export class Url {
   static base: string;
   static absoluteBase: string;

   static resolve(path: string): string {
      return path.replace("~/", this.base);
   }

   static absolute(path: string): string {
      return path.replace("~/", this.absoluteBase);
   }

   static unresolve(path: string): string {
      if (path.indexOf("~/") == 0) return path;

      const absBase = this.absoluteBase || "";

      //handle paths like /app and /app/
      if (path.length == absBase.length - 1 && absBase == path + "/") return "~/";

      if (path.indexOf(absBase) == 0) return "~/" + path.substring(absBase.length);

      return "~/" + path.substring(this.base.length);
   }

   static getAbsoluteBase(): string {
      return this.absoluteBase;
   }

   static isLocal(url: string): boolean {
      const absBase = this.getAbsoluteBase();
      return url.indexOf("~/") == 0 || url.indexOf(absBase) == 0 || url.indexOf(this.base) == 0;
   }

   static setBase(base: string): void {
      if (!base || base[base.length - 1] != "/") base += "/";
      this.base = base;
      if (typeof window != "undefined")
         this.absoluteBase = window.location.protocol + "//" + window.location.host + this.base;
   }

   static getOrigin(): string {
      if (typeof window == "undefined") return "";
      return (
         window.location.protocol +
         "//" +
         window.location.hostname +
         (window.location.port ? ":" + window.location.port : "")
      );
   }

   static getBaseFromScriptSrc(src: string, scriptPath: string | RegExp): string | false {
      if (!(scriptPath instanceof RegExp)) scriptPath = getBasePathRegex(scriptPath);

      let index = src.search(scriptPath);
      if (index == -1) return false;

      let origin = this.getOrigin();
      return src.substring(src.indexOf(origin) == 0 ? origin.length : 0, index);
   }

   static setBaseFromScript(scriptPath: string | RegExp): void {
      const scripts = document.getElementsByTagName("script");
      let base: string | false;

      if (!(scriptPath instanceof RegExp)) scriptPath = getBasePathRegex(scriptPath);

      for (let i = 0; i < scripts.length; i++) {
         base = this.getBaseFromScriptSrc(scripts[i].src, scriptPath);
         if (base) {
            this.setBase(base);
            return;
         }
      }

      throw new Error(`Could not resolve url base from script matching '${scriptPath}'.`);
   }
}

Url.setBase('/');

function getBasePathRegex(str: string): RegExp {
   let regex = "";
   let start = 0;
   if (str.indexOf("~/") == 0) start = 2;

   for (let i = start; i < str.length; i++) {
      switch (str[i]) {
         case ".":
            regex += "\\.";
            break;

         case "*":
            regex += ".*";
            break;

         default:
            regex += str[i];
      }
   }
   return new RegExp(regex + "(\\?.*)?$", "i");
}