use super::song::Song;
use rand::seq::SliceRandom;
use serenity::model::id::UserId;
use std::collections::HashMap;
use std::{cmp::min, collections::VecDeque};

#[derive(Clone)]
pub struct SongQueue {
    queues: HashMap<UserId, VecDeque<Song>>,
    users: VecDeque<UserId>,
}

impl SongQueue {
    pub fn new() -> SongQueue {
        SongQueue {
            queues: HashMap::new(),
            users: VecDeque::new(),
        }
    }
    fn new_user_queue(&mut self, user: UserId) {
        if self.queues.get(&user).is_none() {
            self.queues.insert(user, VecDeque::new());
        }
        if !self.users.contains(&user) {
            self.users.push_back(user);
        }
    }
    pub fn push(&mut self, songs: Vec<Song>) {
        for song in songs.into_iter() {
            self.new_user_queue(song.queuer.id);
            let deque = self.queues.get_mut(&song.queuer.id).unwrap();
            deque.push_back(song);
        }
    }
    pub fn peek(&self) -> Option<Song> {
        let user = match self.users.front() {
            Some(user) => user,
            None => return None,
        };
        let deque = self.queues.get(&user).unwrap();
        deque.front().cloned()
    }
    pub fn pop(&mut self) -> Option<Song> {
        let user = match self.users.pop_front() {
            Some(user) => user,
            None => return None,
        };
        let deque = self.queues.get_mut(&user).unwrap();
        let song = deque.pop_front();
        if deque.len() > 0 {
            self.users.push_back(user);
        }
        song
    }
    pub fn shuffle(&mut self) -> Result<(), String> {
        if self.users.len() == 0 {
            return Err("queue is empty".to_string());
        }
        for deque in self.queues.values_mut() {
            deque.make_contiguous().shuffle(&mut rand::thread_rng());
        }

        Ok(())
    }
    pub fn clear(&mut self) -> Result<(), String> {
        if self.users.len() == 0 {
            return Err("queue is empty".to_string());
        };
        self.queues.clear();
        self.users.clear();
        Ok(())
    }
    pub fn get_string(&self) -> String {
        if self.users.len() == 0 {
            return "*empty*".to_string();
        };
        let mut s = String::new();
        let queue = self.as_vec();
        s.push_str(&format!(
            "*Showing {} of {} songs*\n",
            min(20, queue.len()),
            queue.len()
        ));
        for (i, song) in queue.iter().take(20).enumerate() {
            s += &format!(
                "{}: {} (queued by {})\n",
                i + 1,
                &song.get_string(),
                song.queuer.name
            );
        }
        s
    }
    fn as_vec(&self) -> Vec<Song> {
        let mut clone = self.clone();
        let mut queue = vec![];
        while let Some(song) = clone.pop() {
            queue.push(song);
        }
        queue
    }
}