// TODO: replace various u32s and usizes denoting item amounts for ItemAmount(u32) for consistency
use crate::ship::items::ClientItemId;
use crate::entity::item::{Meseta, ItemNote};
use async_std::sync::Arc;
use std::future::Future;
use futures::future::BoxFuture;
use std::pin::Pin;
use std::iter::IntoIterator;
use anyhow::Context;

use libpso::packet::{ship::Message, messages::GameMessage};
use crate::entity::character::{CharacterEntity, CharacterEntityId};
use crate::entity::gateway::{EntityGateway, EntityGatewayTransaction};
use crate::entity::item::{ItemDetail, NewItemEntity, TradeId, ItemModifier};
use crate::entity::item::tool::Tool;
use crate::entity::room::RoomEntityId;
use crate::ship::map::MapArea;
use crate::ship::ship::SendShipPacket;
use crate::ship::items::state::{ItemStateProxy, ItemStateError, AddItemResult, StackedItemDetail, IndividualItemDetail};
use crate::ship::items::bank::{BankItem, BankItemDetail};
use crate::ship::items::inventory::{InventoryItem, InventoryItemDetail};
use crate::ship::items::floor::{FloorItem, FloorItemDetail};
use crate::ship::items::apply_item::{apply_item, ApplyItemAction};
use crate::ship::shops::ShopItem;
use crate::ship::drops::{ItemDrop, ItemDropType};
use crate::ship::packet::builder;
use crate::ship::location::AreaClient;
use crate::ship::monster::MonsterType;

pub enum TriggerCreateItem {
    Yes,
    No
}

pub(super) fn take_item_from_floor<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>> + 'a
where
    EG: EntityGateway + Send,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction): (ItemStateProxy, TR) , _| {
        Box::pin(async move {
            let mut floor = item_state.floor(&character_id).await?;
            let item = floor.take_item(&item_id).ok_or_else(|| ItemStateError::NoFloorItem(item_id))?;
            item_state.set_floor(floor).await;

            Ok(((item_state, transaction), item))
        })
    }
}

pub(super) fn add_floor_item_to_inventory<'a, EG, TR>(
    character: &CharacterEntity
) -> impl Fn((ItemStateProxy, TR), FloorItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), TriggerCreateItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + Clone + 'a,
{
    let character = character.clone();
    move |(mut item_state, transaction), floor_item| {
        let character = character.clone();
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character.id).await?;

            let character_id = character.id;
            let transaction = floor_item.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::Pickup {
                        character_id
                    }).await?;
                    Ok(transaction)
                }}).await?;

            let mut transaction = floor_item.with_mag(transaction, |mut transaction, entity_id, _mag| {
                let character = character.clone();
                async move {
                    transaction.gateway().change_mag_owner(&entity_id, &character).await?;
                    Ok(transaction)
                }}).await?;

            let add_result = inventory.add_floor_item(floor_item)?;
            transaction.gateway().set_character_inventory(&character.id, &inventory.as_inventory_entity(&character.id)).await?;
            transaction.gateway().set_character_meseta(&character_id, inventory.meseta).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction),
                match add_result {
                    AddItemResult::NewItem => TriggerCreateItem::Yes,
                    AddItemResult::AddToStack => TriggerCreateItem::No,
                    AddItemResult::Meseta => TriggerCreateItem::No,
                }))
        })
    }
}


pub(super) fn remove_item_from_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItemDetail), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            let item = inventory.remove_item(&item_id, amount)
                .await
                .ok_or_else(|| ItemStateError::NoInventoryItem(item_id))
                .with_context(|| format!("{inventory:#?}"))?;

            transaction.gateway().set_character_inventory(&character_id, &inventory.as_inventory_entity(&character_id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), item))
        })
    }
}

pub(super) fn take_item_from_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>>
where
    EG: EntityGateway + 'a,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            let item = inventory.take_item(&item_id, amount)
                .await
                .ok_or_else(|| ItemStateError::NoInventoryItem(item_id))
                .with_context(|| format!("{inventory:#?}"))?;

            transaction.gateway().set_character_inventory(&character_id, &inventory.as_inventory_entity(&character_id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), item))
        })
    }
}


