import { NextRequest, NextResponse } from "next/server";
import { getServerSession } from 'next-auth';
import { authOptions } from '@/app/api/auth/[...nextauth]/route';
import db from "@/db/db";
import { eq } from "drizzle-orm";
import { rfqLastAttachments, rfqLastAttachmentRevisions } from "@/db/schema";
import { saveFile, deleteFile } from "@/lib/file-storage";

export async function POST(request: NextRequest) {
  try {
    const session = await getServerSession(authOptions);
    if (!session?.user?.id) {
      return NextResponse.json(
        { success: false, message: "인증이 필요합니다" },
        { status: 401 }
      );
    }

    const formData = await request.formData();
    const attachmentId = parseInt(formData.get("attachmentId") as string);
    const revisionComment = formData.get("revisionComment") as string;
    const file = formData.get("file") as File;

    if (!file || file.size === 0) {
      return NextResponse.json(
        { success: false, message: "파일이 없습니다" },
        { status: 400 }
      );
    }

    // 파일 크기 검증 (100MB)
    if (file.size > 100 * 1024 * 1024) {
      return NextResponse.json(
        { success: false, message: "파일 크기는 100MB를 초과할 수 없습니다" },
        { status: 400 }
      );
    }

    // 트랜잭션 시작
    const result = await db.transaction(async (tx) => {
      // 1. 기존 첨부파일 정보 조회
      const [existingAttachment] = await tx
        .select()
        .from(rfqLastAttachments)
        .where(eq(rfqLastAttachments.id, attachmentId));
      
      if (!existingAttachment) {
        throw new Error("첨부파일을 찾을 수 없습니다");
      }
      
      // 2. 현재 리비전 번호 계산
      const currentRevision = existingAttachment.currentRevision || "A";
      const nextRevision = String.fromCharCode(currentRevision.charCodeAt(0) + 1);
      
      // 3. 공용 파일 저장 함수 사용
      const saveResult = await saveFile({
        file,
        directory: `uploads/rfq-attachments/rfq-${existingAttachment.rfqId}`,
        originalName: file.name,
        userId: session.user.id,
      });

      if (!saveResult.success) {
        throw new Error(saveResult.error || "파일 저장 실패");
      }
      
      // 4. 기존 latest 플래그 해제
      if (existingAttachment.latestRevisionId) {
        await tx
          .update(rfqLastAttachmentRevisions)
          .set({ isLatest: false })
          .where(eq(rfqLastAttachmentRevisions.id, existingAttachment.latestRevisionId));
      }
      
      // 5. 새 리비전 생성
      const [revision] = await tx
        .insert(rfqLastAttachmentRevisions)
        .values({
          attachmentId,
          revisionNo: nextRevision,
          fileName: saveResult.fileName!,
          originalFileName: saveResult.originalName!,
          filePath: saveResult.publicPath!,
          fileSize: saveResult.fileSize!,
          fileType: file.type || "unknown",
          isLatest: true,
          revisionComment,
          uploadedBy: parseInt(session.user.id),
          uploadedAt: new Date(),
        })
        .returning();
      
      // 6. 첨부파일 정보 업데이트
      await tx
        .update(rfqLastAttachments)
        .set({
          currentRevision: nextRevision,
          latestRevisionId: revision.id,
          updatedAt: new Date(),
        })
        .where(eq(rfqLastAttachments.id, attachmentId));
      
      return { attachment: existingAttachment, revision };
    });

    return NextResponse.json({
      success: true,
      message: `새 버전이 업로드되었습니다 (Rev. ${result.revision.revisionNo})`,
      data: result.revision,
    });
    
  } catch (error) {
    console.error("Update revision error:", error);
    return NextResponse.json(
      { 
        success: false, 
        message: error instanceof Error ? error.message : "리비전 업데이트 실패" 
      },
      { status: 500 }
    );
  }
}