'use strict';

const fs = require('fs'),
  { Errors } = require('./constants'),
  { AppInputError, AppParamError } = require('./app_error');

function splitDMS(dms) {
  if (!dms || dms.length !== 13) AppInputError.throw(Errors.INVALID_DMS);
  const fields = dms.trim().split(new RegExp('\\s+')).map(it => it.trim());
  return {
    deg: fields[0],
    min: fields[1],
    sec: fields[2].slice(0, fields[2].length - 1),
    hem: fields[2].slice(-1)
  };
}

function trimProps(objectToTrim) {
  for (const key in objectToTrim) {
    if (objectToTrim[key].constructor && objectToTrim[key].constructor == Object)
      trimProps(objectToTrim[key]);
    else if (objectToTrim[key].trim)
      objectToTrim[key] = objectToTrim[key].trim();
  }
}

function readObstacles(filePath, cb) {
  //# .Dat files have fixed-width columns; the data is always in the same position within a row
  fs.readFile(filePath, 'utf8', function (err, data) {
    // fs.truncateSync(testRes);
    if (err) throw err;
    let failed = false;
    let lines = data.toString().split('\n');
    let obs = [];
    let startLat = -1, startLatDeg = -1, startLonDeg = -1, startAGL = -1, startHT = -1, startType = -1, startAct = -1; // startASML = -1;

    try {
      for (let i = 0; i < lines.length; i++) {
        if (failed)
          break;
        let line = lines[i];
        let latDms, lonDms, ob = {};
        // Skip the first 4 rows (they include poorly formatted header information)
        if (i === 1) {
          startLat = line.toUpperCase().indexOf("LATITUDE");
          startAGL = line.toUpperCase().indexOf("AGL");
          // startASML = line.toUpperCase().indexOf("AMSL");
          startAct = line.toUpperCase().indexOf("ACTION");
        } else if (i === 2) {
          startLatDeg = line.toUpperCase().indexOf("DEG");
          startLonDeg = line.toUpperCase().indexOf("DEG", startLatDeg + 1);
          startHT = line.toUpperCase().indexOf("HT");
          startType = line.toUpperCase().indexOf("TYPE");
        }

        if (i < 4 || line.trim().length === 0) continue;
        // Verify file format, then to know where to get important fields
        if (!(startLat >= startLatDeg && startAGL === startHT) || (!startLat || !startLatDeg || !startLonDeg || !startAGL || !startHT || !startType || !startAct))
          AppParamError.throw(Errors.INVALID_OBSTACLE_FILE_FORMAT);

        ob.ors = line.slice(0, 9); // The first 9 characters of the row represent the Obstacle number
        ob.v = line.slice(10, 11);

        latDms = splitDMS(line.substring(startLatDeg, startLatDeg + 13));
        ob.latDeg = latDms.deg;
        ob.latMin = latDms.min;
        ob.latSec = latDms.sec;
        ob.latHem = latDms.hem;

        lonDms = splitDMS(line.substring(startLonDeg, startLonDeg + 13));
        ob.lonDeg = lonDms.deg;
        ob.lonMin = lonDms.min;
        ob.lonSec = lonDms.sec;
        ob.lonHem = lonDms.hem;

        ob.type = line.substring(startType, startType + 17);
        ob.agl = line.substring(startAGL, startAGL + 5);
        ob.amsl = line.substring(startAGL + 6, (startAGL + 6) + 5);
        ob.action = line.substring(startAct, startAct + 3);

        //Convert DMS to Decimal Degrees (N vs. S determines if the value is positive or negative)
        if (ob.latHem == "N")
          ob.latitude = (parseFloat(ob.latDeg) + (parseFloat(ob.latMin) / 60) + (parseFloat(ob.latSec) / 3600));
        else
          ob.latitude = -1 * (parseFloat(ob.latDeg) + (parseFloat(ob.latMin) / 60) + (parseFloat(ob.latSec) / 3600));

        // Convert DMS to Decimal Degrees (E vs. W determines if the value is positive or negative)
        if (ob.lonHem == "E")
          ob.longitude = (parseFloat(ob.lonDeg) + (parseFloat(ob.lonMin) / 60) + (parseFloat(ob.lonSec) / 3600));
        else
          ob.longitude = -1 * (parseFloat(ob.lonDeg) + (parseFloat(ob.lonMin) / 60) + (parseFloat(ob.lonSec) / 3600));

        trimProps(ob);
        ob.latitude = ob.latitude.toFixed(7);
        ob.longitude = ob.longitude.toFixed(7);

        const geoObstacle = {
          properties: {
            name: ob.ors,
            type: ob.type,
            agl: parseFloat(ob.agl),  // Above ground level in feet
            amsl: parseFloat(ob.amsl),  // Average mean sea level in feet
          },
          geometry: {
            type: 'Point',
            coordinates: [ob.longitude, ob.latitude]
          }
        };
        obs.push(geoObstacle);
      }
      return cb && cb(null, obs.slice(0));
    } catch (err) {
      // debug(err.message, "\n", err.stack);
      failed = true;
      return cb && cb(err.message);
    }
    // fs.appendFileSync(testRes, JSON.stringify(obs, null, 2));
  });
}

module.exports = {
  readObstacles
}