pub(super) fn add_inventory_item_to_shared_floor<'a, EG, TR>(
    character_id: CharacterEntityId,
    map_area: MapArea,
    drop_position: (f32, f32, f32),
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), inventory_item| {
        Box::pin(async move {
            let transaction = inventory_item.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::PlayerDrop {
                        character_id,
                        map_area,
                        x: drop_position.0,
                        y: drop_position.1,
                        z: drop_position.2,
                    }).await?;
                    Ok(transaction)
                }}).await?;

            let mut floor = item_state.floor(&character_id).await?;
            let floor_item = floor.add_inventory_item(inventory_item, map_area, drop_position).clone();
            item_state.set_floor(floor).await;

            Ok(((item_state, transaction), floor_item))
        })
    }
}


pub(super) fn take_meseta_from_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.remove_meseta(amount)?;
            transaction.gateway().set_character_meseta(&character_id, inventory.meseta).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}

pub(super) fn add_meseta_to_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.add_meseta(amount)?;
            transaction.gateway().set_character_meseta(&character_id, inventory.meseta).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}

pub(super) fn add_meseta_to_shared_floor<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32,
    map_area: MapArea,
    drop_position: (f32, f32)
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), _| {
        Box::pin(async move {
            let floor_item = FloorItem {
                item_id: item_state.new_item_id().await?,
                item: FloorItemDetail::Meseta(Meseta(amount)),
                map_area,
                x: drop_position.0,
                y: 0.0,
                z: drop_position.1,
            };

            let mut floor = item_state.floor(&character_id).await?;
            let floor_item = floor.add_shared_item(floor_item).clone();
            item_state.set_floor(floor).await;

            Ok(((item_state, transaction), floor_item))
        })
    }
}

pub(super) fn take_meseta_from_bank<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut bank = item_state.bank(&character_id).await?;
            bank.remove_meseta(amount)?;
            transaction.gateway().set_bank_meseta(&character_id, &bank.identifier, bank.meseta).await?;
            item_state.set_bank(bank).await;

            Ok(((item_state, transaction), ()))
        })
    }
}

pub(super) fn add_meseta_from_bank_to_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.add_meseta_no_overflow(amount)?;
            transaction.gateway().set_character_meseta(&character_id, inventory.meseta).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}


pub(super) fn add_meseta_to_bank<'a, EG, TR>(
    character_id: CharacterEntityId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut bank = item_state.bank(&character_id).await?;
            bank.add_meseta(amount)?;
            transaction.gateway().set_bank_meseta(&character_id, &bank.identifier, bank.meseta).await?;
            item_state.set_bank(bank).await;

            Ok(((item_state, transaction), ()))
        })
    }
}


pub(super) fn take_item_from_bank<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), BankItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut bank = item_state.bank(&character_id).await?;
            let item = bank.take_item(&item_id, amount)
                .await
                .ok_or_else(|| ItemStateError::NoBankItem(item_id))?;
            transaction.gateway().set_character_bank(&character_id, &bank.as_bank_entity(), &bank.identifier).await?;
            item_state.set_bank(bank).await;

            Ok(((item_state, transaction), item))
        })
    }
}

pub(super) fn add_bank_item_to_inventory<'a, EG, TR>(
    character: &CharacterEntity,
) -> impl Fn((ItemStateProxy, TR), BankItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    let character = character.clone();
    move |(mut item_state, transaction), bank_item| {
        let character = character.clone();
        Box::pin(async move {
            let bank_identifier = item_state.bank(&character.id).await?.identifier;
            let mut inventory = item_state.inventory(&character.id).await?;

            let character_id = character.id;
            let transaction = bank_item.with_entity_id(transaction, |mut transaction, entity_id| {
                let bank_identifier = bank_identifier.clone();
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::Withdraw {
                        character_id,
                        bank: bank_identifier,
                    }).await?;
                    Ok(transaction)
                }}).await?;

            let inventory_item = InventoryItem {
                item_id: bank_item.item_id,
                item: match bank_item.item {
                    BankItemDetail::Individual(individual_item) => InventoryItemDetail::Individual(individual_item),
                    BankItemDetail::Stacked(stacked_item) => InventoryItemDetail::Stacked(stacked_item),
                },
            };

