Extracting an edge list from Canvas Discussion Topics API using Google Apps Script

gistfile1.js

function getCanvasDiscussionEdges() {
  var canvas = "learn.canvas.net";
  var type = "courses";
  var id = "33";
  var output = [["vert1_name","vert2_name","vert1_id","vert2_id","vert1_image_url","vert2_image_url","topic_id","topic_title","topic_url","created_at", "message_id", "message_text"]];
  var doc = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = doc.getSheetByName("Sheet1");
  var db = ScriptDb.getMyDb();
  var topicList = callCanvasAPI(canvas, type, id, "discussion_topics", 50);
  var participants = {}
  for (i in topicList.result){
    var topic = topicList.result[i];
    var data = callCanvasAPI(canvas, type, id, "discussion_topics/"+topicList.result[i].id+"/view");
    var participant_data = data.result.participants;
    for (p in participant_data){
      participants[participant_data[p].id] = participant_data[p];
    }
    for (j in data.result.view){
      var view = data.result.view[j];
      if (!view.deleted){
        var vert1_name = participants[view.user_id].display_name;
        var vert2_name = topic.author.display_name;
        var vert1_id = view.user_id;
        var vert2_id = topic.author.id;
        var vert1_image_url = participants[view.user_id].avatar_image_url;
        var vert2_image_url = topic.author.avatar_image_url;
        var topic_id = topic.id;
        var topic_title = topic.title;
        var topic_url = topic.url;
        var topic_url = topic.url;
        var created_at = getDateFromIso(view.created_at);
        var message_id = view.id;
        output.push([vert1_name, vert2_name, vert1_id, vert2_id, vert1_image_url, vert2_image_url, topic_id, topic_title, topic_url, created_at, message_id, stripHTML(view.message)]);
        output = output.concat(getReplies(view, participants, topic));
      }
    }
  }
  sheet.getRange(1, 1, output.length, output[0].length).setValues(output);
}

function getReplies(view, participants, topic){
  var rows = [];
  if (!view.deleted){ 
    if (view.replies != undefined){
      for (r in view.replies){
        var reply = view.replies[r];
        if (!reply.deleted){
          var vert1_name = participants[reply.user_id].display_name;
          var vert2_name = participants[view.user_id].display_name;
          var vert1_id = reply.user_id;
          var vert2_id = view.user_id;
          var vert1_image_url = participants[reply.user_id].avatar_image_url;
          var vert2_image_url = participants[view.user_id].avatar_image_url;
          var topic_id = topic.id;
          var topic_title = topic.title;
          var topic_url = topic.url;
          var created_at = getDateFromIso(reply.created_at);
          var message_id = view.id;
          rows.push([vert1_name, vert2_name, vert1_id, vert2_id, vert1_image_url, vert2_image_url, topic_id, topic_title, topic_url, created_at, message_id, stripHTML(reply.message)]);
          rows = rows.concat(getReplies(reply, participants, topic));
        }
      }
    }
  }
  return rows;
}

function callCanvasAPI(canvas, type, id, call, optPerPage){
  var perpage = (optPerPage != undefined) ? "?per_page="+optPerPage : "";
  var resp = {};
  var requestData = { method: "get",
                      headers: { "Authorization": "Bearer " + PropertiesService.getScriptProperties().getProperty("access_token")}};
  var result = UrlFetchApp.fetch("https://"+canvas+"/api/v1/"+type+"/"+id+"/"+call+perpage, requestData);
  if (result.getResponseCode() == 200){
    var header = result.getHeaders();
    if (header.Link) {
      resp.linkHeader = parseLinkHeader(header.Link).rels;
    }
    resp.result = JSON.parse(result.getContentText());
    resp.responseCode = 200;
  } else {
    resp.responseCode = result.getResponseCode();
  }
  return resp;
}

function stripHTML(string){
  var regex = /(<([^>]+)>)/ig;
  return string.replace(regex, "");
}

// http://delete.me.uk/2005/03/iso8601.html
function getDateFromIso(string) {
  try{
    var aDate = new Date();
    var regexp = "([0-9]{4})(-([0-9]{2})(-([0-9]{2})" +
        "(T([0-9]{2}):([0-9]{2})(:([0-9]{2})(\.([0-9]+))?)?" +
        "(Z|(([-+])([0-9]{2}):([0-9]{2})))?)?)?)?";
    var d = string.match(new RegExp(regexp));

    var offset = 0;
    var date = new Date(d[1], 0, 1);

    if (d[3]) { date.setMonth(d[3] - 1); }
    if (d[5]) { date.setDate(d[5]); }
    if (d[7]) { date.setHours(d[7]); }
    if (d[8]) { date.setMinutes(d[8]); }
    if (d[10]) { date.setSeconds(d[10]); }
    if (d[12]) { date.setMilliseconds(Number("0." + d[12]) * 1000); }
    if (d[14]) {
      offset = (Number(d[16]) * 60) + Number(d[17]);
      offset *= ((d[15] == '-') ? 1 : -1);
    }

    offset -= date.getTimezoneOffset();
    time = (Number(date) + (offset * 60 * 1000));
    return new Date(aDate.setTime(Number(time)));
  } catch(e){
    return;
  }
}



// http://bill.burkecentral.com/2009/10/15/parsing-link-headers-with-javascript-and-java/
function parseLinkHeader(value) {
  var linkexp=/<[^>]*>\s*(\s*;\s*[^\(\)<>@,;:"\/\[\]\?={} \t]+=(([^\(\)<>@,;:"\/\[\]\?={} \t]+)|("[^"]*")))*(,|$)/g;
  var paramexp=/[^\(\)<>@,;:"\/\[\]\?={} \t]+=(([^\(\)<>@,;:"\/\[\]\?={} \t]+)|("[^"]*"))/g;
  var matches = value.match(linkexp);
  var rels = new Object();
  var titles = new Object();
  for (i = 0; i < matches.length; i++)
  {
    var split = matches[i].split('>');
    var href = split[0].substring(1);
    var ps = split[1];
    var link = new Object();
    link.href = href;
    var s = ps.match(paramexp);
    for (j = 0; j < s.length; j++) {
      var p = s[j];
      var paramsplit = p.split('=');
      var name = paramsplit[0];
      link[name] = unquote(paramsplit[1]);
    }
    if (link.rel != undefined) {
      rels[link.rel] = link;
    }
    if (link.title != undefined)  {
      titles[link.title] = link;
    }
  }
  var linkheader = new Object();
  linkheader.rels = rels;
  linkheader.titles = titles;
  return linkheader;
}

function unquote(value) {
  if (value.charAt(0) == '"' && value.charAt(value.length - 1) == '"') return value.substring(1, value.length - 1);
  return value;
}