use linked_list::dodd::helpers;
use linked_list::dodd::item::Item;
use linked_list::dodd::node::Node;

use num::bigint::BigInt;
use once_cell::sync::OnceCell;
use regex::Regex;

use std::io;
use std::str::FromStr;

fn trim_newline(string: &mut String) {
    if string.ends_with('\n') {
        string.pop();
        if string.ends_with('\r') {
            string.pop();
        }
    }
}

fn is_valid_string(string: &str) -> bool {
    static VALID_REGEX: OnceCell<Regex> = OnceCell::new();
    let regex = VALID_REGEX.get_or_init(
        || Regex::new("^(0|-?[1-9][0-9]*|[A-Za-z][0-9A-Z_a-z]*)$").unwrap()
    );
    regex.is_match(string)
}

fn insert_before(val: &String, oth: &Item<String>) -> bool {
    if let Ok(x) = BigInt::from_str(val) {
        if let Ok(y) = BigInt::from_str(&oth.value) {
            return x <= y
        }
    }
    val <= &oth.value
}

fn value_equals(item: &Item<String>, val: &String) -> bool {
    &item.value == val
}

fn main() {
    let mut start = Node::empty();

    let mut begin = true;
    let mut input;

    loop {
        if !begin {
            println!();
        }
        else {
            begin = false;
        }

        println!("Awaiting input...");
        let mut string = String::new();
        io::stdin().read_line(&mut string).expect("Failed to read line!");
        trim_newline(&mut string);

        if string.is_empty() {
            println!("\nProgram terminated!");
            return;
        }
        else if string.starts_with('~') {
            if string.len() == 1 {
                println!("\nDeleting list...");
                helpers::remove_all(&mut start);
            }
            else {
                input = &string[1..];
                if is_valid_string(input) {
                    println!("\nRemoving item...");
                    helpers::remove_item(&mut start, String::from(input), value_equals);
                }
                else {
                    println!("\nCould not parse input!");
                }
            }
        }
        else if string == "l" {
            println!("\nList print...");
            helpers::print_list(&start);
        }
        else if string == "i" {
            println!("\nIterator print...");
            helpers::print_iterator(&start);
        }
        else if string == "a" {
            println!("\nArray print...");
            helpers::print_array(&start);
        }
        else if string == "r" {
            println!("\nRecursive print...");
            helpers::print_recursive(&start);
        }
        else if is_valid_string(&string[..]) {
            println!("\nInserting item...");
            helpers::insert_item(&mut start, string, insert_before);
        }
        else {
            println!("\nCould not parse input!");
        }
    }
}