/* 此文件实现了有理数与二次根式形成的数域
 * 需要在pubspec.yaml中添加依赖rational: ^2.2.3
 * 使用方法请看最后的测试用例
 * Ksqrt类表示有理数乘以根号整数
 * RationalExtend类表示多个Ksqrt类根式相加
 * Author：nonvioce
 * Time: 2025.10.26
*/
import 'package:rational/rational.dart';
import 'dart:math';

class Ksqrt {
  Rational k; // 有理数系数
  int q;      // 底数（整数）

  Ksqrt(this.k, this.q) {
    if (q < 0) throw ArgumentError("底数q不能为负数");
  }

  // 从整数创建（系数为整数，底数为1）
  factory Ksqrt.fromInt(int value) {
    return Ksqrt(Rational.fromInt(value), 1);
  }

  // 从Rational创建（系数为有理数，底数为1）
  factory Ksqrt.fromRational(Rational rational) {
    return Ksqrt(rational, 1);
  }

  // 增强的字符串解析 - 增加小数支持
  factory Ksqrt.parse(String str) {
    str = str.trim();

    // 处理纯数字（整数或小数）
    if (RegExp(r'^-?\d+(\.\d+)?$').hasMatch(str)) {
      return Ksqrt.fromRational(_parseRational(str));
    }

    // 处理分数（不包含根号）
    if (str.contains('/') && !str.contains('√')) {
      try {
        var parts = str.split('/');
        if (parts.length != 2) throw FormatException("无效的分数格式: $str");

        var numerator = _parseRational(parts[0]);
        var denominator = _parseRational(parts[1]);

        if (denominator == Rational.zero) throw FormatException("分母不能为零: $str");

        return Ksqrt.fromRational(numerator / denominator);
      } catch (e) {
        throw FormatException("无效的分数格式: $str, 错误: $e");
      }
    }

    // 处理根式
    if (str.contains('√')) {
      var sqrtIndex = str.indexOf('√');
      var coefficientStr = str.substring(0, sqrtIndex);
      var radicandStr = str.substring(sqrtIndex + 1);

      // 处理括号内的底数
      if (radicandStr.startsWith('(') && radicandStr.endsWith(')')) {
        radicandStr = radicandStr.substring(1, radicandStr.length - 1);
      }

      Rational k;

      // 解析系数
      if (coefficientStr.isEmpty || coefficientStr == "+") {
        k = Rational.one;
      } else if (coefficientStr == "-") {
        k = -Rational.one;
      } else {
        coefficientStr = coefficientStr.replaceAll('*', '');
        try {
          if (coefficientStr.contains('/')) {
            var coeffParts = coefficientStr.split('/');
            if (coeffParts.length != 2) throw FormatException("无效的系数格式: $coefficientStr");

            var num = _parseRational(coeffParts[0]);
            var den = _parseRational(coeffParts[1]);
            if (den == Rational.zero) throw FormatException("分母不能为零: $coefficientStr");

            k = num / den;
          } else {
            k = _parseRational(coefficientStr);
          }
        } catch (e) {
          throw FormatException("无效的系数格式: $coefficientStr");
        }
      }

      // 解析底数
      int q;
      if (radicandStr.contains('/')) {
        throw FormatException("分数底数暂不支持: $str");
      } else {
        try {
          // 底数必须是整数，所以使用int.parse而不是_parseRational
          q = int.parse(radicandStr);
        } catch (e) {
          throw FormatException("无效的底数格式: $radicandStr");
        }
      }

      return Ksqrt(k, q)..simplify();
    }

    // 尝试解析为有理数（包括小数）
    try {
      return Ksqrt.fromRational(_parseRational(str));
    } catch (e) {
      throw FormatException("无法解析的字符串: $str");
    }
  }

  // 小数转有理数的辅助函数
  static Rational _parseRational(String input) {
    try {
      input = input.trim();

      if (input.contains('/')) {
        List<String> parts = input.split('/');
        if (parts.length == 2) {
          String numerator = parts[0].trim();
          String denominator = parts[1].trim();

          // 修复：直接使用 Rational 构造函数而不是 parse
          BigInt num = BigInt.parse(numerator);
          BigInt den = BigInt.parse(denominator);

          if (den == BigInt.zero) {
            throw FormatException('分母不能为零');
          }

          return Rational(num, den);
        }
      }

      // 处理小数
      if (input.contains('.')) {
        return _decimalToRational(input);
      }

