<?php
/**
 * Database Size check.
 *
 * @package advanced-analytics
 *
 * @since 4.9.0
 */

declare(strict_types=1);

namespace ADVAN\Checks\Migration;

use ADVAN\Checks\Abstract_Check;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'ADVAN\Checks\Migration\Database_Size_Check' ) ) {

	/**
	 * Database Size check class.
	 *
	 * @since 4.9.0
	 */
	class Database_Size_Check extends Abstract_Check {

		/**
		 * Check identifier (slug).
		 *
		 * @var string Check identifier (slug).
		 *
		 * @since 4.9.0
		 */
		protected static string $id = 'database-size';

		/**
		 * Check category.
		 *
		 * @var string Check category.
		 *
		 * @since 4.9.0
		 */
		protected static string $category = 'resources';

		/**
		 * Check weight (1-10).
		 *
		 * @var int Check weight (1-10).
		 *
		 * @since 4.9.0
		 */
		protected static int $weight = 6;

		/**
		 * Check title (translatable).
		 *
		 * @return string Check title.
		 *
		 * @since 4.9.0
		 */
		public static function get_title(): string {
			return __( 'Database Size', '0-day-analytics' );
		}

		/**
		 * Check description (translatable).
		 *
		 * @return string Check description.
		 *
		 * @since 4.9.0
		 */
		public static function get_description(): string {
			return __( 'Checks database size for migration planning.', '0-day-analytics' );
		}

		/**
		 * Run the check.
		 *
		 * @return array Check result.
		 *
		 * @since 4.9.0
		 */
		public static function run(): array {
			global $wpdb;

			// Get database size - use COALESCE to handle NULL values.
			$tables = $wpdb->get_results(
				$wpdb->prepare(
					'SELECT table_name AS name,
				COALESCE(data_length, 0) + COALESCE(index_length, 0) AS "size",
				COALESCE(table_rows, 0) AS "rows"
				FROM information_schema.TABLES
				WHERE table_schema = %s
				AND table_name LIKE %s
				ORDER BY size DESC',
					DB_NAME,
					$wpdb->esc_like( $wpdb->prefix ) . '%'
				)
			);

			$total_size  = 0;
			$total_rows  = 0;
			$table_count = 0;
			$largest     = array();

			// If the query returned results, calculate sizes.
			if ( ! empty( $tables ) ) {
				foreach ( $tables as $table ) {
					$total_size += (int) $table->size;
					$total_rows += (int) $table->rows;
					++$table_count;

					if ( count( $largest ) < 5 ) {
						$largest[] = array(
							'name' => $table->name,
							'size' => static::format_bytes( (int) $table->size ),
							'rows' => static::format_number( (int) $table->rows ),
						);
					}
				}
			}

			// Fallback: If size is still 0, try alternative method.
			if ( 0 === $total_size && $table_count > 0 ) {
				$size_result = $wpdb->get_var(
					$wpdb->prepare(
						'SELECT SUM(COALESCE(data_length, 0) + COALESCE(index_length, 0))
					FROM information_schema.TABLES
					WHERE table_schema = %s',
						DB_NAME
					)
				);
				$total_size  = (int) $size_result;
			}

			// Second fallback: Count WordPress tables only (with prefix filter).
			// This handles edge cases where the first query returned no results.
			if ( 0 === $table_count ) {
				// Try again with explicit prefix filter - the first query may have failed.
				$prefix_pattern = $wpdb->esc_like( $wpdb->prefix ) . '%';
				$all_tables     = $wpdb->get_results(
					$wpdb->prepare(
						'SELECT table_name AS name,
					COALESCE(data_length, 0) + COALESCE(index_length, 0) AS size,
					COALESCE(table_rows, 0) AS rows
					FROM information_schema.TABLES
					WHERE table_schema = %s
					AND table_name LIKE %s
					ORDER BY size DESC',
						DB_NAME,
						$prefix_pattern
					)
				);

				if ( ! empty( $all_tables ) ) {
					foreach ( $all_tables as $table ) {
						$total_size += (int) $table->size;
						$total_rows += (int) $table->rows;
						++$table_count;

						if ( count( $largest ) < 5 ) {
							$largest[] = array(
								'name' => $table->name,
								'size' => static::format_bytes( $table->size ),
								'rows' => static::format_number( $table->rows ),
							);
						}
					}
				}
			}

			$size_mb = $total_size / 1024 / 1024;

			$details = array(
				'total_size'     => static::format_bytes( $total_size ),
				'size_mb'        => round( $size_mb, 2 ),
				'total_rows'     => static::format_number( $total_rows ),
				'table_count'    => $table_count,
				'largest_tables' => $largest,
			);

			if ( $size_mb > 1000 ) {
				return static::fail(
					'medium',
					sprintf(
					/* translators: %s: database size */
						__( 'Your database is %s, which is quite large. This will significantly increase migration time and may cause timeouts with some migration tools.', '0-day-analytics' ),
						static::format_bytes( $total_size )
					),
					__( 'Consider cleaning up old revisions, spam comments, and transients before migrating. Use a migration tool that handles large databases in chunks, or export/import via command line.', '0-day-analytics' ),
					$details
				);
			}

			if ( $size_mb > 500 ) {
				return static::warning(
					sprintf(
					/* translators: %s: database size */
						__( 'Your database is %s. This is manageable but may take longer to migrate. Consider cleaning up before migration.', '0-day-analytics' ),
						static::format_bytes( $total_size )
					),
					__( 'Clean up post revisions, spam, and expired transients to speed up migration. Tools like WP-Optimize can help.', '0-day-analytics' ),
					$details
				);
			}

			if ( $size_mb > 100 ) {
				return static::info(
					sprintf(
					/* translators: %s: database size */
						__( 'Your database is %s, which is a typical size for an established site. Standard migration tools should handle this without issues.', '0-day-analytics' ),
						static::format_bytes( $total_size )
					),
					$details
				);
			}

			return static::pass(
				sprintf(
				/* translators: %s: database size */
					__( 'Your database is %s, which is small and will migrate quickly with any standard migration method.', '0-day-analytics' ),
					static::format_bytes( $total_size )
				),
				$details
			);
		}
	}
}