use std::env;
use std::io::BufReader;
use std::io::BufRead;
use std::fs::File;
use std::process;
use std::collections::HashSet;

fn main() {
  let args: Vec<String> = env::args().collect();
  if args.len() != 2 {
    println!("Wrong number of arguments. Provide just a file name.");
    process::exit(1);
  }
  let filename = &args[1];
  println!("Using file {} as input.", filename);
  let f = match File::open(filename) {
    Ok(file) => file,
    Err(e) => {
      println!("Failed to open file {}. {:?}", filename, e);
      process::exit(1);
    }
  };
  let file = BufReader::new(&f);

  let mut strings: Vec<String> = Vec::new();
  // exercise 1
  for line in file.lines() {
    let l = line.unwrap();
    strings.push(l);
  }

  // exercise 1
  let mut doubles = 0;
  let mut triples = 0;

  for string in &strings {
    let chars: Vec<char> = string.chars().collect();
    let mut is_double = false;
    let mut is_triple = false;
    for ch in &chars {
      let exacts: Vec<&char> = chars.iter().filter(|&c| c == ch).collect();
      let count = exacts.len();
      match count {
        2 => { is_double = true; }
        3 => { is_triple = true; }
        _ => {}
      }
    }

    if is_double {
      doubles += 1;
    }

    if is_triple {
      triples += 1;
    }
  }

  println!("Doubles: {}", doubles);
  println!("Triples: {}", triples);
  let checksum = doubles * triples;
  println!("Checksum: {}", checksum);

  // exercise 2
  let n = strings.len();
  for i in 0..n {
    let string = &strings[i];
    let s_chars: Vec<char> = string.chars().collect();

    let char_count = s_chars.len();
    for j in (i + 1)..n {
      let other = &strings[j];
      let o_chars: Vec<char> = other.chars().collect();

      let mut commons: Vec<&char> = Vec::new();
      for k in 0..char_count {
        if s_chars[k] == o_chars[k] {
          commons.push(&s_chars[k]);
        }
      }

      if commons.len() == char_count - 1 {
        let sol: String = commons.into_iter().collect();
        println!("Solution: {}", sol);
      }
    }
  }
}