use crate::{
    draw_target::DrawTarget,
    geometry::{Dimensions, Point},
    pixelcolor::PixelColor,
    primitives::{
        common::{ClosedThickSegmentIter, PointType, Scanline, StrokeOffset},
        styled::{StyledDimensions, StyledDrawable, StyledPixels},
        triangle::{scanline_iterator::ScanlineIterator, Triangle},
        PrimitiveStyle, Rectangle, StrokeAlignment,
    },
    Pixel,
};

/// Pixel iterator for each pixel in the triangle border
#[derive(Clone, Eq, PartialEq, Hash, Debug)]
pub struct StyledPixelsIterator<C> {
    lines_iter: ScanlineIterator,
    current_line: Scanline,
    current_color: Option<C>,
    fill_color: Option<C>,
    stroke_color: Option<C>,
}

impl<C: PixelColor> StyledPixelsIterator<C> {
    pub(in crate::primitives) fn new(primitive: &Triangle, style: &PrimitiveStyle<C>) -> Self {
        let mut lines_iter = ScanlineIterator::new(
            &primitive,
            style.stroke_width,
            StrokeOffset::from(style.stroke_alignment),
            style.fill_color.is_some(),
            &primitive.styled_bounding_box(style),
        );

        let (current_line, point_type) = lines_iter
            .next()
            .unwrap_or_else(|| (Scanline::new_empty(0), PointType::Stroke));

        let current_color = match point_type {
            PointType::Stroke => style.effective_stroke_color(),
            PointType::Fill => style.fill_color,
        };

        Self {
            lines_iter,
            current_line,
            current_color,
            fill_color: style.fill_color,
            stroke_color: style.effective_stroke_color(),
        }
    }
}

impl<C: PixelColor> Iterator for StyledPixelsIterator<C> {
    type Item = Pixel<C>;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
            if let Some(p) = self.current_line.next() {
                return Some(Pixel(p, self.current_color?));
            } else {
                let (next_line, next_type) = self.lines_iter.next()?;

                self.current_line = next_line;

                self.current_color = match next_type {
                    PointType::Stroke => self.stroke_color,
                    PointType::Fill => self.fill_color,
                };
            }
        }
    }
}

impl<C: PixelColor> StyledPixels<PrimitiveStyle<C>> for Triangle {
    type Iter = StyledPixelsIterator<C>;

    fn pixels(&self, style: &PrimitiveStyle<C>) -> Self::Iter {
        StyledPixelsIterator::new(self, style)
    }
}

impl<C: PixelColor> StyledDrawable<PrimitiveStyle<C>> for Triangle {
    type Color = C;
    type Output = ();

    fn draw_styled<D>(
        &self,
        style: &PrimitiveStyle<C>,
        target: &mut D,
    ) -> Result<Self::Output, D::Error>
    where
        D: DrawTarget<Color = C>,
    {
        if style.is_transparent() {
            return Ok(());
        }

        for (line, kind) in ScanlineIterator::new(
            &self,
            style.stroke_width,
            StrokeOffset::from(style.stroke_alignment),
            style.fill_color.is_some(),
            &self.styled_bounding_box(style),
        ) {
            let color = match kind {
                PointType::Stroke => style.effective_stroke_color(),
                PointType::Fill => style.fill_color,
            };

            if let Some(color) = color {
                let rect = line.to_rectangle();

                if !rect.is_zero_sized() {
                    target.fill_solid(&rect, color)?;
                }
            }
        }

        Ok(())
    }
}

impl<C: PixelColor> StyledDimensions<PrimitiveStyle<C>> for Triangle {
    fn styled_bounding_box(&self, style: &PrimitiveStyle<C>) -> Rectangle {
        // Short circuit special cases
        if style.stroke_width < 2 || style.stroke_alignment == StrokeAlignment::Inside {
            return self.bounding_box();
        }

        let t = self.sorted_clockwise();

        let (min, max) = ClosedThickSegmentIter::new(
            &t.vertices,
            style.stroke_width,
            StrokeOffset::from(style.stroke_alignment),
        )
        .fold(
            (
                Point::new_equal(core::i32::MAX),
                Point::new_equal(core::i32::MIN),
            ),
            |(min, max), segment| {
                let bb = segment.edges_bounding_box();

                (
                    min.component_min(bb.top_left),
                    max.component_max(bb.bottom_right().unwrap_or(bb.top_left)),
                )
            },
        );

        Rectangle::with_corners(min, max)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        geometry::Point,
        mock_display::MockDisplay,
        pixelcolor::{BinaryColor, Rgb565, Rgb888, RgbColor},
        primitives::{Line, Primitive, PrimitiveStyleBuilder, StrokeAlignment},
        transform::Transform,
        Drawable,
    };

    #[test]
    fn unfilled_no_stroke_width_no_triangle() {
        let mut tri = Triangle::new(Point::new(2, 2), Point::new(4, 2), Point::new(2, 4))
            .into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 0))
            .pixels();

        assert_eq!(tri.next(), None);
    }

    #[test]
    fn issue_308_infinite() {
        let mut display: MockDisplay<BinaryColor> = MockDisplay::new();
        display.set_allow_out_of_bounds_drawing(true);

