<?php
/**
 * Eventual hosted experiment registration, separate from local delivery.
 *
 * Only cron contacts the service. A temporary failure never changes a
 * committed experiment or its visitor-facing execution.
 *
 * @package abtestkit
 */

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

define( 'ABTESTKIT_CONNECTED_REGISTRATION_OPTION', 'abtestkit_connected_registration_state' );

/** One bounded, non-autoloaded map keyed by hashes of local test IDs. */
function abtestkit_connected_registration_state() : array {
    $state = get_option( ABTESTKIT_CONNECTED_REGISTRATION_OPTION, array() );
    return is_array( $state ) && isset( $state['records'] ) && is_array( $state['records'] ) ? $state : array( 'records' => array() );
}

function abtestkit_connected_registration_save( array $state ) : bool {
    update_option( ABTESTKIT_CONNECTED_REGISTRATION_OPTION, $state, false );
    return get_option( ABTESTKIT_CONNECTED_REGISTRATION_OPTION, null ) === $state;
}

function abtestkit_connected_registration_clear() : void {
    delete_option( ABTESTKIT_CONNECTED_REGISTRATION_OPTION );
}

/** Derive only the desired hosted state from a committed local registry row. */
function abtestkit_connected_registration_desired_state( ?array $test ) : string {
    if ( null === $test ) {
        return 'deleted';
    }
    $status = (string) ( $test['status'] ?? '' );
    if ( 'running' === $status ) {
        return 'active';
    }
    return in_array( $status, array( 'winner', 'complete' ), true ) ? 'complete' : 'paused';
}

/** Update the desired-state ledger only after a verified experiment write. */
function abtestkit_connected_registration_observe_change( array $before, array $after ) : void {
    if ( ! abtestkit_connected_platform_can_create_or_launch() ) {
        return;
    }
    $old = array();
    $new = array();
    foreach ( $before as $test ) {
        if ( is_array( $test ) && ! empty( $test['id'] ) ) {
            $old[ (string) $test['id'] ] = $test;
        }
    }
    foreach ( $after as $test ) {
        if ( is_array( $test ) && ! empty( $test['id'] ) ) {
            $new[ (string) $test['id'] ] = $test;
        }
    }
    $ledger = abtestkit_connected_registration_state();
    $changed = false;
    foreach ( $old + $new as $test_id => $unused ) {
        $previous = $old[ $test_id ] ?? null;
        $current = $new[ $test_id ] ?? null;
        if ( is_array( $previous ) && is_array( $current ) && $previous === $current ) {
            continue;
        }
        $desired = abtestkit_connected_registration_desired_state( $current );
        $key = hash( 'sha256', (string) $test_id );
        $record = $ledger['records'][ $key ] ?? null;
        if ( is_array( $record ) && $desired === ( $record['state'] ?? '' ) ) {
            continue;
        }
        if ( count( $ledger['records'] ) >= 5000 && ! is_array( $record ) ) {
            abtestkit_connected_collection_gap( 'registration_capacity' );
            continue;
        }
        $ref = abtestkit_connected_test_ref_record( (string) $test_id );
        if ( is_wp_error( $ref ) ) {
            abtestkit_connected_collection_gap( $ref->get_error_code() );
            continue;
        }
        $ledger['records'][ $key ] = array(
            'test_ref' => (string) $ref['test_ref'],
            'state' => $desired,
            'revision' => is_array( $record ) ? min( 2147483647, (int) $record['revision'] + 1 ) : 1,
            'confirmed_revision' => is_array( $record ) ? (int) ( $record['confirmed_revision'] ?? 0 ) : 0,
            'confirmed_site_ref' => is_array( $record ) ? (string) ( $record['confirmed_site_ref'] ?? '' ) : '',
        );
        $changed = true;
    }
    if ( $changed && ! abtestkit_connected_registration_save( $ledger ) ) {
        abtestkit_connected_collection_gap( 'registration_write_failed' );
    }
}

/** Repair missed observations and backfill at most 20 records per cron tick. */
function abtestkit_connected_registration_reconcile( array $ledger ) : array {
    $tests = get_option( 'abtestkit_page_tests', array() );
    if ( ! is_array( $tests ) ) {
        return $ledger;
    }
    $changed = 0;
    $seen = array();
    foreach ( $tests as $test ) {
        if ( ! is_array( $test ) || empty( $test['id'] ) ) {
            continue;
        }
        $test_id = (string) $test['id'];
        $key = hash( 'sha256', $test_id );
        $seen[ $key ] = true;
        if ( isset( $ledger['records'][ $key ] ) ) {
            $desired = abtestkit_connected_registration_desired_state( $test );
            if ( $desired !== ( $ledger['records'][ $key ]['state'] ?? '' ) && $changed < 20 ) {
                $ledger['records'][ $key ]['state'] = $desired;
                $ledger['records'][ $key ]['revision'] = min( 2147483647, (int) $ledger['records'][ $key ]['revision'] + 1 );
                ++$changed;
            }
            continue;
        }
        if ( $changed >= 20 || count( $ledger['records'] ) >= 5000 ) {
            continue;
        }
        $ref = abtestkit_connected_test_ref_record( $test_id );
        if ( is_wp_error( $ref ) ) {
            abtestkit_connected_collection_gap( $ref->get_error_code() );
            continue;
        }
        $ledger['records'][ $key ] = array(
            'test_ref' => (string) $ref['test_ref'],
            'state' => abtestkit_connected_registration_desired_state( $test ),
            'revision' => 1,
            'confirmed_revision' => 0,
            'confirmed_site_ref' => '',
        );
        ++$changed;
    }
    foreach ( $ledger['records'] as $key => $record ) {
        if ( $changed >= 20 ) {
            break;
        }
        if ( ! isset( $seen[ $key ] ) && is_array( $record ) && 'deleted' !== ( $record['state'] ?? '' ) ) {
            $ledger['records'][ $key ]['state'] = 'deleted';
            $ledger['records'][ $key ]['revision'] = min( 2147483647, (int) $record['revision'] + 1 );
            ++$changed;
        }
    }
    if ( $changed && ! abtestkit_connected_registration_save( $ledger ) ) {
        abtestkit_connected_collection_gap( 'registration_write_failed' );
    }
    return $ledger;
}