      // 处理整数
      return Rational.parse(input);
    } catch (e) {
      throw FormatException('无效的分数格式: $input');
    }
  }

  // 小数转有理数的实现
  static Rational _decimalToRational(String decimalStr) {
    if (!decimalStr.contains('.')) {
      return Rational.parse(decimalStr);
    }

    List<String> parts = decimalStr.split('.');
    String integerPart = parts[0];
    String decimalPart = parts[1];

    // 处理负号
    bool isNegative = integerPart.startsWith('-');
    if (isNegative) {
      integerPart = integerPart.substring(1);
    }

    // 如果整数部分是空的，设为0
    if (integerPart.isEmpty) {
      integerPart = '0';
    }

    // 计算分母：10的decimalPart长度次方
    BigInt denominator = BigInt.from(10).pow(decimalPart.length);
    // 计算分子：整数部分 * 分母 + 小数部分
    BigInt numerator =
    BigInt.parse(integerPart) * denominator + BigInt.parse(decimalPart);

    if (isNegative) {
      numerator = -numerator;
    }

    return Rational(numerator, denominator);
  }

  // 取反运算
  Ksqrt operator -() {
    return Ksqrt(-k, q);
  }

  // 修复的化简方法
  void simplify() {
    if (k == Rational.zero) {
      q = 1;
      return;
    }

    if (q == 0 || q == 1) return;

    // 提取平方因子
    int squareFactor = 1;
    int temp = q;

    for (int i = 2; i * i <= temp; i++) {
      while (temp % (i * i) == 0) {
        squareFactor *= i;
        temp ~/= (i * i);
      }
    }

    // 更新系数和底数
    if (squareFactor > 1) {
      k *= Rational.fromInt(squareFactor);
      q = temp;
    }
  }

  // 判断两个Ksqrt是否同类项
  bool isLikeTerm(Ksqrt other) {
    Ksqrt thisCopy = Ksqrt(k, q);
    Ksqrt otherCopy = Ksqrt(other.k, other.q);
    thisCopy.simplify();
    otherCopy.simplify();
    return thisCopy.q == otherCopy.q;
  }

  // 加法运算
  Ksqrt operator +(Ksqrt other) {
    if (!isLikeTerm(other)) {
      throw ArgumentError("底数不同无法相加: ${this.q} 和 ${other.q}");
    }

    Ksqrt thisCopy = Ksqrt(k, q);
    Ksqrt otherCopy = Ksqrt(other.k, other.q);
    thisCopy.simplify();
    otherCopy.simplify();

    return Ksqrt(thisCopy.k + otherCopy.k, thisCopy.q);
  }

  // 减法运算
  Ksqrt operator -(Ksqrt other) {
    if (!isLikeTerm(other)) {
      throw ArgumentError("底数不同无法相减: ${this.q} 和 ${other.q}");
    }

    Ksqrt thisCopy = Ksqrt(k, q);
    Ksqrt otherCopy = Ksqrt(other.k, other.q);
    thisCopy.simplify();
    otherCopy.simplify();

    return Ksqrt(thisCopy.k - otherCopy.k, thisCopy.q);
  }

  // 乘法运算
  Ksqrt operator *(Ksqrt other) {
    Rational newK = k * other.k;
    int newQ = q * other.q;

    Ksqrt result = Ksqrt(newK, newQ);
    result.simplify();
    return result;
  }

  // 修复的除法运算
  Ksqrt operator /(Ksqrt other) {
    if (other.k == Rational.zero) {
      throw ArgumentError("除数不能为零");
    }

    // 分子分母同乘以分母的根号部分进行有理化
    Rational newK = k * other.k;
    int newQ = q * other.q;

    // 除以分母系数的平方（因为分母是k√q，有理化后分母变为k²q）
    Rational denominator = other.k * other.k * Rational.fromInt(other.q);

    Ksqrt result = Ksqrt(newK / denominator, newQ);
    result.simplify();
    return result;
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other is! Ksqrt) return false;

    Ksqrt thisSimplified = Ksqrt(k, q)..simplify();
    Ksqrt otherSimplified = Ksqrt(other.k, other.q)..simplify();

    return thisSimplified.k == otherSimplified.k &&
    thisSimplified.q == otherSimplified.q;
  }

  @override
  int get hashCode {
    Ksqrt simplified = Ksqrt(k, q)..simplify();
    return Object.hash(simplified.k, simplified.q);
  }

