/*
 * Copyright (c) 2002, Stefan Farfeleder <e0026813@stud3.tuwien.ac.at>
 * $Id: conffile.cc,v 1.2 2002/09/10 16:43:18 stefan Exp $
 */
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iterator>
#include <map>
#include <sstream>
#include <string>

#include "conffile.h"
#include "exception.h"

using std::map;
using std::string;
using namespace JFK;

/*
 * 'ce' points to an array of 'n' variable that are allowed variables in
 * 'filename'.
 */
conffile::conffile(const variable* ce, size_t n, const char* filename)
    : fn(filename)
{
    char*       p;

    /* replace leading ~ with $HOME if the latter is set */
    if (std::strncmp(filename, "~/", 2) == 0 &&
        (p = std::getenv("HOME")) != NULL)
    {
        fn.replace(0, 1, p);
    }

    /* load variables list into the map */
    for (size_t i = 0; i < n; i++)
    {
        if (ce[i].def_val != NULL)
            m[ce[i].name].value = ce[i].def_val;
        m[ce[i].name].ce = &ce[i];
    }
}

/*
 * Strip white space at the front and the back.
 */
static string
remove_ws(const string& s)
{
    string::size_type   front;
    string::size_type   back;

    for (front = 0; isspace((unsigned char)s[front]); front++)
        ;
    for (back = s.size();
         back > 0 && isspace((unsigned char)s[back - 1]);
         back--)
        ;

    return s.substr(front, back - front);
}

/*
 * Read the file (name given to constructor) and store the values into the
 * map.
 */
void
conffile::read()
{
    std::ifstream   file(fn.c_str());
    /* Do not complain about a missing config file. However getvar() of a
     * variable without a default value will fail. */
    if (!file.is_open())
        return;

    string          line;
    for (int linenr = 1; std::getline(file, line); linenr++)
    {
        string      name;
        string      value;

        /* skip emtpy and comment lines */
        if (line.size() == 0 || line[0] == '#')
            continue;

        string::size_type   asmt_pos = line.find('=');

        /* '=' found */
        if (asmt_pos != line.npos)
        {
            name = remove_ws(line.substr(0, asmt_pos));
            value = remove_ws(line.substr(asmt_pos + 1));
        }

        /* no '=' found or emtpy strings */
        if (name.size() == 0 || value.size() == 0)
        {
            std::ostringstream  msg;

            msg << fn << ':' << linenr << ": syntax error";
            throw exception(msg.str());
        }

        setvar(name, value);
    }
}

void
conffile::write()
{
    /* TODO */
}

/*
 * Return the value of the variable 'name'. Variables not included in the
 * variable list are considered as an error.
 */
const string
conffile::getvar(const string& name) const
{
    varmap::const_iterator  i = m.find(name);

    if (i == m.end())
        throw exception("variable '" + name + "' unknown");

    if (i->second.value == "" && i->second.ce->def_val == NULL)
        throw exception("variable '" + name + "' must be set in " + fn);

    return i->second.value;
}

/*
 * Set the value of the variable 'name' to 'val' (after the checking its
 * validity). Variables not included in the variable list are considered
 * as an error.
 */
void
conffile::setvar(const string& name, const string& val)
{
    varmap::iterator        i = m.find(name);

    if (i == m.end())
        throw exception("variable '" + name + "' unknown");

    const variable&         c = *i->second.ce;

    if (c.value_checker != NULL)
    {
        if (!c.value_checker(val))
            throw exception('\'' + val + "\' unacceptable value for '" + name + '\'');
    }

    i->second.value = val;
}