use std::fs::File;
use std::io;
use std::io::BufRead;
use std::path::Path;

pub mod cafeteria;
pub mod printing_department;
pub mod trash_compactor;

pub trait Solver {
    fn get_puzzle_index(&self) -> u8;
    fn get_puzzle_name(&self) -> &str;
    fn get_input_filename(&self) -> &str;
    fn get_part1(&self) -> u64;
    fn get_part2(&self) -> u64;
    fn process_data(&mut self, lines: io::Lines<io::BufReader<File>>);
}

pub fn run(mut solver: Box<dyn Solver>) {
    println!(
        "--- Day {}: {} ---",
        solver.get_puzzle_index(),
        solver.get_puzzle_name()
    );

    // The "../../data" and "../../../data" paths are useful for running the binary from
    // "target/release/" directory with "data/" directory in package root or parent directory.
    let paths = vec!["./data", "../data", "../../data", "../../../data"];

    match read_data_file(solver.get_input_filename(), &paths) {
        Ok(lines) => {
            solver.process_data(lines);
            print_result(solver);
        }
        Err(error) => eprintln!("{}", error),
    };
}

fn print_result(solver: Box<dyn Solver>) {
    println!(
        "Part 1: {:?}\nPart 2: {:?}\n",
        solver.get_part1(),
        solver.get_part2()
    );
}

fn read_data_file<T>(
    filename: T,
    search_paths: &Vec<T>,
) -> Result<io::Lines<io::BufReader<File>>, String>
where
    T: AsRef<Path>,
{
    for path in search_paths {
        if let Ok(lines) = read_lines(path.as_ref().join(&filename)) {
            return Ok(lines);
        }
    }

    let message = search_paths
        .iter()
        .map(|path| path.as_ref().join(&filename).display().to_string())
        .collect::<Vec<_>>()
        .join("\n");
    Err(format!(
        "Cannot open puzzle input file, searched these paths:\n{}",
        message
    ))
}

// This code is taken from https://doc.rust-lang.org/stable/rust-by-example/std_misc/file/read_lines.html
fn read_lines<T>(filename: T) -> io::Result<io::Lines<io::BufReader<File>>>
where
    T: AsRef<Path>,
{
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}