'use strict';

const DotParser = require('dotparser');

const internals = {

  // Extract vertices and dependencies

  parseDotObject(entries) {

    const vertices = new Set();
    const dependencies = {};

    entries.forEach((entry) => {

      if (entry.node_id) {
        vertices.add(entry.node_id.id);
      }

      if (entry.edge_list) {
        vertices.add(entry.edge_list[0].id);
        vertices.add(entry.edge_list[1].id);

        dependencies[entry.edge_list[1].id] = dependencies[entry.edge_list[1].id] || new Set();
        dependencies[entry.edge_list[1].id].add(entry.edge_list[0].id);
      }

    });

    return {
      vertices,
      dependencies
    };
  },

  // Generate grafn code from a list of vertices and dependencies

  generateCode(vertices, dependencies) {

    const code = ['const Grafn = require(\'grafn\')', 'const graph = new Grafn()'];

    for (const vertex of vertices) {
      const vertexDependencies = Array.from(dependencies[vertex] || []);

      code.push('graph.vertex({');
      code.push(`  name: '${vertex}',`);
      code.push(`  dependencies: ${JSON.stringify(vertexDependencies).replace(/"/g, '\'')},`);
      code.push('  action: async () => {}');
      code.push('});');
    }

    return code.join('\n');
  }
};

// Take some dot source code... make it grafn source code.

module.exports = function graphvizToGrafn(dotSource) {

  const dotObject = DotParser(dotSource);
  const { vertices, dependencies } = internals.parseDotObject(dotObject[0].children);

  return internals.generateCode(vertices, dependencies);
};