<?php
/**
 * Saves the transfer-tuning fields on the Settings screen.
 *
 * @package Shiftora\Migration
 */

declare(strict_types=1);

namespace Shiftora\Migration;

use Shiftora\Support\HttpClient;
use WP_Error;

// Prevent direct file access.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Reads and writes the options a slow host or unreliable link is the reason to change.
 *
 * current() reports what a migration actually runs at, not the raw stored value:
 * `shiftora_chunk_size` can hold a value the engine treats as unset (see
 * DatabaseExporter::effective_chunk_size()).
 *
 * save() deletes the option when a submitted value equals the engine default, so an
 * untouched field does not pin a site to today's constants. A value matching what
 * the site already had is still stored; telling them apart would cost a read per save.
 */
final class TransferSettings {

	public const NONCE_ACTION = 'shiftora_transfer_settings';

	/** @var array<string, array{min:int, max:int, default:int}> Field name to its allowed range and engine default. */
	private const BOUNDS = [
		'shiftora_chunk_size'         => [
			'min'     => DatabaseExporter::MIN_EFFECTIVE_CHUNK_SIZE,
			'max'     => DatabaseExporter::MAX_CHUNK_SIZE,
			'default' => DatabaseExporter::DEFAULT_CHUNK_SIZE,
		],
		'shiftora_sql_byte_budget'    => [
			'min'     => 64 * 1024,
			'max'     => 32 * 1024 * 1024,
			'default' => DatabaseExporter::SQL_BYTE_BUDGET,
		],
		'shiftora_sql_encoded_budget' => [
			'min'     => 64 * 1024,
			'max'     => 32 * 1024 * 1024,
			'default' => DatabaseExporter::SQL_ENCODED_BUDGET,
		],
		'shiftora_request_timeout'    => [
			'min'     => 10,
			'max'     => 300,
			'default' => HttpClient::INSTALLED_DEFAULT_TIMEOUT,
		],
	];

		/**
		 * The current values, resolved the way a migration would read them.
		 *
		 * @return array{chunk_size:int, sql_byte_budget:int, sql_encoded_budget:int, request_timeout:int, ssl_verify:string}
		 */
	public static function current(): array {
		$raw_chunk_size = (int) get_option( 'shiftora_chunk_size', DatabaseExporter::DEFAULT_CHUNK_SIZE );

		return [
			'chunk_size'         => self::clamp( 'shiftora_chunk_size', DatabaseExporter::effective_chunk_size( $raw_chunk_size ) ),
			'sql_byte_budget'    => self::clamp( 'shiftora_sql_byte_budget', (int) get_option( 'shiftora_sql_byte_budget', DatabaseExporter::SQL_BYTE_BUDGET ) ),
			'sql_encoded_budget' => self::clamp( 'shiftora_sql_encoded_budget', (int) get_option( 'shiftora_sql_encoded_budget', DatabaseExporter::SQL_ENCODED_BUDGET ) ),
			'request_timeout'    => self::clamp( 'shiftora_request_timeout', (int) get_option( 'shiftora_request_timeout', HttpClient::INSTALLED_DEFAULT_TIMEOUT ) ),
			'ssl_verify'         => HttpClient::tls_mode( get_option( 'shiftora_ssl_verify', HttpClient::TLS_AUTO ) ),
		];
	}

	/**
	 * @return array{min:int, max:int}
	 */
	public static function bounds( string $field ): array {
		return [
			'min' => self::BOUNDS[ $field ]['min'],
			'max' => self::BOUNDS[ $field ]['max'],
		];
	}

		/**
		 * Keeps a value inside the field's HTML min/max so a stored value from outside
		 * the range (older version, a filter, WP-CLI) still renders as submittable.
		 */
	private static function clamp( string $field, int $value ): int {
		$range = self::BOUNDS[ $field ];

		return max( $range['min'], min( $range['max'], $value ) );
	}

	/**
	 * Every request field save() reads besides the nonce; the admin-post handler passes nothing else on.
	 *
	 * @return string[]
	 */
	public static function field_names(): array {
		return [ ...array_keys( self::BOUNDS ), 'shiftora_ssl_verify' ];
	}

		/**
		 * Validate and store the submitted fields.
		 *
		 * @param array<string, mixed> $request Submitted fields, i.e. $_POST.
		 *
		 * @return bool|WP_Error True when saved, otherwise why not.
		 */
	public function save( array $request ): bool|WP_Error {
		if ( ! current_user_can( 'manage_options' ) ) {
			return new WP_Error(
				'shiftora_settings_forbidden',
				__( 'You do not have permission to change this setting.', 'shiftora' )
			);
		}

		if ( ! wp_verify_nonce( sanitize_text_field( wp_unslash( (string) ( $request['_wpnonce'] ?? '' ) ) ), self::NONCE_ACTION ) ) {
			return new WP_Error(
				'shiftora_settings_forbidden',
				__( 'This request could not be verified. Please reload the page and try again.', 'shiftora' ),
				[ 'status' => 403 ]
			);
		}

		foreach ( self::BOUNDS as $field => $range ) {
			$raw = $request[ $field ] ?? null;

			if ( null === $raw || '' === trim( (string) $raw ) || ! is_numeric( $raw ) ) {
				continue; // Left blank: keep whatever is already stored.
			}

			$value = max( $range['min'], min( $range['max'], (int) $raw ) );

			if ( $value === $range['default'] ) {
				delete_option( $field );
			} else {
				update_option( $field, $value );
			}
		}

		// Auto is the default and is stored as no option; true is how "always" has been stored since the checkbox.
		$tls_mode = HttpClient::tls_mode( $request['shiftora_ssl_verify'] ?? null );
		if ( HttpClient::TLS_ALWAYS === $tls_mode ) {
			update_option( 'shiftora_ssl_verify', true );
		} elseif ( HttpClient::TLS_NEVER === $tls_mode ) {
			update_option( 'shiftora_ssl_verify', HttpClient::TLS_NEVER );
		} else {
			delete_option( 'shiftora_ssl_verify' );
		}

		return true;
	}
}