//! Broccoli is a broad-phase collision detection library.
//! The base data structure is a hybrid between a [KD Tree](https://en.wikipedia.org/wiki/K-d_tree) and [Sweep and Prune](https://en.wikipedia.org/wiki/Sweep_and_prune).
//!
//! Checkout the github [examples](https://github.com/tiby312/broccoli-project/tree/master/broccoli/examples).

#![doc(
    html_logo_url = "https://raw.githubusercontent.com/tiby312/broccoli-project/master/assets/logo.png",
    html_favicon_url = "https://raw.githubusercontent.com/tiby312/broccoli-project/master/assets/logo.png"
)]
#![forbid(unsafe_code)]

#[cfg(doctest)]
mod test_readme {
    macro_rules! external_doc_test {
        ($x:expr) => {
            #[doc = $x]
            extern "C" {}
        };
    }

    external_doc_test!(include_str!("../../README.md"));
}

#[macro_use]
extern crate alloc;

pub use axgeom;
pub mod build;
pub mod node;

pub mod aabb;

use aabb::pin::AabbPin;
use aabb::pin::AabbPinIter;
use aabb::pin::*;
use aabb::*;

use axgeom::*;
use build::*;
use node::*;

#[cfg(test)]
mod tests;

pub mod assert;
pub mod queries;

use assert::Assert;
use assert::Naive;

pub use axgeom::rect;

///Shorthand constructor of [`BBox`]
#[inline(always)]
#[must_use]
pub fn bbox<N, T>(rect: axgeom::Rect<N>, inner: T) -> BBox<N, T> {
    BBox::new(rect, inner)
}

///Shorthand constructor of [`BBoxMut`]
#[inline(always)]
#[must_use]
pub fn bbox_mut<N, T>(rect: axgeom::Rect<N>, inner: &mut T) -> BBoxMut<N, T> {
    BBoxMut::new(rect, inner)
}

///
/// Used to de-couple tree information from
/// the underlying lifetimed slice of elements
/// to be combined again later on.
///
/// See [`Tree::get_tree_data()`] and [`Tree::from_tree_data()`]
///
#[derive(Clone)]
pub struct TreeData<N: Num> {
    nodes: Vec<NodeData<N>>,
}

///
/// Convenience function to call unpack_inner on any number of arguments.
///
#[macro_export]
macro_rules! unpack {
    ( $( $x:ident ),* ) => {
        $(
            let mut $x = $x.unpack_inner();
        )*
    };
}

///
/// Use a macro to save a step build the Cache and calling build on it.
///
#[macro_export]
macro_rules! from_cached_key {
    ( $x:ident ,$y:expr,$z:expr) => {
        let mut $x = $crate::Cached::new_by_cached_key($y, $z);
        let mut $x = $x.build();
    };
}

///
/// Automatically create semi-direct bbox layouts
///
pub struct Cached<'a, N, T> {
    rects: Vec<BBoxMut<'a, N, T>>,
}
impl<'a, N: Num, T> Cached<'a, N, T> {
    ///
    /// Finish building the tree
    ///
    pub fn build<'b>(&'b mut self) -> Tree<'b, BBoxMut<'a, N, T>> {
        Tree::new(&mut self.rects)
    }

    ///
    /// Caches the bboxes one time and sorts them.
    ///
    pub fn new_by_cached_key(
        a: &'a mut [T],
        mut key: impl FnMut(&T) -> Rect<N>,
    ) -> Cached<'a, N, T> {
        let rects = a.iter_mut().map(|a| BBoxMut::new(key(a), a)).collect();
        Cached { rects }
    }
}

///
/// A broccoli Tree.
///
pub struct Tree<'a, T: Aabb> {
    nodes: Box<[Node<'a, T, T::Num>]>,
}

impl<'a, T: Aabb + 'a> Tree<'a, T> {
    ///
    /// User responsibility to provide a distribution that is a
    /// valid broccoli tree.
    ///
    pub fn from_nodes(nodes: Vec<Node<'a, T, T::Num>>) -> Self {
        Tree {
            nodes: nodes.into_boxed_slice(),
        }
    }

    ///
    /// Return the underlying data.
    ///
    pub fn into_nodes(self) -> Vec<Node<'a, T, T::Num>> {
        self.nodes.into_vec()
    }

    ///
    /// Store tree data such as the number of
    /// elements per node, as well as the bounding
    /// range for each node.
    ///
    pub fn get_tree_data(&self) -> TreeData<T::Num> {
        let nodes = self.nodes.iter().map(|x| x.as_data()).collect();
        TreeData { nodes }
    }

