'use strict';

const { spawnSync } = require('node:child_process');

function mermaid(config) {
  return function(args, content) {
    let options = Object.assign({}, config);
    let caption = '';
    for (const arg in args) {
      const arr = arg.split(':');
      if (arr.length == 1) {
        caption = arr;
      } else {
        const { key, val } = arr;
        options[key] = val;
      }
    }

    const args = [
      '-t', options.theme || 'default',
      '-w', options.width || 800,
      '-H', options.height || 600,
      '-e', options.format || 'svg',
      '-b', options.background || 'white',
      '-s', options.scale || 1,
      '-i', '-',
      '-o', '-'
    ];

    const result = spawnSync(options.mmdcPath, args, {
      cwd: process.cwd(),
      env: process.env,
      input: content,
      encoding: 'utf8',
      timeout: options.timeout
    });

    if (result.status === 0) {
      if (result.stderr) {
        console.warn(result.stderr);
      }
      const path = 'data:image/svg+xml;base64,' + Buffer.from(result.stdout).toString('base64');
      
      if (caption != '') {
        return `<figure><img src="${ path }" alt="${ caption }"/><figcaption>${ caption }</figcaption></figure>`
      } else {
        return `<p><image src="${ path }"/></p>`;
      }
    }
    if (result.error) {
      throw result.error;
    }
    throw Error('mmdc exited with code ' + result.status + (result.stderr ? ': ' + result.stderr : '.'));
  };
}

module.exports = mermaid;