import 'dart:math';
import 'package:aoc2020/aocbase.dart';
import 'package:aoc2020/model/readdata.dart';

class AOC20201213 extends AOCBase {
  var mylist = <String>[];
  int get arrival => int.parse(mylist.first);
  var busId = <int>[];
  var busIdSec2 = <int>[];

  void init(bool test) async {
    mylist = await ReadData.readFile<String>(classString, test: test);
    busId = mylist.last.split(',').where((id) => id != 'x').toList().map((id) => int.parse(id)).toList();
    busIdSec2 = mylist.last.split(',').map((id) => id == 'x' ? 1 : int.parse(id)).toList();
  }

  @override
  Future<void> a({bool test}) async {
    await init(test);
    var _mods = busId.map((id) => id - (arrival % id)).toList();
    var _minTime = _mods.reduce(min);
    var myBusId = busId[_mods.indexOf(_minTime)];
    answerA = myBusId * _minTime;
  }

  @override
  Future<void> b({bool test}) async {
    await init(test);
    var maxTime = busIdSec2.reduce(max);
    var indexOfMax = busIdSec2.indexOf(maxTime);
    var offsets = <int>[];
    for (var index = 0; index < busIdSec2.length; index++) {
      if (busIdSec2[index] != 1) offsets.add(index - indexOfMax);
    }
    // var mapOfBusIds =  = busId.asMap();
    var mapOfBusIdtoOffsets = <int, int>{};
    var mapOfIndexToBusId = <int, int>{};
    for (var i = 0; i < busId.length; i++) {
      mapOfBusIdtoOffsets[busId[i]] = offsets[i];
      mapOfIndexToBusId[i] = busId[i];
    }
    busId.sort((b, a) => a.compareTo(b));

    // void printSched(int time, int increment, int currIndex) {
    //   stdout.write('$time [$increment:$currIndex]');
    //   for (var index = 0; index < busId.length; index++) {
    //     var busid = mapOfIndexToBusId[index];
    //     var str = (time + mapOfBusIdtoOffsets[busid]) % busid == 0 ? 'D' : '.';
    //     stdout.write('    $str');
    //   }
    //   print(' ');
    // }

    int calcFor({int number, int inputTime, int increment}) {
      var time = inputTime;
      var notdone = true;
      do {
        var fail = false;
        time += increment;
        for (var index = 0; index < number && !fail; index++) {
          var offset = mapOfBusIdtoOffsets[busId[index]];
          fail = (time + offset) % busId[index] != 0;
        }
        notdone = fail;
      } while (notdone && time > 0);
      return time;
    }

    var time1 = calcFor(number: 4, inputTime: 0, increment: maxTime);
    var time2 = calcFor(number: 4, inputTime: time1, increment: maxTime);
    var diffTime = time2 - time1;
    print('$time2 - $time1 = ${diffTime}');

    var time = calcFor(number: busId.length, inputTime: time2, increment: diffTime);
    answerB = time - indexOfMax;
  }
}