        Triangle::new(Point::new(10, 10), Point::new(20, 30), Point::new(30, -10))
            .into_styled(PrimitiveStyle::with_fill(BinaryColor::On))
            .draw(&mut display)
            .unwrap();
    }

    #[test]
    fn it_draws_filled_strokeless_tri() {
        let mut display: MockDisplay<BinaryColor> = MockDisplay::new();

        Triangle::new(Point::new(2, 2), Point::new(2, 4), Point::new(4, 2))
            .into_styled(PrimitiveStyle::with_fill(BinaryColor::On))
            .draw(&mut display)
            .unwrap();

        display.assert_pattern(&[
            "     ", //
            "     ", //
            "  ###", //
            "  ## ", //
            "  #  ", //
        ]);
    }

    #[test]
    fn stroke_fill_colors() {
        let mut display: MockDisplay<Rgb888> = MockDisplay::new();

        Triangle::new(Point::new(2, 2), Point::new(8, 2), Point::new(2, 8))
            .into_styled(
                PrimitiveStyleBuilder::new()
                    .stroke_width(1)
                    .stroke_color(Rgb888::RED)
                    .fill_color(Rgb888::GREEN)
                    .build(),
            )
            .draw(&mut display)
            .unwrap();

        display.assert_pattern(&[
            "          ",
            "          ",
            "  RRRRRRR ",
            "  RGGGGR  ",
            "  RGGGR   ",
            "  RGGR    ",
            "  RGR     ",
            "  RR      ",
            "  R       ",
        ]);
    }

    #[test]
    fn off_screen() {
        let mut display: MockDisplay<BinaryColor> = MockDisplay::new();
        display.set_allow_out_of_bounds_drawing(true);

        Triangle::new(Point::new(5, 5), Point::new(10, 15), Point::new(15, -5))
            .into_styled(PrimitiveStyle::with_fill(BinaryColor::On))
            .draw(&mut display)
            .unwrap();

        display.assert_pattern(&[
            "          #####",
            "         ######",
            "        ###### ",
            "       ####### ",
            "      ######## ",
            "     ######### ",
            "     ########  ",
            "      #######  ",
            "      #######  ",
            "       ######  ",
            "       #####   ",
            "        ####   ",
            "        ####   ",
            "         ###   ",
            "         ##    ",
            "          #    ",
        ]);
    }

    #[test]
    fn styled_off_screen_still_draws_points() {
        let off_screen = Triangle::new(Point::new(10, 10), Point::new(20, 20), Point::new(30, -30))
            .into_styled(PrimitiveStyle::with_fill(BinaryColor::On));
        let on_screen = off_screen.translate(Point::new(0, 35));

        assert!(off_screen.pixels().eq(on_screen
            .pixels()
            .map(|Pixel(p, col)| Pixel(p - Point::new(0, 35), col))));
    }

    #[test]
    fn styled_stroke_equals_lines() {
        let triangle = Triangle::new(Point::new(10, 10), Point::new(30, 20), Point::new(20, 25));

        let styled = triangle.into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 1));

        let mut tri_display: MockDisplay<BinaryColor> = MockDisplay::new();
        styled.draw(&mut tri_display).unwrap();

        let mut lines_display: MockDisplay<BinaryColor> = MockDisplay::new();
        lines_display.set_allow_overdraw(true);

        let [p1, p2, p3] = triangle.vertices;

        Line::new(p1, p2)
            .into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 1))
            .draw(&mut lines_display)
            .unwrap();
        Line::new(p2, p3)
            .into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 1))
            .draw(&mut lines_display)
            .unwrap();
        Line::new(p3, p1)
            .into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 1))
            .draw(&mut lines_display)
            .unwrap();

        tri_display.assert_eq(&lines_display);
    }

    #[test]
    fn no_stroke_overdraw() {
        let triangle = Triangle::new(Point::new(10, 10), Point::new(30, 20), Point::new(20, 25));

        let styled = triangle.into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 1));

        let mut display: MockDisplay<BinaryColor> = MockDisplay::new();

        styled.draw(&mut display).unwrap();
    }

    #[test]
    fn bounding_box() {
        let triangle = Triangle::new(Point::new(10, 10), Point::new(30, 20), Point::new(20, 25));

        let styled = triangle.into_styled(PrimitiveStyle::with_stroke(BinaryColor::On, 20));

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();
        assert_eq!(display.affected_area(), styled.bounding_box());
    }

    #[test]
    fn bounding_box_is_independent_of_colors() {
        let triangle = Triangle::new(Point::new(10, 10), Point::new(30, 20), Point::new(20, 25));

        let transparent = triangle.into_styled(PrimitiveStyle::<BinaryColor>::new());
        let filled = triangle.into_styled(PrimitiveStyle::with_fill(BinaryColor::On));

        assert_eq!(transparent.bounding_box(), filled.bounding_box(),);
    }

    #[test]
    fn outside_rendering_missing_lines() {
        let p1 = Point::new(10, 11);
        let p2 = Point::new(20, 11);
        let p3 = Point::new(8, 4);

        let styled = Triangle::new(p1, p2, p3).into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Outside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .fill_color(Rgb565::GREEN)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();

