extern crate regex;
use std::env;
use std::process;
use std::fs::File;
use std::io::prelude::*;
use regex::Regex;
use std::fmt::{ Formatter, Debug };
use std::fmt;

fn main() {
    let args = env::args().collect();

    let filename = parse_filename(&args);

    let mut contents = String::new();
    get_contents(&filename, &mut contents);

    //println!("{}", contents);

    let (samples, program) = parse_content(&contents);

    //println!("Samples:\n{:?}\n\nProgram:\n{:?}", samples, program);

    let part1 = has3pos(&samples);

    println!("Part1: {}", part1);

    let opcodes = deduce_opcodes(&samples);

    let part2 = execute(program, opcodes)[0];

    println!("Part2: {}", part2);

}

fn execute(program: Program, opcodes: Vec<OpCode>) -> Vec<usize> {
    let mut codes = opcodes.clone();
    codes.sort_by_key(|code| code.num);
    println!("{:?}", codes);
    let mut reg = vec![0,0,0,0];

    for line in program.lines.iter() {
        //println!("{:?}", reg);
        let params = line[1..4].to_vec();
        println!("{:?}", line);
        println!("{} {:?}",codes[line[0]].name, params);
        (codes[line[0]].f)(&params,&mut reg);
        //println!("");
    }

    reg
}

fn deduce_opcodes(samples: &Vec<Sample>) -> Vec<OpCode> {
    let mut opcodes = Vec::new();
    let named_functions = get_named_functions();

    let mut candidates = Vec::new();
    for (name, function) in named_functions.iter() {
        let mut possibilities = Vec::new();
        for num in 0..16 {
            let no_possibility = samples.iter()
                .filter(|sample| sample.code[0] == num)
                .any(|sample| !sample.could_be(function));

            if !no_possibility{
                let opcode = OpCode {name: name.clone(), num: num, f: *function};
                possibilities.push(opcode)
            }
        }
        //println!("Possibilities:\n{:?}", possibilities);
        candidates.push(possibilities);
    }

    //println!("Candidates:\n{:?}", candidates);
    let mut found = Vec::new();

    while found.len() < 16 {
        for possibilities in candidates.iter() {
            let new: Vec<OpCode> = possibilities.iter().cloned().filter(|pos| !found.contains(&pos.num)).collect();
            if new.len() == 1 {
                opcodes.push(new[0].clone());
                found.push(new[0].num)
            }
        }
    }

    opcodes
}

fn get_functions() -> Vec<fn(&Vec<usize>, &mut Vec<usize>)> {
    let mut functions: Vec<fn(&Vec<usize>, &mut Vec<usize>)> = Vec::new();
    functions.push(addi); functions.push(addr);
    functions.push(muli); functions.push(mulr);
    functions.push(bani); functions.push(banr);
    functions.push(bori); functions.push(borr);
    functions.push(seti); functions.push(setr);
    functions.push(gtir); functions.push(gtri); functions.push(gtrr);
    functions.push(eqir); functions.push(eqri); functions.push(eqrr);
    functions
}

fn get_named_functions() -> Vec<(String, fn(&Vec<usize>, &mut Vec<usize>))> {
    let mut functions: Vec<(String, fn(&Vec<usize>, &mut Vec<usize>))> = Vec::new();
    functions.push(("addi".to_string(),addi)); functions.push(("addr".to_string(), addr));
    functions.push(("muli".to_string(),muli)); functions.push(("mulr".to_string(),mulr));
    functions.push(("bani".to_string(),bani)); functions.push(("banr".to_string(),banr));
    functions.push(("bori".to_string(),bori)); functions.push(("borr".to_string(),borr));
    functions.push(("seti".to_string(),seti)); functions.push(("setr".to_string(),setr));
    functions.push(("gtir".to_string(),gtir)); functions.push(("gtri".to_string(),gtri)); functions.push(("gtrr".to_string(),gtrr));
    functions.push(("eqir".to_string(),eqir)); functions.push(("eqri".to_string(),eqri)); functions.push(("eqrr".to_string(),eqrr));
    functions
}

fn has3pos(samples: &Vec<Sample>) -> i64 {
    let functions = get_functions();

    samples.iter().map(|sample| sample.num_candidates(&functions)).filter(|num| *num >= 3).count() as i64

