import { decode } from 'html-entities';
import { existsSync } from 'fs';
import { resolve } from 'path';

const latexTypes = ['', 'section', 'subsection', 'paragraph', 'subparagraph'];

const sanitize = (text?: string) => {
  if (!text) {
    return '';
  }
  return decode(text)
    .replace('&', '\\&')
    .replace('_', '\\_')
    .replace(/([^\\])\}/g, '$1\\}')
    .replace(/([^\\])\{/g, '$1\\{')
    .replace(/[^\\]\[/g, '\\[')
    .replace(/#/g, '\\#');
};

type Renderer = (depth: number) => {
  heading?: (text: string, depth: number) => string;
  code?: (input: string) => string;
  text?: (input: string) => string;
  paragraph?: (input: string) => string;
  list?: (input: string) => string;
  listitem?: (input: string) => string;
  link?: (href: string, text: string) => string;
  strong?: (text: string) => string;
  em?: (text: string) => string;
  codespan?: (code: string) => string;
  image?: (link: string) => string;
};

const renderer = (outerDepth: number, cwd: string) => ({
  heading: (text: string, depth: number) => {
    return `\\${latexTypes[outerDepth + depth]}{${sanitize(text)}}\n\n`;
  },
  code: (input: string) => {
    return `
    \\begin{lstlisting}
    ${input}
    \\end{lstlisting}
    `;
  },
  text: (input: string) => {
    return sanitize(input);
  },
  blockquote: (input: string) => {
    return sanitize(input);
  },
  paragraph: (input: string) => {
    return `${input}\n\n`;
  },
  list: (input: string) => {
    return `
    \\begin{itemize}
    ${input}
    \\end{itemize}
    `;
  },
  listitem: (input: string) => {
    return `\\item{${input}}`;
  },
  link: (href: string, text: string) => {
    if (!text || text === href) {
      return `\\url{${sanitize(href)}}`;
    }
    return `${sanitize(text)} (\\url{${sanitize(href)}})`;
  },
  strong: (text: string) => {
    return `\\textbf{${sanitize(text)}}`;
  },
  em: (text: string) => {
    return `\\textbf{${sanitize(text)}}`;
  },
  codespan: (code: string) => {
    return `\\texttt{${sanitize(code)}}`;
  },
  image: (link: string) => {
    const path = resolve(cwd, link);
    if (!existsSync(path)) {
      return `Online image not supported ${path}`;
    }
    return `
  \\noindent\\includegraphics[width=\\linewidth]{${path}}
`;
  },
});

export type { Renderer };
export { sanitize, renderer };