PHP script to read Country and Zip information from a CSV file, look up the address from the Nominatim API and save the data to a new file including the new information.

process-csv.php

<?php
// Turn off all error reporting
// We don't want notices screwing up and responses
error_reporting(0);

$file = 'mailing_list.csv';
$resultfile = 'mailing_list_nominatim_location.csv';
$start = 1;
$chunk = 20;

function toCSV($data, $outstream, $header=true) {
  if (count($data)) {
    if ($header) {
      fputcsv($outstream, array_keys($data[0]));
    }

    foreach ($data as $row) {
      fputcsv($outstream, $row);
    }
  }
}

function geocode($address){

  // google map geocode api url
  $url = "http://nominatim.openstreetmap.org/search?{$address}&format=json&&addressdetails=1";

  // get the json response
  $resp_json = file_get_contents($url);

  // decode the json
  $resp = json_decode($resp_json, true);

  // get the important data
  $lat = !empty($resp[0]['lat']) ? $resp[0]['lat'] : '';
  $lng = !empty($resp[0]['lon']) ? $resp[0]['lon'] : '';
  $formatted_address = !empty($resp[0]['display_name']) ? $resp[0]['display_name'] : '';
  $state = !empty($resp[0]['address']['state']) ? $resp[0]['address']['state'] : '';
  $county = !empty($resp[0]['address']['county']) ? $resp[0]['address']['county'] : '';
  $city = !empty($resp[0]['address']['city']) ? $resp[0]['address']['city'] : '';
  $village = !empty($resp[0]['address']['village']) ? $resp[0]['address']['village'] : '';
  $hamlet = !empty($resp[0]['address']['hamlet']) ? $resp[0]['address']['hamlet'] : '';

  // put the data in the array
  $data_arr = array(
    'lat' => $lat,
    'lng' => $lng,
    'formattedaddress' => $formatted_address,
    'state' => $state,
    'county' => $county,
    'city' => $city,
    'village' => $village,
    'hamlet' => $hamlet
  );

  return $data_arr;

}

function _combine_array(&$row, $key, $header) {
  $row = array_combine($header, $row);
}

function process($start=1, $chunk=20, $file=null, $resultfile=null) {

  $csv = array_map('str_getcsv', file($file));

  $header = array_shift($csv);

  array_walk($csv, '_combine_array', $header);

  $total_rows = count($csv);

  // If the last number to be processed is larger than the total then this is the last chunk
  $continue = (($start + $chunk) > $total_rows) ? false : true;

  //Cut out the rows we want to process
  $lines_to_process = array_slice($csv, $start, $chunk);

  // CHange these if you headers are different
  $zipHeader = 'postal code';
  $countryHeader = 'country';

  foreach ($lines_to_process as $line) {

    $addressString = '';
    if ($line[$countryHeader] !== '') {
      $addressString .= 'country='.$line[$countryHeader];
    }
    if ($line[$zipHeader] !== '') {
      if ($line[$countryHeader] !== '') {
        $addressString .= '&';
      }
      $addressString .= 'postalcode='.$line[$zipHeader];
    }

    if ($addressString === '') {
      // The file is missing address details for this row.
      $line = array_merge($line, array('lat' => '',
      'lng' => '',
      'formattedaddress' => '',
      'state' => '',
      'county' => '',
      'city' => '',
      'village' => '',
      'hamlet' => ''
    ));
  } else {
    // Use the geocode function with the address string
    $loc = geocode($addressString);
    if (is_array($loc)) {
      // We have results
      $line = array_merge($line, $loc);
    } else {
      // No results so add blank fields
      $line = array_merge($line, array('lat' => '',
      'lng' => '',
      'formattedaddress' => '',
      'state' => '',
      'county' => '',
      'city' => '',
      'village' => '',
      'hamlet' => ''
    ));
  }

}

$output[] = $line;

//Nominim allows one lookup per second so we need to wait iif we don't want to get blocked
sleep(1);

}

// 'w' writes the file wiping any content, 'a' appends to the existing file, keeping previous content.
// If we are appending then we don't want to write the headers again.
$method = $start === 1 ? 'w' : 'a';
$header = $start === 1 ? true : false;
toCSV($output, fopen($resultfile, $method), $header);

return json_encode(array(
  'success' => true,
  'results' => $output,
  'next' => $continue,
  'start' => $start,
  'chunk' => $chunk
));

}


if(isset($_POST['action']) && !empty($_POST['action'])) {
  $action = $_POST['action'];

  if(isset($_POST['start']) && !empty($_POST['start'])) {
    $start = (int)$_POST['start'];
  }

  if(isset($_POST['chunk']) && !empty($_POST['chunk'])) {
    $chunk = (int)$_POST['chunk'];
  }

  if($action == 'process') {
    echo process($start, $chunk, $file, $resultfile);
    exit();
  }

}
?>
<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap 3 Template</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">

  <!-- Bootstrap core CSS -->
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">

  <!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->
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  <script src="http://cdnjs.cloudflare.com/ajax/libs/respond.js/1.4.2/respond.js"></script>
  <![endif]-->
</head>
<body>
  <div class="container">
    <?php if (file_exists('mailing_list.csv')) : ?>
      <p class="mt-3">CSV file found....<br>Click the button to begin.</p>
      <button id="start" class="btn btn-large btn-primary">GO!</button>
    <?php else : ?>
      <div class="alert alert-error">
        <p>Cannot find a mailing_list.csv file!</p>
      </div>
    <?php endif; ?>
    <div id="results"></div>
  </div>

  <!-- Bootstrap core JavaScript
  ================================================== -->
  <!-- Placed at the end of the document so the pages load faster -->
  <script src="https://code.jquery.com/jquery-3.1.1.min.js" crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>

  <script>
  $(document).ready(function($) {

    var line = 1;
    var chunksize = 20;

    function process(start, chunksize) {
      if (line > 1) {
        $('#results').append('Done!<br>');
      }
      $('#results').append('processing lines ' + line + ' to ' + (line + chunksize - 1) + '...');

      $.ajax({
        type: 'post',
        url: window.location.href,
        data: {
          action: 'process',
          start: line,
          chunk: chunksize
        },
        success: function(response) {
          var data = JSON.parse(response);
          //console.log(response);
          if (data.success) {


            if (data.next) {
              line = line + chunksize;
              console.log('new start:' + line);
              process(line, chunksize);
            } else {
              $('#results').append('<p>Finished!</p>');
              $("#start").html('Done!').removeClass('btn-warning').addClass('btn-success');
            }

          }
        }
      });
    }

    $('#start').click(function() {
      $("#start").html('Working...').removeClass('btn-primary').addClass('btn-warning').attr('disabled', true);
      process(line, chunksize);
    })

  });
  </script>

</body>
</html>