use crate::*;

#[derive(Default, Debug)] pub struct Pool<T>(pub Arc<RwLock<Vec<Slot<T>>>>);
pub type SamplePool = Pool<Sample>;
pub type ClipPool = Pool<MidiClip>;
impl<T> Clone for Pool<T> { fn clone (&self) -> Self { Pool(self.0.clone()) } }
impl<T> Pool<T> {
    pub fn slot (&self, index: usize) -> Slot<T> {
        let mut state = self.0.write();
        while index >= state.len() {
            state.push(Slot::new(None));
        }
        state[index].clone()
    }
    pub fn delete (&self, index: usize) -> Option<Arc<RwLock<T>>> {
        let mut none = None;
        let mut slot = self.slot(index).write();
        std::mem::swap(&mut none, &mut slot);
        none
    }
    pub fn len (&self) -> usize {
        self.0.read().len()
    }
    pub fn get (&self, index: usize) -> Option<ArcRwLockReadGuard<RawRwLock, Option<Arc<RwLock<T>>>>> {
        self.0.read_arc().get(index).map(|clip|clip.read())
    }
    pub fn set (&self, index: usize, value: Option<T>) {
        self.write()[index] = Slot::new(value);
    }
    pub fn read (&self) -> ArcRwLockReadGuard<RawRwLock, Vec<Slot<T>>> {
        self.0.read_arc()
    }
    pub fn write (&self) -> ArcRwLockWriteGuard<RawRwLock, Vec<Slot<T>>> {
        self.0.write_arc()
    }
    pub fn append (&self, value: Option<T>) -> Slot<T> {
        let slot = Slot::new(value);
        self.0.write().push(slot.clone());
        slot
    }
}

impl Pool<MidiClip> {
    pub fn eval <'a, T> (_: &T, _: impl Language) -> Perhaps<ClipPool> {
        todo!()
    }
    pub fn remove (&self, filter: &MidiClip) {
        let mut iter = self.0.write();
        iter.retain(|x|if let Some(x) = &*x.0.read() {
            &*x.read() != filter
        } else {
            true
        })
    }
}

impl Pool<Sample> {
    pub fn eval <'a> (_: &App, _: impl Language) -> Perhaps<SamplePool> {
        todo!()
    }
}

impl<T> From<Vec<Option<T>>> for Pool<T> {
    fn from (values: Vec<Option<T>>) -> Self {
        Self(Arc::new(RwLock::new(values.into_iter().map(Slot::new).collect())))
    }
}

#[derive(Default, Debug)] pub struct Slot<T>(pub Arc<RwLock<Option<Arc<RwLock<T>>>>>);
pub type SampleSlot = Slot<Sample>;
pub type ClipSlot = Slot<MidiClip>;

impl<T> Clone for Slot<T> {
    fn clone (&self) -> Self {
        Slot(self.0.clone())
    }
}

impl<T> Slot<T> {
    pub fn new (value: impl Into<Option<T>>) -> Self {
        Self(Arc::new(RwLock::new(value.into().map(|value|Arc::new(RwLock::new(value))))))
    }
    pub fn read (&self) -> ArcRwLockReadGuard<RawRwLock, Option<Arc<RwLock<T>>>> {
        self.0.read_arc()
    }
    pub fn write (&self) -> ArcRwLockWriteGuard<RawRwLock, Option<Arc<RwLock<T>>>> {
        self.0.write_arc()
    }
    pub fn set_to (&mut self, value: Self) {
        self.0 = value.0;
    }
    pub fn set (&self, value: Option<T>) -> Option<Arc<RwLock<T>>> {
        let mut value = value.map(|value|Arc::new(RwLock::new(value)));
        std::mem::swap(&mut*self.0.write(), &mut value);
        value
    }
}
pub trait SlotExt<T> {
    fn map_inner <U> (&self, cb: impl FnOnce(&T)->U) -> Option<U>;
    fn map_inner_mut <U> (&self, cb: impl FnOnce(&mut T)->U) -> Option<U>;
}
impl<T> SlotExt<T> for Slot<T> {
    fn map_inner <U> (&self, cb: impl FnOnce(&T)->U) -> Option<U> {
        self.read().as_ref().map(|x|cb(&*x.read()))
    }
    fn map_inner_mut <U> (&self, cb: impl FnOnce(&mut T)->U) -> Option<U> {
        self.read().as_ref().map(|x|cb(&mut*x.write()))
    }
}
impl<T> SlotExt<T> for Option<Slot<T>> {
    fn map_inner <U> (&self, cb: impl FnOnce(&T)->U) -> Option<U> {
        self.as_ref().map(|x|x.map_inner(cb))?
    }
    fn map_inner_mut <U> (&self, cb: impl FnOnce(&mut T)->U) -> Option<U> {
        self.as_ref().map(|x|x.map_inner_mut(cb))?
    }
}

impl Slot<MidiClip> {
    pub fn eval <'a> (state: &App, src: impl Language) -> Perhaps<ClipSlot> {
        eval_word(src, |word|Ok(match word {

            ":selected" if let Selection::TrackClip { track, scene } = state.selection() => {
                state.scenes()[*scene].clips.slot(*track)
            },

            //":selected-or-create" if let Selection::TrackClip {
                //track, scene
            //} = state.selection() => Some(if let Some(Some(clip)) = state.scenes()[*scene].clips.get(*track) {
                //clip.clone()
            //} else {
                //let clip: Arc<RwLock<MidiClip>> = Arc::new(RwLock::new(Default::default()));
                //state.scenes()[*scene].clips[*track] = Some(clip.clone());
                //clip
            //}),

            _ => return err!("not a clip: {word}")

        }))
    }
}

impl Slot<Sample> {
    pub fn eval <'a> (_: &App, _: impl Language) -> Perhaps<SampleSlot> {
        todo!()
    }
}