You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: area_ending_point.rs
    path of file: ./repos/rustrogueliketutorial/chapter-69-mushrooms2/src/map_builders
    
    the code of the file until where you have to start completion: use super::{MetaMapBuilder, BuilderMap, TileType};
use crate::map;
use rltk::RandomNumberGenerator;

#[allow(dead_code)]
pub enum XEnd { LEFT, CENTER, RIGHT }

#[allow(dead_code)]
pub enum YEnd{ TOP, CENTER, BOTTOM }

pub struct AreaEndingPosition {
    x : XEnd,
    y : YEnd
}

impl MetaMapBuilder for AreaEndingPosition {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl AreaEndingPosition {
    #[allow(dead_code)]
    pub fn new(x : XEnd, y : YEnd) -> Box<AreaEndingPosition> {
        Box::new(AreaEndingPosition{
            x, y
        })
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let seed_x;
        let seed_y;

        match self.x {
            XEnd::LEFT => seed_x = 1,
            XEnd::CENTER => seed_x = build_data.map.width / 2,
            XEnd::RIGHT => seed_x = build_data.map.width - 2
        }

        match self.y {
            YEnd::TOP => seed_y = 1,
            YEnd::CENTER => seed_y
    
    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let seed_x;
        let seed_y;

        match self.x {
            XEnd::LEFT => seed_x = 1,
            XEnd::CENTER => seed_x = build_data.map.width / 2,
            XEnd::RIGHT => seed_x = build_data.map.width - 2
        }

        match self.y {
            YEnd::TOP => seed_y = 1,
            YEnd::CENTER => seed_y = build_data.map.height / 2,
            YEnd::BOTTOM => seed_y = build_data.map.height - 2
        }

        let mut available_floors : Vec<(usize, f32)> = Vec::new();
        for (idx, tiletype) in build_data.map.tiles.iter().enumerate() {
            if map::tile_walkable(*tiletype) {
                available_floors.push(
                    (
                        idx,
                        rltk::DistanceAlg::PythagorasSquared.distance2d(
                            rltk::Point::new(idx as i32 % build_data.map.width, idx as i32 / build_data.map.width),
                            rltk::Point::new(seed_x, seed_y)
                        )
                    )
                );
            }
        }
        if available_floors.is_empty() {
            panic!("No valid floors to start on");
        }

        available_floors.sort_by(|a,b| a.1.partial_cmp(&b.1).unwrap());

        build_data.map.tiles[available_floors[0].0] = TileType::DownStairs;
        build_data.take_snapshot();
    }