function ind(x: number | undefined | null, str: string): string {
  return "  ".repeat(x ?? 0) + str;
};

var tagsToReplace: Record<string, string> = {
  '&': '&amp;',
  '<': '&lt;',
  '>': '&gt;'
};

export function escapeHtmlShitty(x: string): string {
  return x.replace(/[&<>]/g, (tag) => tagsToReplace[tag] || tag);
}

export interface HtmlEnt {
  toHtmlStr(indent?: number): string;
};

class HtmlElem implements HtmlEnt {
  public name: string;
  public attrs: { [id: string]: string | boolean | undefined } = {};
  public content: HtmlEnt[] = [];

  constructor(n: string) {
    this.name = n;
  }

  setAttribute(id: string, val: string | boolean) {
    this.attrs[id] = val;
  }

  appendChild(...c: HtmlEnt[]) {
    this.content.push(...c);
  }

  toHtmlStr(indent?: number) {
    const out: string[] = [];
    const tag: string[] = [`<${this.name}`];
    for (const key of Object.keys(this.attrs)) {
      if (!this.attrs.hasOwnProperty(key)) continue;

      const x = this.attrs[key];
      if (x === undefined) continue;
      if (typeof x === "boolean" && !!x) {
        tag.push(key);
      } else {
        tag.push(`${key}="${x}"`);
      }
    }
    if (this.content.length === 0) {
      return ind(indent, tag.join(" ")) + " />";
    }

    out.push(ind(indent, tag.join(" ")) + '>');
    for (const e of this.content) {
      try {
        out.push(e.toHtmlStr((indent ?? 0) + 2));
      } catch(exc) {
        out.push(e.toString());
      }
    }
    out.push(ind(indent, `</${this.name}>`));
    return out.join("\n");
  }
}

class HtmlText implements HtmlEnt {
  public value: string;
  constructor(v: string) {
    this.value = v;
  }

  toHtmlStr(indent?: number) {
    return ind(indent, this.value);
  }
}

type Content = HtmlEnt | string | Content[] | undefined;

const add = (element: HtmlElem, child: Content) => {
  if (typeof child === 'string') {
    element.appendChild(new HtmlText(child.toString()))
  } else if (child instanceof Array) {
    child.forEach((x) => add(element, x));
  } else if (child === undefined) {
    return;
  } else {
    element.appendChild(child);
  }
};

type JSXName<T> = string | ((props: T) => HtmlEnt);
type ElemProps = { [id: string]: string | boolean }

export class JSX {
  static createElement<T>(fn: (props: T) => HtmlEnt, props: T, ...content: Content[]): HtmlEnt;
  static createElement<P, T extends JSXName<P>>(name: T, arg: T extends 'string' ? ElemProps : P, ...content: Content[]): HtmlEnt {
    if (typeof name !== 'string') {
      return name(arg);
    } else {
      const element = new HtmlElem(name);
      const props = (arg as { [id: string]: string | boolean }) || {};

      for (let name in props) {
        if (name && props.hasOwnProperty(name)) {
          let value = props[name];
          if (value === true) {
            element.setAttribute(name, name);
          } else if (value !== false && value != null) {
            element.setAttribute(name, value.toString());
          }
        }
      }

      for (let i = 0; i < content.length; i++) {
        let child = content[i];
        add(element, child);
      }
      return element;
    }
  }
};

export default JSX;