use crate::prelude::*;
use anyhow::Result;
use assetpath::AssetPath;

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

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

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

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

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

impl<F: Fn() -> 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()
    }
}

struct State {
    name: String,

    top_level_gui: Arc<dyn TopLevelGui>,

    on_activate: RwLock<Option<Box<dyn Fn() -> Result<()> + Send + Sync>>>,
    on_deactivate: RwLock<Option<Box<dyn Fn() -> Result<()> + Send + Sync>>>,

    next_tab: RwLock<Option<Box<dyn Fn() -> Result<()> + Send + Sync>>>,
    previous_tab: RwLock<Option<Box<dyn Fn() -> Result<()> + Send + Sync>>>,
    decline: RwLock<Option<Box<dyn Fn() -> Result<()> + Send + Sync>>>,
}

/// Opaque handle for a State
/// only used for updating callbacks
#[derive(Clone)]
pub struct StateHandle {
    state: Weak<State>,
}

impl StateHandle {
    pub fn update<'a>(&self, update_type: StateUpdateType<'a>) -> Result<()> {
        self.state.upgrade().unwrap().update(update_type)
    }
}

impl GetElement<Button> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<Button>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<Grid> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<Grid>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<Label> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<Label>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<TextField> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<TextField>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<MultiLineTextField> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<MultiLineTextField>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<Icon> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<Icon>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

impl GetElement<ProgressBar> for StateHandle {
    fn element(&self, id: &str) -> Result<Arc<ProgressBar>> {
        let state = self.state.upgrade().unwrap();

        match state.top_level_gui.elements() {
            Some(elements) => elements.element(id),
            None => panic!("state ({}) has no elements", state.name),
        }
    }
}

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

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

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

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

    /// Updates callbacks by identifier
    SelectCallbacks(Vec<(&'a str, Box<CustomCallback<bool, ()>>)>),

    /// Updates callbacks by identifier
    CustomClickCallbacks(Vec<(&'a str, Box<CustomCallback<ControllerButton, bool>>)>),

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

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

    /// Updates the callback which is executed when this state gets deactivated on state change
    OnDeactivate(Option<Box<dyn Fn() -> 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 {
    gui_handler: Arc<GuiHandler>,

    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(gui_handler: Arc<GuiHandler>) -> Result<Self> {
        Ok(States {
            gui_handler,

            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
    }

    /// Adds a single state
    pub fn add_state<'a>(
        &mut self,
        id: &str,
        creation_type: impl Into<CreationType<'a>>,
    ) -> Result<()> {
        self.states.insert(
            id.to_string(),
            State::new(&self.gui_handler, 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, id: impl Into<Option<&'b str>>) -> Result<()> {
        Self::_set_state(
            id.into().map(|id| self.get_state(id)).transpose()?,
            &mut *self.current_state.lock().unwrap(),
            if self.control_top_gui {
                Some(self.gui_handler.clone())
            } else {
                None
            },
            self.log_state_change,
        )
    }

    fn _set_state(
        state: Option<Arc<State>>,
        current: &mut Option<Arc<State>>,
        gui_handler: Option<Arc<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.deactivate()?;
        }

        // set new state, either no state or requested state
        match state {
            Some(state) => {
                state.activate()?;

                if let Some(gui_handler) = gui_handler {
                    gui_handler.set_top_gui(Some(state.clone()));
                }

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

                *current = Some(state);
            }
            None => {
                if let Some(gui_handler) = gui_handler {
                    gui_handler.set_top_gui(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(StateHandle {
            state: Arc::downgrade(&self.get_state(id)?),
        })
    }

    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 gui_handler = if self.control_top_gui {
            Some(Arc::downgrade(&self.gui_handler))
        } else {
            None
        };
        let logging = self.log_state_change;

        Ok(Box::new(move || {
            if let Some(current) = weak_current_state.upgrade() {
                Self::_set_state(
                    weak_state.as_ref().map(|w| w.upgrade()).flatten(),
                    &mut *current.lock().unwrap(),
                    gui_handler.as_ref().map(|h| h.upgrade()).flatten(),
                    logging,
                )?;
            }

