use itertools::Itertools;

use std::cmp::min;

use integral_geometry::{Line, Point, Rect, Size};

use land2d::Land2D;

use outline_template::OutlineTemplate;

pub struct OutlinePoints {

    pub islands: Vec<Vec<Point>>,

    pub fill_points: Vec<Point>,

    pub size: Size,

    pub play_box: Rect,

}

impl OutlinePoints {

    pub fn from_outline_template<I: Iterator<Item = u32>>(

        outline_template: &OutlineTemplate,

        play_box: Rect,

        size: Size,

        random_numbers: &mut I,

    ) -> Self {

        Self {

            play_box,

            size,

            islands: outline_template

                .islands

                .iter()

                .map(|i| {

                    i.iter()

                        .zip(random_numbers.tuples())

                        .map(|(rect, (rnd_a, rnd_b))| {

                            rect.top_left()

                                + Point::new(

                                    (rnd_a % rect.width) as i32,

                                    (rnd_b % rect.height) as i32,

                                )

                                + play_box.top_left()

                        }).collect()

                }).collect(),

            fill_points: outline_template.fill_points.clone(),

        }

    }

    pub fn total_len(&self) -> usize {

        self.islands.iter().map(|i| i.len()).sum::<usize>() + self.fill_points.len()

    }

    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Point> {

        self.islands

            .iter_mut()

            .flat_map(|i| i.iter_mut())

            .chain(self.fill_points.iter_mut())

    }

    fn divide_edge<I: Iterator<Item = u32>>(

        &self,

        segment: Line,

        random_numbers: &mut I,

    ) -> Option<Point> {

        let min_distance = 40;

        // new point should fall inside this box

        let map_box = self.play_box.with_margin(min_distance);

        let p = Point::new(

            segment.end.y - segment.start.y,

            segment.start.x - segment.start.y,

        );

        let mid_point = segment.center();

        if (p.integral_norm() < min_distance as u32 * 3) || !map_box.contains_inside(p) {

            return None;

        }

        let full_box = Rect::from_size(Point::zero(), self.size).with_margin(min_distance);

        let mut dist_left = (self.size.width + self.size.height) as u32;

        let mut dist_right = dist_left;

        // find distances to map borders

        if p.x != 0 {

            // check against left border

            let iyl = (map_box.left() - mid_point.x) * p.y / p.x + mid_point.y;

            let dl = Point::new(mid_point.x - map_box.left(), mid_point.y - iyl).integral_norm();

            let t = p.x * (mid_point.x - full_box.left()) + p.y * (mid_point.y - iyl);

            if t > 0 {

                dist_left = dl;

            } else {

                dist_right = dl;

            }

            // right border

            let iyr = (map_box.right() - mid_point.x) * p.y / p.x + mid_point.y;

            let dr = Point::new(mid_point.x - full_box.right(), mid_point.y - iyr).integral_norm();

            if t > 0 {

                dist_right = dr;

            } else {

                dist_left = dr;

            }

        }

        if p.y != 0 {

            // top border

            let ixl = (map_box.top() - mid_point.y) * p.x / p.y + mid_point.x;

            let dl = Point::new(mid_point.y - map_box.top(), mid_point.x - ixl).integral_norm();

            let t = p.y * (mid_point.y - full_box.top()) + p.x * (mid_point.x - ixl);

            if t > 0 {

                dist_left = min(dist_left, dl);

            } else {

                dist_right = min(dist_right, dl);

            }

            // bottom border

            let ixr = (map_box.bottom() - mid_point.y) * p.x / p.y + mid_point.x;

            let dr = Point::new(mid_point.y - full_box.bottom(), mid_point.x - ixr).integral_norm();

            if t > 0 {

                dist_right = min(dist_right, dr);

            } else {

                dist_left = min(dist_left, dr);

            }

        }

        // now go through all other segments

        None

    }

    fn divide_edges<I: Iterator<Item = u32>>(&mut self, random_numbers: &mut I) {

        for is in 0..self.islands.len() {

            let mut i = 0;

            let mut segment;

            loop {

                {

                    let island = &self.islands[is];

                    let mut end_point;

                    if i < island.len() {

                        end_point = if i + 1 < island.len() {

                            island[i + 1]

                        } else {

                            island[0]

                        };

                    } else {

                        break;

                    }

                    segment = Line::new(island[i], end_point);

                }

                if let Some(new_point) = self.divide_edge(segment, random_numbers) {

                    self.islands[is].insert(i + 1, new_point);

                    i += 2;

                } else {

                    i += 1;

                }

            }

        }

    }

    pub fn bezierize(&mut self) {

        unimplemented!()

    }

    pub fn distort<I: Iterator<Item = u32>>(&mut self, random_numbers: &mut I) {

        loop {

            let old_len = self.total_len();

            self.divide_edges(random_numbers);

            if self.total_len() != old_len {

                break;

            }

        }

        self.bezierize();

    }

    pub fn draw<T: Copy + PartialEq>(&self, land: &mut Land2D<T>, value: T) {

        for segment in self.segments_iter() {

            land.draw_line(segment, value);

        }

    }

    fn segments_iter(&self) -> OutlineSegmentsIterator {

        OutlineSegmentsIterator {

            outline: self,

            island: 0,

            index: 0,

        }

    }

}

struct OutlineSegmentsIterator<'a> {

    outline: &'a OutlinePoints,

    island: usize,

    index: usize,

}

impl<'a> Iterator for OutlineSegmentsIterator<'a> {

    type Item = Line;

    fn next(&mut self) -> Option<Self::Item> {

        if self.island < self.outline.islands.len() {

            if self.index + 1 < self.outline.islands[self.island].len() {

                let result = Some(Line::new(

                    self.outline.islands[self.island][self.index],

                    self.outline.islands[self.island][self.index + 1],

                ));

                self.index += 1;

                result

            } else if self.index + 1 == self.outline.islands[self.island].len() {

                let result = Some(Line::new(

                    self.outline.islands[self.island][self.index],

                    self.outline.islands[self.island][0],

                ));

                self.island += 1;

                self.index = 0;

                result

            } else {

                self.island += 1;

                self.index = 0;

                self.next()

            }

        } else {

            None

        }

    }

}

#[test()]

fn points_test() {

    let mut points = OutlinePoints {

        islands: vec![

            vec![Point::new(0, 0), Point::new(20, 0), Point::new(30, 30)],

            vec![Point::new(10, 15), Point::new(15, 20), Point::new(20, 15)],

        ],

        fill_points: vec![Point::new(1, 1)],

        play_box: Rect::from_box(0, 100, 0, 100).with_margin(10),

        size: Size::square(100),

    };

    let segments: Vec<Line> = points.segments_iter().collect();

    assert_eq!(

        segments.first(),

        Some(&Line::new(Point::new(0, 0), Point::new(20, 0)))

    );

    assert_eq!(

        segments.last(),

        Some(&Line::new(Point::new(20, 15), Point::new(10, 15)))

    );

    points.iter_mut().for_each(|p| p.x = 2);

    assert_eq!(points.fill_points[0].x, 2);

    assert_eq!(points.islands[0][0].x, 2);

}