use crate::prelude::*;
use anyhow::Result;
use assetpath::AssetPath;
use ecs::World;
use utilities::prelude::remove_life_time_mut;

use std::any::Any;
use std::collections::HashMap;

use std::sync::{Arc, Mutex};

pub trait FutureStateChange: Fn(&mut World) -> Result<()> + Send + Sync {
    fn clone_box<'a>(&self) -> Box<dyn 'a + FutureStateChange>
    where
        Self: 'a;

    fn as_fn(&self) -> &(dyn Fn(&mut World) -> Result<()> + Send + Sync)
    where
        Self: Sized,
    {
        self
    }

    fn as_static(
        &'static self,
    ) -> &'static (dyn Fn(&mut World) -> Result<()> + Send + Sync + 'static)
    where
        Self: Sized,
    {
        self
    }
}

impl<F: Fn(&mut World) -> Result<()> + Clone + Send + Sync> FutureStateChange for F {
    fn clone_box<'a>(&self) -> Box<dyn 'a + FutureStateChange>
    where
        Self: 'a,
    {
        Box::new(self.clone())
    }
}

impl<'a> Clone for Box<dyn 'a + FutureStateChange> {
    fn clone(&self) -> Self {
        (**self).clone_box()
    }
}

/// Update type
pub enum StateUpdateType<'a> {
    /// Updates the callback which is executed on next tab event
    NextTab(Option<Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>>),

    /// Updates the callback which is executed on previous tab event
    PreviousTab(Option<Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>>),

    /// Updates the callback which is executed on decline event
    Decline(Option<Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>>),

    /// Updates callbacks by identifier
    ClickCallbacks(Vec<(&'a str, Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>)>),

    /// Updates callbacks by identifier
    SelectCallbacks(
        Vec<(
            &'a str,
            Box<dyn Fn(&mut World, bool) -> Result<()> + Send + Sync>,
        )>,
    ),

    /// Updates callbacks by identifier
    CustomClickCallbacks(
        Vec<(
            &'a str,
            Box<dyn Fn(&mut World, ControllerButton) -> Result<bool> + Send + Sync>,
        )>,
    ),

    /// Updates callbacks by identifier with input parameters
    VecCallbacks(
        Vec<(
            &'a str,
            Box<dyn Fn(&mut World, &dyn Any) -> Result<()> + Send + Sync>,
        )>,
    ),

    /// Updates the callback which is executed when this state gets activated on state change
    OnActivate(Option<Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>>),

    /// Updates the callback which is executed when this state gets deactivated on state change
    OnDeactivate(Option<Box<dyn Fn(&mut World) -> Result<()> + Send + Sync>>),
}

/// Type of the state to be created
pub enum CreationType<'a> {
    /// Path to an xml-gui file, that state is created internally
    File(&'a AssetPath),

    /// A Arc<> that is already created and implements `TopLevelGui`
    TopGui(Arc<dyn TopLevelGui>),
}

impl<'a> From<&'a AssetPath> for CreationType<'a> {
    fn from(s: &'a AssetPath) -> Self {
        Self::File(s)
    }
}

impl<'a, T: TopLevelGui + 'static> From<Arc<T>> for CreationType<'a> {
    fn from(top_level_gui: Arc<T>) -> Self {
        Self::TopGui(top_level_gui)
    }
}

impl<'a, T: TopLevelGui + 'static> From<T> for CreationType<'a> {
    fn from(top_level_gui: T) -> Self {
        Self::TopGui(Arc::new(top_level_gui))
    }
}

/// Collection and handler for your UI (basically a state machine)
pub struct States {
    states: HashMap<String, Arc<State>>,
    current_state: Arc<Mutex<Option<Arc<State>>>>,

    control_top_gui: bool,
    log_state_change: bool,
}

impl States {
    /// Creates an empty States struct
    pub fn new() -> Result<Self> {
        Ok(States {
            states: HashMap::new(),
            current_state: Arc::new(Mutex::new(None)),

            control_top_gui: true,
            log_state_change: false,
        })
    }

    pub fn change_logging(mut self, logging: bool) -> Self {
        self.log_state_change = logging;
        self
    }

