import fs from "fs";
import assert from "assert";
import logging from '../lib/logging.js';
import glob from "fast-glob";
import path from "path";
import template from "lodash/template.js";

const log = logging.create(import.meta.url);

export const description = "Describe your command here."

// your command uses the npm package commander's options format
export const options = [
  ["--list", "List the available templates to use."],
  ["--force", "Overwrite the output if it exists."],
  ["--output <string>", "Save to file rather than stdout."],
  ["--template <name>", "Name of the template to generate. Use --list to see."]
]

const check = (test, fail_message) => {
  if(!test) {
    log.error(fail_message);
    process.exit(1);
  }
}

export const main = async (opts) => {
  try {
    if(opts.list) {
      const available = glob.sync("./static/djenterator/!(*.vars|*.swp)");
      for(let name of available) {
        console.log(name);
      }
    } else {
      check(opts.template, "--template is required.");
      check(opts.output, "--output is required.");

      check(fs.existsSync(opts.template), `template file ${opts.template} does not exist`);

      const in_template = fs.readFileSync(opts.template).toString();

      const vars_file = `${opts.template}.vars`;
      const in_vars = fs.existsSync(vars_file) ? fs.readFileSync(vars_file) : {};

      const renderer = template(in_template);
      const result = renderer(JSON.parse(in_vars));

      if(!opts.force) {
        check(!fs.existsSync(opts.output), `output file ${opts.output} exists already won't overwrite.`);
      }

      fs.writeFileSync(opts.output, result);
    }
  } catch(error) {
    log.error(error);
    process.exit(1);
  }

  process.exit(0);
}