  // 计算表达式的近似浮点数值
  double toDouble() {
    if (k == Rational.zero) return 0.0;

    double sqrtQ = sqrt(q.toDouble());
    double kValue = k.toDouble();

    return kValue * sqrtQ;
  }

  @override
  String toString() {
    if (k == Rational.zero) return '0';
    if (q == 1) return k.toString();

    String kStr;
    if (k == Rational.one) {
      kStr = '';
    } else if (k == -Rational.one) {
      kStr = '-';
    } else {
      if (k.isInteger) {
        kStr = k.toDouble().toInt().toString();
      } else {
        kStr = '($k)';
      }
      kStr += '*';
    }

    return '${kStr}√$q';
  }
}

class RationalExtend {
  List<Ksqrt> terms;

  RationalExtend(this.terms);

  factory RationalExtend.fromInt(int value) {
    return RationalExtend([Ksqrt.fromInt(value)]);
  }

  factory RationalExtend.fromRational(Rational rational) {
    return RationalExtend([Ksqrt.fromRational(rational)]);
  }

  // 改进的字符串解析 - 现在支持小数
  factory RationalExtend.parse(String str) {
    str = str.replaceAll(' ', '');

    if (str.isEmpty) return RationalExtend([]);

    // 处理单个项的情况
    if (!str.contains('+') && !str.contains('-')) {
      return RationalExtend([Ksqrt.parse(str)]);
    }

    // 处理以负号开头的情况
    if (str.startsWith('-')) {
      var rest = str.substring(1);
      if (!rest.contains('+') && !rest.contains('-')) {
        return RationalExtend([Ksqrt.parse(str)]);
      }
    }

    List<Ksqrt> terms = [];
    List<String> termStrs = [];

    // 改进的分割逻辑：正确处理符号
    int start = 0;
    for (int i = 1; i < str.length; i++) {
      if ((str[i] == '+' || str[i] == '-') &&
        str[i-1] != '*' && str[i-1] != '/' && str[i-1] != '^') {
        termStrs.add(str.substring(start, i));
      start = i;
        }
    }
    termStrs.add(str.substring(start));

    // 解析各项
    for (var termStr in termStrs) {
      if (termStr.isEmpty) continue;
      if (termStr == '+') continue;

      try {
        terms.add(Ksqrt.parse(termStr));
      } catch (e) {
        throw FormatException("无法解析项: $termStr, 错误: $e");
      }
    }

    return RationalExtend(terms)..simplify();
  }

  void addTerm(Ksqrt term) {
    terms.add(term);
  }

  // 化简方法：合并同类项
  void simplify() {
    if (terms.isEmpty) return;

    // 首先对每个项进行化简
    for (var term in terms) {
      term.simplify();
    }

    // 合并同类项
    Map<int, Rational> termMap = {};

    for (var term in terms) {
      if (termMap.containsKey(term.q)) {
        termMap[term.q] = termMap[term.q]! + term.k;
      } else {
        termMap[term.q] = term.k;
      }
    }

    // 重建terms列表
    terms.clear();
    termMap.forEach((q, k) {
      if (k != Rational.zero) {
        terms.add(Ksqrt(k, q));
      }
    });

    // 按底数排序
    terms.sort((a, b) => a.q.compareTo(b.q));

    if (terms.isEmpty) {
      terms.add(Ksqrt.fromInt(0));
    }
  }

  // 获取共轭表达式
  RationalExtend get conjugate {
    if (terms.length == 1) {
      return RationalExtend([terms[0]]);
    } else if (terms.length == 2) {
      return RationalExtend([
        terms[0],
        Ksqrt(-terms[1].k, terms[1].q)
      ]);
    } else {
      List<Ksqrt> conjugateTerms = [terms[0]];
      for (int i = 1; i < terms.length; i++) {
        conjugateTerms.add(Ksqrt(-terms[i].k, terms[i].q));
      }
      return RationalExtend(conjugateTerms);
    }
  }

  // 检查是否是有理数
  bool get isRational {
    for (var term in terms) {
      if (term.q != 1) return false;
    }
    return true;
  }

  // 获取有理数部分的值
  Rational get rationalValue {
    if (!isRational) {
      throw StateError("表达式包含根号，不是纯有理数");
    }

    Rational sum = Rational.zero;
    for (var term in terms) {
      sum += term.k;
    }
    return sum;
  }