            let mut transaction = inventory_item.with_mag(transaction, |mut transaction, entity_id, _mag| {
                let character = character.clone();
                async move {
                    transaction.gateway().change_mag_owner(&entity_id, &character).await?;
                    Ok(transaction)
                }}).await?;

            inventory.add_item(inventory_item.clone())?;
            transaction.gateway().set_character_inventory(&character.id, &inventory.as_inventory_entity(&character.id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), inventory_item))
        })
    }
}


pub(super) fn add_inventory_item_to_bank<'a, EG, TR>(
    character_id: CharacterEntityId,
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), inventory_item| {
        Box::pin(async move {
            let mut bank = item_state.bank(&character_id).await?;
            let bank_identifier = bank.identifier.clone();
            let mut transaction = inventory_item.with_entity_id(transaction, move |mut transaction, entity_id| {
                let bank_identifier = bank_identifier.clone();
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::Deposit {
                        character_id,
                        bank: bank_identifier,
                    }).await?;
                    Ok(transaction)
                }}).await?;

            bank.add_inventory_item(inventory_item)?;

            transaction.gateway().set_character_bank(&character_id, &bank.as_bank_entity(), &bank.identifier).await?;
            item_state.set_bank(bank).await;

            Ok(((item_state, transaction), ()))
        })
    }
}


pub(super) fn equip_inventory_item<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId,
    equip_slot: u8,
) -> impl Fn((ItemStateProxy, TR), ())
                     -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.equip(&item_id, equip_slot);
            transaction.gateway().set_character_equips(&character_id, &inventory.as_equipped_entity()).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}


pub(super) fn unequip_inventory_item<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_id: ClientItemId,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.unequip(&item_id);
            transaction.gateway().set_character_equips(&character_id, &inventory.as_equipped_entity()).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}



pub(super) fn sort_inventory_items<'a, EG, TR>(
    character_id: CharacterEntityId,
    item_ids: Vec<ClientItemId>,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        let item_ids = item_ids.clone();
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            inventory.sort(&item_ids);
            transaction.gateway().set_character_inventory(&character_id, &inventory.as_inventory_entity(&character_id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), ()))
        })
    }
}


pub(super) fn use_consumed_item<'a, EG, TR>(
    character: &CharacterEntity,
) -> impl Fn((ItemStateProxy, TR), InventoryItemDetail)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), Vec<ApplyItemAction>), anyhow::Error>>
where
    EG: EntityGateway + Clone + 'a,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    let character = character.clone();
    move |(mut item_state, transaction), inventory_item| {
        let mut character = character.clone();
        Box::pin(async move {
            let mut transaction = inventory_item.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::Consumed {
                        character_id: character.id,
                    }).await?;
                    Ok(transaction)
                }}).await?;

            let apply_item_actions = apply_item(&mut item_state, transaction.gateway(), &mut character, inventory_item).await?;

            Ok(((item_state, transaction), apply_item_actions))
        })
    }
}


pub(super) fn feed_mag_item<'a, EG, TR>(
    character: CharacterEntity,
    mag_item_id: ClientItemId,
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), CharacterEntity), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), tool| {
        let character = character.clone();
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character.id).await?;
            let mag_entity = inventory.get_by_client_id_mut(&mag_item_id)
                .ok_or_else(|| ItemStateError::InvalidItemId(mag_item_id))?
                .item
                .as_individual_mut()
                .ok_or_else(|| ItemStateError::NotAMag(mag_item_id))?;
            let mag_entity_id = mag_entity.entity_id;

            let mut transaction = tool.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::FedToMag {
                        character_id: character.id,
                        mag: mag_entity_id,
                    }).await?;
                    transaction.gateway().feed_mag(&mag_entity_id, &entity_id).await?;
                    Ok(transaction)
                }}).await?;

            let food_tool = tool
                .item
                .stacked()
                .ok_or_else(|| ItemStateError::NotMagFood(tool.item_id))?
                .tool
                .tool;

            let mag_entity = mag_entity
                .as_mag_mut()
                .ok_or_else(|| ItemStateError::NotAMag(mag_item_id))?;

            mag_entity.feed(food_tool);

            transaction.gateway().set_character_inventory(&character.id, &inventory.as_inventory_entity(&character.id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), character))
        })
    }
}

