import 'sentence.dart';
import 'types.dart';

class Parser {
  BaseSentence baseSentence;
  String? _err;

  Parser(this.baseSentence);

  void assertType(String typ) {
    if (baseSentence.type != typ) {
      setErr('type', baseSentence.type);
    }
  }

  String? err() {
    return _err;
  }

  void setErr(String context, String value) {
    _err ??= 'nmea: ${baseSentence.prefix()} invalid $context: $value';
  }

  String string(int i, String context) {
    if (_err != null) {
      return '';
    }
    if (i < 0 || i >= baseSentence.fields.length) {
      setErr(context, 'index out of range');
      return '';
    }
    return baseSentence.fields[i];
  }

  List<String> listString(int from, String context) {
    if (_err != null) {
      return [];
    }
    if (from < 0 || from >= baseSentence.fields.length) {
      setErr(context, 'index out of range');
      return [];
    }
    return baseSentence.fields.sublist(from);
  }

  String enumString(
    int i,
    String context,
    List<String> options,
  ) {
    String? s = string(i, context);
    if (_err != null || s == '') {
      return '';
    }
    if (options.contains(s)) {
      return s;
    } else {
      setErr(context, s);
      return '';
    }
  }

  List<String> enumChars(int i, String context, List<String> options) {
    String? s = string(i, context);
    if (_err != null || s == '') {
      return [];
    }
    List<String> strs = [];
    for (int j = 0; j < s.length; j++) {
      String rs = s[j];
      if (options.contains(rs)) {
        strs.add(rs);
      }
    }
    if (strs.length != s.length) {
      setErr(context, s);
      return [];
    }
    return strs;
  }

  int hexInt64(int i, String context) {
    String? s = string(i, context);
    if (_err != null) {
      return 0;
    }
    if (s == '') {
      return 0;
    }
    int value = int.parse(s, radix: 16);
    return value;
  }

  int int64(int i, String context) {
    return nullInt64(i, context).value;
  }

  Int64 nullInt64(int i, String context) {
    String? s = string(i, context);
    if (_err != null) {
      return Int64(0, false);
    }
    if (s == '') {
      return Int64(0, false);
    }
    int? v = int.tryParse(s);
    if (v == null) {
      setErr(context, s);
      return Int64(0, false);
    }
    return Int64(v, true);
  }

  double float64(int i, String context) {
    return nullFloat64(i, context).value;
  }

  Float64 nullFloat64(int i, String context) {
    String? s = string(i, context);
    if (_err != null) {
      return Float64(0, false);
    }
    if (s == '') {
      return Float64(0, false);
    }
    double? v = double.tryParse(s);
    if (v == null) {
      setErr(context, s);
      return Float64(0, false);
    }
    return Float64(v, true);
  }

  Time time(int i, String context) {
    String? s = string(i, context);
    if (_err != null) {
      return Time(false, 0, 0, 0, 0);
    }
    try {
      return parseTime(s);
    } catch (e) {
      setErr(context, s);
      return Time(false, 0, 0, 0, 0);
    }
  }

  Date date(int i, String context) {
    String? s = string(i, context);
    if (_err != null) {
      return Date(false, 0, 0, 0);
    }
    try {
      return parseDate(s);
    } catch (e) {
      setErr(context, s);
      return Date(false, 0, 0, 0);
    }
  }

  double latLong(int i, int j, String context) {
    String a = string(i, context);
    String b = string(j, context);
    if (_err != null) {
      return 0;
    }
    String s = '$a $b';
    double? v = parseLatLong(s);
    if ((b == 'North' || b == 'South') && (v < -90.0 || v > 90.0)) {
      setErr(context, 'latitude is not in range (-90, 90)');
      return 0;
    } else if ((b == 'West' || b == 'East') && (v < -180.0 || v > 180.0)) {
      setErr(context, 'longitude is not in range (-180, 180)');
      return 0;
    }
    return v;
  }

  List<int> sixBitASCIIArmour(int i, int fillBits, String context) {
    if (_err != null) {
      return [];
    }
    if (fillBits < 0 || fillBits >= 6) {
      setErr(context, 'fill bits');
      return [];
    }

    List<int> payload = string(i, 'encoded payload').codeUnits;
    int numBits = payload.length * 6 - fillBits;

    if (numBits < 0) {
      setErr(context, 'num bits');
      return [];
    }

    List<int> result = List.filled(numBits, 0);
    int resultIndex = 0;

    for (int v in payload) {
      if (v < 48 || v >= 120) {
        setErr(context, 'data byte');
        return [];
      }

      int d = v - 48;
      if (d > 40) {
        d -= 8;
      }

      for (int i = 5; i >= 0 && resultIndex < result.length; i--) {
        result[resultIndex] = (d >> i) & 1;
        resultIndex++;
      }
    }

    return result;
  }
}

class Time {
  bool isValid;
  int hour;
  int minute;
  int second;
  int millisecond;

  Time(this.isValid, this.hour, this.minute, this.second, this.millisecond);
}

Time parseTime(String s) {
  if (s == "") {
    return Time(false, 0, 0, 0, 0);
  }
  RegExp timeRe = RegExp(r"^\d{6}(\.\d*)?$");
  if (!timeRe.hasMatch(s)) {
    throw Exception("parse time: expected hhmmss.ss format, got '$s'");
  }
  int hour = int.parse(s.substring(0, 2));
  int minute = int.parse(s.substring(2, 4));
  double second = double.parse(s.substring(4));

  int whole = second.floor(); // 获取整数部分
  double frac = second - whole; // 获取小数部分
  return Time(true, hour, minute, whole.toInt(), (frac * 1000).round());
}

mixin math {}

class Int64 {
  int value;
  bool valid;

  Int64(this.value, this.valid);
}

class Float64 {
  double value;
  bool valid;

  Float64(this.value, this.valid);
}