  // 加法运算
  RationalExtend operator +(RationalExtend other) {
    List<Ksqrt> newTerms = List.from(terms);
    newTerms.addAll(other.terms);

    RationalExtend result = RationalExtend(newTerms);
    result.simplify();
    return result;
  }

  // 减法运算
  RationalExtend operator -(RationalExtend other) {
    List<Ksqrt> newTerms = List.from(terms);
    for (var term in other.terms) {
      newTerms.add(Ksqrt(-term.k, term.q));
    }

    RationalExtend result = RationalExtend(newTerms);
    result.simplify();
    return result;
  }

  // 乘法运算
  RationalExtend operator *(RationalExtend other) {
    List<Ksqrt> productTerms = [];

    for (var term1 in terms) {
      for (var term2 in other.terms) {
        productTerms.add(term1 * term2);
      }
    }

    RationalExtend result = RationalExtend(productTerms);
    result.simplify();
    return result;
  }

  // 修复的除法运算
  RationalExtend operator /(RationalExtend other) {
    if (other.terms.isEmpty) {
      throw ArgumentError("除数不能为空");
    }

    // 特殊情况：除数是单项式
    if (other.terms.length == 1) {
      List<Ksqrt> newTerms = [];
      for (var term in terms) {
        newTerms.add(term / other.terms[0]);
      }
      return RationalExtend(newTerms)..simplify();
    }

    // 一般情况：使用分母有理化
    RationalExtend conjugate = other.conjugate;
    RationalExtend numerator = this * conjugate;
    RationalExtend denominator = other * conjugate;

    if (!denominator.isRational) {
      throw StateError("分母有理化失败，结果仍包含根号");
    }

    Rational denomValue = denominator.rationalValue;

    if (denomValue == Rational.zero) {
      throw ArgumentError("分母有理化后为0，无法进行除法");
    }

    // 将分子中的每一项除以分母的有理数值
    List<Ksqrt> resultTerms = [];
    for (var term in numerator.terms) {
      resultTerms.add(Ksqrt(term.k / denomValue, term.q));
    }

    return RationalExtend(resultTerms)..simplify();
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other is! RationalExtend) return false;

    RationalExtend thisSimplified = RationalExtend(List.from(terms))..simplify();
    RationalExtend otherSimplified = RationalExtend(List.from(other.terms))..simplify();

    if (thisSimplified.terms.length != otherSimplified.terms.length) return false;

    for (int i = 0; i < thisSimplified.terms.length; i++) {
      if (thisSimplified.terms[i] != otherSimplified.terms[i]) {
        return false;
      }
    }

    return true;
  }

  @override
  int get hashCode {
    RationalExtend simplified = RationalExtend(List.from(terms))..simplify();
    return simplified.terms.fold(0, (hash, term) => hash ^ term.hashCode);
  }

  // 计算表达式的近似浮点数值
  double toDouble() {
    double sum = 0.0;
    for (var term in terms) {
      sum += term.toDouble();
    }
    return sum;
  }

  @override
  String toString() {
    if (terms.isEmpty) return "0";

    RationalExtend simplified = RationalExtend(List.from(terms))..simplify();

    if (simplified.terms.isEmpty) return "0";

    List<String> termStrings = [];
    for (var term in simplified.terms) {
      String termStr = term.toString();
      if (termStr.startsWith('-')) {
        termStrings.add(termStr);
      } else if (termStrings.isNotEmpty) {
        termStrings.add('+$termStr');
      } else {
        termStrings.add(termStr);
      }
    }

    String result = termStrings.join('');
    if (result.startsWith('+')) {
      result = result.substring(1);
    }

    return result;
  }
}

extension RationalExtendMath on RationalExtend {
  RationalExtend square() {
    return this * this;
  }

  RationalExtend abs() {
    double value = this.toDouble();
    if (value < 0) {
      return RationalExtend(terms.map((term) => Ksqrt(-term.k, term.q)).toList());
    }
    return this;
  }

  bool get isZero {
    RationalExtend simplified = RationalExtend(List.from(terms))..simplify();
    return simplified.terms.length == 1 &&
    simplified.terms[0].k == Rational.zero;
  }

  Rational get rationalPart {
    Rational sum = Rational.zero;
    for (var term in terms) {
      if (term.q == 1) {
        sum += term.k;
      }
    }
    return sum;
  }

