// MakeDB

// Converts a Scheme database for unicalc, e.g.,
//  (list 'km                     (make-QL 1.0 '(kilometer) '()))
//  (list 'kph                    (make-QL 1.0 '(kilometer) '(hour)))
//  (list 'kwh                    (make-QL 1.0 '(hour kilowatt) '()))
//  (list 'l                      (make-QL 1.0 '(liter) '()))
//  (list 'lb                     (make-QL 1.0 '(pound) '()))
// Into Java code to construct the database, e.g.,
//    db.put("km", new Quantity(1.0, 0.0, Arrays.asList("kilometer"), Collections.<String>emptyList()));
//    db.put("kph", new Quantity(1.0, 0.0, Arrays.asList("kilometer"), Arrays.asList("hour")));
//    db.put("kwh", new Quantity(1.0, 0.0, Arrays.asList("hour", "kilowatt"), Collections.<String>emptyList()));
//    db.put("l", new Quantity(1.0, 0.0, Arrays.asList("liter"), Collections.<String>emptyList()));
//    db.put("lb", new Quantity(1.0, 0.0, Arrays.asList("pound"), Collections.<String>emptyList()));

import java.util.Scanner;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.io.FileInputStream;  

class MakeDB
{
  public static void main(String[] args)
  {
    try {
      // Get the filename from the command-line (e.g. "run MakeDB udb.rkt")
      String fileName = args[0];
      // Try to open the file.
      FileInputStream fin = new FileInputStream(fileName);

      // Scanners give us a nicer interface to files
      //   (e.g., reading a line at a time)
      Scanner scan = new Scanner(fin);
      
      // We want to check each line of the input file
      // against a regular expression.  Tell Java
      // about this regular expression

      Pattern linePat =
        Pattern.compile(
          "\\(list '(\\w+)\\s+\\(make-QL\\s+([-0-9.e]+)\\s+'\\(([^)]*)\\)\\s+'\\(([^)]*)\\)\\)\\)");
      
      // Loop over all lines in the file      
      while (scan.hasNextLine()) {
        // Get the next line
        String line = scan.nextLine();

        // Get ready to start searching this string
        Matcher m = linePat.matcher(line);

        // Loop over all pattern matches (database entries) in this line.
        while (m.find()) {
          String unitName = m.group(1);
          String valueString = m.group(2);
          String numeratorSymbols = m.group(3);
          String denominatorSymbols = m.group(4);

          // Display the Java code
          System.out.println
            ("    db.put(\"" + unitName + "\", new Quantity(" 
               + valueString + ", 0.0, " 
               + makeJavaList(numeratorSymbols) + ", " 
               + makeJavaList(denominatorSymbols) + "));");
        }
      }
      return;
    } catch (Exception e) {
      System.out.println("Missing file, or file not found.");
    }
  }

  // Helper method makeJava list
  // Given a space-separated list of symbols (a Scheme list without
  //    the parentheses), turn it into Java code to create
  //    a list of strings.
  private static String makeJavaList(String symbols)
  {
    if (symbols.equals("")) {
      // Zero symbols. Code for an empty list of strings.
      return "Collections.<String>emptyList()";
    } else {
      // replace whilespace by quote-comma-quote, and add
      //    more double-quotes at the beginning and end.
      String addCommasAndQuotes =
        "\"" + symbols.replaceAll("\\s+", "\", \"") + "\"";
      // Code for a non-empty list of strings
      return ("Arrays.asList(" + addCommasAndQuotes + ")");
    }
  }

}