
	 * @param string $type    Export type slug.
	 * @param array  $headers Column headers.
	 * @param array  $rows    Data rows.
	 * @return void
	 */
	private static function respond( string $format, string $type, array $headers, array $rows ): void {
		if ( 'json' === $format ) {
			self::respond_json( $type, $rows );
			return;
		}
		self::respond_csv( $type, $headers, $rows );
	}

	/**
	 * Send CSV response.
	 *
	 * @param string $type    Export type slug.
	 * @param array  $headers Column headers.
	 * @param array  $rows    Data rows.
	 * @return void
	 */
	private static function respond_csv( string $type, array $headers, array $rows ): void {
		$body = TMDO_CSV_Writer::build( $headers, $rows );
		self::send_attachment( $type, 'csv', 'text/csv; charset=UTF-8', $body );
	}

	/**
	 * Send JSON response.
	 *
	 * @param string $type Export type slug.
	 * @param array  $rows Data rows.
	 * @return void
	 */
	private static function respond_json( string $type, array $rows ): void {
		$body = wp_json_encode( $rows, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
		self::send_attachment( $type, 'json', 'application/json; charset=UTF-8', (string) $body );
	}

	/**
	 * Send file attachment response.
	 *
	 * @param string $type Export type slug.
	 * @param string $ext  File extension.
	 * @param string $mime MIME type.
	 * @param string $body File body content.
	 * @return void
	 */
	private static function send_attachment( string $type, string $ext, string $mime, string $body ): void {
		$site_slug = sanitize_title( (string) get_option( 'blogname', 'site' ) ) ?: 'site';
		$filename  = sprintf( 'wpdo-%s-%s-%s.%s', $type, $site_slug, gmdate( 'Ymd' ), $ext );
		nocache_headers();
		header( 'Content-Type: ' . $mime );
		header( 'Content-Disposition: attachment; filename="' . $filename . '"' );
		header( 'Content-Length: ' . strlen( $body ) );
		echo $body; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		exit;
	}
}