/**
 * 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;
}