/** Cron-only, at most 20 authenticated registration writes per tick. */
function abtestkit_connected_registration_run() : void {
    if ( ! abtestkit_connected_platform_can_create_or_launch() ) {
        return;
    }
    $connection = abtestkit_hosted_get_connection();
    if ( ! is_array( $connection ) ) {
        return;
    }
    $ledger = abtestkit_connected_registration_reconcile( abtestkit_connected_registration_state() );
    $sent = 0;
    foreach ( $ledger['records'] as $key => $record ) {
        if ( $sent >= 20 ) {
            break;
        }
        if ( ! is_array( $record ) || (
            (int) ( $record['confirmed_revision'] ?? 0 ) === (int) ( $record['revision'] ?? 0 ) &&
            (string) ( $record['confirmed_site_ref'] ?? '' ) === (string) $connection['site_ref']
        ) ) {
            continue;
        }
        if (
            ! is_string( $record['test_ref'] ?? null ) ||
            1 !== preg_match( '/^test_[A-Za-z0-9_-]{43}$/D', $record['test_ref'] ) ||
            ! is_int( $record['revision'] ?? null ) ||
            $record['revision'] < 1 || $record['revision'] > 2147483647 ||
            ! in_array( $record['state'] ?? null, array( 'active', 'paused', 'complete', 'deleted' ), true )
        ) {
            abtestkit_connected_registration_error( 'invalid_local_registration' );
            break;
        }
        ++$sent;
        $response = abtestkit_hosted_service_request(
            'PUT',
            '/sites/' . (string) $connection['site_ref'] . '/experiments/' . (string) $record['test_ref'] . '/registration',
            array( 'schema_version' => 1, 'revision' => (int) $record['revision'], 'state' => (string) $record['state'] ),
            (string) $connection['credential']
        );
        if ( is_wp_error( $response ) ) {
            abtestkit_connected_registration_error( 'transport' );
            break;
        }
        $status = (int) $response['status'];
        if ( 401 === $status ) {
            if ( ! abtestkit_connected_registration_revoke_connection( $connection ) ) {
                abtestkit_connected_registration_error( 'credential_changed' );
            }
            break;
        }
        if ( 404 === $status ) {
            // An older service may not have this route; 404 is not proof of
            // revocation. Keep local execution and retry after deployment.
            abtestkit_connected_registration_error( 'service_route_unavailable' );
            break;
        }
        if ( 403 === $status && in_array( $response['data']['code'] ?? '', array( 'abtk_hosted_platform_agreement_required', 'abtk_hosted_account_inactive' ), true ) ) {
            if ( ! abtestkit_connected_registration_revoke_connection( $connection ) ) {
                abtestkit_connected_registration_error( 'credential_changed' );
            }
            break;
        }
        $data = $response['data'];
        if (
            ! in_array( $status, array( 200, 201 ), true ) ||
            ! is_array( $data ) ||
            (int) ( $data['schema_version'] ?? 0 ) !== 1 ||
            (int) ( $data['revision'] ?? 0 ) !== (int) $record['revision'] ||
            (string) ( $data['state'] ?? '' ) !== (string) $record['state'] ||
            ! is_bool( $data['duplicate'] ?? null )
        ) {
            abtestkit_connected_registration_error( $status >= 500 || 429 === $status ? 'service_unavailable' : 'service_rejected' );
            break;
        }
        $ledger['records'][ $key ]['confirmed_revision'] = (int) $record['revision'];
        $ledger['records'][ $key ]['confirmed_site_ref'] = (string) $connection['site_ref'];
        if ( ! abtestkit_connected_registration_save( $ledger ) ) {
            abtestkit_connected_registration_error( 'storage_unavailable' );
            break;
        }
        abtestkit_connected_registration_error( '' );
        $ledger = abtestkit_connected_registration_state();
    }
}
add_action( ABTESTKIT_CONNECTED_TRANSPORT_HOOK, 'abtestkit_connected_registration_run', 20 );

/** A confirmed credential/agreement denial removes only the connection used by the request. */
function abtestkit_connected_registration_revoke_connection( array $connection ) : bool {
    return abtestkit_hosted_remove_local_connection( $connection );
}

/** Local diagnostic only; no payloads or credentials. */
function abtestkit_connected_registration_error( string $code ) : void {
    $ledger = abtestkit_connected_registration_state();
    $ledger['last_error_code'] = $code;
    $ledger['last_attempt_at'] = time();
    if ( '' === $code ) {
        $ledger['last_success_at'] = time();
    }
    abtestkit_connected_registration_save( $ledger );
}