//! Port of BSP toolkit.

use bindings::ffi;
use bindings::AsNative;
use bindings::{c_void, c_bool};
use random::Rng;
use std::ops::{Deref, DerefMut};
use std::fmt;
use std::mem;

#[derive(Copy, Clone, Debug)]
pub enum TraverseOrder {
    PreOrder,
    InOrder,
    PostOrder,
    LevelOrder,
    InvertedLevelOrder,
}

/// This struct encapsulates `TCOD_bsp_t`. It mirrors original's fields (`x`, `y`, etc.)
/// with the exception of `horizontal`. See example.
///
/// # Examples
///
/// ```no_run
/// # use tcod::bsp::*;
/// let mut bsp = Bsp::new_with_size(0, 0, 50, 60);
///
/// assert_eq!(bsp.x, 0);
/// assert_eq!(bsp.y, 0);
/// assert_eq!(bsp.w, 50);
/// assert_eq!(bsp.h, 60);
/// assert_eq!(bsp.horizontal(), false);
///
/// bsp.x = 10;
/// bsp.y = 20;
/// bsp.set_horizontal(true);
/// ```
pub struct Bsp<'a> {
    bsp: &'a mut ffi::TCOD_bsp_t,
    root: bool
}

impl<'a> Deref for Bsp<'a> {
    type Target = ffi::TCOD_bsp_t;

    fn deref(&self) -> &Self::Target {
        self.bsp
    }
}

impl<'a> DerefMut for Bsp<'a> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.bsp
    }
}

impl<'a> fmt::Debug for Bsp<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(f, "Bsp{{x: {}, y:{}, w: {}, h: {}, position: {}, level: {}, horizontal: {} }}",
               self.x, self.y, self.w, self.h, self.position, self.level, self.horizontal)
    }
}


extern "C" fn callback_wrapper<T>(node: *mut ffi::TCOD_bsp_t, user_data: *mut c_void) -> c_bool
    where T: FnMut(&mut Bsp) -> bool
{
    let callback_ptr = user_data as *mut T;
    let cb: &mut T = unsafe {
        &mut *callback_ptr
    };
    if node.is_null() { panic!("Null node when traversing a BSP.") }
    let mut bsp = Bsp { bsp: unsafe { &mut *node }, root: false };
    cb(&mut bsp) as c_bool
}

impl<'a> Bsp<'a> {
    pub fn new_with_size(x: i32, y: i32, w: i32, h: i32) -> Self {
        let bsp = unsafe {
            let pointer = ffi::TCOD_bsp_new_with_size(x, y, w, h);
            if pointer.is_null() {
                panic!("TCOD_bsp_new_with_size returned a NULL BSP.");
            }
            &mut *pointer
        };
        Bsp { bsp: bsp, root: true }
    }

    pub fn remove_sons(&mut self) {
        unsafe { ffi::TCOD_bsp_remove_sons(self.bsp as *mut ffi::TCOD_bsp_t) }
    }

    pub fn split_once(&mut self, horizontal: bool, position: i32) {
        unsafe { ffi::TCOD_bsp_split_once(self.bsp as *mut ffi::TCOD_bsp_t,
                                          horizontal as u8,
                                          position) }
    }

    pub fn split_recursive(&mut self,
                           randomizer: Option<Rng>,
                           nb: i32,
                           min_h_size: i32,
                           min_v_size: i32,
                           max_h_ratio: f32,
                           max_v_ratio: f32) {
        let rnd = randomizer.unwrap_or(Rng::get_instance());
        unsafe {
            ffi::TCOD_bsp_split_recursive(self.bsp as *mut ffi::TCOD_bsp_t,
                                          *rnd.as_native(),
                                          nb,
                                          min_h_size,
                                          min_v_size,
                                          max_h_ratio,
                                          max_v_ratio)
        }
    }

    pub fn resize(&mut self, x: i32, y: i32, w: i32, h: i32) {
        unsafe { ffi::TCOD_bsp_resize(self.bsp as *mut ffi::TCOD_bsp_t, x, y, w, h) }
    }

    /// Returns `Some(Bsp)` with left subtree, or `None` if the BSP has not been split.
    pub fn left(&self) -> Option<Self> {
        unsafe {
            let left = ffi::TCOD_bsp_left(self.bsp as *const ffi::TCOD_bsp_t);
            if left.is_null() {
                None
            } else {
                Some(Bsp {
                    bsp: &mut *left,
                    root: false
                })
            }
        }
    }