#[allow(clippy::needless_lifetimes)] // clippy this lifetime is not needless get off my case
pub(super) fn add_bought_item_to_inventory<'a, EG, TR>(
    character_id: CharacterEntityId,
    shop_item: &'a (dyn ShopItem + Send + Sync),
    item_id: ClientItemId,
    amount: u32,
) -> impl Fn((ItemStateProxy, TR), ())
             -> Pin<Box<dyn Future<Output=Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>> + Send + 'a>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            let bought_item = shop_item.as_item();

            let inventory_item = match bought_item {
                ItemDetail::Tool(tool) if tool.is_stackable() => {
                    let mut item_entities = Vec::new();
                    for _ in 0..amount {
                        let item_entity = transaction.gateway().create_item(NewItemEntity {
                            item: ItemDetail::Tool(tool),
                        }).await?;
                        transaction.gateway().add_item_note(&item_entity.id, ItemNote::BoughtAtShop {
                            character_id,
                        }).await?;
                        item_entities.push(item_entity);
                    }

                    let inventory_item = InventoryItem {
                        item_id,
                        item: InventoryItemDetail::Stacked(StackedItemDetail {
                            entity_ids: item_entities.into_iter().map(|i| i.id).collect(),
                            tool,
                        })
                    };
                    inventory.add_item(inventory_item.clone())
                        .with_context(|| format!("inventory {inventory:?}\nitem {inventory_item:?}"))?.1
                },
                item_detail => {
                    let item_entity = transaction.gateway().create_item(NewItemEntity {
                        item: item_detail.clone(),
                    }).await?;
                    transaction.gateway().add_item_note(&item_entity.id, ItemNote::BoughtAtShop {
                        character_id,
                    }).await?;

                    let inventory_item = InventoryItem {
                        item_id,
                        item: InventoryItemDetail::Individual(IndividualItemDetail {
                            entity_id: item_entity.id,
                            item: item_detail,
                        })
                    };
                    inventory.add_item(inventory_item.clone())
                        .with_context(|| format!("inventory {inventory:?}\nitem {inventory_item:?}"))?.1
                },
            };

            transaction.gateway().set_character_inventory(&character_id, &inventory.as_inventory_entity(&character_id)).await?;
            item_state.set_inventory(inventory).await;
            Ok(((item_state, transaction), inventory_item))
        })
    }
}


pub(super) fn sell_inventory_item<'a, EG, TR>(
    character_id: CharacterEntityId,
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), inventory_item| {
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character_id).await?;
            let price = inventory_item.item.sell_price()?;
            inventory.add_meseta_no_overflow(price)?;

            let mut transaction = inventory_item.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::SoldToShop {
                        character_id,
                    }).await?;
                    Ok(transaction)
                }}).await?;
            transaction.gateway().set_character_meseta(&character_id, inventory.meseta).await?;
            item_state.set_inventory(inventory).await;
            Ok(((item_state, transaction), inventory_item))
        })
    }
}


#[async_recursion::async_recursion]
async fn iterate_inner<'a, EG, TR, I, O, T, F, FR>(
    state: (ItemStateProxy, TR),
    mut input: Vec<I>,
    func: F,
    arg: T,
) -> Result<((ItemStateProxy, TR), Vec<O>), anyhow::Error>
where
    'a: 'async_recursion,
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG>,
    I: Send,
    O: Send,
    T: Clone + Send + Sync,
    F: Fn(I) -> FR + Send + Sync + Clone + 'a,
    FR: Fn((ItemStateProxy, TR), T)
           -> BoxFuture<'a, Result<((ItemStateProxy, TR), O), anyhow::Error>> + Send + Sync,
{
    let item = match input.pop() {
        Some(item) => item,
        None => return Ok((state, Vec::new()))
    };

    let (state, mut output) = iterate_inner(state, input, func.clone(), arg.clone()).await.unwrap();
    let rfunc = func(item);
    let (state, result) = rfunc(state, arg.clone()).await.unwrap();

    output.push(result);

