use std::convert::TryInto;
use libpso::packet::ship::*;
use libpso::packet::messages::*;
use crate::common::serverstate::ClientId;
use crate::ship::ship::{SendShipPacket, ShipError, Clients};
use crate::ship::location::{ClientLocation, ClientLocationError};
use crate::ship::items::{ItemManager, ItemManagerError, ClientItemId, ItemToTradeDetail};
use crate::ship::items::inventory::InventoryItem;
use crate::ship::trade::{TradeItem, TradeState, TradeStatus};
use crate::entity::gateway::EntityGateway;
use crate::ship::packet::builder;

pub const MESETA_ITEM_ID: ClientItemId = ClientItemId(0xFFFFFF01);
pub const OTHER_MESETA_ITEM_ID: ClientItemId = ClientItemId(0xFFFFFFFF);


#[derive(thiserror::Error, Debug, PartialEq, Eq)]
pub enum TradeError {
    #[error("no partner")]
    CouldNotFindTradePartner,
    #[error("invalid item id")]
    InvalidItemId(ClientItemId),
    #[error("item does not match id")]
    ClientItemIdDidNotMatchItem(ClientItemId, [u8; 16]),
    #[error("invalid stack {1}")]
    InvalidStackAmount(ClientItemId, usize),
    #[error("not in trade menu")]
    NotInTradeMenu,
    #[error("trade menu at an invalid point")]
    MismatchedStatus,
    #[error("no space in inventory")]
    NoInventorySpace,
    #[error("no space in stack")]
    NoStackSpace,
    #[error("invalid meseta amount")]
    InvalidMeseta,
    #[error("tried starting a trade while in one already")]
    ClientAlreadyInTrade,
    #[error("tried starting a trade while with player already in a trade")]
    OtherAlreadyInTrade,
    #[error("tried to trade item not specified in trade request")]
    SketchyTrade,
    #[error("items in trade window and items attempted to trade do not match")]
    MismatchedTradeItems,
}


// TODO: remove target
pub async fn trade_request(id: ClientId,
                               trade_request: &TradeRequest,
                               target: u32,
                               client_location: &ClientLocation,
                               clients: &mut Clients,
                               item_manager: &mut ItemManager,
                               trades: &mut TradeState)
                               -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error>
{
    let trade_request = trade_request.clone(); // TODO: make this function take ownership of packet
    match trade_request.trade {
        TradeRequestCommand::Initialize(ref act, _meseta) => {
            match act {
                TradeRequestInitializeCommand::Initialize => {
                    if trades.in_trade(&id) {
                        return Err(TradeError::ClientAlreadyInTrade.into())
                    }
                    let trade_partner = client_location.get_client_neighbors(id)?
                        .into_iter()
                        .find(|ac| {
                            ac.local_client.id() == target as u8 //trade_request.client
                        })
                        .ok_or(TradeError::CouldNotFindTradePartner)?;
                    if trades.in_trade(&trade_partner.client) {
                        return Err(TradeError::OtherAlreadyInTrade.into())
                    }
                    trades.new_trade(&id, &trade_partner.client);
                    Ok(Box::new(client_location.get_all_clients_by_client(id)?.into_iter()
                                .filter(move |client| client.local_client.id() == target as u8)
                                .map(move |client| {
                                    (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                })))
                },
                TradeRequestInitializeCommand::Respond => {
                    Ok(trades
                        .with(&id, |this, other| -> Option<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>> {
                            if this.status == TradeStatus::ReceivedRequest && other.status == TradeStatus::SentRequest {
                                this.status = TradeStatus::Trading;
                                other.status = TradeStatus::Trading;

                                let trade_request = trade_request.clone();
                                Some(Box::new(client_location.get_all_clients_by_client(id).ok()?.into_iter()
                                         .filter(move |client| client.local_client.id() == target as u8)
                                         .map(move |client| {
                                             (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                         })))
                            }
                            else {
                                None
                            }
                        })?
                        .unwrap_or_else(|| -> Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send> {
                            trades.remove_trade(&id);
                            Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                                     .filter(move |client| client.local_client.id() == target as u8)
                                     .map(move |client| {
                                         (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                                     })
                                     .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
                        }))
                }
            }
        },
        TradeRequestCommand::AddItem(item_id, amount) => {
            Ok(trades
                .with(&id, |this, other| -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error> {
                    if this.status == TradeStatus::Trading && other.status == TradeStatus::Trading {
                        let client = clients.get(&this.client()).ok_or_else(|| ShipError::ClientNotFound(this.client()))?;
                        let inventory = item_manager.get_character_inventory(&client.character)?;
                        if ClientItemId(item_id) == MESETA_ITEM_ID {
                            this.meseta += amount as usize;
                        }
                        else {
                            let item = inventory.get_item_by_id(ClientItemId(item_id)).ok_or(ItemManagerError::NoSuchItemId(ClientItemId(item_id)))?;

