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

use bitflags::bitflags;
use bytemuck::{Pod, Zeroable};
pub use glam::Vec2;
use num_derive::{FromPrimitive, ToPrimitive};

pub mod api;

#[repr(C)]
#[derive(Copy, Clone, Debug, Default, Pod, Zeroable)]
pub struct Rect {
    pub tl: Vec2,
    pub br: Vec2,
}

impl Rect {
    pub const NEG_INFINITY: Self = Self {
        tl: Vec2::splat(f32::INFINITY),
        br: Vec2::splat(f32::NEG_INFINITY),
    };

    pub fn from_xy_size(xy: Vec2, size: Vec2) -> Self {
        Self {
            tl: xy,
            br: xy + size,
        }
    }

    pub fn from_circle_bounds(center: Vec2, radius: f32) -> Self {
        Self {
            tl: center - radius,
            br: center + radius,
        }
    }

    pub fn from_triangle_bounds(tri: &ColoredTriangle) -> Self {
        Self {
            tl: tri.v1.min(tri.v2).min(tri.v3),
            br: tri.v1.max(tri.v2).max(tri.v3),
        }
    }

    pub fn inset(&self, d: f32) -> Self {
        Self {
            tl: self.tl + d,
            br: self.br - d,
        }
    }
    
    pub fn bl(&self) -> Vec2 {
        Vec2::new(self.tl.x, self.br.y)
    }

    pub fn tr(&self) -> Vec2 {
        Vec2::new(self.br.x, self.tl.y)
    }

    pub fn offset(&self, offset: Vec2) -> Self {
        Self {
            tl: self.tl + offset,
            br: self.br + offset,
        }
    }

    pub fn scale(&self, scale: f32) -> Self {
        Self {
            tl: self.tl * scale,
            br: self.br * scale,
        }
    }

    pub fn is_valid(&self) -> bool {
        self.tl.cmplt(self.br).all()
    }

    pub fn intersects_rect(&self, other: &Self) -> bool {
        self.tl.cmple(other.br).all() && self.br.cmpge(other.tl).all()
    }

    pub fn intersection(&self, other: &Self) -> Option<Self> {
        let clipped = Self {
            tl: self.tl.max(other.tl),
            br: self.br.min(other.br),
        };

        if clipped.is_valid() {
            Some(clipped)
        } else {
            None
        }
    }

    pub fn union(&self, other: &Self) -> Self {
        Self {
            tl: self.tl.min(other.tl),
            br: self.br.max(other.br),
        }
    }

    pub fn union_point(&self, point: Vec2) -> Self {
        Self {
            tl: self.tl.min(point),
            br: self.br.max(point),
        }
    }

    pub fn contains_rect(&self, other: &Self) -> bool {
        self.tl.x < other.tl.x
            && self.tl.y < other.tl.y
            && self.br.x > other.br.x
            && self.br.y > other.br.y
    }

    pub fn contains_point(&self, xy: Vec2) -> bool {
        self.tl.x < xy.x && self.tl.y < xy.y && self.br.x > xy.x && self.br.y > xy.y
    }

    pub fn size(&self) -> Vec2 {
        self.br - self.tl
    }

    pub fn width(&self) -> f32 {
        self.br.x - self.tl.x
    }

    pub fn height(&self) -> f32 {
        self.br.y - self.tl.y
    }
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Pod, Zeroable)]
pub struct Color(pub u32);

impl From<glam::Vec4> for Color {
    fn from(other: glam::Vec4) -> Self {
        let map = |v: f32| (v * 255.0).floor() as u8;
        Self::new(map(other.x), map(other.y), map(other.z), map(other.w))
    }
}

impl From<Color> for glam::Vec4 {
    fn from(other: Color) -> Self {
        let (r, g, b, a) = other.to_rgba_unmultiplied();
        let map = |v: u8| (v as f32) / 255.0;
        Self::new(map(r), map(g), map(b), map(a))
    }
}

impl Color {
    pub const WHITE: Self = Self(0xffffffff);
    pub const BLACK: Self = Self(0x000000ff);
    pub const TRANSPARENT: Self = Self(0);
    pub const RED: Self = Self(0xff0000ff);
    pub const GREEN: Self = Self(0x00ff00ff);
    pub const BLUE: Self = Self(0x0000ffff);
    pub const YELLOW: Self = Self(0xffff00ff);
    pub const MAGENTA: Self = Self(0xff00ffff);
    pub const CYAN: Self = Self(0x00ffffff);

    pub const fn new(r: u8, g: u8, b: u8, a: u8) -> Self {
        Color(((r as u32) << 24) | ((g as u32) << 16) | ((b as u32) << 8) | (a as u32))
    }

    pub fn to_rgba_unmultiplied(&self) -> (u8, u8, u8, u8) {
        (
            (self.0 >> 24) as u8,
            (self.0 >> 16) as u8,
            (self.0 >> 8) as u8,
            self.0 as u8,
        )
    }

    pub const fn alpha_multiply(&self, mul: u8) -> Self {
        let a = self.0 as u8 as u16;
        let multiplied = ((a * (mul as u16)) >> 8) as u8;
        self.with_alpha(multiplied)
    }

    pub const fn with_alpha(&self, alpha: u8) -> Self {
        Self(self.0 & 0xffffff00 | alpha as u32)
    }

    pub fn lerp(self, target: Self, blend: f32) -> Self {
        let s: glam::Vec4 = self.into();
        let o: glam::Vec4 = target.into();
        (o * blend + s * (1.0 - blend)).into()
    }
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Pod, Zeroable)]
pub struct MeshVertex {
    pub position: Vec2,
    pub color: Color,
}

pub type MeshIndex = u32;

#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum CursorEventKind {
    Hover = 0,
    Select = 1,
    Drag = 2,
    Deselect = 3,
}

#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum Corner {
    TopRight = 0,
    BottomRight = 1,
    BottomLeft = 2,
    TopLeft = 3,
}

bitflags! {
    pub struct CornerFlags: u8 {
        const TOP_RIGHT = 0x01;
        const BOTTOM_RIGHT = 0x02;
        const BOTTOM_LEFT = 0x04;
        const TOP_LEFT = 0x08;
        const TOP = 0x09;
        const RIGHT = 0x03;
        const BOTTOM = 0x06;
        const LEFT = 0x0C;
        const ALL = 0x0F;
    }
}

#[derive(Copy, Clone, Debug)]
pub enum Side {
    Top,
    Right,
    Bottom,
    Left,
}

#[derive(Copy, Clone)]
pub struct ColoredTriangle {
    pub v1: Vec2,
    pub v2: Vec2,
    pub v3: Vec2,
    pub color: Color,
}