<?php

declare(strict_types=1);

namespace app\adminapi\service;

use think\facade\Log;

/** A request-local, patient-free timing record for the diagnosis assistant SSE path. */
final class AssistantSseTiming
{
    private const PHASES = ['prepare', 'sse_start', 'first_delta', 'upstream_done', 'sse_done'];

    private const NUMBER_FIELDS = [
        'duration_ms', 'aggregate_ms', 'compaction_ms', 'retry_ms',
        'source_bytes', 'query_bytes', 'attachment_count',
        'delta_bytes', 'delta_count', 'first_delta_ms',
    ];

    private const BOOLEAN_FIELDS = ['compaction_attempted', 'retry_attempted', 'first_delta_observed'];

    private const ERROR_CODES = [
        'AI_ASSISTANT_FAILED', 'UPSTREAM_UNAVAILABLE', 'UPSTREAM_REJECTED',
        'INCOMPLETE_RESPONSE', 'EMPTY_RESPONSE', 'UPSTREAM_TIMEOUT',
        'CONFIG_DISABLED', 'INVALID_PROFILE', 'CONFIG_MISSING', 'CONFIG_INVALID',
        'CURL_UNAVAILABLE', 'SKILL_UNAVAILABLE', 'CLIENT_DISCONNECTED',
        'STREAM_DELIVERY_FAILED', 'REQUEST_BUILD_FAILED', 'CURL_INIT_FAILED',
        'UPSTREAM_BUSY', 'INVALID_RESPONSE',
    ];

    private string $traceId;

    public function __construct()
    {
        $this->traceId = bin2hex(random_bytes(16));
    }

    public function id(): string
    {
        return $this->traceId;
    }

    public static function elapsedMs(int $startedAt): int
    {
        return max(0, (int) floor((hrtime(true) - $startedAt) / 1000000));
    }

    /**
     * Only a fixed set of numeric and boolean metadata reaches the log. In particular,
     * arbitrary prompt text, patient identifiers, URLs and credentials are discarded.
     *
     * @param array<string,mixed> $metrics
     * @return array<string,int|bool|string>
     */
    public function event(string $phase, array $metrics = []): array
    {
        $event = [
            'trace_id' => $this->traceId,
            'phase' => in_array($phase, self::PHASES, true) ? $phase : 'upstream_done',
        ];
        foreach (self::NUMBER_FIELDS as $field) {
            if (isset($metrics[$field]) && is_int($metrics[$field])) {
                $event[$field] = max(0, $metrics[$field]);
            }
        }
        foreach (self::BOOLEAN_FIELDS as $field) {
            if (isset($metrics[$field]) && is_bool($metrics[$field])) {
                $event[$field] = $metrics[$field];
            }
        }
        if (isset($metrics['status']) && in_array($metrics['status'], ['ok', 'error', 'exception', 'disconnected'], true)) {
            $event['status'] = $metrics['status'];
        }
        if (isset($metrics['error_code']) && in_array($metrics['error_code'], self::ERROR_CODES, true)) {
            $event['error_code'] = $metrics['error_code'];
        }
        return $event;
    }

    /** @param array<string,mixed> $metrics */
    public function log(string $phase, array $metrics = []): void
    {
        try {
            Log::info('diagnosis ai assistant timing ' . json_encode($this->event($phase, $metrics)));
        } catch (\Throwable $ignored) {
            // Telemetry must never interrupt the clinical request.
        }
    }
}