                            match item {
                                InventoryItem::Individual(_) => {
                                    this.items.push(TradeItem::Individual(ClientItemId(item_id)));
                                },
                                InventoryItem::Stacked(stacked_item) => {
                                    if stacked_item.count() < amount as usize {
                                        return Err(TradeError::InvalidStackAmount(ClientItemId(item_id), amount as usize).into());
                                    }
                                    this.items.push(TradeItem::Stacked(ClientItemId(item_id), amount as usize));
                                },
                            }
                        }

                        let trade_request = trade_request.clone();
                        Ok(Box::new(client_location.get_all_clients_by_client(id)?.into_iter()
                                    .filter(move |client| client.local_client.id() == target as u8)
                                    .map(move |client| {
                                        (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                    })))
                    }
                    else {
                        Err(TradeError::MismatchedStatus.into())
                    }
                })?
                .unwrap_or_else(|_err| {
                    trades.remove_trade(&id);
                    Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                             .filter(move |client| client.local_client.id() == target as u8)
                             .map(move |client| {
                                 (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                             })
                             .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
                }))
        },
        TradeRequestCommand::RemoveItem(item_id, amount) => {
            Ok(trades
                .with(&id, |this, other| -> Option<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>> {
                    if this.status == TradeStatus::Trading && other.status == TradeStatus::Trading {
                        let client = clients.get(&this.client())?; //.ok_or(ShipError::ClientNotFound(id)).ok()?;
                        let inventory = item_manager.get_character_inventory(&client.character).ok()?;
                        if ClientItemId(item_id) == MESETA_ITEM_ID {
                            this.meseta -= amount as usize;
                        }
                        else {
                            let item = inventory.get_item_by_id(ClientItemId(item_id))?;

                            match item {
                                InventoryItem::Individual(_) => {
                                    this.items.retain(|item| {
                                        item.item_id() != ClientItemId(item_id)
                                    })
                                },
                                InventoryItem::Stacked(_stacked_item) => {
                                    let trade_item_index = this.items.iter()
                                        .position(|item| {
                                            item.item_id() == ClientItemId(item_id)
                                        })?;

                                    match this.items[trade_item_index].stacked()?.1.cmp(&(amount as usize)) {
                                        std::cmp::Ordering::Greater => {
                                            *this.items[trade_item_index].stacked_mut()?.1 -= amount as usize;
                                        },
                                        std::cmp::Ordering::Equal => {
                                            this.items.remove(trade_item_index);
                                        },
                                        std::cmp::Ordering::Less => {
                                            return None
                                        }
                                    }
                                },
                            }
                        }
                        let trade_request = trade_request.clone();
                        Some(Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                                    .filter(move |client| client.local_client.id() == target as u8)
                                    .map(move |client| {
                                        (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                    })))
                    }
                    else {
                        None
                    }
                })?
                .unwrap_or_else(|| {
                    trades.remove_trade(&id);
                    Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                             .filter(move |client| client.local_client.id() == target as u8)
                             .map(move |client| {
                                 (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                             })
                             .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
                }))
        },
        TradeRequestCommand::Confirm => {
            Ok(trades
                .with(&id, |this, other| -> Option<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>> {
                    if status_is(&this.status, &[TradeStatus::Trading]) && status_is(&other.status, &[TradeStatus::Trading, TradeStatus::Confirmed]) {
                        this.status = TradeStatus::Confirmed;