}

fn parse_content(contents: &str) -> (Vec<Sample>, Program) {
    let mut samples = Vec::new();
    let mut prog = Vec::new();
    let mut lines = contents.trim_right().lines();
    let re = Regex::new(r"(\d+)").unwrap();

    while let Some(line) = lines.next() {
         if line.starts_with("Before") {
             let mut before = Vec::new();
             for cap in re.captures_iter(line) {
                 before.push(cap[1].parse::<usize>().unwrap());
             }

             let mut code = Vec::new();
             let code_line = lines.next().expect("Wrongly formatted sample");
             for cap in re.captures_iter(code_line) {
                 code.push(cap[1].parse::<usize>().unwrap());
             }

             let mut after = Vec::new();
             let after_line = lines.next().expect("Wrongly formatted sample");
             for cap in re.captures_iter(after_line) {
                 after.push(cap[1].parse::<usize>().unwrap());
             }

             samples.push(Sample {before, code, after} );

         } else {
         if line != "" {
             let mut source = Vec::new();
             for cap in re.captures_iter(line) {
                 source.push(cap[1].parse::<usize>().unwrap());
             }
             prog.push(source);
         }
         }
    }

    (samples, Program {lines: prog})
}

#[derive(Clone)]
struct OpCode {
    name: String,
    num: usize,
    f: fn(&Vec<usize>, &mut Vec<usize>),
}

impl Debug for OpCode {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        write!(f, "OpCode {{ name: {}, num: {} }}", self.name, self.num)
    }

}

#[derive(Debug)]
struct Sample {
    before: Vec<usize>,
    code: Vec<usize>,
    after: Vec<usize>,
}

impl Sample {
    fn could_be(&self, f: impl Fn(&Vec<usize>, &mut Vec<usize>)) -> bool {
        let mut reg = self.before.clone();
        f(&self.code[1..4].to_vec(), &mut reg);
        reg == self.after
    }

    fn num_candidates(&self, functions: &Vec<fn(&Vec<usize>, &mut Vec<usize>)>) -> i64 {
        functions.iter().filter(|f| self.could_be(f)).count() as i64
    }
}

#[derive(Debug)]
struct Program {
    lines: Vec<Vec<usize>>,
}

fn parse_filename(args: &Vec<String>) -> &str {

    if args.len() < 2 {
        println!("Too few arguements, please give a filename");
        process::exit(1);
    }
    args.get(1).expect("No filename provided")
}

fn get_contents(filename: &str, contents: &mut String) {
    let mut f = File::open(filename).expect("File not found");

    f.read_to_string(contents)
        .expect("Something went wrong reading the file");
}

fn addr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] + reg[b];
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn addi(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] + b;
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn mulr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] * reg[b];
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn muli(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] * b;
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn banr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] & reg[b];
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn bani(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] & b;
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn borr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] | reg[b];
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn bori(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = reg[a] | b;
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn setr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,_b,c] = params[0..3] {
        reg[c] = reg[a];
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn seti(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,_b,c] = params[0..3] {
        reg[c] = a;
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn gtir(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if a > reg[b] { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn gtri(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if reg[a] > b { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn gtrr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if reg[a] > reg[b] { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn eqir(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if a == reg[b] { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn eqri(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if reg[a] == b { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}

fn eqrr(params: &Vec<usize>, reg: &mut Vec<usize>) {
    if let [a,b,c] = params[0..3] {
        reg[c] = if reg[a] == reg[b] { 1 } else { 0 }
    } else {
        panic!("Wrong amount of paramters to addr")
    }
}