feat(导出功能): 添加对话导出 API 路由

- 实现 GET /api/conversations/[id]/export 接口
- 支持 markdown/json/html/pdf 四种导出格式
- 添加用户身份验证和权限检查
- PDF 格式返回数据供客户端生成

src/app/api/conversations/[id]/export/route.ts

@@ -0,0 +1,167 @@
+/**
+ * 对话导出 API
+ * GET /api/conversations/[id]/export?format=markdown|json|html|pdf
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { db } from '@/drizzle/db';
+import { conversations, messages } from '@/drizzle/schema';
+import { eq, asc } from 'drizzle-orm';
+import { getCurrentUser } from '@/lib/auth';
+import {
+  exportConversation,
+  getExportContentType,
+  generateExportFilename,
+  DEFAULT_EXPORT_OPTIONS,
+  type ExportFormat,
+  type ExportData,
+  type ExportMessageData,
+} from '@/lib/export';
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  try {
+    // 验证用户身份
+    const user = await getCurrentUser();
+    if (!user) {
+      return NextResponse.json({ error: '未登录' }, { status: 401 });
+    }
+
+    const { id: conversationId } = await params;
+
+    // 获取导出参数
+    const searchParams = request.nextUrl.searchParams;
+    const format = (searchParams.get('format') || 'markdown') as ExportFormat;
+    const includeThinking = searchParams.get('includeThinking') !== 'false';
+    const includeToolCalls = searchParams.get('includeToolCalls') !== 'false';
+    const includeImages = searchParams.get('includeImages') !== 'false';
+
+    // 验证格式
+    if (!['markdown', 'json', 'html', 'pdf'].includes(format)) {
+      return NextResponse.json(
+        { error: '不支持的导出格式' },
+        { status: 400 }
+      );
+    }
+
+    // PDF 导出需要在客户端执行，服务端只返回数据
+    if (format === 'pdf') {
+      // 对于 PDF，返回 JSON 数据让客户端生成
+      const exportData = await getExportData(conversationId, user.userId);
+      if (!exportData) {
+        return NextResponse.json(
+          { error: '对话不存在或无权访问' },
+          { status: 404 }
+        );
+      }
+      return NextResponse.json({
+        ...exportData,
+        exportFormat: 'pdf',
+        message: '请在客户端生成 PDF',
+      });
+    }
+
+    // 获取对话和消息数据
+    const exportData = await getExportData(conversationId, user.userId);
+    if (!exportData) {
+      return NextResponse.json(
+        { error: '对话不存在或无权访问' },
+        { status: 404 }
+      );
+    }
+
+    // 执行导出
+    const content = await exportConversation(exportData, {
+      format,
+      includeThinking,
+      includeToolCalls,
+      includeImages,
+    });
+
+    // 生成文件名
+    const filename = generateExportFilename(exportData.conversation.title, format);
+    const contentType = getExportContentType(format);
+
+    // 返回文件
+    return new NextResponse(content as string, {
+      headers: {
+        'Content-Type': contentType,
+        'Content-Disposition': `attachment; filename*=UTF-8''${encodeURIComponent(filename)}`,
+      },
+    });
+  } catch (error) {
+    console.error('Export error:', error);
+    return NextResponse.json(
+      { error: '导出失败' },
+      { status: 500 }
+    );
+  }
+}
+
+/**
+ * 获取导出数据
+ */
+async function getExportData(
+  conversationId: string,
+  userId: string
+): Promise<ExportData | null> {
+  // 获取对话
+  const conversation = await db.query.conversations.findFirst({
+    where: eq(conversations.conversationId, conversationId),
+  });
+
+  if (!conversation) {
+    return null;
+  }
+
+  // 验证权限
+  if (conversation.userId !== userId) {
+    return null;
+  }
+
+  // 获取消息
+  const messageList = await db.query.messages.findMany({
+    where: eq(messages.conversationId, conversationId),
+    orderBy: [asc(messages.createdAt)],
+  });
+
+  // 构建导出数据
+  const exportData: ExportData = {
+    exportInfo: {
+      exportedAt: new Date().toISOString(),
+      format: 'json', // 将在实际导出时更新
+      version: '1.0',
+    },
+    conversation: {
+      id: conversation.conversationId,
+      title: conversation.title,
+      model: conversation.model,
+      enableThinking: conversation.enableThinking || false,
+      tools: (conversation.tools as string[]) || [],
+      messageCount: conversation.messageCount || 0,
+      totalTokens: conversation.totalTokens || 0,
+      createdAt: conversation.createdAt?.toISOString() || new Date().toISOString(),
+      updatedAt: conversation.updatedAt?.toISOString() || new Date().toISOString(),
+    },
+    messages: messageList.map((msg): ExportMessageData => ({
+      id: msg.messageId,
+      role: msg.role as 'user' | 'assistant' | 'system',
+      content: msg.content,
+      thinkingContent: msg.thinkingContent,
+      toolCalls: msg.toolCalls as ExportMessageData['toolCalls'],
+      toolResults: msg.toolResults as ExportMessageData['toolResults'],
+      images: msg.images as string[] | null,
+      uploadedImages: msg.uploadedImages as string[] | null,
+      uploadedDocuments: msg.uploadedDocuments as ExportMessageData['uploadedDocuments'],
+      usedTools: msg.usedTools as string[] | null,
+      searchImages: msg.searchImages as ExportMessageData['searchImages'],
+      inputTokens: msg.inputTokens,
+      outputTokens: msg.outputTokens,
+      createdAt: msg.createdAt?.toISOString() || new Date().toISOString(),
+    })),
+  };
+
+  return exportData;
+}