import { Utils } from "../Utils";

/**
 * Content disposition of HTTP
 * https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
 */
export class ContentDisposition {
  constructor(type: "inline" | "attachment", filename: string);
  constructor(type: "form-data", filename: string, name: string);
  constructor(
    public readonly type: string,
    public readonly filename: string,
    public readonly name?: string
  ) {}

  /**
   * Format to standard output
   * @returns Result
   */
  format() {
    const items = [this.type];
    if (this.name) items.push(`name="${this.name}"`);
    const filename1 = this.filename.replace(/[^a-zA-Z0-9\.-]/g, "_");
    items.push(`filename="${filename1}"`);
    if (filename1 != this.filename)
      items.push(`filename*="UTF-8''${encodeURIComponent(this.filename)}"`);
    return items.join("; ");
  }

  /**
   * Parse header value
   * @param header Content-Disposition header value
   * @returns Object
   */
  static parse(header: string | undefined | null) {
    if (!header) return undefined;

    const parts = header.trim().split(/\s*;\s*/g);
    const len = parts.length;
    if (len < 2) return undefined;

    const type = parts[0];
    let name: string | undefined;
    let filename: string = "";

    for (let i = 1; i < len; i++) {
      const part = parts[i];
      let [field, value] = part.split(/\s*=\s*/g);

      // case-insensitive
      field = field.toLowerCase();

      // Remove quotes
      value = Utils.trim(value, '"');

      if (field === "name") {
        name = value;
      } else if (field === "filename") {
        if (filename === "") filename = value;
      } else if (field === "filename*") {
        const pos = value.indexOf("''");
        filename =
          pos == -1 ? value : decodeURIComponent(value.substring(pos + 2));
      }
    }

    if (type === "form-data") {
      return new ContentDisposition(type, filename, name ?? "file");
    }

    if (type === "inline" || type === "attachment") {
      return new ContentDisposition(type, filename);
    }

    return undefined;
  }
}