queries-to-json

#!/usr/bin/env node
/*! @license MIT ©2014–2016 Ruben Verborgh, Ghent University – imec */
/* Merges the queries from the 'queries' folder into 'settings.json'. */

var fs = require('fs'),
    path = require('path');

var queryDir = path.join(__dirname, 'queries'),
    settingsFile = path.join(__dirname, 'settings.json'),
    outputFile = path.join(__dirname, 'queries.json');

// Write the settings with queries to the output file
var settings = JSON.parse(fs.readFileSync(settingsFile, { encoding: 'utf8' }));
settings.queries = readQueryDirectory(queryDir)
   // Sort by ascending priority and name
   .sort(function (a, b) {
      return (a.priority - b.priority) ||
             (a.name.toLowerCase() > b.name.toLowerCase() ? 1 : -1);
    })
    // Remove priority numbers in output
    .map(function (d) { return delete d.priority, d; });
fs.writeFileSync(outputFile, JSON.stringify(settings));

// Recursively reads queries in the given directory
function readQueryDirectory(directory) {
  return [].concat.apply([], fs.readdirSync(directory).map(function (filename) {
    filename = path.join(directory, filename);
    if (fs.statSync(filename).isDirectory())
      return readQueryDirectory(filename);
    else if (/\.(sparql)|(graphql)$/.test(filename))
      return readQuery(filename);
    else
      return [];
  }));
}

// Creates a query from the file
function readQuery(queryFile) {
  // Construct the initial query
  var query = {
    name: queryFile.replace(/^.+\/|\.\w+$/g, ''),
    priority: 1000, datasources: []
  };

  // Parse query comments for metadata
  var inputLines = fs.readFileSync(queryFile, {encoding: 'utf8'}).split('\n'), outputLines = [];
  inputLines.forEach(function (line, index) {
    // The line might be a key/value pair
    var keyValue = line.match(/^#\s*(\w+)\s*:\s*(.*)\s*/);
    if (keyValue) {
      var key = keyValue[1].toLowerCase(), value = keyValue[2];
      switch (key) {
      case 'datasource':
      case 'datasources':
        value.split(/\s+/)
          .forEach(function (d) {
            if (d.length) query.datasources.push(d);
          });
        return;
      }
    }
    // The first line might contain a name
    if (index === 0 && line[0] === '#') {
      query.name = line.replace(/#\s*/, '');
      // A number preceding the name indicates the priority
      if (/^\d/.test(query.name)) {
        query.priority = parseInt(query.name, 10);
        query.name = query.name.replace(/^\d+\W\s*/, '');
      }
    }
    // Any other line is part of the query
    else {
      outputLines.push(line);
    }
  });

  // Depending on the file name, assume a different query format
  if (queryFile.endsWith('graphql')) {
    var emptyLineIndex = outputLines.indexOf('');
    if (emptyLineIndex < 0)
      throw new Error(queryFile + ' does not have an empty line between GraphQL query and JSON-LD context');
    query.queryFormat = 'graphql';
    query.query = outputLines.slice(0, emptyLineIndex).join('\n').trim();
    query.context = outputLines.slice(emptyLineIndex + 1).join('\n').trim();
  }
  else {
    query.queryFormat = 'sparql';
    query.query = outputLines.join('\n').trim();
  }

  // Skip disabled query formats
  if (!settings.queryFormats[query.queryFormat]) {
    return [];
  }

  return query;
}