Advent_of_Code/day_5/src/main.rs

use std::{io::prelude::*, fs::File, path::Path, io, collections::HashMap };


#[derive(Clone, Debug)]
struct SubMap
{
    destination_start: i32,
    source_start: i32,
    length: i32,

    map: HashMap<i32, i32>
}

impl SubMap
{
    fn new() -> SubMap
    {
        SubMap { destination_start: 0, source_start: 0, length: 0, map: HashMap::new() }
    }

    fn map_values(&mut self)
    {
        for i in 0..self.length
        {
            self.map.insert(self.source_start + i, self.destination_start + i);
        }
    }
}

#[derive(Clone, Debug)]
struct Map
{
    name: String,
    sub_maps: Vec<SubMap>,
}

impl Map
{
    fn new(name: &str) -> Map
    {
        Map { name: name.to_string(), sub_maps: Vec::new() }
    }

    fn map_input(&self, input: i32) -> i32
    {
        for sub_map in &self.sub_maps
        {
            if sub_map.map.contains_key(&input)
            {
                return sub_map.map[&input];
            }
        }

        return input;
    }
}

fn main() 
{
    let input = load_data("data/test_input");
    let (seeds, maps) = parse_input(&input);

    println!("SEEDS: {:#?}, MAPS: {:#?}", seeds, maps);
}

fn parse_input(input: &str) -> (Vec<i32>, HashMap<String, Map>) // String is the map name
{
    let mut seeds: Vec<i32> = Vec::new();

    let mut maps: HashMap<String, Map> = HashMap::new();
    let mut current_map = "";
    for (idx, line) in input.to_ascii_lowercase().split("\n").into_iter().enumerate()
    {
        // stupid windows dumb line ending non-sense
        if line.starts_with("\r")
        {
            continue;
        }

        // SEEDS
        if line.contains("seeds:")
        {
            for val in line.trim_start_matches("seeds:").trim().split(" ")
            {
                let num = val.parse::<i32>().expect(&format!("Failed to parse seed value: {}", val));
                seeds.push(num);
            }

            continue;
        }


        // NEW MAP
        if line.contains("map:")
        {
            let name = line.trim_end_matches("map:");
            current_map = name.clone();
            let map = Map::new(&current_map);
            maps.insert(current_map.to_string(), map.clone());
            continue;
        }

        // NEW SUB MAP
        let mut sub_map = SubMap::new();
        let vals: Vec<&str> = line.trim().split(" ").collect();

        if vals.len() < 3
        {
            println!("========INVALID SUBMAP FOR {}: {:#?}========", current_map, vals);
            continue;
        }
        
        sub_map.destination_start = vals[0].parse::<i32>().expect(&format!("Failed to parse dest value: {}", vals[0]));
        sub_map.source_start = vals[1].parse::<i32>().expect(&format!("Failed to parse source value: {}", vals[1]));
        sub_map.length = vals[2].parse::<i32>().expect(&format!("Failed to parse length value: {}", vals[2]));       
        sub_map.map_values();
        if let Some(map) = maps.get_mut(current_map)
        {
            map.sub_maps.push(sub_map.clone());
        }
        else
        {
            println!("========CURRENT MAP NOT FOUND IN MAP: {}========", current_map);
        }
    }

    (seeds, maps)
}


fn load_data(file_name: &str) -> String
{
    let mut file = match File::open(Path::new(file_name))
    {
        Ok(file) => file,
        Err(why) => panic!("Could not open file {}: {}", Path::new(file_name).display(), why),
    };

    let mut s = String::new();
    let file_contents = match file.read_to_string(&mut s) 
    {
        Err(why) => panic!("couldn't read {}: {}", Path::new(file_name).display(), why),
        Ok(_) => s,
    };
    
    return file_contents;
}