package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

final class Converter {
  private Converter() { }

  static double toNumber(String str) {
    try {
      return Double.valueOf(str).doubleValue();
    }
    catch (NumberFormatException e) {
      return Double.NaN;
    }
  }
  static double toNumber(NodeIterator iter) throws XSLException {
    return toNumber(toString(iter));
  }
  static double toNumber(boolean b) {
    return b ? 1.0 : 0.0;
  }

  static boolean toBoolean(String str) {
    return str.length() != 0;
  }
  static boolean toBoolean(double num) {
    return num != 0.0 && num == num; // careful with NaN
  }
  static boolean toBoolean(NodeIterator iter) throws XSLException {
    return iter.next() != null;
  }

  static String toString(NodeIterator iter) throws XSLException {
    return toString(iter.next());
  }

  static String toString(Node node) throws XSLException {
    if (node == null)
      return "";
    String value = node.getData();
    if (value != null)
      return value;
    StringBuffer buf = new StringBuffer();
    addContent(node, buf);
    return buf.toString();
  }

  private static void addContent(Node node, StringBuffer result) throws XSLException {
    switch (node.getType()) {
    case Node.TEXT:
      result.append(node.getData());
      break;
    case Node.ELEMENT:
    case Node.ROOT:
      for (NodeIterator iter = node.getChildren();;) {
	node = iter.next();
	if (node == null)
	  break;
	addContent(node, result);
      }
    }
  }

  static String toString(double num) {
    String s = Double.toString(num);
    int len = s.length();
    if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0') {
      s = s.substring(0, len - 2);
      if (s.equals("-0"))
        return "0";
      return s;
    }
    int e = s.indexOf('E');
    if (e < 0)
      return s;
    int exp = Integer.parseInt(s.substring(e + 1));
    String sign;
    if (s.charAt(0) == '-') {
      sign = "-";
      s = s.substring(1);
      --e;
    }
    else
      sign = "";
    int nDigits = e - 2;
    if (exp >= nDigits)
      return sign + s.substring(0, 1) + s.substring(2, e) + zeros(exp - nDigits);
    if (exp > 0)
      return sign + s.substring(0, 1) + s.substring(2, 2 + exp) + "." + s.substring(2 + exp, e);
    return sign + "0." + zeros(-1 - exp) + s.substring(0, 1) + s.substring(2, e);
  }
    
  static private String zeros(int n) {
    char[] buf = new char[n];
    for (int i = 0; i < n; i++)
      buf[i] = '0';
    return new String(buf);
  }

  static String toString(boolean b) {
    return b ? "true" : "false";
  }

  static boolean positionToBoolean(double d, ExprContext context) throws XSLException {
    return context.getPosition() == d;
  }
}