    /// Sets a flag if states should set and unset top gui of the gui handler
    pub fn set_control_top_gui(mut self, control_top_gui: bool) -> Self {
        self.control_top_gui = control_top_gui;
        self
    }

    /// lists available states
    pub fn states(&self) -> impl Iterator<Item = &str> {
        self.states.keys().map(|s| s.as_str())
    }

    /// Adds a single state
    pub fn add_state<'a>(
        &mut self,
        world: &mut World,
        id: &str,
        creation_type: impl Into<CreationType<'a>>,
    ) -> Result<()> {
        self.states
            .insert(id.to_string(), State::new(world, id, creation_type.into())?);

        Ok(())
    }

    /// Returns the name of the current state if possible
    pub fn current_state(&self) -> Result<Option<String>> {
        match self.current_state.lock().unwrap().as_ref() {
            Some(state) => Ok(Some(state.name.clone())),
            None => Ok(None),
        }
    }

    /// Changes the state
    ///
    /// # Arguments
    ///
    /// * `id` - Set state with the given identifier or None
    pub fn set_state<'b>(&self, world: &mut World, id: impl Into<Option<&'b str>>) -> Result<()> {
        let gui_handler = unsafe { remove_life_time_mut(world.resources.get_mut::<GuiHandler>()) };

        Self::_set_state(
            id.into().map(|id| self.get_state(id)).transpose()?,
            &mut *self.current_state.lock().unwrap(),
            world,
            gui_handler,
            self.log_state_change,
        )
    }

    fn _set_state(
        state: Option<Arc<State>>,
        current: &mut Option<Arc<State>>,
        world: &mut World,
        gui_handler: &mut GuiHandler,
        logging: bool,
    ) -> Result<()> {
        if let Some(old_state) = current {
            // check if requested state is already in use
            if let Some(new_state) = &state {
                if new_state.name == old_state.name {
                    return Ok(());
                }
            }

            // execute deactivate on old state
            old_state.disable(world)?;
        }

        // set new state, either no state or requested state
        match state {
            Some(state) => {
                state.enable(world)?;
                gui_handler.set_top_gui(world, Some(state.clone()))?;

                if logging {
                    println!("Change UI State to {}", state.name);
                }

                *current = Some(state);
            }
            None => {
                gui_handler.set_top_gui(world, None)?;

                if logging {
                    println!("Change UI State to None");
                }

                *current = None;
            }
        }

        Ok(())
    }

    /// Retrieve a StateHandle
    pub fn state_handle(&self, id: &str) -> Result<StateHandle> {
        Ok(self.get_state(id)?.into())
    }

    fn get_state(&self, id: &str) -> Result<Arc<State>> {
        match self.states.get(id) {
            Some(state) => Ok(state.clone()),
            None => Err(anyhow::Error::msg(format!("UiState not found: {}", id))),
        }
    }

    pub fn future_state_change<'b>(
        &self,
        id: impl Into<Option<&'b str>>,
    ) -> Result<Box<dyn FutureStateChange>> {
        let state: Option<Arc<State>> = id.into().map(|id| self.get_state(id)).transpose()?;
        let weak_state = state.map(|s| Arc::downgrade(&s));
        let weak_current_state = Arc::downgrade(&self.current_state);
        let logging = self.log_state_change;

        Ok(Box::new(move |world: &mut World| {
            if let Some(current) = weak_current_state.upgrade() {
                let gui_handler =
                    unsafe { remove_life_time_mut(world.resources.get_mut::<GuiHandler>()) };

                Self::_set_state(
                    weak_state.as_ref().map(|w| w.upgrade()).flatten(),
                    &mut *current.lock().unwrap(),
                    world,
                    gui_handler,
                    logging,
                )?;
            }

            Ok(())
        }))
    }
}