    /// Returns `Some(Bsp)` with right subtree, or `None` if the BSP has not been split.
    pub fn right(&self) -> Option<Self> {
        unsafe {
            let right = ffi::TCOD_bsp_right(self.bsp as *const ffi::TCOD_bsp_t) ;
            if right.is_null() {
                None
            } else {
                Some(Bsp {
                    bsp: &mut *right,
                    root:false
                })
            }
        }
    }

    /// Returns `Some(Bsp)` with father, or `None` if the node is root.
    pub fn father(&self) -> Option<Self> {
        unsafe {
            let father = ffi::TCOD_bsp_father(self.bsp as *const ffi::TCOD_bsp_t);
            if father.is_null() {
                None
            } else {
                Some(Bsp {
                    bsp: &mut *father,
                    root: false,
                })
            }
        }
    }

    pub fn is_leaf(&self) -> bool {
        unsafe { ffi::TCOD_bsp_is_leaf(self.bsp as *const ffi::TCOD_bsp_t) != 0 }
    }

    pub fn contains(&self, cx: i32, cy: i32) -> bool {
        unsafe { ffi::TCOD_bsp_contains(self.bsp as *const ffi::TCOD_bsp_t, cx, cy) != 0 }
    }

    pub fn find_node(&self, cx: i32, cy: i32) -> Option<Self> {
        unsafe {
            let pointer = ffi::TCOD_bsp_find_node(self.bsp as *const ffi::TCOD_bsp_t,
                                                  cx, cy);
            if pointer.is_null() {
                None
            } else {
                Some(Bsp {
                    bsp: &mut *pointer,
                    root: false
                })
            }
        }
    }

    pub fn horizontal(&self) -> bool {
        self.horizontal != 0
    }

    pub fn set_horizontal(&mut self, h: bool) {
        self.horizontal = h as u8;
    }

    /// Instead of 5 `traverse*` functions as in original API, Rust binding
    /// provides a single `traverse` function with an `order` parameter.
    ///
    /// # Examples
    ///
    /// ```no_run
    ///    # use tcod::bsp::*;
    ///    let bsp = Bsp::new_with_size(0, 0, 50, 50);
    ///    let mut counter = 0;
    ///
    ///    bsp.traverse(TraverseOrder::PreOrder, |node| {
    ///        counter += 1;
    ///        true
    ///    });
    ///    assert_eq!(counter, 1);
    /// ```
    pub fn traverse<F>(&self, order: TraverseOrder, mut callback: F) -> bool
        where F: FnMut(&mut Bsp) -> bool
    {
        let mut cb: &mut FnMut(&mut Bsp) -> bool = &mut callback;
        let retval = unsafe {
            let bsp = mem::transmute(self.bsp as *const ffi::TCOD_bsp_t);
            match order {
                TraverseOrder::PreOrder =>
                    ffi::TCOD_bsp_traverse_pre_order(bsp,
                                                     Some(callback_wrapper::<F>),
                                                     cb as *mut _ as *mut c_void),
                TraverseOrder::InOrder =>
                    ffi::TCOD_bsp_traverse_in_order(bsp,
                                                    Some(callback_wrapper::<F>),
                                                    cb as *mut _ as *mut c_void),
                TraverseOrder::PostOrder =>
                    ffi::TCOD_bsp_traverse_post_order(bsp,
                                                      Some(callback_wrapper::<F>),
                                                      cb as *mut _ as *mut c_void),
                TraverseOrder::LevelOrder =>
                    ffi::TCOD_bsp_traverse_level_order(bsp,
                                                       Some(callback_wrapper::<F>),
                                                       cb as *mut _ as *mut c_void),
                TraverseOrder::InvertedLevelOrder =>
                    ffi::TCOD_bsp_traverse_inverted_level_order(bsp,
                                                                Some(callback_wrapper::<F>),
                                                                cb as *mut _ as *mut c_void),
            }
        };
        retval != 0
    }
}

impl<'a> Drop for Bsp<'a> {
    fn drop(&mut self) {
        if self.root {
            unsafe { ffi::TCOD_bsp_delete(self.bsp as *mut ffi::TCOD_bsp_t) }
        }
    }
}

