/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#include "util/debug.h"
#include "bindings/lua/util.h"
#include "bindings/lua/lua_ref.h"

namespace lean {
lua_ref::lua_ref(lua_State * L, int i) {
    lean_assert(L);
    m_state = L;
    lua_pushvalue(m_state, i);
    m_ref   = luaL_ref(m_state, LUA_REGISTRYINDEX);
}

lua_ref::lua_ref(lua_ref const & r) {
    m_state = r.m_state;
    if (m_state) {
        r.push();
        m_ref   = luaL_ref(m_state, LUA_REGISTRYINDEX);
    }
}

lua_ref::lua_ref(lua_ref && r) {
    m_state = r.m_state;
    m_ref   = r.m_ref;
    r.m_state = nullptr;
}

lua_ref::~lua_ref() {
    if (m_state)
        luaL_unref(m_state, LUA_REGISTRYINDEX, m_ref);
}

lua_ref & lua_ref::operator=(lua_ref const & r) {
    if (m_ref == r.m_ref)
        return *this;
    if (m_state)
        luaL_unref(m_state, LUA_REGISTRYINDEX, m_ref);
    m_state = r.m_state;
    if (m_state) {
        r.push();
        m_ref   = luaL_ref(m_state, LUA_REGISTRYINDEX);
    }
    return *this;
}

void lua_ref::push() const {
    lean_assert(m_state);
    lua_rawgeti(m_state, LUA_REGISTRYINDEX, m_ref);
}

int lua_ref_lt_proc::operator()(lua_ref const & r1, lua_ref const & r2) const {
    lean_assert(r1.get_state() == r2.get_state());
    lua_State * L = r1.get_state();
    r1.push();
    r2.push();
    int r;
    if (lessthan(L, -2, -1)) {
        r = -1;
    } else if (lessthan(L, -1, -2)) {
        r = 1;
    } else if (equal(L, -2, -1)) {
        r = 0;
    } else {
        throw exception("'<' is not a total order for the elements inserted on the table");
    }
    lua_pop(L, 2);
    return r;
}
}