import string;
import c.stdio;

private
{
    template Pair(T)
    {
        struct Pair
        {
            T first, second;
        }
    }
    
    int find(char[] str, char c, int startPos)
    {
        while (startPos < str.length)
            if (str[startPos] == c)
                return startPos;
            else
                startPos++;
        return -1;
    }
    
    alias instance Pair(int).Pair IntPair;
}

private class Formatter
{
    private
    {
        char[] _formatString;   // The string to parse and format.  We tweak this as we go.

        IntPair nextMetaString()
        {
            IntPair pair;
            
            pair.first = string.find(_formatString, "{%");
            pair.second = find(_formatString, '}', pair.first);
            
            return pair;
        }
        
        void replace(IntPair pos, char[] value)
        {
            _formatString = _formatString[0..pos.first] ~ value ~ _formatString[(pos.second + 1).._formatString.length];
            
            //printf("\t%s\n", &_formatString[0]);
        }
    }
        
    public
    {
        this(char[] s)
        {
            _formatString = s;
        }
        
        char[] toString()
        {
            return _formatString;
        }
        
        Formatter mod(real r)
        {
            IntPair meta = nextMetaString();
            if (meta.first == -1 || meta.second == -1)
                return this;
            
            char[64] c;
            c[] = 0;
            sprintf(c, "%f", cast(double)r);
            
            // TODO: play with the meta to get things like precision
            replace(meta, c[0..strlen(c)]);
            return this;
        }
        
        Formatter mod(int i)
        {
            IntPair meta = nextMetaString();
            if (meta.first == -1 || meta.second == -1)
                return this;
            
            replace(meta, string.toString(i));

            return this;
        }
        
        Formatter mod(char[] s)
        {
            IntPair meta = nextMetaString();
            if (meta.first == -1 || meta.second == -1)
                return this;
            
            // TODO: play with the meta to get things like precision
            replace(meta, s);
            return this;
        }
        
        Formatter mod(Object o)
        {
            IntPair meta = nextMetaString();
            if (meta.first == -1 || meta.second == -1)
                return this;
            
            replace(meta, o.toString());
            return this;
        }
    }
}

void main()
{
    Formatter s = new Formatter("blah blah {%} {%} {%} blah {%} blah{%}") % "String!" % 13 % cast(real)3.5 % "!";
    char[] c = s.toString();
    
    printf("%s", toStringz(c));
    
    delete s;
}