use rand::Rng;
use std::io::{stdin,stdout,Write};

fn output_levels(starting_level: u64, ending_level: u64, character_x_coord: u8, character_icon: char, levels: &Vec<Vec<u8>>) {
    print!("{}[2J", 27 as char);
    for i in starting_level..ending_level {
        print!("{}   ", i);
        for j in 0..levels[i as usize].len() {
            let object = levels[i as usize][j as usize];
            if i == starting_level && j == character_x_coord as usize { print!("{}",character_icon) }
            else if object >= 4 { print!(" ") }
            else if object == 3 { print!("¯") }
            else if object == 2 { print!("\\") }
            else if object == 1 { print!("/") }
            else { print!("|") }
        }
        println!();
    }
}
fn generate_level(level_to_generate: u64, difficulty: u8, mut left_wall: u8, mut right_wall: u8, levels: &mut Vec<Vec<u8>>) {
    let mut new_level: Vec<u8> = Vec::new();

    let left_wall_change = rand::thread_rng().gen_range(-2..2);
    let right_wall_change = rand::thread_rng().gen_range(-1..1);
    let mut left_wall_temp = left_wall as i8 + left_wall_change;
    if left_wall_temp >= 0 { left_wall = left_wall_temp as u8 }
    right_wall = (right_wall as i8 + right_wall_change) as u8;

    for i in 0..right_wall+1 {
        new_level.push(4)
    }

    new_level[left_wall as usize] = 0;
    for i in left_wall+1..right_wall-1 {
        let mut rng = rand::thread_rng();
        let object: u8 = rand::thread_rng().gen_range(3..difficulty);
        new_level[i as usize] = object;
    }
    new_level[right_wall as usize] = 0;
    levels.push(new_level);
}

fn input() -> String{
    let mut s=String::new();
    let _=stdout().flush();
    stdin().read_line(&mut s).expect("Did not enter a correct string");
    if let Some('\n')=s.chars().next_back() {
        s.pop();
    }
    if let Some('\r')=s.chars().next_back() {
        s.pop();
    }
    return s;
}

fn main() {
    let mut levels: Vec<Vec<u8>> = Vec::new();
    
    let screen_height: u8 = 20;
    let screen_width: u8 = 11;
    let difficulty: u8 = 10;
    

    let mut current_level: u64 = 0;
    let character_icon: char = 'µ';
    let mut x_coord: u8 = (screen_width as f32/ 2.0) as u8; // Distance from left wall
    let mut left_wall: u8 = 0;
    let mut right_wall: u8 = screen_width;


    for i in 1..screen_height {
        generate_level(i as u64, difficulty, left_wall, right_wall, &mut levels)
    };
    loop {
        generate_level(current_level, difficulty, left_wall, right_wall, &mut levels);
        output_levels(current_level, current_level + screen_height as u64, x_coord, character_icon, &levels);
        let direction = input();
        if direction == "r" { 
            if x_coord < screen_width-1 { 
                x_coord += 1 
            }
        }
        else if direction == "l" { 
            if x_coord > 1 {
                x_coord -= 1 
            }
        }
        current_level+=1
    }
}