#[cfg(test)]
mod test {
    use super::Bsp;
    use super::TraverseOrder;
    use bindings::ffi;

    #[test]
    #[allow(unused_variables)]
    fn created_destroyed_no_panic() {
        let bsp = Bsp::new_with_size(0, 0, 50, 50);
        let left = bsp.left(); // left has null .bsp
    }

    #[test]
    fn accessors() {
        let mut bsp = Bsp::new_with_size(0, 0, 50, 60);

        assert_eq!(bsp.x, 0);
        assert_eq!(bsp.y, 0);
        assert_eq!(bsp.w, 50);
        assert_eq!(bsp.h, 60);
        assert_eq!(bsp.horizontal(), false);
        bsp.x = 10;
        bsp.y = 20;
        bsp.set_horizontal(true);
        assert_eq!(bsp.x, 10);
        assert_eq!(bsp.y, 20);
        assert_eq!(bsp.horizontal(), true);
    }

    #[test]
    fn split() {
        let mut bsp = Bsp::new_with_size(0, 0, 50, 50);

        assert_eq!(bsp.position, 0);
        assert_eq!(bsp.horizontal(), false);

        bsp.split_once(true, 20);
        assert_eq!(bsp.position, 20);
        assert_eq!(bsp.horizontal(), true);
    }

    #[test]
    fn split_recursive() {
        let mut bsp = Bsp::new_with_size(0, 0, 100,100);
        let mut counter = 0;

        bsp.split_recursive(None, 2, 5, 5, 1.5, 1.5);
        bsp.traverse(TraverseOrder::PreOrder, |node| {
            assert!(node.h >= 5);
            assert!(node.w >= 5);
            counter += 1;
            true
        });
        assert_eq!(counter, 7);
    }

    #[test]
    fn children() {
        let mut bsp = Bsp::new_with_size(0, 0, 50, 50);

        assert!(bsp.left().is_none());
        assert_eq!(bsp.level, 0);

        bsp.split_once(false, 20);
        assert!(bsp.left().is_some());
        assert!(bsp.right().is_some());
        assert_eq!(bsp.left().unwrap().level, 1);
        assert_eq!(bsp.right().unwrap().level, 1);
    }

    #[test]
    fn father() {
        let mut bsp = Bsp::new_with_size(0, 0, 50, 50);
        assert!(bsp.father().is_none());

        bsp.split_once(false, 30);
        assert!(bsp.left().unwrap().father().is_some());
        assert!(bsp.right().unwrap().father().is_some());
    }

    #[test]
    fn traverse() {
        let mut bsp = Bsp::new_with_size(0, 0, 50, 50);
        let mut counter = 0;

        bsp.traverse(TraverseOrder::PreOrder, |node| {
            assert!(cmp(node, &bsp));
            counter += 1;
            true
        });
        assert_eq!(counter, 1);

        counter = 0;
        bsp.split_once(true, 25);
        bsp.traverse(TraverseOrder::PreOrder, |_node| {
            counter += 1;
            true
        });
        assert_eq!(counter, 3);
    }

    fn cmp(a: &ffi::TCOD_bsp_t, b: &ffi::TCOD_bsp_t) -> bool {
        a.x == b.x
            && a.y == b.y
            && a.w == b.w
            && a.h == b.h
            && a.position == b.position
            && a.level == b.level
            && a.horizontal == b.horizontal
    }

    #[test]
    fn traverse_orders() {
        let mut root = Bsp::new_with_size(0, 0, 100,100);
        let mut counter = 0;

        root.split_recursive(None, 2, 5, 5, 1.5, 1.5);

        let middle_left = root.left().unwrap();
        let middle_right = root.right().unwrap();
        let leaf1 = middle_left.left().unwrap();
        let leaf2 = middle_left.right().unwrap();
        let leaf3 = middle_right.left().unwrap();
        let leaf4 = middle_right.right().unwrap();