    ///
    /// Create a Tree using stored treedata and the original
    /// list of elements in the same order.
    ///
    /// Use this function if you want to store a constructed tree
    /// outside of lifetimes.
    ///
    /// It is the user responsibility to feed this function the same
    /// distribution of aabbs in the same order as the distribution that
    /// was used in the original tree from which [`Tree::get_tree_data()`] was called.
    /// Not doing so will make an invalid tree with no error notification.
    ///
    /// Consider calling [`assert::assert_tree_invariants()`] after tree construction
    /// if you don't know if it was the same distribution which will atleast tell
    /// you if the distribution makes a valid tree.
    ///
    pub fn from_tree_data(bots: &'a mut [T], data: &TreeData<T::Num>) -> Self {
        let mut last = Some(bots);

        let nodes = data
            .nodes
            .iter()
            .map(|x| {
                let (range, rest) = last.take().unwrap().split_at_mut(x.range);
                last = Some(rest);
                Node {
                    range: AabbPin::from_mut(range),
                    cont: x.cont,
                    div: x.div,
                    min_elem: x.min_elem,
                    //num_elem: x.num_elem,
                }
            })
            .collect();
        assert!(last.unwrap().is_empty());
        Tree { nodes }
    }

    ///
    /// Create a new tree with the default tree height heuristic
    ///
    pub fn new(bots: &'a mut [T]) -> Self
    where
        T: ManySwap,
    {
        let (mut e, v) = TreeEmbryo::new(bots);
        e.recurse(v, &mut DefaultSorter);
        e.finish()
    }

    #[inline(always)]
    pub fn vistr_mut(&mut self) -> VistrMutPin<Node<'a, T, T::Num>> {
        let tree = compt::dfs_order::CompleteTreeMut::from_preorder_mut(&mut self.nodes).unwrap();
        VistrMutPin::new(tree.vistr_mut())
    }

    #[inline(always)]
    pub fn vistr(&self) -> Vistr<Node<'a, T, T::Num>> {
        let tree = compt::dfs_order::CompleteTree::from_preorder(&self.nodes).unwrap();

        tree.vistr()
    }

    #[must_use]
    #[inline(always)]
    pub fn num_levels(&self) -> usize {
        compt::dfs_order::CompleteTree::from_preorder(&self.nodes)
            .unwrap()
            .get_height()
    }

    #[must_use]
    #[inline(always)]
    pub fn num_nodes(&self) -> usize {
        self.nodes.len()
    }

    #[must_use]
    #[inline(always)]
    pub fn get_nodes(&self) -> &[Node<'a, T, T::Num>] {
        &self.nodes
    }

    #[must_use]
    #[inline(always)]
    pub fn get_nodes_mut(&mut self) -> AabbPin<&mut [Node<'a, T, T::Num>]> {
        AabbPin::from_mut(&mut self.nodes)
    }
}

///
/// Tools to determine the best tree height for the given number of elements.
///
pub mod num_level {

    #[cfg(test)]
    mod test {
        use super::*;
        #[test]
        fn test_num_nodes() {
            assert_eq!(num_nodes(1), 01);
            assert_eq!(num_nodes(2), 03);
            assert_eq!(num_nodes(3), 07);
            assert_eq!(num_nodes(4), 15);
        }
    }

    ///
    /// The number of nodes for a tree with the given height.
    ///
    pub const fn num_nodes(num_levels: usize) -> usize {
        assert!(num_levels >= 1);
        2usize.rotate_left((num_levels - 1) as u32) - 1
    }

    ///The default number of elements per node
    ///
    ///If we had a node per bot, the tree would have too many levels. Too much time would be spent recursing.
    ///If we had too many bots per node, you would lose the properties of a tree, and end up with plain sweep and prune.
    ///Theory would tell you to just make a node per bot, but there is
    ///a sweet spot inbetween determined by the real-word properties of your computer.
    ///we want each node to have space for around num_per_node bots.
    ///there are 2^h nodes.
    ///2^h*200>=num_bots.  Solve for h s.t. h is an integer.
    ///Make this number too small, and the tree will have too many levels,
    ///and too much time will be spent recursing.
    ///Make this number too high, and you will lose the properties of a tree,
    ///and you will end up with just sweep and prune.
    ///This number was chosen empirically from running the Tree_alg_data project,
    ///on two different machines.
    pub const DEFAULT_NUMBER_ELEM_PER_NODE: usize = 80;

    ///
    /// Use the default heuristic for tree height.
    ///
    #[must_use]
    pub fn default(num_elements: usize) -> usize {
        with_num_elem_in_leaf(num_elements, DEFAULT_NUMBER_ELEM_PER_NODE)
    }

    ///Specify a custom default number of elements per leaf
    #[must_use]
    pub const fn with_num_elem_in_leaf(num_elements: usize, num_elem_leaf: usize) -> usize {
        #[must_use]
        const fn log_2(x: u64) -> u64 {
            const fn num_bits<T>() -> usize {
                core::mem::size_of::<T>() * 8
            }
            num_bits::<u64>() as u64 - x.leading_zeros() as u64 - 1
        }

        //we want each node to have space for around 300 bots.
        //there are 2^h nodes.
        //2^h*200>=num_bots.  Solve for h s.t. h is an integer.

        if num_elements <= num_elem_leaf {
            1
        } else {
            let (num_bots, num_per_node) = (num_elements as u64, num_elem_leaf as u64);
            let a = num_bots / num_per_node;
            let a = log_2(a);
            let k = (((a / 2) * 2) + 1) as usize;
            assert!(k % 2 == 1);
            assert!(k >= 1);
            k
        }
    }
}