// Copyright (c) 2022 Marceline Cramer
// SPDX-License-Identifier: Apache-2.0

use super::*;

use num_traits::FromPrimitive;

pub mod abi;

#[macro_export]
macro_rules! export_abi {
    ($bind_panel: ident) => {
        #[no_mangle]
        pub extern "C" fn bind_panel(panel: u32, protocol: u32, msg: u32) -> u32 {
            ::canary_script::api::abi::bind_panel($bind_panel, panel, protocol, msg)
        }

        #[no_mangle]
        pub extern "C" fn update(panel_data: u32, dt: f32) {
            ::canary_script::api::abi::update(panel_data, dt)
        }

        #[no_mangle]
        pub extern "C" fn draw(panel_data: u32) {
            ::canary_script::api::abi::draw(panel_data)
        }

        #[no_mangle]
        pub extern "C" fn on_resize(panel_data: u32, width: f32, height: f32) {
            ::canary_script::api::abi::on_resize(panel_data, width, height)
        }

        #[no_mangle]
        pub extern "C" fn on_cursor_event(panel_data: u32, kind: u32, x: f32, y: f32) {
            ::canary_script::api::abi::on_cursor_event(panel_data, kind, x, y)
        }

        #[no_mangle]
        pub extern "C" fn on_message(panel_data: u32, msg: u32) {
            ::canary_script::api::abi::on_message(panel_data, msg)
        }
    };
}

pub trait PanelImpl {
    fn update(&mut self, dt: f32);
    fn draw(&mut self);
    fn on_resize(&mut self, new_size: Vec2);
    fn on_cursor_event(&mut self, kind: CursorEventKind, at: Vec2);
    fn on_message(&mut self, msg: Message);
}

#[repr(transparent)]
#[derive(Copy, Clone)]
pub struct Panel(u32);

impl Panel {
    pub unsafe fn bind(id: u32) -> Self {
        Self(id)
    }

    pub fn draw_indexed(&self, vertices: &[MeshVertex], indices: &[MeshIndex]) {
        unsafe {
            draw_indexed(
                vertices.as_ptr() as u32,
                vertices.len() as u32,
                indices.as_ptr() as u32,
                indices.len() as u32,
            )
        }
    }

    pub fn draw_text_layout(&self, layout: &TextLayout, offset: Vec2, scale: f32, color: Color) {
        unsafe { draw_text_layout(layout.0, offset.x, offset.y, scale, color.0) }
    }

    pub fn draw_triangle(&self, v1: Vec2, v2: Vec2, v3: Vec2, color: Color) {
        let vertices = [
            MeshVertex {
                position: v1,
                color,
            },
            MeshVertex {
                position: v2,
                color,
            },
            MeshVertex {
                position: v3,
                color,
            },
        ];

        let indices = [0, 1, 2];

        self.draw_indexed(&vertices, &indices);
    }

    pub fn send_message(&self, message: &[u8]) {
        unsafe { panel_send_message(self.0, message.as_ptr() as u32, message.len() as u32) }
    }
}

#[repr(transparent)]
#[derive(Copy, Clone)]
pub struct Font(u32);

impl Font {
    pub fn new(family: &str) -> Self {
        unsafe { Self(font_load(family.as_ptr() as u32, family.len() as u32)) }
    }
}

#[repr(transparent)]
pub struct TextLayout(u32);

impl TextLayout {
    pub fn new(font: &Font, text: &str) -> Self {
        unsafe {
            Self(text_layout_new(
                font.0,
                text.as_ptr() as u32,
                text.len() as u32,
            ))
        }
    }

    pub fn get_bounds(&self) -> Rect {
        unsafe {
            let mut bounds = Rect::default();
            let bounds_ptr: *mut Rect = &mut bounds;
            text_layout_get_bounds(self.0, bounds_ptr as u32);
            bounds
        }
    }
}

impl Drop for TextLayout {
    fn drop(&mut self) {
        unsafe { text_layout_delete(self.0) }
    }
}