    Ok((state, output))
}

pub(super) fn iterate<'a, EG, TR, I, O, T, F, FR>(
    input: Vec<I>,
    func: F,
) -> impl Fn((ItemStateProxy, TR), T)
                     -> BoxFuture<'a, Result<((ItemStateProxy, TR), Vec<O>), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
    O: Send,
    I: Send + Clone + 'static + std::fmt::Debug,
    T: Send + Clone +  'static + std::fmt::Debug,
    F: Fn(I) -> FR + Send + Sync + Clone + 'a,
    FR: Fn((ItemStateProxy, TR), T)
           -> BoxFuture<'a, Result<((ItemStateProxy, TR), O), anyhow::Error>> + Send + Sync,
    T: Clone + Send + Sync,
{
    move |(item_state, transaction), arg| {
        let input = input.clone();
        let func = func.clone();
        Box::pin(async move {
            let (state, result) = iterate_inner((item_state, transaction), input, func, arg.clone()).await?;
            Ok((state, result))
        })
    }
}


#[async_recursion::async_recursion]
async fn foreach_inner<'a, EG, TR, O, T, F, I>(
    state: (ItemStateProxy, TR),
    mut input: I,
    func: Arc<F>,
) -> Result<((ItemStateProxy, TR), Vec<O>), anyhow::Error>
where
    'a: 'async_recursion,
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
    O: Send,
    T: Send,
    F: Fn((ItemStateProxy, TR), T)
                   -> BoxFuture<'a, Result<((ItemStateProxy, TR), O), anyhow::Error>> + Send + Sync,
    I: Iterator<Item = T> + Send + Sync + 'a,
{
    let item = match input.next() {
        Some(item) => item,
        None => return Ok((state, Vec::new()))
    };

    let (state, mut output) = foreach_inner(state, input, func.clone()).await?;
    let (state, result) = func(state, item).await?;

    output.push(result);

    Ok((state, output))
}

pub(super) fn foreach<'a, EG, TR, O, T, F, I>(
    func: F
) -> impl Fn((ItemStateProxy, TR), I)
                     -> BoxFuture<'a, Result<((ItemStateProxy, TR), Vec<O>), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
    O: Send,
    T: Send + Clone +  'static + std::fmt::Debug,
    F: Fn((ItemStateProxy, TR), T)
          -> BoxFuture<'a, Result<((ItemStateProxy, TR), O), anyhow::Error>> + Send + Sync + 'a,
    T: Send + Sync,
    I: IntoIterator<Item = T> + Send + Sync + 'a,
    I::IntoIter: Send + Sync,
{
    let func = Arc::new(func);
    move |(item_state, transaction), items| {
        let func = func.clone();
        let items = items.into_iter();
        Box::pin(async move {
            let (state, result) = foreach_inner((item_state, transaction), items, func).await?;
            Ok((state, result))
        })
    }
}

pub(super) fn insert<'a, EG, TR, T>(
    element: T
) -> impl Fn((ItemStateProxy, TR), ())
             -> Pin<Box<dyn Future<Output=Result<((ItemStateProxy, TR), T), anyhow::Error>> + Send + 'a>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
    T: Send + Clone + 'a,
{
    move |state, _| {
        let element = element.clone();
        Box::pin(async move {
            Ok((state, element))
        })
    }
}

pub(super) fn fork<'a, EG, TR, F1, F2, T, O1, O2>(
    func1: F1,
    func2: F2,
) -> impl Fn((ItemStateProxy, TR), T)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), (O1, O2)), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
    F1: Fn((ItemStateProxy, TR), T) -> BoxFuture<'a, Result<((ItemStateProxy, TR), O1), anyhow::Error>> + Send + Sync + 'a,
    F2: Fn((ItemStateProxy, TR), T) -> BoxFuture<'a, Result<((ItemStateProxy, TR), O2), anyhow::Error>> + Send + Sync + 'a,
    T: Send + Sync + Clone + 'a,
    O1: Send,
    O2: Send,
{
    let func1 = Arc::new(func1);
    let func2 = Arc::new(func2);
    move |(item_state, transaction), input| {
        let func1 = func1.clone();
        let func2 = func2.clone();
        Box::pin(async move {
            let ((item_state, transaction), result1) = func1((item_state, transaction), input.clone()).await?;
            let ((item_state, transaction), result2) = func2((item_state, transaction), input).await?;

