import "server-only";

import { uploadFile } from "@/lib/storage/service";

const DATA_IMAGE_URL_PATTERN = /^data:(image\/[a-z0-9.+-]+);base64,([a-z0-9+/=\s]+)$/i;

const MIME_TYPE_EXTENSION_MAP: Record<string, string> = {
  "image/jpeg": "jpg",
  "image/jpg": "jpg",
  "image/png": "png",
  "image/webp": "webp",
  "image/gif": "gif",
  "image/bmp": "bmp",
  "image/tiff": "tiff",
  "image/svg+xml": "svg",
};

function normalizeImageMimeType(mimeType: string) {
  return String(mimeType || "").trim().toLowerCase();
}

function resolveImageExtension(mimeType: string) {
  const normalized = normalizeImageMimeType(mimeType);
  return MIME_TYPE_EXTENSION_MAP[normalized] || normalized.split("/")[1] || "png";
}

function toArrayBuffer(buffer: Buffer) {
  return buffer.buffer.slice(
    buffer.byteOffset,
    buffer.byteOffset + buffer.byteLength
  ) as ArrayBuffer;
}

export function parseDataImageUrl(raw: string) {
  const trimmed = String(raw || "").trim();
  const match = trimmed.match(DATA_IMAGE_URL_PATTERN);
  if (!match) return null;

  const mimeType = normalizeImageMimeType(match[1]);
  const base64Payload = match[2].replace(/\s+/g, "");

  return {
    mimeType,
    base64Payload,
    extension: resolveImageExtension(mimeType),
  };
}

export async function uploadDataImageUrl(params: {
  imageUrl: string;
  prefix: string;
}) {
  const parsed = parseDataImageUrl(params.imageUrl);
  if (!parsed) {
    throw new Error("图片必须是有效的 data:image;base64 格式");
  }

  const buffer = Buffer.from(parsed.base64Payload, "base64");
  const filename = `${params.prefix}-${Date.now()}-${Math.random()
    .toString(36)
    .slice(2, 8)}.${parsed.extension}`;
  const uploaded = await uploadFile(filename, toArrayBuffer(buffer));
  return uploaded.url;
}

export async function ensurePublicImageUrl(params: {
  imageUrl: string;
  prefix: string;
  requestOrigin?: string;
}) {
  const trimmed = String(params.imageUrl || "").trim();
  if (!trimmed) {
    throw new Error("缺少输入图片");
  }

  if (/^https?:\/\//i.test(trimmed)) {
    return trimmed;
  }

  if (params.requestOrigin && trimmed.startsWith("/")) {
    return new URL(trimmed, params.requestOrigin).toString();
  }

  if (trimmed.startsWith("data:")) {
    return uploadDataImageUrl({
      imageUrl: trimmed,
      prefix: params.prefix,
    });
  }

  throw new Error("图片必须是公网 URL、站内相对路径或 data:image;base64");
}