tagtransform-lua.cpp

/**
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * This file is part of osm2pgsql (https://osm2pgsql.org/).
 *
 * Copyright (C) 2006-2025 by the osm2pgsql developer community.
 * For a full list of authors see the git log.
 */

#include "format.hpp"
#include "lua-utils.hpp"
#include "tagtransform-lua.hpp"

#include <stdexcept>

lua_tagtransform_t::lua_tagtransform_t(std::string const *tag_transform_script,
                                       bool extra_attributes)
: m_lua_file(tag_transform_script), m_extra_attributes(extra_attributes)
{
    m_lua_state.reset(luaL_newstate());
    luaL_openlibs(lua_state());
    if (luaL_dofile(lua_state(), m_lua_file->c_str())) {
        throw fmt_error("Lua tag transform style error: {}.",
                        lua_tostring(lua_state(), -1));
    }

    check_lua_function_exists(NODE_FUNC);
    check_lua_function_exists(WAY_FUNC);
    check_lua_function_exists(REL_FUNC);
    check_lua_function_exists(REL_MEM_FUNC);
}

std::unique_ptr<tagtransform_t> lua_tagtransform_t::clone() const
{
    return std::make_unique<lua_tagtransform_t>(m_lua_file, m_extra_attributes);
}

void lua_tagtransform_t::check_lua_function_exists(char const *func_name)
{
    lua_getglobal(lua_state(), func_name);
    if (!lua_isfunction(lua_state(), -1)) {
        throw fmt_error("Tag transform style does not contain a function {}.",
                        func_name);
    }
    lua_pop(lua_state(), 1);
}

namespace {

/**
 * Read tags from the Lua table on the stack and write them to out_tags
 */
void get_out_tags(lua_State *lua_state, taglist_t *out_tags)
{
    luaX_for_each(lua_state, [&]() {
        auto const key_type = lua_type(lua_state, -2);
        // They key must be a string, otherwise the lua_tostring() function
        // below will change it to a string and the Lua array iteration will
        // break.
        if (key_type != LUA_TSTRING) {
            throw fmt_error("Basic tag processing found incorrect data type"
                            " '{}', use a string.",
                            lua_typename(lua_state, key_type));
        }

        auto const value_type = lua_type(lua_state, -1);
        // They key must be a string or number (which will automatically be
        // converted to a string).
        if (value_type != LUA_TSTRING && value_type != LUA_TNUMBER) {
            throw fmt_error("Basic tag processing found incorrect data type"
                            " '{}', use a string.",
                            lua_typename(lua_state, value_type));
        }

        char const *const key = lua_tostring(lua_state, -2);
        char const *const value = lua_tostring(lua_state, -1);
        out_tags->add_tag(key, value);
    });
    lua_pop(lua_state, 1);
}

} // anonymous namespace

bool lua_tagtransform_t::filter_tags(osmium::OSMObject const &o, bool *polygon,
                                     bool *roads, taglist_t *out_tags)
{
    switch (o.type()) {
    case osmium::item_type::node:
        lua_getglobal(lua_state(), NODE_FUNC);
        break;
    case osmium::item_type::way:
        lua_getglobal(lua_state(), WAY_FUNC);
        break;
    case osmium::item_type::relation:
        lua_getglobal(lua_state(), REL_FUNC);
        break;
    default:
        throw std::runtime_error{"Unknown OSM type."};
    }

    lua_newtable(lua_state()); /* key value table */

    lua_Integer sz = 0;
    for (auto const &t : o.tags()) {
        lua_pushstring(lua_state(), t.key());
        lua_pushstring(lua_state(), t.value());
        lua_rawset(lua_state(), -3);
        ++sz;
    }
    if (m_extra_attributes && o.version() > 0) {
        taglist_t tags;
        tags.add_attributes(o);
        for (auto const &t : tags) {
            luaX_pushstring(lua_state(), t.key);
            luaX_pushstring(lua_state(), t.value);
            lua_rawset(lua_state(), -3);
            ++sz;
        }
    }

    lua_pushinteger(lua_state(), sz);

    if (lua_pcall(lua_state(), 2, (o.type() == osmium::item_type::way) ? 4 : 2,
                  0)) {
        /* lua function failed */
        throw fmt_error("Failed to execute lua function for"
                        " basic tag processing: {}.",
                        lua_tostring(lua_state(), -1));
    }

    if (o.type() == osmium::item_type::way) {
        if (roads) {
            *roads = (int)lua_tointeger(lua_state(), -1);
        }
        lua_pop(lua_state(), 1);
        if (polygon) {
            *polygon = (int)lua_tointeger(lua_state(), -1);
        }
        lua_pop(lua_state(), 1);
    }

    get_out_tags(lua_state(), out_tags);

    bool const filter = lua_tointeger(lua_state(), -1);
    lua_pop(lua_state(), 1);

    return filter;
}

bool lua_tagtransform_t::filter_rel_member_tags(
    taglist_t const &rel_tags, osmium::memory::Buffer const &members,
    rolelist_t const &member_roles, bool *make_boundary, bool *make_polygon,
    bool *roads, taglist_t *out_tags)
{
    size_t const num_members = member_roles.size();
    lua_getglobal(lua_state(), REL_MEM_FUNC);

    lua_newtable(lua_state()); /* relations key value table */

    for (auto const &rel_tag : rel_tags) {
        luaX_pushstring(lua_state(), rel_tag.key);
        luaX_pushstring(lua_state(), rel_tag.value);
        lua_rawset(lua_state(), -3);
    }

    lua_newtable(lua_state()); /* member tags table */

    int idx = 1;
    for (auto const &w : members.select<osmium::Way>()) {
        lua_pushnumber(lua_state(), idx++);
        lua_newtable(lua_state()); /* member key value table */
        for (auto const &member_tag : w.tags()) {
            lua_pushstring(lua_state(), member_tag.key());
            lua_pushstring(lua_state(), member_tag.value());
            lua_rawset(lua_state(), -3);
        }
        lua_rawset(lua_state(), -3);
    }

    lua_newtable(lua_state()); /* member roles table */

    for (size_t i = 0; i < num_members; ++i) {
        lua_pushnumber(lua_state(), static_cast<lua_Number>(i + 1));
        lua_pushstring(lua_state(), member_roles[i]);
        lua_rawset(lua_state(), -3);
    }

    lua_pushnumber(lua_state(), static_cast<lua_Number>(num_members));

    if (lua_pcall(lua_state(), 4, 6, 0)) {
        /* lua function failed */
        throw fmt_error("Failed to execute lua function for"
                        " relation tag processing: {}.",
                        lua_tostring(lua_state(), -1));
    }

    *roads = (int)lua_tointeger(lua_state(), -1);
    lua_pop(lua_state(), 1);
    *make_polygon = (int)lua_tointeger(lua_state(), -1);
    lua_pop(lua_state(), 1);
    *make_boundary = (int)lua_tointeger(lua_state(), -1);
    lua_pop(lua_state(), 1);

    // obsolete member superseded is ignored.
    lua_pop(lua_state(), 1);

    get_out_tags(lua_state(), out_tags);

    bool const filter = lua_tointeger(lua_state(), -1);
    lua_pop(lua_state(), 1);

    return filter;
}