                        let trade_request = trade_request.clone();
                        Some(Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                                    .filter(move |client| client.local_client.id() == target as u8)
                                    .map(move |client| {
                                        (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                    })))
                    }
                    else {
                        None
                    }
                })?
                .unwrap_or_else(|| {
                    trades.remove_trade(&id);
                    Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                             .filter(move |client| client.local_client.id() == target as u8)
                             .map(move |client| {
                                 (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                             })
                             .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
                }))
        },
        TradeRequestCommand::FinalConfirm => {
            Ok(trades
                .with(&id, |this, other| -> Option<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>> {
                    if this.status == TradeStatus::Confirmed && (other.status == TradeStatus::Confirmed || other.status == TradeStatus::FinalConfirm) {
                        this.status = TradeStatus::FinalConfirm;

                        let trade_request = trade_request.clone();
                        Some(Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                                    .filter(move |client| client.local_client.id() == target as u8)
                                    .map(move |client| {
                                        (client.client, SendShipPacket::DirectMessage(DirectMessage::new(target, GameMessage::TradeRequest(trade_request.clone()))))
                                    })))
                    }
                    else {
                        None
                    }
                })?
                .unwrap_or_else(|| {
                    trades.remove_trade(&id);
                    Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                             .filter(move |client| client.local_client.id() == target as u8)
                             .map(move |client| {
                                 (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                             })
                             .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
                }))
        },
        TradeRequestCommand::Cancel => {
            trades.remove_trade(&id);
            Ok(Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                        .filter(move |client| client.local_client.id() == target as u8)
                        .map(move |client| {
                            (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                        })
                        .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {}))))))
        }
    }
}


fn status_is<const N: usize>(status: &TradeStatus, statuses: &[TradeStatus; N]) -> bool {
    statuses.iter().any(|s| s == status)
}

fn status_is_not<const N: usize>(status: &TradeStatus, statuses: &[TradeStatus; N]) -> bool {
    !status_is(status, statuses)
}

pub async fn inner_items_to_trade(id: ClientId,
                                  items_to_trade: &ItemsToTrade,
                                  client_location: &ClientLocation,
                                  clients: &mut Clients,
                                  item_manager: &mut ItemManager,
                                  trades: &mut TradeState)
                                  -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error>
{
    Ok(trades
        .with(&id, |this, other| -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error> {
            if status_is_not(&this.status, &[TradeStatus::FinalConfirm]) || status_is_not(&other.status, &[TradeStatus::FinalConfirm, TradeStatus::ItemsChecked]) {
                return Err(TradeError::MismatchedStatus.into())
            }

            let client = clients.get(&this.client()).ok_or_else(|| ShipError::ClientNotFound(this.client()))?;
            let other_client = clients.get(&other.client()).ok_or_else(|| ShipError::ClientNotFound(other.client()))?;
            let inventory = item_manager.get_character_inventory(&client.character)?;

            if items_to_trade.count as usize != (this.items.len() + (if this.meseta != 0 { 1 } else { 0 }))  {
                return Err(TradeError::MismatchedTradeItems.into())
            }

            items_to_trade.items
                .iter()
                .take(items_to_trade.count as usize)
                .map(|item| {
                    if ClientItemId(item.item_id) == OTHER_MESETA_ITEM_ID {
                        if item.item_data[0] != 4 {
                            return Err(TradeError::InvalidItemId(ClientItemId(item.item_id)).into())
                        }
                        let amount = u32::from_le_bytes(item.item_data2);
                        let character_meseta = item_manager.get_character_meseta(&client.character.id).map_err(|_| TradeError::InvalidMeseta)?;
                        let other_character_meseta = item_manager.get_character_meseta(&other_client.character.id).map_err(|_| TradeError::InvalidMeseta)?;
                        if amount > character_meseta.0 {
                            return Err(TradeError::InvalidMeseta.into())
                        }
                        if (amount + other_character_meseta.0) > 999999 {
                            return Err(TradeError::InvalidMeseta.into())
                        }
                        if amount != this.meseta as u32{
                            return Err(TradeError::InvalidMeseta.into())
                        }
                        Ok(())
                    }
                    else {
                        let real_item = inventory.get_item_by_id(ClientItemId(item.item_id))
                            .ok_or(ItemManagerError::NoSuchItemId(ClientItemId(item.item_id)))?;
                        let real_trade_item = this.items
                            .iter()
                            .find(|i| i.item_id() == ClientItemId(item.item_id))
                            .ok_or(TradeError::SketchyTrade)?;
                        let trade_item_bytes: [u8; 16] = item.item_data.iter()
                            .chain(item.item_data2.iter())
                            .cloned().collect::<Vec<u8>>()
                            .try_into()
                            .unwrap();
                        match real_item {
                            InventoryItem::Individual(_individual_inventory_item) => {
                                if real_item.as_client_bytes() == trade_item_bytes {
                                    Ok(())
                                }
                                else {
                                    Err(TradeError::ClientItemIdDidNotMatchItem(ClientItemId(item.item_id), trade_item_bytes).into())
                                }
                            },
                            InventoryItem::Stacked(stacked_inventory_item) => {
                                if real_item.as_client_bytes()[0..4] == trade_item_bytes[0..4] {
                                    let amount = trade_item_bytes[5] as usize;
                                    if amount <= stacked_inventory_item.entity_ids.len() {
                                        if real_trade_item.stacked().ok_or(TradeError::SketchyTrade)?.1 == amount {
                                            Ok(())
                                        }
                                        else {
                                            Err(TradeError::InvalidStackAmount(stacked_inventory_item.item_id, amount).into())
                                        }
                                    }
                                    else {
                                        Err(TradeError::InvalidStackAmount(stacked_inventory_item.item_id, amount).into())
                                    }
                                }
                                else {
                                    Err(TradeError::ClientItemIdDidNotMatchItem(ClientItemId(item.item_id), trade_item_bytes).into())
                                }
                            }
                        }
                    }
                })
                .collect::<Result<Vec<_>, anyhow::Error>>()?;

