// sprit-forth: A portable subroutine-threaded Forth.
// Copyright (C) 2023  Clyne Sullivan <clyne@bitgloo.com>
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// This library is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE.  See the GNU Library General Public License for
// more details.
//
// You should have received a copy of the GNU Library General Public License
// along with this library; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.

#include "core.hpp"
#include "state.hpp"
#include "types.hpp"

#include <cctype>
#include <cstdlib>

__attribute__((weak))
int findword(const char *, int)
{
    return -1;
}

[[nodiscard]]
static Error parseword(const char *start, const char *end)
{
    auto result = Error::none;

    if (start != end) {
        if (auto word = find(start, end - start); word) {
            if (!word->immediate() && STATE) {
                comma((Cell)word->list);
            } else {
                result = execute1(word);
            }
        } else if (isdigit(*start) || (*start == '-' && isdigit(*(start + 1)))) {
            push(std::atoi(start));

            if (STATE)
                compileliteral();
        } else if (findword(start, end - start)) {
            return Error::noword;
        }
    }

    return result;
}

[[nodiscard]]
static Error parseSource()
{
    auto result = Error::none;
    char *start = nullptr;
    char *end;
    char *s;

    while (result == Error::none && haskey()) {
        s = (char *)DICT[DIdxSource];

        ++DICT[DIdxSource];
        --DICT[DIdxSrcLen];

        if (isspace(*s)) {
            if (start) {
                result = parseword(start, end + 1);
                start = nullptr;
            }
        } else {
            if (!start) {
                start = s;
                end = start;
            } else {
                ++end;
            }
        }
    }

    // Parse the final word if it is non-empty.
    if (start)
        result = parseword(start, s + 1);

    return result;
}

[[nodiscard]]
Error parse()
{
    // Reset source buffer and try to fill it with getinput().
    DICT[DIdxSource] = (Cell)&DICT[DIdxBegin];
    DICT[DIdxSrcLen] = 0;
    getinput();

    return parseSource();
}