/**
 * Automatically determine the value for snow line height and set it
 * @param flat_world_height value >= 0: land height a flat world gets
 *                          value == -1: not generating a flat world
 */
void DetermineSnowLineHeight(int flat_world_height)
{
    /* Determine snow line height only when snow_line_height is lower or higher than the minimum or maximum values for the setting */
    if (_settings_game.game_creation.snow_line_height != MIN_SNOWLINE_HEIGHT - 1 && _settings_game.game_creation.snow_line_height != MAX_SNOWLINE_HEIGHT + 1) return;

    if (flat_world_height >= 0) { // generating a flat world
        /* This doesn't require the extensive computations below */
        int max_value = min(MAX_SNOWLINE_HEIGHT, max((int)MIN_SNOWLINE_HEIGHT, flat_world_height - 2));
        uint half_max_value = max_value / 2 + max_value % 2;
        _settings_game.game_creation.snow_line_height = max(MIN_SNOWLINE_HEIGHT, half_max_value);
    }

    if (flat_world_height == -1) { // generating landscape
        int h0_tile_count = 0; // count tiles at sea level
        int highest_height = 0;
        for (uint y = 0; y < MapSizeY(); y++) {
            for (uint x = 0; x < MapSizeX(); x++) {
                int height = TileHeight(TileXY(x, y));
                if (height == 0) h0_tile_count++;
                if (height > highest_height) highest_height = height;
            }
        }

        /* Determine the snow line height and make it so that it's at most 50% of the land mass */
        int land_mass_size = MapSizeX() * MapSizeY() - h0_tile_count; // available tiles above sea
        int tile_count = 0, snow_line_height = 1;
        while (tile_count < land_mass_size / 2 && snow_line_height <= highest_height) {
            for (uint y = 0; y < MapSizeY(); y++) {
                for (uint x = 0; x < MapSizeX(); x++) {
                    if (TileHeight(TileXY(x, y)) == snow_line_height) tile_count++;
                }
            }
            snow_line_height++;
        }

        /* Farms can only generate below 'snow_line_height - 2' which limits
         * minimum snow_line_height to 'snow_line_height - 2 > 0', thus '3'.
         * Forests can only generate at a minimum of 'snow_line_height + 2'
         * which limits maximum snow_line_height to 'highest_height - 2'.
         * @see CheckNewIndustry_Farm and CheckNewIndustry_Forest. */
        _settings_game.game_creation.snow_line_height = Clamp(snow_line_height, 3, max(3, min(MAX_SNOWLINE_HEIGHT, highest_height - 2)));
    }
}