use crate::tracker_manager::{TrackerId, TrackerManager};
use bytes::Bytes;
use ring::digest::{digest, SHA1_FOR_LEGACY_USE_ONLY};
use std::collections::{HashMap, HashSet, VecDeque};
use std::net::SocketAddr;
use std::ops::Index;
use std::option::Option::Some;
use std::path::PathBuf;
use torment_core::infohash::v1::U160;
use torment_core::metainfo::{MetaInfo, Torrent};
use torment_core::Bitfield;
use torment_peer::message::{Handshake, Message, PieceMessage, SelectionMessage};
use torment_peer::{Peer, PeerProtocol};
use torment_storage::{StorageMap, ToStorageMap};

#[derive(Debug)]
pub enum Source {
    Torrent(TorrentSource),
    MetaInfo(MetaInfoSource),
}

#[derive(Debug)]
pub struct MetaInfoSource {
    info_hash: U160,
}

#[derive(Debug)]
pub struct TorrentSource {
    file: Option<PathBuf>,
    torrent: Option<Torrent>,
}

#[derive(Debug)]
pub struct TorrentTarget {
    pub path: PathBuf,
    pub is_base_path: bool,
}

#[derive(Debug)]
pub struct TorrentManager {
    info_hash: U160,
    bitfield: Bitfield,
    trackers: Vec<Vec<TrackerId>>,
    source: Source,
    target: TorrentTarget,
    peers: HashMap<U160, Peer>,
    queue: VecDeque<(U160, Message)>,
    storage_map: StorageMap,
}

pub const REQUEST_SIZE: usize = 16384;

impl TorrentManager {
    pub fn info_hash(&self) -> U160 {
        self.info_hash
    }

    pub fn from_torrent(
        torrent: Torrent,
        target: TorrentTarget,
        tracker_manager: Option<&mut TrackerManager>,
    ) -> TorrentManager {
        let trackers = tracker_manager
            .map(|manager| {
                torrent
                    .announce_list()
                    .iter()
                    .map(|tier_list| {
                        tier_list
                            .iter()
                            .filter_map(|tracker| manager.get_tracker_id(tracker))
                            .collect::<Vec<_>>()
                    })
                    .collect::<Vec<_>>()
            })
            .unwrap_or(vec![]);

        TorrentManager {
            info_hash: torrent.info_hash(),
            bitfield: Bitfield::with_size(torrent.meta_info().pieces()),
            trackers,
            source: Source::Torrent(TorrentSource {
                file: None,
                torrent: Some(torrent.clone()),
            }),
            storage_map: torrent.to_storage_map(&target.path, target.is_base_path),
            target,
            peers: HashMap::new(),
            queue: Default::default(),
        }
    }

    pub fn handshake(
        &mut self,
        handshake: Handshake,
        addr: SocketAddr,
        protocol: PeerProtocol,
    ) -> bool {
        if handshake.info_hash() != self.info_hash {
            return false;
        }

        if let Some(peer) = self.peers.get(&handshake.peer_id()) {
            if peer.addr() != addr {
                return false;
            }
        }

        let meta_info = self.meta_info();
        let peer = Peer::new(addr, protocol, handshake, meta_info);
        self.peers.insert(peer.id(), peer);

        true
    }

    fn meta_info(&mut self) -> &MetaInfo {
        if let Source::Torrent(torrent) = &self.source {
            return torrent
                .torrent
                .as_ref()
                .expect("No torrent loaded uh oh missing functionality")
                .meta_info();
        }

        panic!("Can't resolve MetaInfo for torrent")
    }

    pub fn process(&mut self, peer_id: U160, message: Message) -> bool {
        let mut queue = vec![];
        let ok = if let Some(peer) = self.peers.get_mut(&peer_id) {
            if peer.process(message) {
                while let Some(message) = peer.next() {
                    self.queue.push_back((peer_id, message));
                }

                while let Some(piece) = peer.next_piece() {
                    if self.storage_map.has_piece(piece.index() as usize) {
                        continue;
                    }

                    if self
                        .storage_map
                        .write(
                            piece.index() as usize,
                            piece.offset() as usize,
                            piece.piece(),
                        )
                        .unwrap()
                    {
                        queue.push(piece.index() as usize);
                    }
                }

                while let Some(piece_request) = peer.next_request() {
                    if !self.bitfield.get(piece_request.index()) {
                        continue;
                    }

                    let mut buffer = vec![0u8; piece_request.length() as usize];
                    self.storage_map
                        .read(
                            piece_request.index() as usize,
                            piece_request.offset() as usize,
                            &mut buffer,
                        )
                        .unwrap();

                    self.queue.push_back((
                        peer_id,
                        Message::Piece(PieceMessage {
                            index: piece_request.index(),
                            offset: piece_request.offset(),
                            piece: Bytes::from(buffer),
                        }),
                    ))
                }

                true
            } else {
                false
            }
        } else {
            false
        };

        for have in queue {
            let piece_hash = self.meta_info().hash(have);
            let piece_data = self.storage_map.read_piece(have).unwrap();
            let res = digest(&SHA1_FOR_LEGACY_USE_ONLY, &piece_data);
            if piece_hash != res.as_ref() {
                println!("=> Piece#{} failed verification", have);
                self.storage_map.wipe_piece(have);
                continue;
            } else {
                println!("=> Piece#{} verified", have);
            }

            self.bitfield.set(have as u32);

            let keys = self.peers.keys().copied().collect::<Vec<_>>();
            for key in keys {
                self.queue.push_back((key, Message::Have(have as u32)));

                if !self.peers[&key].has_piece(have as u32) && self.peers[&key].we_choked() {
                    self.peers.get_mut(&key).unwrap().set_we_choked(false);
                    self.queue.push_back((key, Message::Unchoke));
                }
            }
        }

        ok
    }

    pub fn next(&mut self) -> Option<(U160, Message)> {
        self.queue.pop_front()
    }

    pub fn house_keeping(&mut self) {
        let mut peers = self
            .peers
            .iter()
            .filter_map(|(_, peer)| {
                if peer.has()1

                if peer.is_choked() {
                    None
                } else {
                    Some(peer.id())
                }
            })
            .collect::<HashSet<_>>();

        let pieces = self.meta_info().pieces() as u32;
        for i in 0u32..pieces {
            if self.bitfield.get(i) {
                continue;
            }

            let length = self.storage_map.get_piece_length(i as usize);
            let mut offset = 0;

            for peer in &peers.clone() {
                if !self.peers[peer].has_piece(i) {
                    continue;
                }

                while offset < length && self.peers[peer].count_open_requests() < 25 {
                    if !self.storage_map.has_piece_bit(i as usize, offset) {
                        let request_length = if (offset + REQUEST_SIZE) > length {
                            length - offset
                        } else {
                            REQUEST_SIZE
                        };

                        let msg = SelectionMessage::new(i, offset as u32, request_length as u32);

                        if self.peers.get_mut(peer).unwrap().requested(msg) {
                            self.queue.push_back((*peer, Message::Request(msg)));
                        }
                    }

                    offset += REQUEST_SIZE;
                }

                if self.peers[peer].count_open_requests() >= 25 {
                    peers.remove(peer);
                }

                if offset >= length {
                    break;
                }
            }
        }
    }
}