<?php

declare(strict_types=1);

namespace WordPress\CloudflareWorkersAiProvider\Diagnostics;

use WordPress\CloudflareWorkersAiProvider\Admin\SettingsPage;
use WordPress\CloudflareWorkersAiProvider\Embeddings\EmbeddingClient;
use WordPress\CloudflareWorkersAiProvider\Features\Agents;
use WordPress\CloudflareWorkersAiProvider\Embeddings\Ingest;
use WordPress\CloudflareWorkersAiProvider\Embeddings\Settings as EmbeddingSettings;
use WordPress\CloudflareWorkersAiProvider\Embeddings\State;
use WordPress\CloudflareWorkersAiProvider\Embeddings\Stores\StoreFactory;
use WordPress\CloudflareWorkersAiProvider\Routing\TaskContext;
use WordPress\CloudflareWorkersAiProvider\Usage\UsageTracker;

use function WordPress\CloudflareWorkersAiProvider\ai_plugin_status;
use function WordPress\CloudflareWorkersAiProvider\get_account_id;
use function WordPress\CloudflareWorkersAiProvider\get_api_key;
use function WordPress\CloudflareWorkersAiProvider\get_default_model_id;
use function WordPress\CloudflareWorkersAiProvider\is_connector_approved;
use function WordPress\CloudflareWorkersAiProvider\pretty_model_name;

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

/**
 * "Run all checks": each part AIPCF depends on, tried for real, with what to do when it fails.
 * The chat and the embedding check are tiny requests (a few neurons), counted as Diagnostics.
 */
final class Checks
{
    public const TASK = 'diagnostics';

    /** The last results, per user, for Help and the report. */
    private const TRANSIENT = 'aipcf_checks_';

    /**
     * @return list<array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}>
     */
    public static function run(): array
    {
        $out       = [];
        $connected = get_account_id() !== '' && get_api_key() !== '';
        $gate      = class_exists('\\WordPress\\AI\\Connector_Approval\\Approvals_Store');
        $connect   = [__('Settings > Connection', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::settingsUrl('connection')];

        $out[] = self::result('credentials', __('Account ID and API token are saved', 'aipcf-ai-provider-for-cloudflare'), $connected ? 'ok' : 'bad', $connected ? '' : __('Enter both to connect.', 'aipcf-ai-provider-for-cloudflare'), $connected ? null : $connect);
        if ($gate) {
            $ok    = is_connector_approved();
            $out[] = self::result('approval', __('The AI plugin allows AIPCF', 'aipcf-ai-provider-for-cloudflare'), $ok ? 'ok' : 'bad', $ok ? '' : __('Until it is allowed, every AI request is blocked.', 'aipcf-ai-provider-for-cloudflare'), $ok ? null : [__('Connector Approvals', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::connectorApprovalUrl()]);
        }
        if ($connected && (!$gate || is_connector_approved())) {
            TaskContext::pin(self::TASK); // so a failure shows up as Diagnostics in Recent errors
            $test = SettingsPage::testCredentials(get_account_id(), get_api_key());
            TaskContext::clear();
            $out[] = self::result('answers', __('Cloudflare accepts the token', 'aipcf-ai-provider-for-cloudflare'), $test === true ? 'ok' : 'bad', $test === true ? '' : (string) $test, $test === true ? null : $connect);
            if ($test === true) {
                $out[] = self::chat();
                if (EmbeddingSettings::enabled()) {
                    $out[] = self::embedding();
                    $out[] = self::store();
                }
            }
        }
        if (!empty(\WordPress\CloudflareWorkersAiProvider\Features\Settings::get('agents_enabled'))) {
            $out[] = self::agents();
        }
        $out[] = self::cron();
        $out[] = self::budget();
        $out[] = self::aiPlugin();
        $recent = ErrorLog::countSince(DAY_IN_SECONDS);
        $out[]  = self::result(
            'errors',
            __('No failed requests in the last day', 'aipcf-ai-provider-for-cloudflare'),
            $recent === 0 ? 'ok' : 'warn',
            /* translators: %d: number of failed requests */
            $recent === 0 ? '' : sprintf(_n('%d failed request in the last day. See Recent errors.', '%d failed requests in the last day. See Recent errors.', $recent, 'aipcf-ai-provider-for-cloudflare'), $recent),
            null
        );
        set_transient(self::TRANSIENT . get_current_user_id(), ['at' => time(), 'results' => $out], HOUR_IN_SECONDS);
        return $out;
    }