            Ok(((item_state, transaction), (result1, result2)))
        })
    }
}

pub(super) fn add_item_to_inventory<'a, EG, TR>(
    character: CharacterEntity,
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), inventory_item| {
        let character = character.clone();
        Box::pin(async move {
            let mut inventory = item_state.inventory(&character.id).await?;
            let mut transaction = inventory_item.with_mag(transaction, |mut transaction, entity_id, _mag| {
                let character = character.clone();
                async move {
                    transaction.gateway().change_mag_owner(&entity_id, &character).await?;
                    Ok(transaction)
                }}).await?;

            inventory.add_item(inventory_item.clone())?;
            transaction.gateway().set_character_inventory(&character.id, &inventory.as_inventory_entity(&character.id)).await?;
            item_state.set_inventory(inventory).await;

            Ok(((item_state, transaction), inventory_item))
        })
    }
}

pub(super) fn record_trade<'a, EG, TR>(
    trade_id: TradeId,
    character_to: CharacterEntityId,
    character_from: CharacterEntityId,
) -> impl Fn((ItemStateProxy, TR), Vec<InventoryItem>)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), Vec<InventoryItem>), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(item_state, mut transaction), traded_items| {
        Box::pin(async move {
            for item in &traded_items {
                transaction = item.with_entity_id(transaction, |mut transaction, entity_id| {
                    async move {
                        transaction.gateway().add_item_note(&entity_id, ItemNote::Trade {
                            trade_id,
                            character_to,
                            character_from,
                        }).await?;
                        Ok(transaction)
                    }}).await?;
            }
            Ok(((item_state, transaction), traded_items))
        })
    }
}


pub(super) fn assign_new_item_id<'a, EG, TR>(
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction), mut inventory_item| {
        Box::pin(async move {
            inventory_item.item_id = item_state.new_item_id().await?;
            Ok(((item_state, transaction), inventory_item))
        })
    }
}


pub(super) fn convert_item_drop_to_floor_item<'a, EG, TR>(
    item_drop: ItemDrop,
) -> impl Fn((ItemStateProxy, TR), ())
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), _| {
        let item_drop = item_drop.clone();
        Box::pin(async move {
            enum ItemOrMeseta {
                Individual(ItemDetail),
                Stacked(Tool),
                Meseta(Meseta)
            }

            let item = match item_drop.item {
                ItemDropType::Weapon(w) => ItemOrMeseta::Individual(ItemDetail::Weapon(w)),
                ItemDropType::Armor(w) => ItemOrMeseta::Individual(ItemDetail::Armor(w)),
                ItemDropType::Shield(w) => ItemOrMeseta::Individual(ItemDetail::Shield(w)),
                ItemDropType::Unit(w) => ItemOrMeseta::Individual(ItemDetail::Unit(w)),
                ItemDropType::TechniqueDisk(w) => ItemOrMeseta::Individual(ItemDetail::TechniqueDisk(w)),
                ItemDropType::Mag(w) => ItemOrMeseta::Individual(ItemDetail::Mag(w)),
                ItemDropType::Tool(t) => {
                    if t.tool.is_stackable() {
                        ItemOrMeseta::Stacked(t)
                    }
                    else {
                        ItemOrMeseta::Individual(ItemDetail::Tool(t))
                    }
                },
                ItemDropType::Meseta(m) => ItemOrMeseta::Meseta(Meseta(m)),
            };

            let item_id = item_state.new_item_id().await?;

            let floor_item = match item {
                ItemOrMeseta::Individual(item_detail) => {
                    let entity = transaction.gateway().create_item(NewItemEntity {
                        item: item_detail.clone(),
                    }).await?;
                    FloorItem {
                        item_id,
                        item: FloorItemDetail::Individual(IndividualItemDetail {
                            entity_id: entity.id,
                            item: item_detail,
                        }),
                        map_area: item_drop.map_area,
                        x: item_drop.x,
                        y: item_drop.y,
                        z: item_drop.z,
                    }
                },
                ItemOrMeseta::Stacked(tool) => {
                    let entity = transaction.gateway().create_item(NewItemEntity {
                        item: ItemDetail::Tool(tool),
                    }).await?;
                    FloorItem {
                        item_id,
                        item: FloorItemDetail::Stacked(StackedItemDetail{
                            entity_ids: vec![entity.id],
                            tool,
                        }),
                        map_area: item_drop.map_area,
                        x: item_drop.x,
                        y: item_drop.y,
                        z: item_drop.z,
                    }
                },
                ItemOrMeseta::Meseta(meseta) => {
                    FloorItem {
                        item_id,
                        item: FloorItemDetail::Meseta(meseta),
                        map_area: item_drop.map_area,
                        x: item_drop.x,
                        y: item_drop.y,
                        z: item_drop.z,
                    }
                },
            };