            Ok(())
        }))
    }
}

impl State {
    fn new<'a>(
        gui_handler: &Arc<GuiHandler>,
        name: &str,
        creation_type: CreationType<'a>,
    ) -> Result<Arc<Self>> {
        let gui = match creation_type {
            CreationType::File(path) => GuiBuilder::new(gui_handler, path)?,
            CreationType::TopGui(top_gui) => top_gui,
        };

        Ok(Arc::new(State {
            name: name.to_string(),

            top_level_gui: gui,

            on_activate: RwLock::new(None),
            on_deactivate: RwLock::new(None),

            next_tab: RwLock::new(None),
            previous_tab: RwLock::new(None),
            decline: RwLock::new(None),
        }))
    }

    fn update<'a>(&self, update_type: StateUpdateType<'a>) -> Result<()> {
        match update_type {
            StateUpdateType::NextTab(next_tab) => self.set_next_tab(next_tab),
            StateUpdateType::PreviousTab(previous_tab) => self.set_previous_tab(previous_tab),
            StateUpdateType::Decline(decline) => self.set_decline(decline),
            StateUpdateType::OnActivate(oa) => self.set_on_activate(oa),
            StateUpdateType::OnDeactivate(oda) => self.set_on_deactivate(oda),
            StateUpdateType::ClickCallbacks(cbs) => {
                let functionality = self.functionality()?;
                functionality.set_click_callbacks(cbs)?;
            }
            StateUpdateType::SelectCallbacks(cbs) => {
                let functionality = self.functionality()?;
                functionality.set_select_callbacks(cbs)?;
            }
            StateUpdateType::CustomClickCallbacks(cbs) => {
                let functionality = self.functionality()?;
                functionality.set_custom_callbacks(cbs)?;
            }
            StateUpdateType::VecCallbacks(vcbs) => {
                let functionality = self.functionality()?;
                functionality.set_vec_callbacks(vcbs)?;
            }
        }

        Ok(())
    }

    fn functionality(&self) -> Result<&dyn Functionality> {
        match self.top_level_gui.functionality() {
            Some(functionality) => Ok(functionality),
            None => panic!("state ’{}' does not implement Functionality", &self.name),
        }
    }

    fn activate(&self) -> Result<()> {
        self.top_level_gui.enable()?;

        if let Some(activate) = self.on_activate.read().unwrap().as_ref() {
            (activate)()?;
        }

        Ok(())
    }

    fn deactivate(&self) -> Result<()> {
        self.top_level_gui.disable()?;

        if let Some(deactivate) = self.on_deactivate.read().unwrap().as_ref() {
            (deactivate)()?;
        }

        Ok(())
    }

    fn set_on_activate(&self, on_activate: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>) {
        *self.on_activate.write().unwrap() = on_activate;
    }

    fn set_on_deactivate(&self, on_deactivate: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>) {
        *self.on_deactivate.write().unwrap() = on_deactivate;
    }

    fn set_previous_tab(&self, previous_tab: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>) {
        *self.previous_tab.write().unwrap() = previous_tab;
    }

    fn set_next_tab(&self, next_tab: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>) {
        *self.next_tab.write().unwrap() = next_tab;
    }

    fn set_decline(&self, decline: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>) {
        *self.decline.write().unwrap() = decline;
    }
}

impl TopGui for State {
    fn decline(&self) -> Result<()> {
        match self.decline.read().unwrap().as_ref() {
            Some(decline) => {
                (decline)()?;
            }
            None => {
                if let Some(top_gui) = self.top_level_gui.top_gui() {
                    top_gui.decline()?;
                }
            }
        }

        Ok(())
    }

    fn next_tab(&self, second_level: bool) -> Result<()> {
        match self.next_tab.read().unwrap().as_ref() {
            Some(next_tab) => {
                (next_tab)()?;
            }
            None => {
                if let Some(top_gui) = self.top_level_gui.top_gui() {
                    top_gui.next_tab(second_level)?;
                }
            }
        }

        Ok(())
    }

    fn previous_tab(&self, second_level: bool) -> Result<()> {
        match self.previous_tab.read().unwrap().as_ref() {
            Some(previous_tab) => {
                (previous_tab)()?;
            }
            None => {
                if let Some(top_gui) = self.top_level_gui.top_gui() {
                    top_gui.previous_tab(second_level)?;
                }
            }
        }

        Ok(())
    }
}