<?php

declare(strict_types=1);

namespace WordPress\CloudflareWorkersAiProvider\Embeddings;

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

/**
 * The ingest pipeline's own state (not settings): index generation, pause reason,
 * reconcile progress and the last run's outcome.
 */
final class State
{
    public const OPTION = 'aipcf_embed_state';

    /**
     * move: a move to another vector store under way (see Mover), or null.
     * moved_from: the store a finished move left vectors in, until they are deleted or kept.
     * index_model / previous_model: the model the current and the previous index were written
     * with, so readers stay on a rebuild's previous index only while its vectors still fit.
     *
     * @phpstan-impure
     *
     * @return array{generation: int, previous_index: string, previous_model: string, index_model: string, paused: string, reconcile: array<string, mixed>|null, move: array<string, mixed>|null, moved_from: array<string, mixed>|null, last_run: int, last_message: string, last_error: string, done: int, failed: int}
     */
    public static function get(): array
    {
        $s = get_option(self::OPTION, []);
        $s = is_array($s) ? $s : [];
        return [
            'generation'     => max(1, (int) ($s['generation'] ?? 1)),
            'previous_index' => (string) ($s['previous_index'] ?? ''),
            'previous_model' => (string) ($s['previous_model'] ?? ''),
            'index_model'    => (string) ($s['index_model'] ?? ''),
            'paused'         => (string) ($s['paused'] ?? ''),
            'reconcile'      => is_array($s['reconcile'] ?? null) ? $s['reconcile'] : null,
            'move'           => is_array($s['move'] ?? null) ? $s['move'] : null,
            'moved_from'     => is_array($s['moved_from'] ?? null) ? $s['moved_from'] : null,
            'last_run'       => (int) ($s['last_run'] ?? 0),
            'last_message'   => (string) ($s['last_message'] ?? ''),
            'last_error'     => (string) ($s['last_error'] ?? ''),
            'done'           => (int) ($s['done'] ?? 0),
            'failed'         => (int) ($s['failed'] ?? 0),
        ];
    }

    /**
     * @param array<string, mixed> $changes
     */
    public static function update(array $changes): void
    {
        update_option(self::OPTION, array_merge(self::get(), $changes), false);
    }

    public static function generation(): int
    {
        return self::get()['generation'];
    }

    /**
     * A store name with the generation appended from the second generation on
     * ("name-g2"), kept within $max bytes.
     */
    public static function suffixed(string $base, int $max, string $separator = '-'): string
    {
        $gen = self::generation();
        if ($gen <= 1) {
            return substr($base, 0, $max);
        }
        $suffix = $separator . 'g' . $gen;
        return rtrim(substr($base, 0, $max - strlen($suffix)), '-_') . $suffix;
    }

    public static function pause(string $reason): void
    {
        self::update(['paused' => $reason, 'last_error' => $reason]);
    }

    public static function resume(): void
    {
        self::update(['paused' => '']);
    }
}