//! Basic implementation of a stack/linked list.

use crate::func::{context::*, controlflow::ControlFlow};
use crate::rcore::*;
use crate::rstd::{inlining::*, nullable::*, point::*, *};

/// Node containing a (nullable) reference to the next node and an element.
pub struct StackNode<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> {
    /// Reference comes first due to being inlineable.
    pub rest: Stack<'a, Ctx, A>,
    /// Unlike the original implementation in Python, doesn't default to using Point.
    pub element: A,
}

/// Type representing a stack, an alias to a [Nullable] of a [StackNode].
pub type Stack<'a, Ctx, A> = Nullable<'a, Ctx, StackNode<'a, Ctx, A>>;

#[derive(Clone)]
pub struct StackNodeFactory<F> {
    element_factory: F,
}

impl<F> StackNodeFactory<F> {
    fn new(factory: F) -> Self {
        StackNodeFactory {
            element_factory: factory,
        }
    }
}

impl<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> Serializable for StackNode<'a, Ctx, A> {
    fn serialize(&self, serializer: &mut dyn Serializer) {
        self.rest.serialize(serializer);
        self.element.serialize(serializer);
    }
}

impl<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> MentionableBase<'a, Ctx>
    for StackNode<'a, Ctx, A>
{
    type Fctr = StackNodeFactory<A::Fctr>;

    fn factory(&self) -> Self::Fctr {
        StackNodeFactory::new(self.element.factory())
    }
}

impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx>> MentionableTop<'a, Ctx>
    for StackNode<'a, Ctx, A>
{
    fn points_typed(&self, points: &mut impl PointsVisitor<'a, Ctx>)
    where
        Self: Mentionable<'a, Ctx>,
    {
        self.rest.points_typed(points);
        self.element.points_typed(points);
    }
}

#[derive(Debug)]
pub enum StackParseError<ElementParseError: Error> {
    Point(PointParseError),
    Element(ElementParseError),
}

impl<E: Error> From<PointParseError> for StackParseError<E> {
    fn from(value: PointParseError) -> Self {
        Self::Point(value)
    }
}

impl<ElementParseError: Error> Display for StackParseError<ElementParseError> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Point(ppe) => {
                write!(f, "can't parse stack's next pointer: {}", ppe)
            }
            Self::Element(epe) => {
                write!(f, "can't parse stack's element: {}", epe)
            }
        }
    }
}

impl<ElementParseError: Error> Error for StackParseError<ElementParseError> {}

impl<F> StackNodeFactory<F> {
    fn parse_point<'a, Ctx: Context<'a>, I: InCtx<'a, Ctx>>(
        &self,
        inctx: I,
    ) -> IParseResult<'a, Ctx, NullableFactory<Self>, I>
    where
        StackNodeFactory<F>: Factory<'a, Ctx>,
    {
        NullableFactory::new(self.clone()).ideserialize(inctx)
    }
}

impl<'a, Ctx: Context<'a>, F: FactoryBase<'a, Ctx>> FactoryBase<'a, Ctx> for StackNodeFactory<F> {
    type Mtbl = StackNode<'a, Ctx, F::Mtbl>;

    type ParseError = StackParseError<ParseError<'a, Ctx, F>>;
}

impl<F: ParseMode> ImplMode for StackNodeFactory<F> {
    type Mode = F::Mode;
}

impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx> + RegularFactory<'a, Ctx>> QRegularFactory<'a, Ctx>
    for StackNodeFactory<F>
where
    F::Mtbl: MentionableTop<'a, Ctx>,
{
    fn qrdeserialize(&self, inctx: impl InCtx<'a, Ctx>) -> ParseResult<'a, Ctx, Self> {
        let (rest, inctx) = self.parse_point(inctx)?;
        let element = self
            .element_factory
            .deserialize(inctx)
            .map_err(StackParseError::Element)?;
        Ok(StackNode { rest, element })
    }

    fn qrextend(&self, mut mentionable: Self::Mtbl, tail: &[u8]) -> ParseResult<'a, Ctx, Self> {
        mentionable.element = self
            .element_factory
            .extend(mentionable.element, tail)
            .map_err(StackParseError::Element)?;
        Ok(mentionable)
    }
}

