const testit = require('testit');
const { fromLatLon, toLatLon } = require('.');
const { expect } = require('chai');

// Arbitrary
const DELTA = 3e-5;

testit('normal conversions', () => {
  for (const [
    name,
    [lat, lon],
    [easting, northing, zoneNum, zoneLetter, northern]
  ] of [
    [
      'Aachen, Germany',
      [50.77535, 6.08389],
      [294409, 5628898, 32, 'U', true]
    ],
    [
      'New York, USA',
      [40.71435, -74.00597],
      [583960, 4507523, 18, 'T', true]
    ],
    [
      'Wellington, New Zealand',
      [-41.28646, 174.77624],
      [313784, 5427057, 60, 'G', false]
    ],
    [
      'Capetown, South Africa',
      [-33.92487, 18.42406],
      [261878, 6243186, 34, 'H', false]
    ],
    [
      'Mendoza, Argentina',
      [-32.89018, -68.84405],
      [514586, 6360877, 19, 'h', false]
    ],
    [
      'Fairbanks, Alaska, USA',
      [64.83778, -147.71639],
      [466013, 7190568, 6, 'W', true]
    ],
    [
      'Ben Nevis, Scotland, UK',
      [56.79680, -5.00601],
      [377486, 6296562, 30, 'V', true]
    ],
    [
      'Latitude 84',
      [84, -5.00601],
      [476594, 9328501, 30, 'X', true]
    ]
  ]) {
    testit(`${name} fromLatLon`, () => {
      check(fromLatLon(lat, lon));
      check(fromLatLon(lat, lon, zoneNum));

      function check(actual) {
        expect(actual.easting).to.be.closeTo(easting, 0.5);
        expect(actual.northing).to.be.closeTo(northing, 0.5);
        expect(actual.zoneNum).to.equal(zoneNum);
        expect(actual.zoneLetter).to.equal(zoneLetter.toUpperCase());
      }
    });

    testit(`${name} toLatLon`, () => {
      check(toLatLon(easting, northing, zoneNum, zoneLetter));
      check(toLatLon(easting, northing, zoneNum, undefined, northern));

      function check(actual) {
        expect(actual.latitude).to.be.closeTo(lat, DELTA);
        expect(actual.longitude).to.be.closeTo(lon, DELTA);
      }
    });
  }
});

testit('range check', () => {
  testit('fromLatLon bad range', () => {
    for (const args of [
      [-100, 0],
      [-80.1, 0],
      [84.1, 0],
      [100, 0],
      [0, -300],
      [0, -180.1],
      [0, 180.1],
      [0, 300],
      [-100, -300],
      [100, -300],
      [-100, 300],
      [100, 300]
    ]) {
      expect(() => fromLatLon(...args)).to.throw(RangeError);
    }
  });

  testit('fromLatLon good range', () => {
    for (const i of range(-80, 84, 0.01)) {
      fromLatLon(i, 0);
    }
    for (const i of range(-180, 180, 0.01)) {
      fromLatLon(0, i);
    }
  });

  testit('toLatLon bad range', () => {
    for (const args of [
      // test easting range
      [0, 5000000, 32, 'U'],
      [99999, 5000000, 32, 'U'],
      [1000000, 5000000, 32, 'U'],
      [100000000000, 5000000, 32, 'U'],

      // test northing range
      [500000, -100000, 32, 'U'],
      [500000, -1, 32, 'U'],
      [500000, 10000001, 32, 'U'],
      [500000, 50000000, 32, 'U'],

      // test zone numbers
      [500000, 5000000, 0, 'U'],
      [500000, 5000000, 61, 'U'],
      [500000, 5000000, 1000, 'U'],

      // test zone letters
      [500000, 5000000, 32, 'A'],
      [500000, 5000000, 32, 'B'],
      [500000, 5000000, 32, 'I'],
      [500000, 5000000, 32, 'O'],
      [500000, 5000000, 32, 'Y'],
      [500000, 5000000, 32, 'Z']
    ]) {
      expect(() => toLatLon(...args)).to.throw(RangeError);
    }
  });

  testit('toLatLon good range', () => {
    for (const i of range(100000, 999999, 1000)) {
      toLatLon(i, 5000000, 32, 'U');
    }
    for (const i of range(10, 10000000, 1000)) {
      toLatLon(500000, i, 32, 'U');
    }
    for (const i of range(1, 60)) {
      toLatLon(500000, 5000000, i, 'U');
    }
    for (const i of range('C'.codePointAt(0), 'X'.codePointAt(0) + 1)) {
      const ch = String.fromCodePoint(i);
      if (ch !== 'I' && ch !== 'O') {
        toLatLon(500000, 5000000, 32, ch);
      }
    }
  });
});

testit('special cases', () => {
  testit('zone 32', () => {
    for (const [lat, lon, zoneNum, zoneLetter] of [
      // inside
      [56, 3, 32, 'V'],
      [56, 6, 32, 'V'],
      [56, 9, 32, 'V'],
      [56, 11.999999, 32, 'V'],

      [60, 3, 32, 'V'],
      [60, 6, 32, 'V'],
      [60, 9, 32, 'V'],
      [60, 11.999999, 32, 'V'],

      [63.999999, 3, 32, 'V'],
      [63.999999, 6, 32, 'V'],
      [63.999999, 9, 32, 'V'],
      [63.999999, 11.999999, 32, 'V'],

      // left of
      [55.999999, 2.999999, 31, 'U'],
      [56, 2.999999, 31, 'V'],
      [60, 2.999999, 31, 'V'],
      [63.999999, 2.999999, 31, 'V'],
      [64, 2.999999, 31, 'W'],

      // right of
      [55.999999, 12, 33, 'U'],
      [56, 12, 33, 'V'],
      [60, 12, 33, 'V'],
      [63.999999, 12, 33, 'V'],
      [64, 12, 33, 'W'],

      // below
      [55.999999, 3, 31, 'U'],
      [55.999999, 6, 32, 'U'],
      [55.999999, 9, 32, 'U'],
      [55.999999, 11.999999, 32, 'U'],
      [55.999999, 12, 33, 'U'],

      // above
      [64, 3, 31, 'W'],
      [64, 6, 32, 'W'],
      [64, 9, 32, 'W'],
      [64, 11.999999, 32, 'W'],
      [64, 12, 33, 'W']
    ]) {
      const results = fromLatLon(lat, lon);
      expect(results.zoneNum).to.equal(zoneNum);
      expect(results.zoneLetter).to.equal(zoneLetter.toUpperCase());
    }
  });

  testit('right boundaries', () => {
    for (const [lat, lon, zoneNum] of [
      [40, 0, 31],
      [40, 5.999999, 31],
      [40, 6, 32],

      [72, 0, 31],
      [72, 5.999999, 31],
      [72, 6, 31],
      [72, 8.999999, 31],
      [72, 9, 33]
    ]) {
      const results = fromLatLon(lat, lon);
      expect(results.zoneNum).to.equal(zoneNum);
    }
  });
});

function* range(start, stop, step = 1) {
  if (arguments.length === 1) {
    stop = start;
    start = 0;
  }

  if (step === 0) {
    throw new RangeError('step must not be zero');
  }

  let cur = start;
  while (step > 0 ? cur < stop : cur > stop) {
    yield cur;
    cur += step;
  }
}