            Ok(((item_state, transaction), floor_item))
        })
    }
}


pub(super) fn item_note_enemy_drop<'a, EG, TR>(
    character_id: CharacterEntityId,
    room_id: RoomEntityId,
    monster_type: MonsterType,
) -> impl Fn((ItemStateProxy, TR), FloorItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(item_state, mut transaction), floor_item| {
        Box::pin(async move {
            match &floor_item.item {
                FloorItemDetail::Individual(individual) => {
                    transaction.gateway().add_item_note(&individual.entity_id, ItemNote::EnemyDrop {
                        character_id,
                        room_id,
                        monster_type,
                        map_area: floor_item.map_area,
                        x: floor_item.x,
                        y: floor_item.y,
                        z: floor_item.z,
                    }).await?;
                },
                FloorItemDetail::Stacked(stacked) => {
                    transaction.gateway().add_item_note(&stacked.entity_ids[0], ItemNote::EnemyDrop {
                        character_id,
                        room_id,
                        monster_type,
                        map_area: floor_item.map_area,
                        x: floor_item.x,
                        y: floor_item.y,
                        z: floor_item.z,
                    }).await?;
                },
                _ => {},
            }
            Ok(((item_state, transaction), floor_item))
        })
    }
}

pub(super) fn item_note_box_drop<'a, EG, TR>(
    character_id: CharacterEntityId,
    room_id: RoomEntityId,
) -> impl Fn((ItemStateProxy, TR), FloorItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>> + Clone
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(item_state, mut transaction), floor_item| {
        Box::pin(async move {
            match &floor_item.item {
                FloorItemDetail::Individual(individual) => {
                    transaction.gateway().add_item_note(&individual.entity_id, ItemNote::BoxDrop {
                        character_id,
                        room_id,
                        map_area: floor_item.map_area,
                        x: floor_item.x,
                        y: floor_item.y,
                        z: floor_item.z,
                    }).await?;
                },
                FloorItemDetail::Stacked(stacked) => {
                    transaction.gateway().add_item_note(&stacked.entity_ids[0], ItemNote::BoxDrop {
                        character_id,
                        room_id,
                        map_area: floor_item.map_area,
                        x: floor_item.x,
                        y: floor_item.y,
                        z: floor_item.z,
                    }).await?;
                },
                _ => {},
            }
            Ok(((item_state, transaction), floor_item))
        })
    }
}

pub(super) fn add_item_to_local_floor<'a, EG, TR>(
    character_id: CharacterEntityId,
) -> impl Fn((ItemStateProxy, TR), FloorItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), FloorItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, transaction) , floor_item| {
        Box::pin(async move {
            let mut floor = item_state.floor(&character_id).await?;
            let item = floor.add_local_item(floor_item).clone();
            item_state.set_floor(floor).await;

            Ok(((item_state, transaction), item))
        })
    }
}

pub(super) fn apply_modifier_to_inventory_item<'a, EG, TR>(
    modifier: ItemModifier,
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), InventoryItem), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(item_state, mut transaction), mut inventory_item| {
        let modifier = modifier.clone();
        Box::pin(async move {
            match (&mut inventory_item.item, modifier) {
                (InventoryItemDetail::Individual(IndividualItemDetail{entity_id, item: ItemDetail::Weapon(ref mut weapon), ..}), ItemModifier::WeaponModifier(modifier)) => {
                    weapon.apply_modifier(&modifier);
                    transaction.gateway().add_weapon_modifier(entity_id, &modifier).await?;
                },
                _ => return Err(ItemStateError::InvalidModifier.into())
            }

