import "server-only";
import sharp from "sharp";
import { generateText } from "ai";
import { getLanguageModelById } from "@/lib/ai/dynamic-provider";
import { getMultimodalAiModelsWithProvider } from "@/lib/db/queries";
import { fetchImageBufferFromUrl } from "@/lib/ai/rmbg/service";
import { LAYOUT_REPLACE_QUALITY_PROMPT, parseLayoutReplaceQuality } from "./layout-replace-quality";
import { LAYOUT_REPLACE_PRODUCT_PROMPT, parseLayoutReplaceProductAnalysis } from "./layout-replace-product-crop";

async function visionInput(buffer: Buffer) {
  const resized = await sharp(buffer, { failOn: "error" }).rotate()
    .resize(1400, 1400, { fit: "inside", withoutEnlargement: true })
    .flatten({ background: "#ffffff" }).jpeg({ quality: 90 }).toBuffer();
  return new URL(`data:image/jpeg;base64,${resized.toString("base64")}`);
}

async function inspectLayoutImages<T>(buffers: Buffer[], prompt: string, parse: (text: string) => T): Promise<T> {
  const candidates = (await getMultimodalAiModelsWithProvider()).filter(({ model }) =>
    model.supportsVision && !model.supportsImageGen && !model.isSubModel
  ).sort((a, b) => Number(b.model.isDefault) - Number(a.model.isDefault) ||
    Number(b.provider.type === "vip98k") - Number(a.provider.type === "vip98k"));
  if (!candidates.length) throw new Error("未配置可用的多模态质量检查模型，未放行未经检查的替换结果");
  const images = await Promise.all(buffers.map(visionInput));
  let lastError: unknown;
  for (const candidate of candidates.slice(0, 2)) {
    try {
      const model = await getLanguageModelById(candidate.model.id);
      if (!model || typeof model === "string") continue;
      const { text } = await generateText({
        model: model as any, maxRetries: 0, maxOutputTokens: 1200,
        abortSignal: AbortSignal.timeout(60_000),
        messages: [{ role: "user", content: [
          { type: "text", text: prompt },
          ...images.map(image => ({ type: "image" as const, image })),
        ] }],
      });
      return parse(text);
    } catch (error) {
      lastError = error;
      // The fallback is another read-only check, never another image generation.
      console.warn("[Canvas Layout Replace] quality verifier unavailable", {
        model: candidate.model.modelId, errorType: error instanceof Error ? error.name : "unknown",
      });
    }
  }
  throw new Error("替换结果质量检查暂不可用，未将未经检查的图片标记为成功", { cause: lastError });
}

export async function locateLayoutReplaceProduct(sourceBuffer: Buffer, templateBuffer: Buffer) {
  return inspectLayoutImages([templateBuffer, sourceBuffer], LAYOUT_REPLACE_PRODUCT_PROMPT, parseLayoutReplaceProductAnalysis);
}

export async function verifyCanvasLayoutReplacement(params: {
  sourceBuffer: Buffer;
  templateBuffer: Buffer;
  resultUrl: string;
  resultBuffer?: Buffer;
  sourceIdentity?: string;
}) {
  const resultBuffer = params.resultBuffer || await fetchImageBufferFromUrl(params.resultUrl);
  const prompt = [LAYOUT_REPLACE_QUALITY_PROMPT, params.sourceIdentity
    ? `生成前识别的新商品结构（仅作核对线索，若与图2矛盾以图2实际图像为准）：${params.sourceIdentity.slice(0, 600)}` : ""].filter(Boolean).join("\n");
  return inspectLayoutImages([params.templateBuffer, params.sourceBuffer, resultBuffer], prompt, parseLayoutReplaceQuality);
}