    /**
     * The last run's results for this user, or null.
     *
     * @return array{at: int, results: list<array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}>}|null
     */
    public static function last(): ?array
    {
        $last = get_transient(self::TRANSIENT . get_current_user_id());
        return is_array($last) && isset($last['results']) ? $last : null;
    }

    /**
     * @param array{0: string, 1: string}|null $fix
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function result(string $key, string $label, string $state, string $detail, ?array $fix): array
    {
        return ['key' => $key, 'label' => $label, 'state' => $state, 'detail' => Redact::text($detail), 'fix' => $fix];
    }

    /**
     * One tiny request to the writing model, through the same path as every feature.
     *
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function chat(): array
    {
        $model = get_default_model_id();
        /* translators: %s: model name */
        $label = sprintf(__('%s answers', 'aipcf-ai-provider-for-cloudflare'), pretty_model_name($model));
        if (!class_exists('\\WordPress\\AiClient\\AiClient')) {
            return self::result('chat', $label, 'skip', __('The WordPress AI Client is not available.', 'aipcf-ai-provider-for-cloudflare'), null);
        }
        $start = microtime(true);
        try {
            TaskContext::pin(self::TASK);
            $provider = \WordPress\AiClient\AiClient::defaultRegistry()->getProviderModel('cloudflare-workers-ai', $model);
            $text     = trim(\WordPress\AiClient\AiClient::prompt('Reply with the single word OK.')->usingModel($provider)->usingMaxTokens(5)->generateTextResult()->toText());
        } catch (\Throwable $e) {
            return self::result('chat', $label, 'bad', $e->getMessage(), [__('Settings > Models', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::settingsUrl('models')]);
        } finally {
            TaskContext::clear();
        }
        /* translators: %s: milliseconds */
        $took = sprintf(__('in %s ms', 'aipcf-ai-provider-for-cloudflare'), number_format_i18n((microtime(true) - $start) * 1000));
        return self::result('chat', $label, $text !== '' ? 'ok' : 'warn', $text !== '' ? $took : __('It answered with nothing.', 'aipcf-ai-provider-for-cloudflare'), null);
    }

    /**
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function embedding(): array
    {
        $r = EmbeddingClient::embed(['AIPCF diagnostics'], null, self::TASK);
        $ok = !is_wp_error($r);
        return self::result('embedding', __('The content index can read text', 'aipcf-ai-provider-for-cloudflare'), $ok ? 'ok' : 'bad', $ok ? '' : $r->get_error_message(), $ok ? null : [__('Content index', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::settingsUrl('content-index')]);
    }

    /**
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function store(): array
    {
        $fix   = [__('Content index', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::settingsUrl('content-index')];
        $label = __('The content index is reachable', 'aipcf-ai-provider-for-cloudflare');
        $store = StoreFactory::reading();
        if (is_wp_error($store)) {
            return self::result('store', $label, 'bad', $store->get_error_message(), $fix);
        }
        $status = $store->status();
        if (is_wp_error($status)) {
            return self::result('store', $label, 'bad', $status->get_error_message(), $fix);
        }
        if (empty($status['exists'])) {
            return self::result('store', $label, 'bad', __('The index does not exist yet. Create it on Settings > Content index.', 'aipcf-ai-provider-for-cloudflare'), $fix);
        }
        /* translators: 1: store name, 2: number of entries */
        return self::result('store', $label, 'ok', sprintf(__('%1$s, %2$s entries.', 'aipcf-ai-provider-for-cloudflare'), StoreFactory::available()[StoreFactory::currentId()] ?? StoreFactory::currentId(), number_format_i18n((int) ($status['vector_count'] ?? 0))), null);
    }

