chat/backend-tp8/app/controller/api/Chat.php

<?php

namespace app\controller\api;

use app\model\Conversation as ConversationModel;
use app\model\Message;
use app\service\OpenAIService;
use app\service\PermissionService;
use app\service\SettingsService;
use think\exception\HttpResponseException;

class Chat extends BaseApi
{
    public function completions()
    {
        $user = $this->authUser();
        PermissionService::checkDailyLimit($user);

        $input = $this->request->post();
        $conversationId = (int) ($input['conversation_id'] ?? 0);
        $content = trim($input['content'] ?? '');
        $attachments = $input['attachments'] ?? [];
        $stream = ($input['stream'] ?? true) !== false;

        if (!$conversationId) {
            return $this->error('缺少 conversation_id');
        }
        if (!$content && empty($attachments)) {
            return $this->error('消息内容不能为空');
        }

        $conversation = ConversationModel::where('id', $conversationId)
            ->where('user_id', $user['id'])
            ->whereNull('deleted_at')
            ->find();

        if (!$conversation) {
            return $this->error('会话不存在', 404);
        }

        $contentType = SettingsService::isFeatureEnabled('markdown') ? 'markdown' : 'text';
        if (!empty($attachments)) {
            $contentType = 'mixed';
        }

        Message::create([
            'conversation_id' => $conversationId,
            'role'            => 'user',
            'content'         => $content,
            'content_type'    => $contentType,
            'attachments'     => $attachments,
        ]);

        PermissionService::incrementDailyCount((int) $user['id']);

        $history = Message::where('conversation_id', $conversationId)
            ->field('role,content,attachments')
            ->order('created_at', 'asc')
            ->limit(50)
            ->select()
            ->toArray();

        $apiMessages = $this->buildApiMessages($history);
        $model = OpenAIService::getModel($conversation->model_id ? (int) $conversation->model_id : null);

        if ((int) $conversation->message_count === 0 && $content) {
            $conversation->save(['title' => mb_substr($content, 0, 30)]);
        }

        $conversation->inc('message_count')->update(['updated_at' => date('Y-m-d H:i:s')]);

        if ($stream) {
            $this->streamResponse($conversationId, $model, $apiMessages, $user);
        }

        return $this->syncResponse($conversationId, $model, $apiMessages, $user);
    }

    private function streamResponse(int $conversationId, $model, array $apiMessages, array $user): void
    {
        OpenAIService::sseHeaders();
        $fullContent = '';

        OpenAIService::streamChat($model, $apiMessages, function ($chunk) use (&$fullContent) {
            $delta = $chunk['choices'][0]['delta']['content'] ?? '';
            if ($delta) {
                $fullContent .= $delta;
                OpenAIService::sseEvent('message', ['content' => $delta]);
            }
        });

        Message::create([
            'conversation_id' => $conversationId,
            'role'            => 'assistant',
            'content'         => $fullContent,
            'content_type'    => 'markdown',
        ]);

        ConversationModel::where('id', $conversationId)->inc('message_count')->update([
            'updated_at' => date('Y-m-d H:i:s'),
        ]);

        PermissionService::incrementDailyCount((int) $user['id']);
        OpenAIService::sseEvent('done', ['content' => $fullContent]);
        exit;
    }

    private function syncResponse(int $conversationId, $model, array $apiMessages, array $user)
    {
        $result = OpenAIService::chat($model, $apiMessages);
        $content = $result['choices'][0]['message']['content'] ?? '';
        $tokens = $result['usage']['total_tokens'] ?? 0;

        Message::create([
            'conversation_id' => $conversationId,
            'role'            => 'assistant',
            'content'         => $content,
            'content_type'    => 'markdown',
            'tokens_used'     => $tokens,
        ]);

        ConversationModel::where('id', $conversationId)->inc('message_count')->update([
            'updated_at' => date('Y-m-d H:i:s'),
        ]);

        PermissionService::incrementDailyCount((int) $user['id']);

        return $this->success(['content' => $content, 'tokens' => $tokens]);
    }

    private function buildApiMessages(array $history): array
    {
        $messages = [];

        foreach ($history as $msg) {
            $content = $msg['content'];
            $attachments = $msg['attachments'] ?? [];
            if (is_string($attachments)) {
                $attachments = json_decode($attachments, true) ?: [];
            }

            if (!empty($attachments) && SettingsService::isFeatureEnabled('image')) {
                $parts = [];
                if ($content) {
                    $parts[] = ['type' => 'text', 'text' => $content];
                }
                foreach ($attachments as $att) {
                    if (($att['type'] ?? '') === 'image') {
                        $parts[] = [
                            'type'      => 'image_url',
                            'image_url' => ['url' => $this->absoluteUrl($att['url'])],
                        ];
                    }
                }
                $messages[] = ['role' => $msg['role'], 'content' => $parts];
            } else {
                $messages[] = ['role' => $msg['role'], 'content' => $content];
            }
        }

        return $messages;
    }

    private function absoluteUrl(string $url): string
    {
        if (str_starts_with($url, 'http')) {
            return $url;
        }
        $scheme = $this->request->scheme();
        $host = $this->request->host();
        return "{$scheme}://{$host}{$url}";
    }
}