  RationalExtend get irrationalPart {
    List<Ksqrt> irrationalTerms = [];
    for (var term in terms) {
      if (term.q != 1) {
        irrationalTerms.add(term);
      }
    }
    return RationalExtend(irrationalTerms)..simplify();
  }
}
/*测试用例
// 测试函数 - 增加小数测试
void main() {
  print('=== Ksqrt 类测试 ===');

  // 基本创建和化简
  var sqrt8 = Ksqrt(Rational.one, 8);
  sqrt8.simplify();
  print('√8 = $sqrt8'); // 应该输出 2√2

  // 算术运算
  var a = Ksqrt.parse('√2');
  var b = Ksqrt.parse('3√2');
  var sum = a + b;
  print('√2 + 3√2 = $sum'); // 应该输出 4√2

  var product = a * b;
  print('√2 * 3√2 = $product'); // 应该输出 6

  // 除法测试 - 修复后
  var c = Ksqrt.parse('√6');
  var d = Ksqrt.parse('√3');
  var quotient = c / d;
  print('√6 / √3 = $quotient'); // 应该输出 √2

  print('\n=== RationalExtend 类测试 ===');

  // 多项式创建和运算
  var expr1 = RationalExtend.parse('√2 + 2√3');
  var expr2 = RationalExtend.parse('√2 - √3');
  print('表达式1: $expr1');
  print('表达式2: $expr2');

  var polySum = expr1 + expr2;
  print('相加: $polySum'); // 应该输出 2√2 + √3

  var polyProduct = expr1 * expr2;
  print('相乘: $polyProduct'); // 应该输出 2 + √6 - 2√3 - 2*3 = -4 + √6 - 2√3

  // 除法测试（分母有理化）- 修复后
  try {
    var polyQuotient = expr1 / expr2;
    print('相除: $polyQuotient'); // 应该输出有理化后的结果
  } catch (e) {
    print('除法错误: $e');
  }

  // 复杂表达式测试
  print('\n=== 复杂表达式测试 ===');
  try {
    var complexExpr = RationalExtend.parse('2/3');
    print('分数解析: $complexExpr');

    var complexExpr2 = RationalExtend.parse('2/3+√2');
    print('分数+根号解析: $complexExpr2');

    var complexExpr3 = RationalExtend.parse('1+√2');
    var mul = complexExpr2 * complexExpr3;
    print('复杂表达式1: $complexExpr2');
    print('复杂表达式2: $complexExpr3');
    print('乘积: $mul');
    print('有理数部分: ${complexExpr2.rationalPart}');
    print('无理数部分: ${complexExpr2.irrationalPart}');
    print('近似值: ${complexExpr2.toDouble()}');
  } catch (e) {
    print('解析错误: $e');
  }

  // 更多测试
  print('\n=== 更多测试 ===');
  try {
    var test1 = Ksqrt.parse('1/2');
    print('分数 1/2: $test1');

    var test2 = Ksqrt.parse('3/4*√2');
    print('分数系数 3/4*√2: $test2');

    var test3 = RationalExtend.parse('1/2 + 1/3*√2');
    print('混合表达式: $test3');
  } catch (e) {
    print('测试错误: $e');
  }

  // 小数测试
  print('\n=== 小数支持测试 ===');
  try {
    var decimal1 = Ksqrt.parse('0.5');
    print('小数 0.5: $decimal1');

    var decimal2 = Ksqrt.parse('0.25√2');
    print('小数系数 0.25√2: $decimal2');

    var decimal3 = Ksqrt.parse('1.5√3');
    print('小数系数 1.5√3: $decimal3');

    var decimal4 = RationalExtend.parse('0.5 + 3/2√2');
    print('混合小数表达式: $decimal4');

    var decimal5 = RationalExtend.parse('1/3 + 0.666√2');
    print('混合小数表达式: $decimal5');

    // 小数运算测试
    var decimalExpr1 = RationalExtend.parse('0.5√2');
    var decimalExpr2 = RationalExtend.parse('0.25√2');
    var decimalSum = decimalExpr1 + decimalExpr2;
    print('0.5√2 + 0.25√2 = $decimalSum'); // 应该输出 0.75√2

    var decimalProduct = decimalExpr1 * decimalExpr2;
    print('0.5√2 * 0.25√2 = $decimalProduct'); // 应该输出 0.25

  } catch (e) {
    print('小数测试错误: $e');
  }
}
*/