    /**
     * Whether the background work runs: WordPress's scheduler must reach the hourly run.
     *
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function cron(): array
    {
        $label = __('Background work runs', 'aipcf-ai-provider-for-cloudflare');
        $next  = wp_next_scheduled(Ingest::HOOK);
        if ($next === false) {
            return self::result('cron', $label, 'warn', __('Nothing is scheduled. Deactivating and activating AIPCF schedules it again.', 'aipcf-ai-provider-for-cloudflare'), null);
        }
        $late = time() - (int) $next;
        if ($late > HOUR_IN_SECONDS) {
            $detail = defined('DISABLE_WP_CRON') && \DISABLE_WP_CRON
                ? __('WordPress\'s scheduler is off (DISABLE_WP_CRON) and no server cron runs wp-cron.php.', 'aipcf-ai-provider-for-cloudflare')
                /* translators: %s: how late, e.g. "3 hours" */
                : sprintf(__('The hourly run is %s late. On quiet sites WordPress runs it only when someone visits.', 'aipcf-ai-provider-for-cloudflare'), human_time_diff((int) $next));
            return self::result('cron', $label, 'warn', $detail, null);
        }
        $last = (int) (State::get()['last_run'] ?? 0);
        /* translators: %s: time since, e.g. "5 mins" */
        return self::result('cron', $label, 'ok', $last > 0 ? sprintf(__('Last run %s ago.', 'aipcf-ai-provider-for-cloudflare'), human_time_diff($last)) : '', null);
    }

    /**
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function budget(): array
    {
        $used   = (float) (UsageTracker::todayTotals()['neurons'] ?? 0);
        $budget = UsageTracker::budgetEnabled() ? UsageTracker::budget() : UsageTracker::FREE_TIER;
        $pct    = (int) round(100 * $used / max(1, $budget));
        $state  = $pct >= 100 ? 'bad' : ($pct >= 80 ? 'warn' : 'ok');
        /* translators: 1: neurons used today, 2: the daily budget, 3: percentage */
        $detail = sprintf(__('%1$s of %2$s neurons today (%3$d%%).', 'aipcf-ai-provider-for-cloudflare'), number_format_i18n($used), number_format_i18n($budget), $pct);
        return self::result('budget', __('Today\'s budget has room', 'aipcf-ai-provider-for-cloudflare'), $state, $detail, $state === 'ok' ? null : [__('Settings > Budget', 'aipcf-ai-provider-for-cloudflare'), SettingsPage::settingsUrl('budget')]);
    }

    /**
     * AI agents: the abilities are registered (so the MCP adapter can offer them).
     *
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function agents(): array
    {
        $label   = __('AI agents can reach the site', 'aipcf-ai-provider-for-cloudflare');
        $fix     = [__('Features > AI agents', 'aipcf-ai-provider-for-cloudflare'), \WordPress\CloudflareWorkersAiProvider\Admin\FeaturesPage::url('agents')];
        $missing = [];
        foreach (array_keys(Agents::names()) as $name) {
            if (!function_exists('wp_has_ability') || !wp_has_ability($name)) {
                $missing[] = $name;
            }
        }
        if ($missing !== []) {
            $why = Agents::enabled() ? implode(', ', $missing) : __('The content index is off.', 'aipcf-ai-provider-for-cloudflare');
            /* translators: %s: ability names, or the reason */
            return self::result('agents', $label, 'bad', sprintf(__('Not registered: %s', 'aipcf-ai-provider-for-cloudflare'), $why), $fix);
        }
        if (!Agents::mcpAdapter()) {
            return self::result('agents', $label, 'warn', __('The abilities work, but the MCP adapter plugin is not active, so agents cannot connect yet.', 'aipcf-ai-provider-for-cloudflare'), $fix);
        }
        /* translators: %d: number of abilities */
        return self::result('agents', $label, 'ok', sprintf(__('%d abilities, through the MCP adapter.', 'aipcf-ai-provider-for-cloudflare'), count(Agents::names())), null);
    }

    /**
     * @return array{key: string, label: string, state: string, detail: string, fix: array{0: string, 1: string}|null}
     */
    private static function aiPlugin(): array
    {
        $ai = ai_plugin_status();
        return self::result('ai_plugin', __('The WordPress AI plugin is on', 'aipcf-ai-provider-for-cloudflare'), $ai['status'] === 'active' ? 'ok' : 'skip', $ai['status'] === 'active' ? '' : __('Optional: it adds AI to the block editor.', 'aipcf-ai-provider-for-cloudflare'), $ai['status'] === 'active' ? null : [$ai['action_label'], $ai['action_url']]);
    }
}