<?php

namespace App\Services\Agent;

use Illuminate\Http\Client\ConnectionException;
use Illuminate\Support\Facades\Http;

class HttpAgentProvider implements AgentProviderInterface
{
    protected string $endpoint;
    protected int $timeoutSeconds;
    protected int $connectTimeoutSeconds;
    protected int $retryTimes;
    protected int $retryBackoffMs;

    public function __construct(?string $endpoint = null)
    {
        $this->endpoint = $endpoint ?? config('agent.provider.endpoint', '');
        $this->timeoutSeconds = (int) config('agent.provider.timeout_seconds', 30);
        $this->connectTimeoutSeconds = (int) config('agent.provider.connect_timeout_seconds', 5);
        $this->retryTimes = (int) config('agent.provider.retry_times', 1);
        $this->retryBackoffMs = (int) config('agent.provider.retry_backoff_ms', 500);
    }

    /**
     * @param array<string, mixed> $context
     * @param array<string, mixed> $options
     */
    public function generate(array $context, array $options = []): string
    {
        if (empty($this->endpoint)) {
            // placeholder to avoid accidental outbound calls when未配置
            return (new DummyAgentProvider())->generate($context, $options);
        }

        $payload = [
            'context' => $context,
            'options' => $options,
        ];

        $attempts = $this->retryTimes + 1;
        $lastException = null;
        $lastResponseBody = null;
        $lastStatus = null;

        for ($attempt = 1; $attempt <= $attempts; $attempt++) {
            try {
                $response = Http::connectTimeout($this->connectTimeoutSeconds)
                    ->timeout($this->timeoutSeconds)
                    ->post($this->endpoint, $payload);

                $lastStatus = $response->status();
                $lastResponseBody = $response->body();

                if ($response->successful()) {
                    $data = $response->json();

                    return is_string($data) ? $data : ($data['content'] ?? '');
                }

                $retryable = $lastStatus === 429 || $lastStatus >= 500;
                if ($retryable && $attempt < $attempts) {
                    usleep($this->retryBackoffMs * 1000);
                    continue;
                }

                throw new ProviderException(
                    'HTTP_ERROR',
                    'Agent provider failed',
                    $retryable,
                    $lastStatus,
                    $lastResponseBody
                );
            } catch (ConnectionException $exception) {
                $lastException = $exception;
                if ($attempt < $attempts) {
                    usleep($this->retryBackoffMs * 1000);
                    continue;
                }
            } catch (\Throwable $exception) {
                $lastException = $exception;
                break;
            }
        }

        $rawMessage = $lastException ? $lastException->getMessage() : $lastResponseBody;

        if ($lastException instanceof ConnectionException) {
            throw new ProviderException(
                'CONNECTION_FAILED',
                'Agent provider connection failed',
                true,
                $lastStatus,
                $rawMessage
            );
        }

        throw new ProviderException(
            'UNKNOWN_ERROR',
            'Agent provider error',
            false,
            $lastStatus,
            $rawMessage
        );
    }
}