use std::collections::HashMap;

fn move_tail(head: &(isize, isize), mut tail: (isize, isize)) -> (isize, isize) {
    if head.0 == tail.0 && head.1 == tail.1 {
        // same spot, wich is fine
    } else if head.1 == tail.1 {
        // x coords are different -> horizontal movement
        if tail.0 + 2 == head.0 {
            tail.0 = tail.0 + 1;
        } else if tail.0 - 2 == head.0 {
            tail.0 = tail.0 - 1;
        }
    } else if head.0 == tail.0 {
        // y coords are different  -> vertical movement
        if tail.1 + 2 == head.1 {
            tail.1 = tail.1 + 1;
        } else if tail.1 - 2 == head.1 {
            tail.1 = tail.1 - 1;
        }
    } else {
        // both coords are different -> horizontal and vertical movement
        if head.0 == tail.0 + 1 {
            if head.1 == tail.1 + 2 {
                tail.0 = tail.0 + 1;
                tail.1 = tail.1 + 1;
            } else if head.1 == tail.1 - 2 {
                tail.0 = tail.0 + 1;
                tail.1 = tail.1 - 1;
            }
        } else if head.0 == tail.0 - 1 {
            if head.1 == tail.1 + 2 {
                tail.0 = tail.0 - 1;
                tail.1 = tail.1 + 1;
            } else if head.1 == tail.1 - 2 {
                tail.0 = tail.0 - 1;
                tail.1 = tail.1 - 1;
            }
        } else if head.0 == tail.0 + 2 {
            if head.1 == tail.1 + 1 {
                tail.0 = tail.0 + 1;
                tail.1 = tail.1 + 1;
            } else if head.1 == tail.1 - 1 {
                tail.0 = tail.0 + 1;
                tail.1 = tail.1 - 1;
            }
        } else if head.0 == tail.0 - 2 {
            if head.1 == tail.1 + 1 {
                tail.0 = tail.0 - 1;
                tail.1 = tail.1 + 1;
            } else if head.1 == tail.1 - 1 {
                tail.0 = tail.0 - 1;
                tail.1 = tail.1 - 1;
            }
        }
    }

    tail
}
pub fn task_one(input: &str) -> String {
    let mut visited_places: HashMap<(isize, isize), u8> = HashMap::new();
    let mut head = (0, 0);
    let mut tail = (0, 0);

    visited_places.insert(tail, 0);

    for line in input.trim().lines() {
        match line.split_once(" ").unwrap() {
            ("U", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    head.1 = head.1 + 1;

                    tail = move_tail(&head, tail);

                    visited_places.insert(tail, 0);
                }
            }
            ("R", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    head.0 = head.0 + 1;

                    tail = move_tail(&head, tail);

                    visited_places.insert(tail, 0);
                }
            }
            ("D", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    head.1 = head.1 - 1;

                    tail = move_tail(&head, tail);

                    visited_places.insert(tail, 0);
                }
            }
            ("L", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    head.0 = head.0 - 1;

                    tail = move_tail(&head, tail);

                    visited_places.insert(tail, 0);
                }
            }
            (_, _) => panic!(),
        }
    }

    visited_places.len().to_string()
}

pub fn task_two(input: &str) -> String {
    let mut visited_places: HashMap<(isize, isize), u8> = HashMap::new();
    let mut knots: [(isize, isize); 10] = [(0, 0); 10];

    visited_places.insert(knots[9], 0);

    for line in input.trim().lines() {
        match line.split_once(" ").unwrap() {
            ("U", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    knots[0].1 = knots[0].1 + 1;

                    for i in 1..10 {
                        knots[i] = move_tail(&knots[i - 1], knots[i]);
                    }

                    visited_places.insert(knots[9], 0);
                }
            }
            ("R", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    knots[0].0 = knots[0].0 + 1;

                    for i in 1..10 {
                        knots[i] = move_tail(&knots[i - 1], knots[i]);
                    }

                    visited_places.insert(knots[9], 0);
                }
            }
            ("D", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    knots[0].1 = knots[0].1 - 1;

                    for i in 1..10 {
                        knots[i] = move_tail(&knots[i - 1], knots[i]);
                    }

                    visited_places.insert(knots[9], 0);
                }
            }
            ("L", count) => {
                for _ in 1..=count.parse::<usize>().unwrap() {
                    knots[0].0 = knots[0].0 - 1;

                    for i in 1..10 {
                        knots[i] = move_tail(&knots[i - 1], knots[i]);
                    }

                    visited_places.insert(knots[9], 0);
                }
            }
            (_, _) => panic!(),
        }
    }

    visited_places.len().to_string()
}