import axios from "axios";
import fs from "node:fs";
import path from "node:path";

export interface AssetMap {
  [originalUrl: string]: string;
}

export class AssetManager {
  private userAgent: string;

  constructor(
    userAgent: string = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36",
  ) {
    this.userAgent = userAgent;
  }

  public sanitizePath(rawPath: string): string {
    return rawPath
      .split("/")
      .map((p) => p.replace(/[^a-z0-9._-]/gi, "_"))
      .join("/");
  }

  public async downloadFile(
    url: string,
    assetsDir: string,
  ): Promise<string | null> {
    if (url.startsWith("//")) url = `https:${url}`;
    if (!url.startsWith("http")) return null;

    try {
      const u = new URL(url);
      const relPath = this.sanitizePath(u.hostname + u.pathname);
      const dest = path.join(assetsDir, relPath);

      if (fs.existsSync(dest)) return `./assets/${relPath}`;

      const res = await axios.get(url, {
        responseType: "arraybuffer",
        headers: { "User-Agent": this.userAgent },
        timeout: 15000,
        validateStatus: () => true,
      });

      if (res.status !== 200) return null;

      if (!fs.existsSync(path.dirname(dest)))
        fs.mkdirSync(path.dirname(dest), { recursive: true });
      fs.writeFileSync(dest, Buffer.from(res.data));
      return `./assets/${relPath}`;
    } catch {
      return null;
    }
  }

  public async processCssRecursively(
    cssContent: string,
    cssUrl: string,
    assetsDir: string,
    urlMap: AssetMap,
    depth = 0,
  ): Promise<string> {
    if (depth > 5) return cssContent;

    const urlRegex = /(?:url\(["']?|@import\s+["'])([^"')]*)["']?\)?/gi;
    let match;
    let newContent = cssContent;

    while ((match = urlRegex.exec(cssContent)) !== null) {
      const originalUrl = match[1];
      if (originalUrl.startsWith("data:") || originalUrl.startsWith("blob:"))
        continue;

      try {
        const absUrl = new URL(originalUrl, cssUrl).href;
        const local = await this.downloadFile(absUrl, assetsDir);

        if (local) {
          const u = new URL(cssUrl);
          const cssPath = u.hostname + u.pathname;
          const assetPath = new URL(absUrl).hostname + new URL(absUrl).pathname;

          const rel = path.relative(
            path.dirname(this.sanitizePath(cssPath)),
            this.sanitizePath(assetPath),
          );

          newContent = newContent.split(originalUrl).join(rel);
          urlMap[absUrl] = local;
        }
      } catch {
        // Ignore
      }
    }
    return newContent;
  }
}