#[repr(transparent)]
pub struct Message(u32);

impl Message {
    pub fn to_vec(self) -> Vec<u8> {
        unsafe {
            let len = message_get_len(self.0) as usize;
            let mut vec = Vec::with_capacity(len);
            vec.set_len(len);
            message_get_data(self.0, vec.as_ptr() as u32);
            vec
        }
    }
}

pub struct DrawContext {
    panel: Panel,
    offset: Option<Vec2>,
    clip_rect: Option<Rect>,
    opacity: Option<u8>,
}

impl DrawContext {
    pub fn new(panel: Panel) -> Self {
        Self {
            panel,
            offset: None,
            clip_rect: None,
            opacity: None,
        }
    }

    pub fn child_at(&self, at: Vec2) -> Self {
        let at = self.offset.map(|old| old + at).unwrap_or(at);
        self.child_at_absolute(at)
    }

    pub fn child_at_absolute(&self, at: Vec2) -> Self {
        Self {
            panel: self.panel,
            offset: Some(at),
            clip_rect: None,
            opacity: None,
        }
    }

    pub fn draw_indexed(&self, vertices: &[MeshVertex], indices: &[MeshIndex]) {
        let mut vertices = vertices.to_vec();

        if let Some(offset) = self.offset {
            for v in vertices.iter_mut() {
                v.position += offset;
            }
        }

        if let Some(opacity) = self.opacity {
            for v in vertices.iter_mut() {
                v.color = v.color.alpha_multiply(opacity);
            }
        }

        self.panel.draw_indexed(&vertices, &indices);
    }

    pub fn draw_triangle(&self, v1: Vec2, v2: Vec2, v3: Vec2, color: Color) {
        if let Some(clip_rect) = self.clip_rect.as_ref() {
            let tri = ColoredTriangle { v1, v2, v3, color };
            let bb = Rect::from_triangle_bounds(&tri);

            if clip_rect.contains_rect(&bb) {
                self.draw_triangle_noclip(tri.v1, tri.v2, tri.v3, tri.color);
            }
        } else {
            self.draw_triangle_noclip(v1, v2, v3, color);
        }
    }

    fn draw_triangle_noclip(&self, mut v1: Vec2, mut v2: Vec2, mut v3: Vec2, mut color: Color) {
        if let Some(offset) = self.offset {
            v1 += offset;
            v2 += offset;
            v3 += offset;
        }

        if let Some(opacity) = self.opacity.as_ref() {
            color = color.alpha_multiply(*opacity);
        }

        self.panel
            .draw_triangle(v1.into(), v2.into(), v3.into(), color);
    }

    pub fn draw_circle(&self, center: Vec2, radius: f32, color: Color) {
        use std::f32::consts::PI;

        let delta = PI / 16.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = Vec2::new(radius + center.x, center.y);
        let mut theta = delta;
        while theta < limit {
            let new_spoke = Vec2::from_angle(theta) * radius + center;
            self.draw_triangle(center, last_spoke, new_spoke, color);
            last_spoke = new_spoke;
            theta += delta;
        }
    }

    pub fn draw_quarter_circle(&self, corner: Corner, center: Vec2, radius: f32, color: Color) {
        use std::f32::consts::{FRAC_PI_2, PI};

        let spoke_num = 16.0;
        let delta = PI / 4.0 / spoke_num;

        let (mut theta, limit) = match corner {
            Corner::TopRight => (FRAC_PI_2 * 3.0, PI * 2.0),
            Corner::BottomRight => (0.0, FRAC_PI_2),
            Corner::BottomLeft => (FRAC_PI_2, PI),
            Corner::TopLeft => (PI, FRAC_PI_2 * 3.0),
        };

        let mut last_spoke = Vec2::from_angle(theta) * radius + center;
        while theta < limit {
            theta += delta;
            let new_spoke = Vec2::from_angle(theta) * radius + center;
            self.draw_triangle(center, last_spoke, new_spoke, color);
            last_spoke = new_spoke;
        }
    }

    pub fn draw_ring(&self, center: Vec2, radius: f32, thickness: f32, color: Color) {
        use std::f32::consts::PI;

        let delta = PI / 64.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = glam::Vec2::new(radius + center.x, center.y);
        let mut last_theta = 0.0;
        let mut theta = delta;
        while theta < limit {
            let angle = Vec2::from_angle(theta);
            let new_spoke = angle * radius + center;
            let new_spoke2 = angle * (radius + thickness) + center;
            let last_spoke2 = Vec2::from_angle(last_theta) * (radius + thickness) + center;

            self.draw_triangle(new_spoke2, last_spoke, new_spoke, color);
            self.draw_triangle(new_spoke2, last_spoke2, last_spoke, color);

            last_spoke = new_spoke;
            last_theta = theta;
            theta += delta;
        }
    }

    pub fn draw_rect(&self, rect: Rect, color: Color) {
        let rect = if let Some(clip_rect) = self.clip_rect.as_ref() {
            if let Some(clipped) = clip_rect.intersection(&rect) {
                clipped
            } else {
                return;
            }
        } else {
            rect
        };