/// See [`StackVecResult`].
pub type StackFaiure<'a, Ctx, A> = ResolutionFailure<'a, Ctx, StackNode<'a, Ctx, A>>;

/// See [`StackVecWrapped`].
pub type StackVecResult<'a, Ctx, A> = Result<Vec<A>, StackFaiure<'a, Ctx, A>>;

/// See [`ExtStackClone::vec`].
pub type StackVecWrapped<'a, Ctx, A> = Wrapped<'a, Ctx, StackVecResult<'a, Ctx, A>>;

/// Extention trait with helper methods for [Stack]s.
pub trait ExtStack<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>>:
    MentionableBase<'a, Ctx>
{
    /// Get an empty stack ([`Nullable::Null`]).
    fn empty(factory: A::Fctr) -> Self;
    /// Get the corresponding factory.
    fn f(factory: A::Fctr) -> Self::Fctr;
    /// Add one element.
    ///
    /// Note: consumes the stack. For non-consuming version do `.clone()` before adding.
    fn add(self, element: A) -> Self;
}

/// Extention trait with helper methods for [Stack]s.
pub trait ExtStackClone<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx> + Clone>:
    MentionableBase<'a, Ctx>
{
    /// Collect all the elements into a [`Vec`].
    fn vec(self) -> StackVecWrapped<'a, Ctx, A>;
}

impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx> + Mentionable<'a, Ctx>> ExtStack<'a, Ctx, A>
    for Stack<'a, Ctx, A>
where
    StackNode<'a, Ctx, A>: Mentionable<'a, Ctx, _Fctr = StackNodeFactory<A::Fctr>>,
{
    fn empty(factory: A::Fctr) -> Self {
        Nullable::Null(StackNodeFactory::new(factory.clone()))
    }
    fn f(factory: A::Fctr) -> Self::Fctr {
        NullableFactory::new(StackNodeFactory::new(factory.clone()))
    }
    fn add(self, element: A) -> Self {
        Nullable::NotNull(
            StackNode {
                rest: self,
                element,
            }
            .into(),
        )
    }
}

impl<'a, Ctx: Context<'a>, A: Mentionable<'a, Ctx> + Clone> ExtStackClone<'a, Ctx, A>
    for Stack<'a, Ctx, A>
where
    StackNode<'a, Ctx, A>: Mentionable<'a, Ctx, _Fctr = StackNodeFactory<A::Fctr>>,
    StackNodeFactory<A::Fctr>: FactoryParse<'a, Ctx>,
{
    fn vec(self) -> StackVecWrapped<'a, Ctx, A> {
        Ctx::T::iterate_mut((vec![], self), |(mut vec, stack)| match stack {
            Nullable::Null(_) => Ctx::pure(ControlFlow::Break(Ok(vec))),
            Nullable::NotNull(point) => point.resolve_map(|resolved| {
                let node = match resolved {
                    Ok(node) => node,
                    Err(error) => {
                        return ControlFlow::Break(Err(error));
                    }
                };
                vec.push(node.element.clone());
                ControlFlow::Continue((vec, node.rest.clone()))
            }),
        })
    }
}

impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx> + InliningFactory<'a, Ctx>> InliningFactory<'a, Ctx>
    for StackNodeFactory<F>
where
    F::Mtbl: MentionableTop<'a, Ctx>,
{
    fn extension_error(&self, tail: &[u8]) -> Self::ParseError {
        StackParseError::Element(self.element_factory.extension_error(tail))
    }

    fn ideserialize<I: InCtx<'a, Ctx>>(&self, inctx: I) -> IParseResult<'a, Ctx, Self, I> {
        let (rest, inctx) = self.parse_point(inctx)?;
        let (element, inctx) = self
            .element_factory
            .ideserialize(inctx)
            .map_err(StackParseError::Element)?;
        Ok((StackNode { rest, element }, inctx))
    }
}

impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx> + FixedSizeFactory<'a, Ctx>>
    FixedSizeFactory<'a, Ctx> for StackNodeFactory<F>
where
    F::Mtbl: MentionableTop<'a, Ctx>,
{
    fn size(&self) -> usize {
        Stack::<'a, Ctx, F::Mtbl>::SIZE + self.element_factory.size()
    }
}

impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx> + ConstSizeFactory<'a, Ctx>>
    ConstSizeFactory<'a, Ctx> for StackNodeFactory<F>
where
    F::Mtbl: MentionableTop<'a, Ctx>,
{
    const SIZE: usize = Stack::<'a, Ctx, F::Mtbl>::SIZE + F::SIZE;
}

#[cfg(test)]
mod tests {
    use std::rc::Rc;

    use crate::rstd::{
        atomic::{atomic_object::*, plain::*},
        tracing::*,
    };
    use crate::testing::{counted::*, traced::*, *};

    use super::*;

    type T<Ctx> = Stack<'static, Ctx, AtomicObject<Plain>>;

    fn unstack(
        stack: &T<TestContextPlain>,
    ) -> Result<Vec<Vec<u8>>, StackFaiure<'static, TestContextPlain, AtomicObject<Plain>>> {
        Ok(stack
            .clone()
            .vec()?
            .iter()
            .map(|plain| plain.raw())
            .collect())
    }

    fn make_stack<Ctx: Context<'static>>() -> T<Ctx> {
        let stack: T<Ctx> = Stack::empty(Plain::f());

        let stack: T<Ctx> = stack.add(Plain::from_slice(b"A0").into());
        let stack: T<Ctx> = stack.add(Plain::from_slice(b"B1").into());
        let stack: T<Ctx> = stack.add(Plain::from_slice(b"C2").into());

        stack
    }

    fn validate_stack(stack: &T<TestContextPlain>) {
        let mut vec: Vec<Vec<u8>> = unstack(stack).unwrap();
        vec.reverse();
        assert_eq!(vec, vec![b"A0".to_vec(), b"B1".to_vec(), b"C2".to_vec()]);
    }

    #[test]
    fn test_stack() -> Result<(), StackFaiure<'static, TestContextPlain, AtomicObject<Plain>>> {
        let stack: T<TestContextPlain> = make_stack();

        validate_stack(&stack);

        let stack: T<TestContextPlain> = reparse(stack.into());

        validate_stack(&stack);

        Ok(())
    }

    #[test]
    fn test_counted() -> Result<(), point::PointParseError> {
        let stack: T<TestContextCounted> = make_stack();
        let count = stack.clone().vec().count();
        assert_eq!(count, 0);
        let stack: T<TestContextCounted> = Rc::new(stack).delay()?;
        let count = stack.clone().vec().count();
        assert_eq!(count, 3);
        Ok(())
    }

    #[test]
    fn test_traced() -> Result<(), point::PointParseError> {
        let stack: T<TestContextTraced> = make_stack();
        let traced = stack.clone().vec();
        assert_eq!(traced.length(), 0);
        assert_eq!(traced.width(), 0);
        assert_eq!(format!("{}", traced.effect), ".");
        let stack: T<TestContextTraced> = Rc::new(stack).trace()?;
        let traced = stack.clone().vec();
        assert_eq!(traced.length(), 3);
        assert_eq!(traced.width(), 1);
        assert_eq!(format!("{}", traced.effect), "( ? > ? > ? )");
        Ok(())
    }

    #[test]
    fn test_rendered() -> Result<(), point::PointParseError> {
        let stack: T<TestContextTraced> = make_stack();
        let rendered = stack.clone().vec().render();
        assert_eq!(rendered.length(), 0);
        assert_eq!(rendered.width(), 0);
        assert_eq!(format!("{}", rendered), ".");
        let stack: T<TestContextTraced> = Rc::new(stack).trace()?;
        let rendered = stack.clone().vec().render();
        assert_eq!(rendered.length(), 3);
        assert_eq!(rendered.width(), 1);
        assert_eq!(format!("{}", rendered), "( ? > ? > ? )");
        Ok(())
    }
}