            this.status = TradeStatus::ItemsChecked;
            if this.status == TradeStatus::ItemsChecked && other.status == TradeStatus::ItemsChecked {
                Ok(Box::new(vec![
                    (this.client(), SendShipPacket::AcknowledgeTrade(AcknowledgeTrade {})),
                    (other.client(), SendShipPacket::AcknowledgeTrade(AcknowledgeTrade {})),
                ].into_iter()))
            }
            else {
                Ok(Box::new(None.into_iter()))
            }
        })?
        .unwrap_or_else(|err| {
            log::warn!("trade error: {:?}", err);
            let (_this, other) = trades.remove_trade(&id);
            Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                     .filter(move |client| other.as_ref().map(|other| client.client == other.client() ).unwrap_or_else(|| false))
                     .map(move |client| {
                         (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                     })
                     .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {})))))
        }))
}

pub async fn items_to_trade(id: ClientId,
                            items_to_trade_pkt: &ItemsToTrade,
                            client_location: &ClientLocation,
                            clients: &mut Clients,
                            item_manager: &mut ItemManager,
                            trades: &mut TradeState)
                            -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error>
{
    let t = inner_items_to_trade(id, items_to_trade_pkt, client_location, clients, item_manager, trades).await;
    match t {
        Ok(p) => Ok(p),
        Err(err) => {
            log::warn!("atrade error: {:?}", err);
            let (_this, other) = trades.remove_trade(&id);
            Ok(Box::new(client_location.get_all_clients_by_client(id)?.into_iter()
                        .filter(move |client| other.as_ref().map(|other| client.client == other.client()).unwrap_or_else(|| false))
                        .map(move |client| {
                            (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                        })
                        .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {}))))))
        }
    }
}

pub async fn trade_confirmed<EG>(id: ClientId,
                                 entity_gateway: &mut EG,
                                 client_location: &ClientLocation,
                                 clients: &mut Clients,
                                 item_manager: &mut ItemManager,
                                 trades: &mut TradeState)
                                 -> Result<Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>, anyhow::Error>
where
    EG: EntityGateway
{
    enum TradeReady<'a> {
        OnePlayer,
        BothPlayers(crate::ship::location::RoomId,
                    (crate::ship::location::AreaClient, &'a crate::ship::ship::ClientState, crate::ship::trade::ClientTradeState),
                    (crate::ship::location::AreaClient, &'a crate::ship::ship::ClientState, crate::ship::trade::ClientTradeState)),
    }

    let trade_instructions = trades
       .with(&id, |this, other| -> Result<_, anyhow::Error> {
           if status_is_not(&this.status, &[TradeStatus::ItemsChecked]) || status_is_not(&other.status, &[TradeStatus::ItemsChecked, TradeStatus::TradeComplete]) {
               return Err(TradeError::MismatchedStatus.into())
           }
           this.status = TradeStatus::TradeComplete;

           if this.status == TradeStatus::TradeComplete && other.status == TradeStatus::TradeComplete {
               let this_client = clients.get(&this.client()).ok_or_else(|| ShipError::ClientNotFound(this.client()))?;
               let other_client = clients.get(&other.client()).ok_or_else(|| ShipError::ClientNotFound(other.client()))?;
               let this_local_client = client_location.get_local_client(this.client())?;
               let other_local_client = client_location.get_local_client(other.client())?;
               let room_id = client_location.get_room(id).map_err(|err| -> ClientLocationError { err.into() })?;