        root.traverse(TraverseOrder::PreOrder, |node| {
            match counter {
                0 => assert!(cmp(node.bsp, root.bsp)),
                1 => assert!(cmp(node.bsp, middle_left.bsp)),
                2 => assert!(cmp(node.bsp, leaf1.bsp)),
                3 => assert!(cmp(node.bsp, leaf2.bsp)),
                4 => assert!(cmp(node.bsp, middle_right.bsp)),
                5 => assert!(cmp(node.bsp, leaf3.bsp)),
                6 => assert!(cmp(node.bsp, leaf4.bsp)),
                _ => panic!("Wrong number of nodes in the tree"),
            };
            counter += 1;
            true
        });

        counter = 0;
        root.traverse(TraverseOrder::InOrder, |node| {
            match counter {
                0 => assert!(cmp(node.bsp, leaf1.bsp)),
                1 => assert!(cmp(node.bsp, middle_left.bsp)),
                2 => assert!(cmp(node.bsp, leaf2.bsp)),
                3 => assert!(cmp(node.bsp, root.bsp)),
                4 => assert!(cmp(node.bsp, leaf3.bsp)),
                5 => assert!(cmp(node.bsp, middle_right.bsp)),
                6 => assert!(cmp(node.bsp, leaf4.bsp)),
                _ => panic!("Wrong number of nodes in the tree"),
            };
            counter += 1;
            true
        });

        counter = 0;
        root.traverse(TraverseOrder::PostOrder, |node| {
            match counter {
                0 => assert!(cmp(node.bsp, leaf1.bsp)),
                1 => assert!(cmp(node.bsp, leaf2.bsp)),
                2 => assert!(cmp(node.bsp, middle_left.bsp)),
                3 => assert!(cmp(node.bsp, leaf3.bsp)),
                4 => assert!(cmp(node.bsp, leaf4.bsp)),
                5 => assert!(cmp(node.bsp, middle_right.bsp)),
                6 => assert!(cmp(node.bsp, root.bsp)),
                _ => panic!("Wrong number of nodes in the tree"),
            };
            counter += 1;
            true
        });

        counter = 0;
        root.traverse(TraverseOrder::LevelOrder, |node| {
            match counter {
                0 => assert!(cmp(node.bsp, root.bsp)),
                1 => assert!(cmp(node.bsp, middle_left.bsp)),
                2 => assert!(cmp(node.bsp, middle_right.bsp)),
                3 => assert!(cmp(node.bsp, leaf1.bsp)),
                4 => assert!(cmp(node.bsp, leaf2.bsp)),
                5 => assert!(cmp(node.bsp, leaf3.bsp)),
                6 => assert!(cmp(node.bsp, leaf4.bsp)),
                _ => panic!("Wrong number of nodes in the tree"),
            };
            counter += 1;
            true
        });

        counter = 0;
        root.traverse(TraverseOrder::InvertedLevelOrder, |node| {
            match counter {
                0 => assert!(cmp(node.bsp, leaf4.bsp)),
                1 => assert!(cmp(node.bsp, leaf3.bsp)),
                2 => assert!(cmp(node.bsp, leaf2.bsp)),
                3 => assert!(cmp(node.bsp, leaf1.bsp)),
                4 => assert!(cmp(node.bsp, middle_right.bsp)),
                5 => assert!(cmp(node.bsp, middle_left.bsp)),
                6 => assert!(cmp(node.bsp, root.bsp)),
                _ => panic!("Wrong number of nodes in the tree"),
            };
            counter += 1;
            true
        });
    }

    #[test]
    fn break_traverse() {
        let mut bsp = Bsp::new_with_size(0, 0, 100,100);
        let mut counter = 0;

        bsp.split_recursive(None, 2, 5, 5, 1.5, 1.5);
        bsp.traverse(TraverseOrder::PreOrder, |_node| {
            counter += 1;
            false
        });
        assert_eq!(counter, 1);
    }

    #[test]
    fn safe_tree_pointer() {
        let mut bsp1 = Bsp::new_with_size(0, 0, 100,100);
        bsp1.split_recursive(None, 2, 5, 5, 1.5, 1.5);
        let mut bsp2 = Bsp::new_with_size(0, 0, 100,100);
        bsp2.split_recursive(None, 2, 5, 5, 1.5, 1.5);

        unsafe {
            assert!(bsp1.left().unwrap().tree().father != bsp2.left().unwrap().tree().father);
            assert!(bsp1.left().unwrap().tree().father == bsp1.right().unwrap().tree().father);
        }
    }
}