#[cfg(feature = "client")]
use crate::{
    backpack::backpack_ui::BackpackUiState, control::BackpackButtonPress, player::LocalPlayer,
    protocol::PlaySound,
};
use crate::{
    cash::CashCollectEvent, global_observer, head_drop::HeadCollected, heads::HeadState,
    heads_database::HeadsDatabase,
};
use bevy::prelude::*;
#[cfg(feature = "client")]
use bevy_replicon::prelude::ClientTriggerExt;
use serde::{Deserialize, Serialize};
pub use ui_head_state::UiHeadState;

pub mod backpack_ui;
pub mod ui_head_state;

#[derive(Component, Default, Reflect, Serialize, Deserialize, PartialEq)]
#[reflect(Component)]
pub struct Backpack {
    pub heads: Vec<HeadState>,
}

impl Backpack {
    pub fn reloading(&self) -> bool {
        for head in &self.heads {
            if !head.has_ammo() {
                return true;
            }
        }

        false
    }

    pub fn contains(&self, head_id: usize) -> bool {
        self.heads.iter().any(|head| head.head == head_id)
    }

    pub fn insert(&mut self, head_id: usize, heads_db: &HeadsDatabase) {
        self.heads.push(HeadState::new(head_id, heads_db));
    }
}

#[derive(Event, Serialize, Deserialize)]
pub struct BackpackSwapEvent(pub usize);

pub fn plugin(app: &mut App) {
    app.register_type::<Backpack>();

    app.add_plugins(backpack_ui::plugin);

    #[cfg(feature = "client")]
    app.add_systems(FixedUpdate, (backpack_inputs, sync_on_change));

    global_observer!(app, on_head_collect);
}

#[cfg(feature = "client")]
#[allow(clippy::too_many_arguments)]
fn backpack_inputs(
    backpacks: Single<(&Backpack, &mut BackpackUiState), With<LocalPlayer>>,
    mut backpack_inputs: MessageReader<BackpackButtonPress>,
    mut commands: Commands,
    time: Res<Time>,
) {
    let (backpack, mut state) = backpacks.into_inner();

    for input in backpack_inputs.read() {
        match input {
            BackpackButtonPress::Toggle => {
                if state.count == 0 {
                    return;
                }

                state.open = !state.open;
                commands.trigger(PlaySound::Backpack { open: state.open });
            }
            BackpackButtonPress::Swap => {
                if !state.open {
                    return;
                }

                commands.client_trigger(BackpackSwapEvent(state.current_slot));
            }
            BackpackButtonPress::Left => {
                if !state.open {
                    return;
                }

                if state.current_slot > 0 {
                    state.current_slot -= 1;

                    commands.trigger(PlaySound::Selection);
                    sync_backpack_ui(backpack, &mut state, time.elapsed_secs());
                }
            }
            BackpackButtonPress::Right => {
                if !state.open {
                    return;
                }

                if state.current_slot < state.count.saturating_sub(1) {
                    state.current_slot += 1;

                    commands.trigger(PlaySound::Selection);
                    sync_backpack_ui(backpack, &mut state, time.elapsed_secs());
                }
            }
        }
    }
}

#[cfg(feature = "client")]
fn sync_on_change(
    backpack: Query<Ref<Backpack>>,
    mut state: Single<&mut BackpackUiState>,
    time: Res<Time>,
) {
    for backpack in backpack.iter() {
        if backpack.is_changed() || backpack.reloading() {
            sync_backpack_ui(&backpack, &mut state, time.elapsed_secs());
        }
    }
}

#[cfg(feature = "client")]
fn sync_backpack_ui(backpack: &Backpack, state: &mut BackpackUiState, time: f32) {
    use crate::backpack::backpack_ui::BACKPACK_HEAD_SLOTS;

    state.count = backpack.heads.len();

    state.scroll = state
        .scroll
        .min(state.count.saturating_sub(BACKPACK_HEAD_SLOTS));

    if state.current_slot >= state.scroll + BACKPACK_HEAD_SLOTS {
        state.scroll = state.current_slot.saturating_sub(BACKPACK_HEAD_SLOTS - 1);
    }
    if state.current_slot < state.scroll {
        state.scroll = state.current_slot;
    }

    for i in 0..BACKPACK_HEAD_SLOTS {
        if let Some(head) = backpack.heads.get(i + state.scroll) {
            use crate::backpack::ui_head_state::UiHeadState;

            state.heads[i] = Some(UiHeadState::new(*head, time));
        } else {
            state.heads[i] = None;
        }
    }
}

fn on_head_collect(
    trigger: On<HeadCollected>,
    mut cmds: Commands,
    mut backpack: Query<&mut Backpack>,
    heads_db: Res<HeadsDatabase>,
) -> Result {
    let HeadCollected { head, entity } = *trigger.event();

    let mut backpack = backpack.get_mut(entity)?;

    if backpack.contains(head) {
        cmds.trigger(CashCollectEvent);
    } else {
        backpack.insert(head, heads_db.as_ref());
    }

    Ok(())
}