        let v1 = rect.tl;
        let v2 = Vec2::new(rect.tl.x, rect.br.y);
        let v3 = Vec2::new(rect.br.x, rect.tl.y);
        let v4 = rect.br;

        self.draw_triangle_noclip(v1, v2, v3, color);
        self.draw_triangle_noclip(v2, v3, v4, color);
    }

    pub fn draw_rounded_rect(&self, rect: Rect, radius: f32, color: Color) {
        self.draw_partially_rounded_rect(CornerFlags::ALL, rect, radius, color);
    }

    pub fn draw_partially_rounded_rect(
        &self,
        corners: CornerFlags,
        rect: Rect,
        radius: f32,
        color: Color,
    ) {
        if corners.is_empty() {
            self.draw_rect(rect, color);
            return;
        }

        let mut inner_rect = rect;
        let inset = rect.inset(radius);

        if corners.intersects(CornerFlags::TOP) {
            inner_rect.tl.y += radius;

            let mut top_edge = Rect {
                tl: rect.tl,
                br: Vec2::new(rect.br.x, rect.tl.y + radius),
            };

            if corners.contains(CornerFlags::TOP_LEFT) {
                top_edge.tl.x += radius;
                self.draw_quarter_circle(Corner::TopLeft, inset.tl, radius, color);
            }

            if corners.contains(CornerFlags::TOP_RIGHT) {
                top_edge.br.x -= radius;
                self.draw_quarter_circle(Corner::TopRight, inset.tr(), radius, color);
            }

            self.draw_rect(top_edge, color);
        }

        if corners.intersects(CornerFlags::BOTTOM) {
            inner_rect.br.y -= radius;

            let mut bottom_edge = Rect {
                tl: Vec2::new(rect.tl.x, rect.br.y - radius),
                br: rect.br,
            };

            if corners.contains(CornerFlags::BOTTOM_LEFT) {
                bottom_edge.tl.x += radius;
                self.draw_quarter_circle(Corner::BottomLeft, inset.bl(), radius, color);
            }

            if corners.contains(CornerFlags::BOTTOM_RIGHT) {
                bottom_edge.br.x -= radius;
                self.draw_quarter_circle(Corner::BottomRight, inset.br, radius, color);
            }

            self.draw_rect(bottom_edge, color);
        }

        self.draw_rect(inner_rect, color);
    }

    pub fn draw_text_layout(
        &self,
        layout: &TextLayout,
        mut offset: Vec2,
        scale: f32,
        mut color: Color,
    ) {
        if let Some(delta) = self.offset {
            offset += delta;
        }

        if let Some(opacity) = self.opacity {
            color = color.alpha_multiply(opacity);
        }

        self.panel
            .draw_text_layout(layout, offset.into(), scale, color);
    }

    pub fn get_clip_rect(&self) -> &Option<Rect> {
        &self.clip_rect
    }

    pub fn with_offset(&self, offset: Vec2) -> Self {
        Self {
            offset: self.offset.map(|old| old + offset).or(Some(offset)),
            clip_rect: self.clip_rect.map(|r| r.offset(-offset)),
            ..*self
        }
    }

    pub fn with_clip_rect(&self, mut clip_rect: Rect) -> Option<Self> {
        if let Some(old) = self.clip_rect {
            if let Some(clipped) = old.intersection(&clip_rect) {
                clip_rect = clipped;
            } else {
                return None;
            }
        }

        Some(Self {
            clip_rect: Some(clip_rect),
            ..*self
        })
    }

    pub fn with_opacity(&self, mut opacity: u8) -> Self {
        if let Some(old) = self.opacity {
            opacity = (((opacity as u16) * (old as u16)) >> 8) as u8;
        }

        Self {
            opacity: Some(opacity),
            ..*self
        }
    }
}

extern "C" {
    fn draw_indexed(vertices_ptr: u32, vertices_num: u32, indices_ptr: u32, indices_num: u32);
    fn draw_text_layout(id: u32, xoff: f32, yoff: f32, scale: f32, color: u32);
    fn font_load(family_ptr: u32, family_len: u32) -> u32;

    fn text_layout_new(font_id: u32, text_ptr: u32, text_len: u32) -> u32;
    fn text_layout_delete(id: u32);
    fn text_layout_get_bounds(id: u32, rect_ptr: u32);

    fn message_get_len(id: u32) -> u32;
    fn message_get_data(id: u32, ptr: u32);

    fn panel_send_message(id: u32, message_ptr: u32, message_len: u32);
}