        // Believe it or not, this is actually a triangle.
        display.assert_pattern(&[
            "          R            ",
            "         RRRR          ",
            "        RRRRRRR        ",
            "       RRRRRRRRR       ",
            "     RRRRRRRRRRRRR     ",
            "    RRRRRRRRRRRRRRRR   ",
            "    RRRRRRGRRRRRRRRRRR ",
            "     RRRRRGGGRRRRRRRRRR",
            "     RRRRRGGGGGRRRRRRRR",
            "     RRRRRGGGGGGRRRRRRR",
            "     RRRRRRGGGGGGGRRRR ",
            "      RRRRRRRRRRRRRRRR ",
            "      RRRRRRRRRRRRRRRR ",
            "      RRRRRRRRRRRRRRR  ",
            "       RRRRRRRRRRRRRR  ",
            "       RRRRRRRRRRRRRR  ",
        ]);
    }

    #[test]
    fn thick_stroke_only_no_overdraw() {
        let p1 = Point::new(10, 11);
        let p2 = Point::new(20, 11);
        let p3 = Point::new(8, 4);

        let styled = Triangle::new(p1, p2, p3).into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Outside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();
    }

    #[test]
    fn inner_fill_leak() {
        let p1 = Point::new(0, 20);
        let p2 = Point::new(20, 0);
        let p3 = Point::new(14, 24);

        let styled = Triangle::new(p1, p2, p3).into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Inside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .fill_color(Rgb565::GREEN)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();

        // In the failing case, there are some `G`s sitting on the end of each line that
        // shouldn't be there.
        display.assert_pattern(&[
            "                    R",
            "                   RR",
            "                  RR ",
            "                 RRR ",
            "                RRRR ",
            "               RRRRR ",
            "              RRRRR  ",
            "             RRRRRR  ",
            "            RRRRRRR  ",
            "           RRRRRRRR  ",
            "          RRRRRRRR   ",
            "         RRRRRRRRR   ",
            "        RRRRRRRRRR   ",
            "       RRRRRRRRRRR   ",
            "      RRRRRRRRRRR    ",
            "     RRRRRRRRRRRR    ",
            "    RRRRRRRGRRRRR    ",
            "   RRRRRRRGRRRRRR    ",
            "  RRRRRRRRGRRRRR     ",
            " RRRRRRRRRRRRRRR     ",
            "RRRRRRRRRRRRRRRR     ",
            "  RRRRRRRRRRRRRR     ",
            "      RRRRRRRRR      ",
            "         RRRRRR      ",
            "             RR      ",
        ]);
    }

    #[test]
    fn colinear() {
        let p1 = Point::new(90, 80);
        let p2 = Point::new(100, 70);
        let p3 = Point::new(95, 75);

        let t = Triangle::new(p1, p2, p3).translate(Point::new(-85, -70));

        let styled = t.into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Inside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .fill_color(Rgb565::GREEN)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();

        display.assert_pattern(&[
            "               R",
            "              R ",
            "             R  ",
            "            R   ",
            "           R    ",
            "          R     ",
            "         R      ",
            "        R       ",
            "       R        ",
            "      R         ",
            "     R          ",
        ]);
    }

    // Original bug has a weird "lump" drawn at one end of a colinear triangle.
    #[test]
    fn colinear_lump() {
        let p1 = Point::new(90, 80);
        let p2 = Point::new(100, 70);
        let p3 = Point::new(102, 73);

        let t = Triangle::new(p1, p2, p3).translate(Point::new(-90, -70));

        let styled = t.into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Inside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .fill_color(Rgb565::GREEN)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();

        display.assert_pattern(&[
            "          R  ",
            "         RRR ",
            "        RRRR ",
            "       RRRRRR",
            "      RRRRRR ",
            "     RRRRR   ",
            "    RRRR     ",
            "   RRR       ",
            "  RRR        ",
            " RR          ",
            "R            ",
        ]);
    }

    #[test]
    fn colinear_lump_2() {
        let p1 = Point::new(90, 80);
        let p2 = Point::new(100, 70);
        let p3 = Point::new(102, 73);

        let t = Triangle::new(p1, p2, p3).translate(Point::new(-90, -70));

        let styled = t.into_styled(
            PrimitiveStyleBuilder::new()
                .stroke_alignment(StrokeAlignment::Inside)
                .stroke_width(5)
                .stroke_color(Rgb565::RED)
                .fill_color(Rgb565::GREEN)
                .build(),
        );

        let mut display = MockDisplay::new();

        styled.draw(&mut display).unwrap();

        display.assert_pattern(&[
            "          R  ",
            "         RRR ",
            "        RRRR ",
            "       RRRRRR",
            "      RRRRRR ",
            "     RRRRR   ",
            "    RRRR     ",
            "   RRR       ",
            "  RRR        ",
            " RR          ",
            "R            ",
        ]);
    }
}