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(&self) -> impl Iterator<Item = &Point> {

        self.islands

            .iter()

            .flat_map(|i| i.iter())

            .chain(self.fill_points.iter())

    }

    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,

        distance_divisor: u32,

        random_numbers: &mut I,

    ) -> Option<Point> {

        #[inline]

        fn intersect(p: &Point, m: &Point, p1: &Point, p2: &Point) -> bool {

            let t1 = (*m - *p1).cross(*p);

            let t2 = (*m - *p2).cross(*p);

            (t1 > 0) != (t2 > 0)

        }

        #[inline]

        fn solve_intersection(p: &Point, m: &Point, s: &Point, e: &Point) -> Option<(i32, u32)> {

            let f = *e - *s;

            let aqpb = p.cross(f) as i64;

            if aqpb != 0 {

                let iy = ((((s.x - m.x) as i64 * p.y as i64 + m.y as i64 * p.x as i64)

                    * f.y as i64

                    - s.y as i64 * f.x as i64 * p.y as i64)

                    / aqpb) as i32;

                let ix = if p.y.abs() > f.y.abs() {

                    (iy - m.y) * p.x / p.y + m.x

                } else {

                    (iy - s.y) * f.x / f.y + s.x

                };

                let intersection_point = Point::new(ix, iy);

                let diff_point = *m - intersection_point;

                let d = diff_point.integral_norm();

                let t = p.dot(diff_point);

                Some((t, d))

            } else {

                None

            }

        }

        let min_distance = 40;

        // new point should fall inside this box

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

        let p = segment.scaled_normal();

        let p_norm = p.integral_norm();

        let mid_point = segment.center();

        if (p_norm < min_distance as u32 * 3) || !map_box.contains_inside(mid_point) {

            return None;

        }

        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 {

            // where the normal line intersects the left map border

            let left_intersection = Point::new(

                map_box.left(),

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

            dist_left = (mid_point - left_intersection).integral_norm();

            // same for the right border

            let right_intersection = Point::new(

                map_box.right(),

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

            dist_right = (mid_point - right_intersection).integral_norm();

            if p.x > 0 {

                std::mem::swap(&mut dist_left, &mut dist_right);

            }

        }

        if p.y != 0 {

            // where the normal line intersects the top map border

            let top_intersection = Point::new(

                (map_box.top() - mid_point.y) * p.x / p.y + mid_point.x,

                map_box.top());

            let dl = (mid_point - top_intersection).integral_norm();

            // same for the bottom border

            let bottom_intersection = Point::new(

                (map_box.bottom() - mid_point.y) * p.x / p.y + mid_point.x,

                map_box.bottom());

            let dr = (mid_point - bottom_intersection).integral_norm();

            if p.y < 0 {

                dist_left = min(dist_left, dl);

                dist_right = min(dist_right, dr);

            } else {

                dist_left = min(dist_left, dr);

                dist_right = min(dist_right, dl);

            }

        }

        // now go through all other segments

        for s in self.segments_iter() {

            if s != segment {

                if intersect(&p, &mid_point, &s.start, &s.end) {

                    if let Some((t, d)) = solve_intersection(&p, &mid_point, &s.start, &s.end) {

                        if t > 0 {

                            dist_right = min(dist_right, d);

                        } else {

                            dist_left = min(dist_left, d);

                        }

                    }

                }

            }

        }

        // go through all points, including fill points

        for pi in self.iter() {

            if *pi != segment.start && *pi != segment.end {

                if intersect(&p, &pi, &segment.start, &segment.end) {

                    // ray from segment.start

                    if let Some((t, d)) = solve_intersection(&p, &mid_point, &segment.start, &pi) {

                        if t > 0 {

                            dist_right = min(dist_right, d);

                        } else {

                            dist_left = min(dist_left, d);

                        }

                    }

                    // ray from segment.end

                    if let Some((t, d)) = solve_intersection(&p, &mid_point, &segment.end, &pi) {

                        if t > 0 {

                            dist_right = min(dist_right, d);

                        } else {

                            dist_left = min(dist_left, d);

                        }

                    }

                }

            }

        }

        let max_dist = p_norm * 100 / distance_divisor;

        dist_left = min(dist_left, max_dist);

        dist_right = min(dist_right, max_dist);

        if dist_right + dist_left < min_distance as u32 * 2 + 10 {

            // limits are too narrow, just divide

            Some(mid_point)

        } else {

            // select distance within [-dist_right; dist_left], keeping min_distance in mind

            let d = -(dist_right as i32)

                + min_distance

                + random_numbers.next().unwrap() as i32

                    % (dist_right as i32 + dist_left as i32 - min_distance * 2);

            Some(Point::new(

                mid_point.x + p.x * d / p_norm as i32,

                mid_point.y + p.y * d / p_norm as i32,

            ))

        }

    }

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

        &mut self,

        distance_divisor: u32,

        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, distance_divisor, random_numbers)

                {

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

                    i += 2;

                } else {

                    i += 1;

                }

            }

        }

    }

    pub fn bezierize(&mut self) {}

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

        &mut self,

        distance_divisor: u32,

        random_numbers: &mut I,

    ) {

        loop {

            let old_len = self.total_len();

            self.divide_edges(distance_divisor, random_numbers);

            if self.total_len() == old_len {

                break;

            }

        }

    }

    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,

        }

    }

    pub fn mirror(&mut self) {

        let r = self.size.width as i32 - 1;

        self.iter_mut().for_each(|p| p.x = r - p.x);

    }

    pub fn flip(&mut self) {

        let t = self.size.height as i32 - 1;

        self.iter_mut().for_each(|p| p.y = t - p.y);

    }

}

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);

}