            Ok(((item_state, transaction), inventory_item))
        })
    }
}

pub(super) fn as_individual_item<'a, EG, TR>(
) -> impl Fn((ItemStateProxy, TR), InventoryItem)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), IndividualItemDetail), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(item_state, transaction), inventory_item| {
        Box::pin(async move {
            let item = match inventory_item.item {
                InventoryItemDetail::Individual(individual_item) => individual_item,
                _ => return Err(ItemStateError::WrongItemType(inventory_item.item_id).into())
            };

            Ok(((item_state, transaction), item))
        })
    }
}


pub(super) fn apply_item_action_packets<'a, EG, TR>(
    character_id: CharacterEntityId,
    area_client: AreaClient,
) -> impl Fn((ItemStateProxy, TR), ApplyItemAction)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), Vec<SendShipPacket>), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    move |(mut item_state, mut transaction), apply_item_action| {
        Box::pin(async move {
            let pkts = if let ApplyItemAction::CreateItem(item_detail) = apply_item_action {
                let new_item = transaction.gateway().create_item(NewItemEntity {
                    item: item_detail.clone(),
                }).await?;

                let item_id = item_state.new_item_id().await?;

                let (inventory_item_detail, create_item) = if item_detail.is_stackable() {
                    let tool = item_detail.as_tool().ok_or_else(|| ItemStateError::NotATool(ClientItemId(0xFFFFFFFF)))?;

                    let create_item = builder::message::create_stacked_item(area_client, item_id, &tool, 1).map_err(|_err| ItemStateError::Dummy)?;
                    let item_detail = StackedItemDetail {
                        entity_ids: vec![new_item.id],
                        tool
                    };
                    (InventoryItemDetail::Stacked(item_detail), create_item)
                }
                else {
                    let item_detail = IndividualItemDetail {
                        entity_id: new_item.id,
                        item: item_detail,
                    };
                    let create_item = builder::message::create_individual_item(area_client, item_id, &item_detail).map_err(|_err| ItemStateError::Dummy)?;
                    (InventoryItemDetail::Individual(item_detail), create_item)
                };

                let inventory_item = InventoryItem {
                    item_id,
                    item: inventory_item_detail,
                };

                let mut inventory = item_state.inventory(&character_id).await?;
                inventory.add_item(inventory_item)?;
                transaction.gateway().set_character_inventory(&character_id, &inventory.as_inventory_entity(&character_id)).await?;
                item_state.set_inventory(inventory).await;

                vec![SendShipPacket::Message(Message::new(GameMessage::CreateItem(create_item)))]
            }
            else {
                Vec::new()
            };

            Ok(((item_state, transaction), pkts))
        })
    }
}

pub(super) fn apply_item_action_character<'a, EG, TR>(
    character: &CharacterEntity
) -> impl Fn((ItemStateProxy, TR), Vec<ApplyItemAction>)
             -> BoxFuture<'a, Result<((ItemStateProxy, TR), CharacterEntity), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + 'a,
{
    let character = character.clone();
    move |(item_state, transaction), apply_item_actions| {
        let mut character = character.clone();
        Box::pin(async move {
            for action in apply_item_actions {
                if let ApplyItemAction::UpdateCharacter(new_character) = action {
                    character = *new_character
                }
            }

            Ok(((item_state, transaction), character))
        })
    }
}

pub(super) fn delete_item_from_floor<'a, EG, TR>(
    map_area: MapArea
) -> impl Fn((ItemStateProxy, TR), FloorItem)
            -> BoxFuture<'a, Result<((ItemStateProxy, TR), ()), anyhow::Error>>
where
    EG: EntityGateway,
    TR: EntityGatewayTransaction<ParentGateway = EG> + Clone + 'a,
{
    move |(item_state, transaction), floor_item| {
        Box::pin(async move {
            let transaction = floor_item.with_entity_id(transaction, |mut transaction, entity_id| {
                async move {
                    transaction.gateway().add_item_note(&entity_id, ItemNote::FloorLimitReached {
                        map_area
                    }).await?;
                    Ok(transaction)
                }}).await?;
            Ok(((item_state, transaction), ()))
        })
    }
}