ai-chatbot/app/api/canvas/text-edit/route.ts

import { NextResponse } from "next/server";
import { z } from "zod";
import { auth } from "@/app/(auth)/auth";
import { getEnabledAiModelsWithProvider } from "@/lib/db/queries";
import { createVolcanoVision } from "@/lib/ai/providers/volcano-vision";

export const runtime = "nodejs";
export const maxDuration = 120;

const textItemSchema = z.object({
  id: z.string().min(1),
  originalText: z.string().min(1),
  editedText: z.string().min(1),
});

const requestSchema = z.object({
  imageUrl: z.string().min(1, "图片地址不能为空"),
  items: z.array(textItemSchema).min(1, "至少需要一条文字修改"),
});

function pickVolcanoModel(models: Awaited<ReturnType<typeof getEnabledAiModelsWithProvider>>) {
  const candidates = models
    .filter((item) => item.model.supportsImageGen && item.provider.type === "volcano-vision")
    .sort((a, b) => {
      const aScore =
        (a.model.isDefault ? 10 : 0) +
        (a.model.modelId?.toLowerCase().includes("seedream") ? 5 : 0) +
        (a.model.displayName?.includes("火山") ? 3 : 0);
      const bScore =
        (b.model.isDefault ? 10 : 0) +
        (b.model.modelId?.toLowerCase().includes("seedream") ? 5 : 0) +
        (b.model.displayName?.includes("火山") ? 3 : 0);
      return bScore - aScore;
    });

  return candidates[0];
}

function parseImageFromMarkdown(markdown: string): { originalUrl: string; thumbnailUrl: string } {
  const strictMatch = markdown.match(/!\[thumb\|\|\|([^|]+)\|\|\|[^\]]*\]\(([^)]+)\)/);
  if (strictMatch) {
    return {
      originalUrl: strictMatch[1],
      thumbnailUrl: strictMatch[2],
    };
  }

  const simpleMatch = markdown.match(/!\[[^\]]*\]\(([^)]+)\)/);
  if (simpleMatch) {
    return {
      originalUrl: simpleMatch[1],
      thumbnailUrl: simpleMatch[1],
    };
  }

  throw new Error("未解析到生成图片");
}

function buildTextEditPrompt(replacements: Array<{ originalText: string; editedText: string }>) {
  const replacementLines = replacements
    .map((item, index) => `${index + 1}. 原文: ${item.originalText}\n   替换为: ${item.editedText}`)
    .join("\n");

  return [
    "请基于输入图片执行精确文字替换。",
    "硬性要求：",
    "1. 仅替换下方列出的文字内容，不要修改其他主体、配色、材质、光影与构图。",
    "2. 必须保持原图排版、字重、笔画风格与字体形状尽可能一致，仅替换指定文字内容，其他视觉元素不变。",
    "3. 输出图严格保持原图宽高比例，不裁切、不拉伸、不加边框。",
    "4. 若目标文案更长，优先微调字距或字号，确保自然贴合原位置。",
    "替换清单：",
    replacementLines,
    "请返回一张最终完成的图片。",
  ].join("\n");
}

export async function POST(request: Request) {
  try {
    const session = await auth();
    if (!session?.user?.id) {
      return NextResponse.json({ success: false, error: "未登录" }, { status: 401 });
    }

    const json = await request.json();
    const parsed = requestSchema.safeParse(json);
    if (!parsed.success) {
      return NextResponse.json({ success: false, error: parsed.error.errors[0]?.message || "参数错误" }, { status: 400 });
    }

    const imageUrl = parsed.data.imageUrl.trim();
    if (!/^https?:\/\//i.test(imageUrl)) {
      return NextResponse.json({ success: false, error: "仅支持 URL 图片，不允许 base64 传输" }, { status: 400 });
    }

    const replacements = parsed.data.items
      .map((item) => ({
        id: item.id,
        originalText: item.originalText.trim(),
        editedText: item.editedText.trim(),
      }))
      .filter((item) => item.originalText && item.editedText && item.originalText !== item.editedText);

    if (replacements.length === 0) {
      return NextResponse.json({ success: false, error: "未检测到有效的文字改动" }, { status: 400 });
    }

    const models = await getEnabledAiModelsWithProvider();
    const selected = pickVolcanoModel(models);

    if (!selected) {
      return NextResponse.json({ success: false, error: "未配置可用的火山生图模型" }, { status: 500 });
    }

    const provider = createVolcanoVision({
      baseURL: selected.provider.baseUrl,
      apiKey: selected.provider.apiKey,
    });

    const prompt = buildTextEditPrompt(replacements);

    const result = await provider.chat(selected.model.modelId).doGenerate({
      messages: [
        {
          role: "user",
          content: [
            { type: "image_url", image_url: { url: imageUrl } },
            { type: "text", text: prompt },
          ],
        },
      ],
      imageParams: {
        imageCount: 1,
      },
    });

    if (!result?.text) {
      throw new Error("模型未返回结果");
    }

    const { originalUrl, thumbnailUrl } = parseImageFromMarkdown(result.text);

    return NextResponse.json({
      success: true,
      data: {
        originalUrl,
        thumbnailUrl,
        model: selected.model.displayName,
      },
    });
  } catch (error) {
    console.error("[Canvas Text Edit] Error:", error);
    return NextResponse.json(
      {
        success: false,
        error: error instanceof Error ? error.message : "文字替换失败",
      },
      { status: 500 },
    );
  }
}