package org.xwt.js;

class GlobalScopeImpl extends JS.Scope {
    private final static Double NaN = new Double(Double.NaN);
    private final static Double POSITIVE_INFINITY = new Double(Double.POSITIVE_INFINITY);
    
    public GlobalScopeImpl(JS.Scope parent) {
        super(parent);
    }
    public Object get(Object key) {
        if(key.equals("NaN")) return NaN;
        if(key.equals("Infinity")) return POSITIVE_INFINITY;
        if(key.equals("undefined")) return null;
        return super.get(key);
    }
    public Object callMethod(Object method, JS.Array args, boolean checkOnly) {
        if(method.equals("parseInt")) {
            if(checkOnly) return Boolean.TRUE;
            return parseInt(args);
        } else if(method.equals("parseFloat")) {
            if(checkOnly) return Boolean.TRUE;
            return parseFloat(args);
        } else if(method.equals("isNaN")) {
            if(checkOnly) return Boolean.TRUE;
            return isNaN(args);
        } else if(method.equals("isFinite")) {
            if(checkOnly) return Boolean.TRUE;
            return isFinite(args);
        } else if(method.equals("decodeURI")) {
            if(checkOnly) return Boolean.TRUE;
            return decodeURI(args);
        } else if(method.equals("decodeURIComponent")) {
            if(checkOnly) return Boolean.TRUE;
            return decodeURIComponent(args);
        } else if(method.equals("encodeURI")) {
            if(checkOnly) return Boolean.TRUE;
            return encodeURI(args);
        } else if(method.equals("encodeURIComponent")) {
            if(checkOnly) return Boolean.TRUE;
            return encodeURIComponent(args);
        } else if(method.equals("escape")) {
            if(checkOnly) return Boolean.TRUE;
            return escape(args);
        } else if(method.equals("unescape")) {
            if(checkOnly) return Boolean.TRUE;
            return unescape(args);
        } else if(method.equals("stringFromCharCode")) {
            if(checkOnly) return Boolean.TRUE;
            return stringFromCharCode(args);
        }
        return super.callMethod(method,args,checkOnly);
    }
    private Object stringFromCharCode(JS.Array args) {
        char buf[] = new char[args.length()];
        for(int i=0;i<args.length();i++)
            buf[i] = (char)(JS.toInt(args.elementAt(i)) & 0xffff);
        return new String(buf);
    }
    private Object parseInt(JS.Array args) {
        String s = args.length() > 0 ? args.elementAt(0).toString() : "";
        int radix = args.length() > 1 ? toInt(args.elementAt(1)) : 0;
        int start = 0;
        int length = s.length();
        int sign = 1;
        long n = 0;
        if(radix != 0 && (radix < 2 || radix > 36)) return NaN;
        while(start < length && Character.isWhitespace(s.charAt(start))) start++;
        if((length >= start+1) && (s.charAt(start) == '+' || s.charAt(start) == '-')) {
            sign = s.charAt(start) == '+' ? 1 : -1;
            start++;
        }
        if(radix == 0 && length >= start+1 && s.charAt(start) == '0') {
            start++;
            if(length >= start+1 && (s.charAt(start) == 'x' || s.charAt(start) == 'X')) {
                start++;
                radix = 16;
            } else {
                radix = 8;
                if(length == start || Character.digit(s.charAt(start+1),8)==-1) return new Integer(0);
            }
        }
        if(radix == 0) radix = 10;
        if(length == start || Character.digit(s.charAt(start),radix) == -1) return NaN;
        // try the fast way first
        try {
            String s2 = start == 0 ? s : s.substring(start);
            return new Integer(sign*Integer.parseInt(s2,radix));
        } catch(NumberFormatException e) { }
        // fall through to a slower but emca-compliant method
        for(int i=start;i<length;i++) {
            int digit = Character.digit(s.charAt(i),radix);
            if(digit < 0) break;
            n = n*radix + digit;
            if(n < 0) return NaN; // overflow;
        }
        if(n <= Integer.MAX_VALUE) return new Integer(sign*(int)n);
        return new Long((long)sign*n);
    }
    private Object parseFloat(JS.Array args) {
        String s = args.length() > 0 ? args.elementAt(0).toString() : "";
        int start = 0;
        int length = s.length();
        while(start < length && Character.isWhitespace(s.charAt(0))) start++;
        int end = length;
        // as long as the string has no trailing garbage,this is fast, its slow with
        // trailing garbage
        while(start < end) {
            try {
                return new Double(s.substring(start,length));
            } catch(NumberFormatException e) { }
            end--;
        }
        return NaN;
    }
    private Object isNaN(JS.Array args) {
        double d = args.length() > 0 ? toDouble(args.elementAt(0)) : Double.NaN;
        return d == d ? Boolean.FALSE : Boolean.TRUE;
    }
    private Object isFinite(JS.Array args) {
        double d = args.length() > 0 ? toDouble(args.elementAt(0)) : Double.NaN;
        return (d == d && !Double.isInfinite(d)) ? Boolean.TRUE : Boolean.FALSE;
    }
    private Object decodeURI(JS.Array args) {
        throw new JS.Exn("decodeURI is unimplemented");
    }
    private Object decodeURIComponent(JS.Array args) {
        throw new JS.Exn("decodeURIComponent is unimplemented");
    }
    private Object encodeURI(JS.Array args) {
        throw new JS.Exn("encodeURI is unimplemented");
    }
    private Object encodeURIComponent(JS.Array args) {
        throw new JS.Exn("encodeURIComponent is unimplemented");
    }
    private Object escape(JS.Array args) {
        throw new JS.Exn("escape is unimplemented");
    }
    private Object unescape(JS.Array args) {
        throw new JS.Exn("unescape is unimplemented");
    }
}