               Ok(TradeReady::BothPlayers(room_id,
                                       (this_local_client, this_client, this.clone()),
                                       (other_local_client, other_client, other.clone())))
           }
           else {
               Ok(TradeReady::OnePlayer)
           }
       });

    // TODO: this match needs to handle errors better
    match trade_instructions {
        Ok(Ok(trade)) => {
            match trade {
                TradeReady::OnePlayer => {
                    Ok(Box::new(None.into_iter()) as Box<dyn Iterator<Item = (ClientId, SendShipPacket)> + Send>)
                },
                TradeReady::BothPlayers(room_id, (this_local_client, this_client, this), (other_local_client, other_client, other)) => {
                    let traded_items = item_manager.trade_items(entity_gateway,
                                                                room_id,
                                                                (&this_local_client, &this_client.character, &this.items, this.meseta),
                                                                (&other_local_client, &other_client.character, &other.items, other.meseta)).await?;

                    let clients_in_room = client_location.get_all_clients_by_client(id)?;
                    let traded_item_packets = traded_items
                        .into_iter()
                        .map(|item| {
                            match item.item_detail {
                                ItemToTradeDetail::Individual(item_detail) => {
                                    [
                                        GameMessage::CreateItem(builder::message::create_individual_item(item.add_to, item.new_item_id, &item_detail).unwrap()),
                                        GameMessage::PlayerNoLongerHasItem(builder::message::player_no_longer_has_item(item.remove_from, item.current_item_id, 1)) // TODO: amount = ?
                                    ]
                                },
                                ItemToTradeDetail::Stacked(tool, amount) => {
                                    [
                                        GameMessage::CreateItem(builder::message::create_stacked_item(item.add_to, item.new_item_id, &tool, amount).unwrap()),
                                        GameMessage::PlayerNoLongerHasItem(builder::message::player_no_longer_has_item(item.remove_from, item.current_item_id, amount as u32))
                                    ]
                                },
                                ItemToTradeDetail::Meseta(amount) => {
                                    [
                                        GameMessage::CreateItem(builder::message::create_meseta(item.add_to, amount)),
                                        GameMessage::PlayerNoLongerHasItem(builder::message::player_no_longer_has_item(item.remove_from, item.current_item_id, amount as u32))
                                    ]
                                },
                            }
                        })
                        .flatten()
                        .map(move |packet| {
                            clients_in_room
                                .clone()
                                .into_iter()
                                .filter_map(move |client| {
                                    match packet {
                                        GameMessage::PlayerNoLongerHasItem(ref no_longer) => {
                                            if client.local_client == no_longer.client {
                                                None
                                            }
                                            else {
                                                Some((client.client, SendShipPacket::Message(Message::new(packet.clone()))))
                                            }
                                        }
                                        _ => Some((client.client, SendShipPacket::Message(Message::new(packet.clone()))))
                                    }
                                })
                        })
                        .flatten();
                    let close_trade = vec![
                        (this.client(), SendShipPacket::TradeSuccessful(TradeSuccessful::default())),
                        (other.client(), SendShipPacket::TradeSuccessful(TradeSuccessful::default()))
                    ].into_iter();
                    Ok(Box::new(traded_item_packets.chain(close_trade)))
                }
            }
        },
        _ => {
            let (_this, other) = trades.remove_trade(&id);
            Ok(Box::new(client_location.get_all_clients_by_client(id).unwrap().into_iter()
                    .filter(move |client| other.as_ref().map(|other| client.client == other.client()).unwrap_or_else(|| false))
                    .map(move |client| {
                        (client.client, SendShipPacket::CancelTrade(CancelTrade {}))
                    })
                    .chain(std::iter::once((id, SendShipPacket::CancelTrade(CancelTrade {}))))))
        }
    }
}