import "server-only";
import { createHash } from "node:crypto";
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";
import { LAYOUT_REPLACE_TEXT_PROMPT, parseLayoutReplaceTextBoxes } from "./layout-replace-text-lock";

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);
}

const textRegions = new Map<string, { expires: number; result: ReturnType<typeof inspectTemplateText> }>();
function inspectTemplateText(buffer: Buffer) {
  return inspectLayoutImages([buffer], LAYOUT_REPLACE_TEXT_PROMPT, parseLayoutReplaceTextBoxes);
}
export async function locateLayoutReplaceTemplateText(buffer: Buffer) {
  const key = createHash("sha256").update(buffer).digest("hex");
  const cached = textRegions.get(key);
  if (cached && cached.expires > Date.now()) return cached.result;
  if (textRegions.size >= 32) textRegions.delete(textRegions.keys().next().value!);
  const result = inspectTemplateText(buffer);
  const entry = { expires: Date.now() + 30 * 60_000, result };
  textRegions.set(key, entry);
  result.catch(() => { if (textRegions.get(key) === entry) textRegions.delete(key); });
  return result;
}

export async function verifyCanvasLayoutReplacement(params: {
  sourceBuffer: Buffer;
  templateBuffer: Buffer;
  resultUrl: string;
  resultBuffer?: Buffer;
  sourceIdentity?: string;
  productBuffer?: Buffer;
}) {
  const resultBuffer = params.resultBuffer || await fetchImageBufferFromUrl(params.resultUrl);
  const prompt = [LAYOUT_REPLACE_QUALITY_PROMPT, params.productBuffer
    ? "图4是图2新商品的放大裁剪，仅用于看清结构细节。逐项核对图4与图3中的开放格、分隔板、门板和下缘支撑，增减任何部件都不合格；图2原图仍为最终依据。" : "", 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,
    ...(params.productBuffer ? [params.productBuffer] : [])], prompt, parseLayoutReplaceQuality);
}